Down-integrate from internal branch

244 files changed, 24555 insertions, 3902 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 737f8659..a21e956c 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,3 +1,61 @@
+2012-09-19 version 2.5.0:
+
+  General
+  * New notion "import public" that allows a proto file to forward the content
+    it imports to its importers. For example,
+      // foo.proto
+      import public "bar.proto";
+      import "baz.proto";
+
+      // qux.proto
+      import "foo.proto";
+      // Stuff defined in bar.proto may be used in this file, but stuff from
+      // baz.proto may NOT be used without importing it explicitly.
+    This is useful for moving proto files. To move a proto file, just leave
+    a single "import public" in the old proto file.
+  * New enum option "allow_alias" that specifies whether different symbols can
+    be assigned the same numeric value. Default value is "true". Setting it to
+    false causes the compiler to reject enum definitions where multiple symbols
+    have the same numeric value.
+
+  C++
+  * New generated method set_allocated_foo(Type* foo) for message and string
+    fields. This method allows you to set the field to a pre-allocated object
+    and the containing message takes the ownership of that object.
+  * Added SetAllocatedExtension() and ReleaseExtension() to extensions API.
+  * Custom options are now formatted correctly when descriptors are printed in
+    text format.
+  * Various speed optimizations.
+
+  Java
+  * Comments in proto files are now collected and put into generated code as
+    comments for corresponding classes and data members.
+  * Added Parser to parse directly into messages without a Builder. For
+    example,
+      Foo foo = Foo.getParser().ParseFrom(input);
+    Using Parser is ~25% faster than using Builder to parse messages.
+  * Added getters/setters to access the underlying ByteString of a string field
+    directly.
+  * ByteString now supports more operations: substring(), prepend(), and
+    append(). The implementation of ByteString uses a binary tree structure
+    to support these operations efficiently.
+  * New method findInitializationErrors() that lists all missing required
+    fields.
+  * Various code size and speed optimizations.
+
+  Python
+  * Added support for dynamic message creation. DescriptorDatabase,
+    DescriptorPool, and MessageFactory work like their C++ couterparts to
+    simplify Descriptor construction from *DescriptorProtos, and MessageFactory
+    provides a message instance from a Descriptor.
+  * Added pickle support for protobuf messages.
+  * Unknown fields are now preserved after parsing.
+  * Fixed bug where custom options were not correctly populated. Custom
+    options can be accessed now.
+  * Added EnumTypeWrapper that provides better accessibility to enum types.
+  * Added ParseMessage(descriptor, bytes) to generate a new Message instance
+    from a descriptor and a byte string.
+
 2011-05-01 version 2.4.1:
 
   C++
diff --git a/java/pom.xml b/java/pom.xml
index e28d6db5..7ec6d918 100644
--- a/java/pom.xml
+++ b/java/pom.xml
@@ -102,6 +102,7 @@
                   <arg value="--proto_path=src/test/java" />
                   <arg value="../src/google/protobuf/unittest.proto" />
                   <arg value="../src/google/protobuf/unittest_import.proto" />
+                  <arg value="../src/google/protobuf/unittest_import_public.proto" />
                   <arg value="../src/google/protobuf/unittest_mset.proto" />
                   <arg
                     value="src/test/java/com/google/protobuf/multiple_files_test.proto" />
@@ -117,6 +118,7 @@
                     value="../src/google/protobuf/unittest_custom_options.proto" />
                   <arg value="../src/google/protobuf/unittest_lite.proto" />
                   <arg value="../src/google/protobuf/unittest_import_lite.proto" />
+                  <arg value="../src/google/protobuf/unittest_import_public_lite.proto" />
                   <arg value="../src/google/protobuf/unittest_lite_imports_nonlite.proto" />
                   <arg value="../src/google/protobuf/unittest_enormous_descriptor.proto" />
                   <arg value="../src/google/protobuf/unittest_no_generic_services.proto" />
@@ -158,6 +160,13 @@
                 <include>**/UninitializedMessageException.java</include>
                 <include>**/UnmodifiableLazyStringList.java</include>
                 <include>**/WireFormat.java</include>
+                <include>**/Parser.java</include>
+                <include>**/AbstractParser.java</include>
+                <include>**/BoundedByteString.java</include>
+                <include>**/LiteralByteString.java</include>
+                <include>**/RopeByteString.java</include>
+                <include>**/Utf8.java</include>
+                <include>**/LazyField.java</include>
               </includes>
               <testIncludes>
                 <testInclude>**/LiteTest.java</testInclude>
diff --git a/java/src/main/java/com/google/protobuf/AbstractMessage.java b/java/src/main/java/com/google/protobuf/AbstractMessage.java
index b9d83016..f4d115de 100644
--- a/java/src/main/java/com/google/protobuf/AbstractMessage.java
+++ b/java/src/main/java/com/google/protobuf/AbstractMessage.java
@@ -32,6 +32,7 @@ package com.google.protobuf;
 
 import com.google.protobuf.Descriptors.Descriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
+import com.google.protobuf.GeneratedMessage.ExtendableBuilder;
 import com.google.protobuf.Internal.EnumLite;
 
 import java.io.IOException;
@@ -81,6 +82,25 @@ public abstract class AbstractMessage extends AbstractMessageLite
     return true;
   }
 
+  public List<String> findInitializationErrors() {
+    return Builder.findMissingFields(this);
+  }
+
+  public String getInitializationErrorString() {
+    return delimitWithCommas(findInitializationErrors());
+  }
+
+  private static String delimitWithCommas(List<String> parts) {
+    StringBuilder result = new StringBuilder();
+    for (String part : parts) {
+      if (result.length() > 0) {
+        result.append(", ");
+      }
+      result.append(part);
+    }
+    return result.toString();
+  }
+
   @Override
   public final String toString() {
     return TextFormat.printToString(this);
@@ -209,6 +229,15 @@ public abstract class AbstractMessage extends AbstractMessageLite
   }
 
   /**
+   * Package private helper method for AbstractParser to create
+   * UninitializedMessageException with missing field information.
+   */
+  @Override
+  UninitializedMessageException newUninitializedMessageException() {
+    return Builder.newUninitializedMessageException(this);
+  }
+
+  /**
    * Helper method for implementing {@link Message#hashCode()}.
    * <p>
    * This is needed because {@link java.lang.Enum#hashCode()} is final, but we
@@ -251,6 +280,14 @@ public abstract class AbstractMessage extends AbstractMessageLite
       return (BuilderType) this;
     }
 
+    public List<String> findInitializationErrors() {
+      return findMissingFields(this);
+    }
+
+    public String getInitializationErrorString() {
+      return delimitWithCommas(findInitializationErrors());
+    }
+
     public BuilderType mergeFrom(final Message other) {
       if (other.getDescriptorForType() != getDescriptorForType()) {
         throw new IllegalArgumentException(
@@ -314,7 +351,7 @@ public abstract class AbstractMessage extends AbstractMessageLite
         }
 
         if (!mergeFieldFrom(input, unknownFields, extensionRegistry,
-                            this, tag)) {
+                            getDescriptorForType(), this, null, tag)) {
           // end group tag
           break;
         }
@@ -323,25 +360,93 @@ public abstract class AbstractMessage extends AbstractMessageLite
       return (BuilderType) this;
     }
 
+    /** helper method to handle {@code builder} and {@code extensions}. */
+    private static void addRepeatedField(
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        FieldDescriptor field,
+        Object value) {
+      if (builder != null) {
+        builder.addRepeatedField(field, value);
+      } else {
+        extensions.addRepeatedField(field, value);
+      }
+    }
+
+    /** helper method to handle {@code builder} and {@code extensions}. */
+    private static void setField(
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        FieldDescriptor field,
+        Object value) {
+      if (builder != null) {
+        builder.setField(field, value);
+      } else {
+        extensions.setField(field, value);
+      }
+    }
+
+    /** helper method to handle {@code builder} and {@code extensions}. */
+    private static boolean hasOriginalMessage(
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        FieldDescriptor field) {
+      if (builder != null) {
+        return builder.hasField(field);
+      } else {
+        return extensions.hasField(field);
+      }
+    }
+
+    /** helper method to handle {@code builder} and {@code extensions}. */
+    private static Message getOriginalMessage(
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        FieldDescriptor field) {
+      if (builder != null) {
+        return (Message) builder.getField(field);
+      } else {
+        return (Message) extensions.getField(field);
+      }
+    }
+
+    /** helper method to handle {@code builder} and {@code extensions}. */
+    private static void mergeOriginalMessage(
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        FieldDescriptor field,
+        Message.Builder subBuilder) {
+      Message originalMessage = getOriginalMessage(builder, extensions, field);
+      if (originalMessage != null) {
+        subBuilder.mergeFrom(originalMessage);
+      }
+    }
+
     /**
-     * Like {@link #mergeFrom(CodedInputStream, UnknownFieldSet.Builder,
-     * ExtensionRegistryLite, Message.Builder)}, but parses a single field.
+     * Like {@link #mergeFrom(CodedInputStream, ExtensionRegistryLite)}, but
+     * parses a single field.
+     *
+     * When {@code builder} is not null, the method will parse and merge the
+     * field into {@code builder}. Otherwise, it will try to parse the field
+     * into {@code extensions}, when it's called by the parsing constructor in
+     * generated classes.
+     *
      * Package-private because it is used by GeneratedMessage.ExtendableMessage.
      * @param tag The tag, which should have already been read.
      * @return {@code true} unless the tag is an end-group tag.
      */
     static boolean mergeFieldFrom(
-        final CodedInputStream input,
-        final UnknownFieldSet.Builder unknownFields,
-        final ExtensionRegistryLite extensionRegistry,
-        final Message.Builder builder,
-        final int tag) throws IOException {
-      final Descriptor type = builder.getDescriptorForType();
-
+        CodedInputStream input,
+        UnknownFieldSet.Builder unknownFields,
+        ExtensionRegistryLite extensionRegistry,
+        Descriptor type,
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions,
+        int tag) throws IOException {
       if (type.getOptions().getMessageSetWireFormat() &&
           tag == WireFormat.MESSAGE_SET_ITEM_TAG) {
         mergeMessageSetExtensionFromCodedStream(
-          input, unknownFields, extensionRegistry, builder);
+            input, unknownFields, extensionRegistry, type, builder, extensions);
         return true;
       }
 
@@ -376,8 +481,10 @@ public abstract class AbstractMessage extends AbstractMessageLite
         } else {
           field = null;
         }
-      } else {
+      } else if (builder != null) {
         field = type.findFieldByNumber(fieldNumber);
+      } else {
+        field = null;
       }
 
       boolean unknown = false;
@@ -413,13 +520,13 @@ public abstract class AbstractMessage extends AbstractMessageLite
               // enum, drop it (don't even add it to unknownFields).
               return true;
             }
-            builder.addRepeatedField(field, value);
+            addRepeatedField(builder, extensions, field, value);
           }
         } else {
           while (input.getBytesUntilLimit() > 0) {
             final Object value =
               FieldSet.readPrimitiveField(input, field.getLiteType());
-            builder.addRepeatedField(field, value);
+            addRepeatedField(builder, extensions, field, value);
           }
         }
         input.popLimit(limit);
@@ -434,10 +541,10 @@ public abstract class AbstractMessage extends AbstractMessageLite
               subBuilder = builder.newBuilderForField(field);
             }
             if (!field.isRepeated()) {
-              subBuilder.mergeFrom((Message) builder.getField(field));
+              mergeOriginalMessage(builder, extensions, field, subBuilder);
             }
             input.readGroup(field.getNumber(), subBuilder, extensionRegistry);
-            value = subBuilder.build();
+            value = subBuilder.buildPartial();
             break;
           }
           case MESSAGE: {
@@ -448,10 +555,10 @@ public abstract class AbstractMessage extends AbstractMessageLite
               subBuilder = builder.newBuilderForField(field);
             }
             if (!field.isRepeated()) {
-              subBuilder.mergeFrom((Message) builder.getField(field));
+              mergeOriginalMessage(builder, extensions, field, subBuilder);
             }
             input.readMessage(subBuilder, extensionRegistry);
-            value = subBuilder.build();
+            value = subBuilder.buildPartial();
             break;
           }
           case ENUM:
@@ -470,22 +577,28 @@ public abstract class AbstractMessage extends AbstractMessageLite
         }
 
         if (field.isRepeated()) {
-          builder.addRepeatedField(field, value);
+          addRepeatedField(builder, extensions, field, value);
         } else {
-          builder.setField(field, value);
+          setField(builder, extensions, field, value);
         }
       }
 
       return true;
     }
 
-    /** Called by {@code #mergeFieldFrom()} to parse a MessageSet extension. */
+    /**
+     * Called by {@code #mergeFieldFrom()} to parse a MessageSet extension.
+     * If {@code builder} is not null, this method will merge MessageSet into
+     * the builder.  Otherwise, it will merge the MessageSet into {@code
+     * extensions}.
+     */
     private static void mergeMessageSetExtensionFromCodedStream(
-        final CodedInputStream input,
-        final UnknownFieldSet.Builder unknownFields,
-        final ExtensionRegistryLite extensionRegistry,
-        final Message.Builder builder) throws IOException {
-      final Descriptor type = builder.getDescriptorForType();
+        CodedInputStream input,
+        UnknownFieldSet.Builder unknownFields,
+        ExtensionRegistryLite extensionRegistry,
+        Descriptor type,
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions) throws IOException {
 
       // The wire format for MessageSet is:
       //   message MessageSet {
@@ -504,10 +617,11 @@ public abstract class AbstractMessage extends AbstractMessageLite
       // should be prepared to accept them.
 
       int typeId = 0;
-      ByteString rawBytes = null;  // If we encounter "message" before "typeId"
-      Message.Builder subBuilder = null;
-      FieldDescriptor field = null;
+      ByteString rawBytes = null; // If we encounter "message" before "typeId"
+      ExtensionRegistry.ExtensionInfo extension = null;
 
+      // Read bytes from input, if we get it's type first then parse it eagerly,
+      // otherwise we store the raw bytes in a local variable.
       while (true) {
         final int tag = input.readTag();
         if (tag == 0) {
@@ -516,75 +630,121 @@ public abstract class AbstractMessage extends AbstractMessageLite
 
         if (tag == WireFormat.MESSAGE_SET_TYPE_ID_TAG) {
           typeId = input.readUInt32();
-          // Zero is not a valid type ID.
           if (typeId != 0) {
-            final ExtensionRegistry.ExtensionInfo extension;
-
             // extensionRegistry may be either ExtensionRegistry or
-            // ExtensionRegistryLite.  Since the type we are parsing is a full
+            // ExtensionRegistryLite. Since the type we are parsing is a full
             // message, only a full ExtensionRegistry could possibly contain
-            // extensions of it.  Otherwise we will treat the registry as if it
+            // extensions of it. Otherwise we will treat the registry as if it
             // were empty.
             if (extensionRegistry instanceof ExtensionRegistry) {
               extension = ((ExtensionRegistry) extensionRegistry)
                   .findExtensionByNumber(type, typeId);
-            } else {
-              extension = null;
-            }
-
-            if (extension != null) {
-              field = extension.descriptor;
-              subBuilder = extension.defaultInstance.newBuilderForType();
-              final Message originalMessage = (Message)builder.getField(field);
-              if (originalMessage != null) {
-                subBuilder.mergeFrom(originalMessage);
-              }
-              if (rawBytes != null) {
-                // We already encountered the message.  Parse it now.
-                subBuilder.mergeFrom(
-                  CodedInputStream.newInstance(rawBytes.newInput()));
-                rawBytes = null;
-              }
-            } else {
-              // Unknown extension number.  If we already saw data, put it
-              // in rawBytes.
-              if (rawBytes != null) {
-                unknownFields.mergeField(typeId,
-                  UnknownFieldSet.Field.newBuilder()
-                    .addLengthDelimited(rawBytes)
-                    .build());
-                rawBytes = null;
-              }
             }
           }
+
         } else if (tag == WireFormat.MESSAGE_SET_MESSAGE_TAG) {
-          if (typeId == 0) {
-            // We haven't seen a type ID yet, so we have to store the raw bytes
-            // for now.
-            rawBytes = input.readBytes();
-          } else if (subBuilder == null) {
-            // We don't know how to parse this.  Ignore it.
-            unknownFields.mergeField(typeId,
-              UnknownFieldSet.Field.newBuilder()
-                .addLengthDelimited(input.readBytes())
-                .build());
-          } else {
-            // We already know the type, so we can parse directly from the input
-            // with no copying.  Hooray!
-            input.readMessage(subBuilder, extensionRegistry);
+          if (typeId != 0) {
+            if (extension != null && ExtensionRegistryLite.isEagerlyParseMessageSets()) {
+              // We already know the type, so we can parse directly from the
+              // input with no copying.  Hooray!
+              eagerlyMergeMessageSetExtension(
+                  input, extension, extensionRegistry, builder, extensions);
+              rawBytes = null;
+              continue;
+            }
           }
-        } else {
-          // Unknown tag.  Skip it.
+          // We haven't seen a type ID yet or we want parse message lazily.
+          rawBytes = input.readBytes();
+
+        } else { // Unknown tag. Skip it.
           if (!input.skipField(tag)) {
-            break;  // end of group
+            break; // End of group
           }
         }
       }
-
       input.checkLastTagWas(WireFormat.MESSAGE_SET_ITEM_END_TAG);
 
-      if (subBuilder != null) {
-        builder.setField(field, subBuilder.build());
+      // Process the raw bytes.
+      if (rawBytes != null && typeId != 0) { // Zero is not a valid type ID.
+        if (extension != null) { // We known the type
+          mergeMessageSetExtensionFromBytes(
+              rawBytes, extension, extensionRegistry, builder, extensions);
+        } else { // We don't know how to parse this. Ignore it.
+          if (rawBytes != null) {
+            unknownFields.mergeField(typeId, UnknownFieldSet.Field.newBuilder()
+                .addLengthDelimited(rawBytes).build());
+          }
+        }
+      }
+    }
+
+    private static void eagerlyMergeMessageSetExtension(
+        CodedInputStream input,
+        ExtensionRegistry.ExtensionInfo extension,
+        ExtensionRegistryLite extensionRegistry,
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions) throws IOException {
+
+      FieldDescriptor field = extension.descriptor;
+      Message value = null;
+      if (hasOriginalMessage(builder, extensions, field)) {
+        Message originalMessage =
+            getOriginalMessage(builder, extensions, field);
+        Message.Builder subBuilder = originalMessage.toBuilder();
+        input.readMessage(subBuilder, extensionRegistry);
+        value = subBuilder.buildPartial();
+      } else {
+        value = input.readMessage(extension.defaultInstance.getParserForType(),
+          extensionRegistry);
+      }
+
+      if (builder != null) {
+        builder.setField(field, value);
+      } else {
+        extensions.setField(field, value);
+      }
+    }
+
+    private static void mergeMessageSetExtensionFromBytes(
+        ByteString rawBytes,
+        ExtensionRegistry.ExtensionInfo extension,
+        ExtensionRegistryLite extensionRegistry,
+        Message.Builder builder,
+        FieldSet<FieldDescriptor> extensions) throws IOException {
+
+      FieldDescriptor field = extension.descriptor;
+      boolean hasOriginalValue = hasOriginalMessage(builder, extensions, field);
+
+      if (hasOriginalValue || ExtensionRegistryLite.isEagerlyParseMessageSets()) {
+        // If the field already exists, we just parse the field.
+        Message value = null;
+        if (hasOriginalValue) {
+          Message originalMessage =
+              getOriginalMessage(builder, extensions, field);
+          Message.Builder subBuilder= originalMessage.toBuilder();
+          subBuilder.mergeFrom(rawBytes, extensionRegistry);
+          value = subBuilder.buildPartial();
+        } else {
+          value = extension.defaultInstance.getParserForType()
+              .parsePartialFrom(rawBytes, extensionRegistry);
+        }
+        setField(builder, extensions, field, value);
+      } else {
+        // Use LazyField to load MessageSet lazily.
+        LazyField lazyField = new LazyField(
+            extension.defaultInstance, extensionRegistry, rawBytes);
+        if (builder != null) {
+          // TODO(xiangl): it looks like this method can only be invoked by
+          // ExtendableBuilder, but I'm not sure. So I double check the type of
+          // builder here. It may be useless and need more investigation.
+          if (builder instanceof ExtendableBuilder) {
+            builder.setField(field, lazyField);
+          } else {
+            builder.setField(field, lazyField.getValue());
+          }
+        } else {
+          extensions.setField(field, lazyField);
+        }
       }
     }
 
@@ -596,6 +756,11 @@ public abstract class AbstractMessage extends AbstractMessageLite
       return (BuilderType) this;
     }
 
+    public Message.Builder getFieldBuilder(final FieldDescriptor field) {
+      throw new UnsupportedOperationException(
+          "getFieldBuilder() called on an unsupported message type.");
+    }
+
     /**
      * Construct an UninitializedMessageException reporting missing fields in
      * the given message.
@@ -609,14 +774,15 @@ public abstract class AbstractMessage extends AbstractMessageLite
      * Populates {@code this.missingFields} with the full "path" of each
      * missing required field in the given message.
      */
-    private static List<String> findMissingFields(final Message message) {
+    private static List<String> findMissingFields(
+        final MessageOrBuilder message) {
       final List<String> results = new ArrayList<String>();
       findMissingFields(message, "", results);
       return results;
     }
 
     /** Recursive helper implementing {@link #findMissingFields(Message)}. */
-    private static void findMissingFields(final Message message,
+    private static void findMissingFields(final MessageOrBuilder message,
                                           final String prefix,
                                           final List<String> results) {
       for (final FieldDescriptor field :
@@ -635,13 +801,13 @@ public abstract class AbstractMessage extends AbstractMessageLite
           if (field.isRepeated()) {
             int i = 0;
             for (final Object element : (List) value) {
-              findMissingFields((Message) element,
+              findMissingFields((MessageOrBuilder) element,
                                 subMessagePrefix(prefix, field, i++),
                                 results);
             }
           } else {
             if (message.hasField(field)) {
-              findMissingFields((Message) value,
+              findMissingFields((MessageOrBuilder) value,
                                 subMessagePrefix(prefix, field, -1),
                                 results);
             }
diff --git a/java/src/main/java/com/google/protobuf/AbstractMessageLite.java b/java/src/main/java/com/google/protobuf/AbstractMessageLite.java
index 77b27370..9926f3db 100644
--- a/java/src/main/java/com/google/protobuf/AbstractMessageLite.java
+++ b/java/src/main/java/com/google/protobuf/AbstractMessageLite.java
@@ -92,6 +92,14 @@ public abstract class AbstractMessageLite implements MessageLite {
   }
 
   /**
+   * Package private helper method for AbstractParser to create
+   * UninitializedMessageException.
+   */
+  UninitializedMessageException newUninitializedMessageException() {
+    return new UninitializedMessageException(this);
+  }
+
+  /**
    * A partial implementation of the {@link Message.Builder} interface which
    * implements as many methods of that interface as possible in terms of
    * other methods.
@@ -307,10 +315,12 @@ public abstract class AbstractMessageLite implements MessageLite {
      */
     protected static <T> void addAll(final Iterable<T> values,
                                      final Collection<? super T> list) {
-      for (final T value : values) {
-        if (value == null) {
-          throw new NullPointerException();
-        }
+      if (values instanceof LazyStringList) {
+        // For StringOrByteStringLists, check the underlying elements to avoid
+        // forcing conversions of ByteStrings to Strings.
+        checkForNullValues(((LazyStringList) values).getUnderlyingElements());
+      } else {
+        checkForNullValues(values);
       }
       if (values instanceof Collection) {
         final Collection<T> collection = (Collection<T>) values;
@@ -321,5 +331,13 @@ public abstract class AbstractMessageLite implements MessageLite {
         }
       }
     }
+
+    private static void checkForNullValues(final Iterable<?> values) {
+      for (final Object value : values) {
+        if (value == null) {
+          throw new NullPointerException();
+        }
+      }
+    }
   }
 }
diff --git a/java/src/main/java/com/google/protobuf/AbstractParser.java b/java/src/main/java/com/google/protobuf/AbstractParser.java
new file mode 100644
index 00000000..9bd9d397
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/AbstractParser.java
@@ -0,0 +1,261 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.AbstractMessageLite.Builder.LimitedInputStream;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * A partial implementation of the {@link Parser} interface which implements
+ * as many methods of that interface as possible in terms of other methods.
+ *
+ * Note: This class implements all the convenience methods in the
+ * {@link Parser} interface. See {@link Parser} for related javadocs.
+ * Subclasses need to implement
+ * {@link Parser#parsePartialFrom(CodedInputStream, ExtensionRegistryLite)}
+ *
+ * @author liujisi@google.com (Pherl Liu)
+ */
+public abstract class AbstractParser<MessageType extends MessageLite>
+    implements Parser<MessageType> {
+  /**
+   * Creates an UninitializedMessageException for MessageType.
+   */
+  private UninitializedMessageException
+      newUninitializedMessageException(MessageType message) {
+    if (message instanceof AbstractMessageLite) {
+      return ((AbstractMessageLite) message).newUninitializedMessageException();
+    }
+    return new UninitializedMessageException(message);
+  }
+
+  /**
+   * Helper method to check if message is initialized.
+   *
+   * @throws InvalidProtocolBufferException if it is not initialized.
+   * @return The message to check.
+   */
+  private MessageType checkMessageInitialized(MessageType message)
+      throws InvalidProtocolBufferException {
+    if (message != null && !message.isInitialized()) {
+      throw newUninitializedMessageException(message)
+          .asInvalidProtocolBufferException()
+          .setUnfinishedMessage(message);
+    }
+    return message;
+  }
+
+  private static final ExtensionRegistryLite EMPTY_REGISTRY
+      = ExtensionRegistryLite.getEmptyRegistry();
+
+  public MessageType parsePartialFrom(CodedInputStream input)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(input, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseFrom(CodedInputStream input,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return checkMessageInitialized(
+        parsePartialFrom(input, extensionRegistry));
+  }
+
+  public MessageType parseFrom(CodedInputStream input)
+      throws InvalidProtocolBufferException {
+    return parseFrom(input, EMPTY_REGISTRY);
+  }
+
+  public MessageType parsePartialFrom(ByteString data,
+                                      ExtensionRegistryLite extensionRegistry)
+    throws InvalidProtocolBufferException {
+    MessageType message;
+    try {
+      CodedInputStream input = data.newCodedInput();
+      message = parsePartialFrom(input, extensionRegistry);
+      try {
+        input.checkLastTagWas(0);
+      } catch (InvalidProtocolBufferException e) {
+        throw e.setUnfinishedMessage(message);
+      }
+      return message;
+    } catch (InvalidProtocolBufferException e) {
+      throw e;
+    } catch (IOException e) {
+      throw new RuntimeException(
+          "Reading from a ByteString threw an IOException (should " +
+          "never happen).", e);
+    }
+  }
+
+  public MessageType parsePartialFrom(ByteString data)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(data, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseFrom(ByteString data,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return checkMessageInitialized(parsePartialFrom(data, extensionRegistry));
+  }
+
+  public MessageType parseFrom(ByteString data)
+      throws InvalidProtocolBufferException {
+    return parseFrom(data, EMPTY_REGISTRY);
+  }
+
+  public MessageType parsePartialFrom(byte[] data, int off, int len,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    try {
+      CodedInputStream input = CodedInputStream.newInstance(data, off, len);
+      MessageType message = parsePartialFrom(input, extensionRegistry);
+      try {
+        input.checkLastTagWas(0);
+      } catch (InvalidProtocolBufferException e) {
+        throw e.setUnfinishedMessage(message);
+      }
+      return message;
+    } catch (InvalidProtocolBufferException e) {
+      throw e;
+    } catch (IOException e) {
+      throw new RuntimeException(
+          "Reading from a byte array threw an IOException (should " +
+          "never happen).", e);
+    }
+  }
+
+  public MessageType parsePartialFrom(byte[] data, int off, int len)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(data, off, len, EMPTY_REGISTRY);
+  }
+
+  public MessageType parsePartialFrom(byte[] data,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(data, 0, data.length, extensionRegistry);
+  }
+
+  public MessageType parsePartialFrom(byte[] data)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(data, 0, data.length, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseFrom(byte[] data, int off, int len,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return checkMessageInitialized(
+        parsePartialFrom(data, off, len, extensionRegistry));
+  }
+
+  public MessageType parseFrom(byte[] data, int off, int len)
+      throws InvalidProtocolBufferException {
+    return parseFrom(data, off, len, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseFrom(byte[] data,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return parseFrom(data, 0, data.length, extensionRegistry);
+  }
+
+  public MessageType parseFrom(byte[] data)
+      throws InvalidProtocolBufferException {
+    return parseFrom(data, EMPTY_REGISTRY);
+  }
+
+  public MessageType parsePartialFrom(InputStream input,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    CodedInputStream codedInput = CodedInputStream.newInstance(input);
+    MessageType message = parsePartialFrom(codedInput, extensionRegistry);
+    try {
+      codedInput.checkLastTagWas(0);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.setUnfinishedMessage(message);
+    }
+    return message;
+  }
+
+  public MessageType parsePartialFrom(InputStream input)
+      throws InvalidProtocolBufferException {
+    return parsePartialFrom(input, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseFrom(InputStream input,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return checkMessageInitialized(
+        parsePartialFrom(input, extensionRegistry));
+  }
+
+  public MessageType parseFrom(InputStream input)
+      throws InvalidProtocolBufferException {
+    return parseFrom(input, EMPTY_REGISTRY);
+  }
+
+  public MessageType parsePartialDelimitedFrom(
+      InputStream input,
+      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    int size;
+    try {
+      int firstByte = input.read();
+      if (firstByte == -1) {
+        return null;
+      }
+      size = CodedInputStream.readRawVarint32(firstByte, input);
+    } catch (IOException e) {
+      throw new InvalidProtocolBufferException(e.getMessage());
+    }
+    InputStream limitedInput = new LimitedInputStream(input, size);
+    return parsePartialFrom(limitedInput, extensionRegistry);
+  }
+
+  public MessageType parsePartialDelimitedFrom(InputStream input)
+      throws InvalidProtocolBufferException {
+    return parsePartialDelimitedFrom(input, EMPTY_REGISTRY);
+  }
+
+  public MessageType parseDelimitedFrom(
+      InputStream input,
+      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException {
+    return checkMessageInitialized(
+        parsePartialDelimitedFrom(input, extensionRegistry));
+  }
+
+  public MessageType parseDelimitedFrom(InputStream input)
+      throws InvalidProtocolBufferException {
+    return parseDelimitedFrom(input, EMPTY_REGISTRY);
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/BoundedByteString.java b/java/src/main/java/com/google/protobuf/BoundedByteString.java
new file mode 100644
index 00000000..cd4982c3
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/BoundedByteString.java
@@ -0,0 +1,163 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.util.NoSuchElementException;
+
+/**
+ * This class is used to represent the substring of a {@link ByteString} over a
+ * single byte array. In terms of the public API of {@link ByteString}, you end
+ * up here by calling {@link ByteString#copyFrom(byte[])} followed by {@link
+ * ByteString#substring(int, int)}.
+ *
+ * <p>This class contains most of the overhead involved in creating a substring
+ * from a {@link LiteralByteString}.  The overhead involves some range-checking
+ * and two extra fields.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+class BoundedByteString extends LiteralByteString {
+
+  private final int bytesOffset;
+  private final int bytesLength;
+
+  /**
+   * Creates a {@code BoundedByteString} backed by the sub-range of given array,
+   * without copying.
+   *
+   * @param bytes  array to wrap
+   * @param offset index to first byte to use in bytes
+   * @param length number of bytes to use from bytes
+   * @throws IllegalArgumentException if {@code offset < 0}, {@code length < 0},
+   *                                  or if {@code offset + length >
+   *                                  bytes.length}.
+   */
+  BoundedByteString(byte[] bytes, int offset, int length) {
+    super(bytes);
+    if (offset < 0) {
+      throw new IllegalArgumentException("Offset too small: " + offset);
+    }
+    if (length < 0) {
+      throw new IllegalArgumentException("Length too small: " + offset);
+    }
+    if ((long) offset + length > bytes.length) {
+      throw new IllegalArgumentException(
+          "Offset+Length too large: " + offset + "+" + length);
+    }
+
+    this.bytesOffset = offset;
+    this.bytesLength = length;
+  }
+
+  /**
+   * Gets the byte at the given index.
+   * Throws {@link ArrayIndexOutOfBoundsException}
+   * for backwards-compatibility reasons although it would more properly be
+   * {@link IndexOutOfBoundsException}.
+   *
+   * @param index index of byte
+   * @return the value
+   * @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size
+   */
+  @Override
+  public byte byteAt(int index) {
+    // We must check the index ourselves as we cannot rely on Java array index
+    // checking for substrings.
+    if (index < 0) {
+      throw new ArrayIndexOutOfBoundsException("Index too small: " + index);
+    }
+    if (index >= size()) {
+      throw new ArrayIndexOutOfBoundsException(
+          "Index too large: " + index + ", " + size());
+    }
+
+    return bytes[bytesOffset + index];
+  }
+
+  @Override
+  public int size() {
+    return bytesLength;
+  }
+
+  @Override
+  protected int getOffsetIntoBytes() {
+    return bytesOffset;
+  }
+
+  // =================================================================
+  // ByteString -> byte[]
+
+  @Override
+  protected void copyToInternal(byte[] target, int sourceOffset, 
+      int targetOffset, int numberToCopy) {
+    System.arraycopy(bytes, getOffsetIntoBytes() + sourceOffset, target,
+        targetOffset, numberToCopy);
+  }
+
+  // =================================================================
+  // ByteIterator
+
+  @Override
+  public ByteIterator iterator() {
+    return new BoundedByteIterator();
+  }
+
+  private class BoundedByteIterator implements ByteIterator {
+
+    private int position;
+    private final int limit;
+
+    private BoundedByteIterator() {
+      position = getOffsetIntoBytes();
+      limit = position + size();
+    }
+
+    public boolean hasNext() {
+      return (position < limit);
+    }
+
+    public Byte next() {
+      // Boxing calls Byte.valueOf(byte), which does not instantiate.
+      return nextByte();
+    }
+
+    public byte nextByte() {
+      if (position >= limit) {
+        throw new NoSuchElementException();
+      }
+      return bytes[position++];
+    }
+
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/ByteString.java b/java/src/main/java/com/google/protobuf/ByteString.java
index 91356357..1b18169e 100644
--- a/java/src/main/java/com/google/protobuf/ByteString.java
+++ b/java/src/main/java/com/google/protobuf/ByteString.java
@@ -30,140 +30,413 @@
 
 package com.google.protobuf;
 
-import java.io.InputStream;
-import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
-import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
+import java.util.NoSuchElementException;
 
 /**
- * Immutable array of bytes.
+ * Immutable sequence of bytes.  Substring is supported by sharing the reference
+ * to the immutable underlying bytes, as with {@link String}.  Concatenation is
+ * likewise supported without copying (long strings) by building a tree of
+ * pieces in {@link RopeByteString}.
+ * <p>
+ * Like {@link String}, the contents of a {@link ByteString} can never be
+ * observed to change, not even in the presence of a data race or incorrect
+ * API usage in the client code.
  *
  * @author crazybob@google.com Bob Lee
  * @author kenton@google.com Kenton Varda
+ * @author carlanton@google.com Carl Haverl
+ * @author martinrb@google.com Martin Buchholz
  */
-public final class ByteString {
-  private final byte[] bytes;
+public abstract class ByteString implements Iterable<Byte> {
 
-  private ByteString(final byte[] bytes) {
-    this.bytes = bytes;
-  }
+  /**
+   * When two strings to be concatenated have a combined length shorter than
+   * this, we just copy their bytes on {@link #concat(ByteString)}.
+   * The trade-off is copy size versus the overhead of creating tree nodes
+   * in {@link RopeByteString}.
+   */
+  static final int CONCATENATE_BY_COPY_SIZE = 128;
+
+  /**
+   * When copying an InputStream into a ByteString with .readFrom(),
+   * the chunks in the underlying rope start at 256 bytes, but double
+   * each iteration up to 8192 bytes.
+   */
+  static final int MIN_READ_FROM_CHUNK_SIZE = 0x100;  // 256b
+  static final int MAX_READ_FROM_CHUNK_SIZE = 0x2000;  // 8k
 
   /**
-   * Gets the byte at the given index.
+   * Empty {@code ByteString}.
+   */
+  public static final ByteString EMPTY = new LiteralByteString(new byte[0]);
+
+  // This constructor is here to prevent subclassing outside of this package,
+  ByteString() {}
+
+  /**
+   * Gets the byte at the given index. This method should be used only for
+   * random access to individual bytes. To access bytes sequentially, use the
+   * {@link ByteIterator} returned by {@link #iterator()}, and call {@link
+   * #substring(int, int)} first if necessary.
    *
+   * @param index index of byte
+   * @return the value
    * @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size
    */
-  public byte byteAt(final int index) {
-    return bytes[index];
+  public abstract byte byteAt(int index);
+
+  /**
+   * Return a {@link ByteString.ByteIterator} over the bytes in the ByteString.
+   * To avoid auto-boxing, you may get the iterator manually and call
+   * {@link ByteIterator#nextByte()}.
+   *
+   * @return the iterator
+   */
+  public abstract ByteIterator iterator();
+
+  /**
+   * This interface extends {@code Iterator<Byte>}, so that we can return an
+   * unboxed {@code byte}.
+   */
+  public interface ByteIterator extends Iterator<Byte> {
+    /**
+     * An alternative to {@link Iterator#next()} that returns an
+     * unboxed primitive {@code byte}.
+     *
+     * @return the next {@code byte} in the iteration
+     * @throws NoSuchElementException if the iteration has no more elements
+     */
+    byte nextByte();
   }
 
   /**
    * Gets the number of bytes.
+   *
+   * @return size in bytes
    */
-  public int size() {
-    return bytes.length;
-  }
+  public abstract int size();
 
   /**
    * Returns {@code true} if the size is {@code 0}, {@code false} otherwise.
+   *
+   * @return true if this is zero bytes long
    */
   public boolean isEmpty() {
-    return bytes.length == 0;
+    return size() == 0;
   }
 
   // =================================================================
-  // byte[] -> ByteString
+  // ByteString -> substring
 
   /**
-   * Empty ByteString.
+   * Return the substring from {@code beginIndex}, inclusive, to the end of the
+   * string.
+   *
+   * @param beginIndex start at this index
+   * @return substring sharing underlying data
+   * @throws IndexOutOfBoundsException if {@code beginIndex < 0} or
+   *     {@code beginIndex > size()}.
    */
-  public static final ByteString EMPTY = new ByteString(new byte[0]);
+  public ByteString substring(int beginIndex) {
+    return substring(beginIndex, size());
+  }
+
+  /**
+   * Return the substring from {@code beginIndex}, inclusive, to {@code
+   * endIndex}, exclusive.
+   *
+   * @param beginIndex start at this index
+   * @param endIndex   the last character is the one before this index
+   * @return substring sharing underlying data
+   * @throws IndexOutOfBoundsException if {@code beginIndex < 0},
+   *     {@code endIndex > size()}, or {@code beginIndex > endIndex}.
+   */
+  public abstract ByteString substring(int beginIndex, int endIndex);
+
+  /**
+   * Tests if this bytestring starts with the specified prefix.
+   * Similar to {@link String#startsWith(String)}
+   *
+   * @param prefix the prefix.
+   * @return <code>true</code> if the byte sequence represented by the
+   *         argument is a prefix of the byte sequence represented by
+   *         this string; <code>false</code> otherwise.
+   */
+  public boolean startsWith(ByteString prefix) {
+    return size() >= prefix.size() &&
+           substring(0, prefix.size()).equals(prefix);
+  }
+
+  // =================================================================
+  // byte[] -> ByteString
 
   /**
    * Copies the given bytes into a {@code ByteString}.
+   *
+   * @param bytes source array
+   * @param offset offset in source array
+   * @param size number of bytes to copy
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFrom(final byte[] bytes, final int offset,
-                                    final int size) {
-    final byte[] copy = new byte[size];
+  public static ByteString copyFrom(byte[] bytes, int offset, int size) {
+    byte[] copy = new byte[size];
     System.arraycopy(bytes, offset, copy, 0, size);
-    return new ByteString(copy);
+    return new LiteralByteString(copy);
   }
 
   /**
    * Copies the given bytes into a {@code ByteString}.
+   *
+   * @param bytes to copy
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFrom(final byte[] bytes) {
+  public static ByteString copyFrom(byte[] bytes) {
     return copyFrom(bytes, 0, bytes.length);
   }
 
   /**
-   * Copies {@code size} bytes from a {@code java.nio.ByteBuffer} into
+   * Copies the next {@code size} bytes from a {@code java.nio.ByteBuffer} into
    * a {@code ByteString}.
+   *
+   * @param bytes source buffer
+   * @param size number of bytes to copy
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFrom(final ByteBuffer bytes, final int size) {
-    final byte[] copy = new byte[size];
+  public static ByteString copyFrom(ByteBuffer bytes, int size) {
+    byte[] copy = new byte[size];
     bytes.get(copy);
-    return new ByteString(copy);
+    return new LiteralByteString(copy);
   }
 
   /**
    * Copies the remaining bytes from a {@code java.nio.ByteBuffer} into
    * a {@code ByteString}.
+   *
+   * @param bytes sourceBuffer
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFrom(final ByteBuffer bytes) {
+  public static ByteString copyFrom(ByteBuffer bytes) {
     return copyFrom(bytes, bytes.remaining());
   }
 
   /**
    * Encodes {@code text} into a sequence of bytes using the named charset
    * and returns the result as a {@code ByteString}.
+   *
+   * @param text source string
+   * @param charsetName encoding to use
+   * @return new {@code ByteString}
+   * @throws UnsupportedEncodingException if the encoding isn't found
    */
-  public static ByteString copyFrom(final String text, final String charsetName)
+  public static ByteString copyFrom(String text, String charsetName)
       throws UnsupportedEncodingException {
-    return new ByteString(text.getBytes(charsetName));
+    return new LiteralByteString(text.getBytes(charsetName));
   }
 
   /**
    * Encodes {@code text} into a sequence of UTF-8 bytes and returns the
    * result as a {@code ByteString}.
+   *
+   * @param text source string
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFromUtf8(final String text) {
+  public static ByteString copyFromUtf8(String text) {
     try {
-      return new ByteString(text.getBytes("UTF-8"));
+      return new LiteralByteString(text.getBytes("UTF-8"));
     } catch (UnsupportedEncodingException e) {
       throw new RuntimeException("UTF-8 not supported?", e);
     }
   }
 
+  // =================================================================
+  // InputStream -> ByteString
+
   /**
-   * Concatenates all byte strings in the list and returns the result.
+   * Completely reads the given stream's bytes into a
+   * {@code ByteString}, blocking if necessary until all bytes are
+   * read through to the end of the stream.
+   *
+   * <b>Performance notes:</b> The returned {@code ByteString} is an
+   * immutable tree of byte arrays ("chunks") of the stream data.  The
+   * first chunk is small, with subsequent chunks each being double
+   * the size, up to 8K.  If the caller knows the precise length of
+   * the stream and wishes to avoid all unnecessary copies and
+   * allocations, consider using the two-argument version of this
+   * method, below.
+   *
+   * @param streamToDrain The source stream, which is read completely
+   *     but not closed.
+   * @return A new {@code ByteString} which is made up of chunks of
+   *     various sizes, depending on the behavior of the underlying
+   *     stream.
+   * @throws IOException IOException is thrown if there is a problem
+   *     reading the underlying stream.
+   */
+  public static ByteString readFrom(InputStream streamToDrain)
+      throws IOException {
+    return readFrom(
+        streamToDrain, MIN_READ_FROM_CHUNK_SIZE, MAX_READ_FROM_CHUNK_SIZE);
+  }
+
+  /**
+   * Completely reads the given stream's bytes into a
+   * {@code ByteString}, blocking if necessary until all bytes are
+   * read through to the end of the stream.
+   *
+   * <b>Performance notes:</b> The returned {@code ByteString} is an
+   * immutable tree of byte arrays ("chunks") of the stream data.  The
+   * chunkSize parameter sets the size of these byte arrays. In
+   * particular, if the chunkSize is precisely the same as the length
+   * of the stream, unnecessary allocations and copies will be
+   * avoided. Otherwise, the chunks will be of the given size, except
+   * for the last chunk, which will be resized (via a reallocation and
+   * copy) to contain the remainder of the stream.
+   *
+   * @param streamToDrain The source stream, which is read completely
+   *     but not closed.
+   * @param chunkSize The size of the chunks in which to read the
+   *     stream.
+   * @return A new {@code ByteString} which is made up of chunks of
+   *     the given size.
+   * @throws IOException IOException is thrown if there is a problem
+   *     reading the underlying stream.
+   */
+  public static ByteString readFrom(InputStream streamToDrain, int chunkSize)
+      throws IOException {
+    return readFrom(streamToDrain, chunkSize, chunkSize);
+  }
+
+  // Helper method that takes the chunk size range as a parameter.
+  public static ByteString readFrom(InputStream streamToDrain, int minChunkSize,
+      int maxChunkSize) throws IOException {
+    Collection<ByteString> results = new ArrayList<ByteString>();
+
+    // copy the inbound bytes into a list of chunks; the chunk size
+    // grows exponentially to support both short and long streams.
+    int chunkSize = minChunkSize;
+    while (true) {
+      ByteString chunk = readChunk(streamToDrain, chunkSize);
+      if (chunk == null) {
+        break;
+      }
+      results.add(chunk);
+      chunkSize = Math.min(chunkSize * 2, maxChunkSize);
+    }
+
+    return ByteString.copyFrom(results);
+  }
+
+  /**
+   * Blocks until a chunk of the given size can be made from the
+   * stream, or EOF is reached.  Calls read() repeatedly in case the
+   * given stream implementation doesn't completely fill the given
+   * buffer in one read() call.
+   *
+   * @return A chunk of the desired size, or else a chunk as large as
+   * was available when end of stream was reached. Returns null if the
+   * given stream had no more data in it.
+   */
+  private static ByteString readChunk(InputStream in, final int chunkSize)
+      throws IOException {
+      final byte[] buf = new byte[chunkSize];
+      int bytesRead = 0;
+      while (bytesRead < chunkSize) {
+        final int count = in.read(buf, bytesRead, chunkSize - bytesRead);
+        if (count == -1) {
+          break;
+        }
+        bytesRead += count;
+      }
+
+      if (bytesRead == 0) {
+        return null;
+      } else {
+        return ByteString.copyFrom(buf, 0, bytesRead);
+      }
+  }
+
+  // =================================================================
+  // Multiple ByteStrings -> One ByteString
+
+  /**
+   * Concatenate the given {@code ByteString} to this one. Short concatenations,
+   * of total size smaller than {@link ByteString#CONCATENATE_BY_COPY_SIZE}, are
+   * produced by copying the underlying bytes (as per Rope.java, <a
+   * href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
+   * BAP95 </a>. In general, the concatenate involves no copying.
+   *
+   * @param other string to concatenate
+   * @return a new {@code ByteString} instance
+   */
+  public ByteString concat(ByteString other) {
+    int thisSize = size();
+    int otherSize = other.size();
+    if ((long) thisSize + otherSize >= Integer.MAX_VALUE) {
+      throw new IllegalArgumentException("ByteString would be too long: " +
+                                         thisSize + "+" + otherSize);
+    }
+
+    return RopeByteString.concatenate(this, other);
+  }
+
+  /**
+   * Concatenates all byte strings in the iterable and returns the result.
+   * This is designed to run in O(list size), not O(total bytes).
    *
    * <p>The returned {@code ByteString} is not necessarily a unique object.
    * If the list is empty, the returned object is the singleton empty
    * {@code ByteString}.  If the list has only one element, that
    * {@code ByteString} will be returned without copying.
+   *
+   * @param byteStrings strings to be concatenated
+   * @return new {@code ByteString}
    */
-  public static ByteString copyFrom(List<ByteString> list) {
-    if (list.size() == 0) {
-      return EMPTY;
-    } else if (list.size() == 1) {
-      return list.get(0);
+  public static ByteString copyFrom(Iterable<ByteString> byteStrings) {
+    Collection<ByteString> collection;
+    if (!(byteStrings instanceof Collection)) {
+      collection = new ArrayList<ByteString>();
+      for (ByteString byteString : byteStrings) {
+        collection.add(byteString);
+      }
+    } else {
+      collection = (Collection<ByteString>) byteStrings;
     }
-
-    int size = 0;
-    for (ByteString str : list) {
-      size += str.size();
+    ByteString result;
+    if (collection.isEmpty()) {
+      result = EMPTY;
+    } else {
+      result = balancedConcat(collection.iterator(), collection.size());
     }
-    byte[] bytes = new byte[size];
-    int pos = 0;
-    for (ByteString str : list) {
-      System.arraycopy(str.bytes, 0, bytes, pos, str.size());
-      pos += str.size();
+    return result;
+  }
+
+  // Internal function used by copyFrom(Iterable<ByteString>).
+  // Create a balanced concatenation of the next "length" elements from the
+  // iterable.
+  private static ByteString balancedConcat(Iterator<ByteString> iterator,
+      int length) {
+    assert length >= 1;
+    ByteString result;
+    if (length == 1) {
+      result = iterator.next();
+    } else {
+      int halfLength = length >>> 1;
+      ByteString left = balancedConcat(iterator, halfLength);
+      ByteString right = balancedConcat(iterator, length - halfLength);
+      result = left.concat(right);
     }
-    return new ByteString(bytes);
+    return result;
   }
 
   // =================================================================
@@ -174,206 +447,446 @@ public final class ByteString {
    *
    * @param target buffer to copy into
    * @param offset in the target buffer
+   * @throws IndexOutOfBoundsException if the offset is negative or too large
    */
-  public void copyTo(final byte[] target, final int offset) {
-    System.arraycopy(bytes, 0, target, offset, bytes.length);
+  public void copyTo(byte[] target, int offset) {
+    copyTo(target, 0, offset, size());
   }
 
   /**
    * Copies bytes into a buffer.
    *
-   * @param target buffer to copy into
+   * @param target       buffer to copy into
    * @param sourceOffset offset within these bytes
    * @param targetOffset offset within the target buffer
-   * @param size number of bytes to copy
+   * @param numberToCopy number of bytes to copy
+   * @throws IndexOutOfBoundsException if an offset or size is negative or too
+   *     large
    */
-  public void copyTo(final byte[] target, final int sourceOffset,
-                     final int targetOffset,
-      final int size) {
-    System.arraycopy(bytes, sourceOffset, target, targetOffset, size);
+  public void copyTo(byte[] target, int sourceOffset, int targetOffset,
+      int numberToCopy) {
+    if (sourceOffset < 0) {
+      throw new IndexOutOfBoundsException("Source offset < 0: " + sourceOffset);
+    }
+    if (targetOffset < 0) {
+      throw new IndexOutOfBoundsException("Target offset < 0: " + targetOffset);
+    }
+    if (numberToCopy < 0) {
+      throw new IndexOutOfBoundsException("Length < 0: " + numberToCopy);
+    }
+    if (sourceOffset + numberToCopy > size()) {
+      throw new IndexOutOfBoundsException(
+          "Source end offset < 0: " + (sourceOffset + numberToCopy));
+    }
+    if (targetOffset + numberToCopy > target.length) {
+      throw new IndexOutOfBoundsException(
+          "Target end offset < 0: " + (targetOffset + numberToCopy));
+    }
+    if (numberToCopy > 0) {
+      copyToInternal(target, sourceOffset, targetOffset, numberToCopy);
+    }
   }
 
   /**
+   * Internal (package private) implementation of
+   * @link{#copyTo(byte[],int,int,int}.
+   * It assumes that all error checking has already been performed and that 
+   * @code{numberToCopy > 0}.
+   */
+  protected abstract void copyToInternal(byte[] target, int sourceOffset,
+      int targetOffset, int numberToCopy);
+
+  /**
    * Copies bytes into a ByteBuffer.
    *
    * @param target ByteBuffer to copy into.
-   * @throws ReadOnlyBufferException if the {@code target} is read-only
-   * @throws BufferOverflowException if the {@code target}'s remaining()
-   *         space is not large enough to hold the data.
+   * @throws java.nio.ReadOnlyBufferException if the {@code target} is read-only
+   * @throws java.nio.BufferOverflowException if the {@code target}'s
+   *     remaining() space is not large enough to hold the data.
    */
-  public void copyTo(ByteBuffer target) {
-    target.put(bytes, 0, bytes.length);
-  }
+  public abstract void copyTo(ByteBuffer target);
 
   /**
    * Copies bytes to a {@code byte[]}.
+   *
+   * @return copied bytes
    */
   public byte[] toByteArray() {
-    final int size = bytes.length;
-    final byte[] copy = new byte[size];
-    System.arraycopy(bytes, 0, copy, 0, size);
-    return copy;
+    int size = size();
+    byte[] result = new byte[size];
+    copyToInternal(result, 0, 0, size);
+    return result;
   }
 
   /**
-   * Constructs a new read-only {@code java.nio.ByteBuffer} with the
-   * same backing byte array.
+   * Writes the complete contents of this byte string to
+   * the specified output stream argument.
+   *
+   * @param  out  the output stream to which to write the data.
+   * @throws IOException  if an I/O error occurs.
    */
-  public ByteBuffer asReadOnlyByteBuffer() {
-    final ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
-    return byteBuffer.asReadOnlyBuffer();
-  }
+  public abstract void writeTo(OutputStream out) throws IOException;
+
+  /**
+   * Constructs a read-only {@code java.nio.ByteBuffer} whose content
+   * is equal to the contents of this byte string.
+   * The result uses the same backing array as the byte string, if possible.
+   *
+   * @return wrapped bytes
+   */
+  public abstract ByteBuffer asReadOnlyByteBuffer();
+
+  /**
+   * Constructs a list of read-only {@code java.nio.ByteBuffer} objects
+   * such that the concatenation of their contents is equal to the contents
+   * of this byte string.  The result uses the same backing arrays as the
+   * byte string.
+   * <p>
+   * By returning a list, implementations of this method may be able to avoid
+   * copying even when there are multiple backing arrays.
+   * 
+   * @return a list of wrapped bytes
+   */
+  public abstract List<ByteBuffer> asReadOnlyByteBufferList();
 
   /**
    * Constructs a new {@code String} by decoding the bytes using the
    * specified charset.
+   *
+   * @param charsetName encode using this charset
+   * @return new string
+   * @throws UnsupportedEncodingException if charset isn't recognized
    */
-  public String toString(final String charsetName)
-      throws UnsupportedEncodingException {
-    return new String(bytes, charsetName);
-  }
+  public abstract String toString(String charsetName)
+      throws UnsupportedEncodingException;
+
+  // =================================================================
+  // UTF-8 decoding
 
   /**
    * Constructs a new {@code String} by decoding the bytes as UTF-8.
+   *
+   * @return new string using UTF-8 encoding
    */
   public String toStringUtf8() {
     try {
-      return new String(bytes, "UTF-8");
+      return toString("UTF-8");
     } catch (UnsupportedEncodingException e) {
       throw new RuntimeException("UTF-8 not supported?", e);
     }
   }
 
+  /**
+   * Tells whether this {@code ByteString} represents a well-formed UTF-8
+   * byte sequence, such that the original bytes can be converted to a
+   * String object and then round tripped back to bytes without loss.
+   *
+   * <p>More precisely, returns {@code true} whenever: <pre> {@code
+   * Arrays.equals(byteString.toByteArray(),
+   *     new String(byteString.toByteArray(), "UTF-8").getBytes("UTF-8"))
+   * }</pre>
+   *
+   * <p>This method returns {@code false} for "overlong" byte sequences,
+   * as well as for 3-byte sequences that would map to a surrogate
+   * character, in accordance with the restricted definition of UTF-8
+   * introduced in Unicode 3.1.  Note that the UTF-8 decoder included in
+   * Oracle's JDK has been modified to also reject "overlong" byte
+   * sequences, but (as of 2011) still accepts 3-byte surrogate
+   * character byte sequences.
+   *
+   * <p>See the Unicode Standard,</br>
+   * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
+   * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
+   *
+   * @return whether the bytes in this {@code ByteString} are a
+   * well-formed UTF-8 byte sequence
+   */
+  public abstract boolean isValidUtf8();
+
+  /**
+   * Tells whether the given byte sequence is a well-formed, malformed, or
+   * incomplete UTF-8 byte sequence.  This method accepts and returns a partial
+   * state result, allowing the bytes for a complete UTF-8 byte sequence to be
+   * composed from multiple {@code ByteString} segments.
+   *
+   * @param state either {@code 0} (if this is the initial decoding operation)
+   *     or the value returned from a call to a partial decoding method for the
+   *     previous bytes
+   * @param offset offset of the first byte to check
+   * @param length number of bytes to check
+   *
+   * @return {@code -1} if the partial byte sequence is definitely malformed,
+   * {@code 0} if it is well-formed (no additional input needed), or, if the
+   * byte sequence is "incomplete", i.e. apparently terminated in the middle of
+   * a character, an opaque integer "state" value containing enough information
+   * to decode the character when passed to a subsequent invocation of a
+   * partial decoding method.
+   */
+  protected abstract int partialIsValidUtf8(int state, int offset, int length);
+
   // =================================================================
   // equals() and hashCode()
 
   @Override
-  public boolean equals(final Object o) {
-    if (o == this) {
-      return true;
-    }
-
-    if (!(o instanceof ByteString)) {
-      return false;
-    }
-
-    final ByteString other = (ByteString) o;
-    final int size = bytes.length;
-    if (size != other.bytes.length) {
-      return false;
-    }
-
-    final byte[] thisBytes = bytes;
-    final byte[] otherBytes = other.bytes;
-    for (int i = 0; i < size; i++) {
-      if (thisBytes[i] != otherBytes[i]) {
-        return false;
-      }
-    }
-
-    return true;
-  }
-
-  private volatile int hash = 0;
+  public abstract boolean equals(Object o);
 
+  /**
+   * Return a non-zero hashCode depending only on the sequence of bytes
+   * in this ByteString.
+   *
+   * @return hashCode value for this object
+   */
   @Override
-  public int hashCode() {
-    int h = hash;
-
-    if (h == 0) {
-      final byte[] thisBytes = bytes;
-      final int size = bytes.length;
-
-      h = size;
-      for (int i = 0; i < size; i++) {
-        h = h * 31 + thisBytes[i];
-      }
-      if (h == 0) {
-        h = 1;
-      }
-
-      hash = h;
-    }
-
-    return h;
-  }
+  public abstract int hashCode();
 
   // =================================================================
   // Input stream
 
   /**
    * Creates an {@code InputStream} which can be used to read the bytes.
+   * <p>
+   * The {@link InputStream} returned by this method is guaranteed to be
+   * completely non-blocking.  The method {@link InputStream#available()}
+   * returns the number of bytes remaining in the stream. The methods
+   * {@link InputStream#read(byte[]), {@link InputStream#read(byte[],int,int)}
+   * and {@link InputStream#skip(long)} will read/skip as many bytes as are
+   * available.
+   * <p>
+   * The methods in the returned {@link InputStream} might <b>not</b> be
+   * thread safe.
+   *
+   * @return an input stream that returns the bytes of this byte string.
    */
-  public InputStream newInput() {
-    return new ByteArrayInputStream(bytes);
-  }
+  public abstract InputStream newInput();
 
   /**
    * Creates a {@link CodedInputStream} which can be used to read the bytes.
-   * Using this is more efficient than creating a {@link CodedInputStream}
-   * wrapping the result of {@link #newInput()}.
+   * Using this is often more efficient than creating a {@link CodedInputStream}
+   * that wraps the result of {@link #newInput()}.
+   *
+   * @return stream based on wrapped data
    */
-  public CodedInputStream newCodedInput() {
-    // We trust CodedInputStream not to modify the bytes, or to give anyone
-    // else access to them.
-    return CodedInputStream.newInstance(bytes);
-  }
+  public abstract CodedInputStream newCodedInput();
 
   // =================================================================
   // Output stream
 
   /**
-   * Creates a new {@link Output} with the given initial capacity.
+   * Creates a new {@link Output} with the given initial capacity. Call {@link
+   * Output#toByteString()} to create the {@code ByteString} instance.
+   * <p>
+   * A {@link ByteString.Output} offers the same functionality as a
+   * {@link ByteArrayOutputStream}, except that it returns a {@link ByteString}
+   * rather than a {@code byte} array.
+   *
+   * @param initialCapacity estimate of number of bytes to be written
+   * @return {@code OutputStream} for building a {@code ByteString}
    */
-  public static Output newOutput(final int initialCapacity) {
-    return new Output(new ByteArrayOutputStream(initialCapacity));
+  public static Output newOutput(int initialCapacity) {
+    return new Output(initialCapacity);
   }
 
   /**
-   * Creates a new {@link Output}.
+   * Creates a new {@link Output}. Call {@link Output#toByteString()} to create
+   * the {@code ByteString} instance.
+   * <p>
+   * A {@link ByteString.Output} offers the same functionality as a
+   * {@link ByteArrayOutputStream}, except that it returns a {@link ByteString}
+   * rather than a {@code byte array}.
+   *
+   * @return {@code OutputStream} for building a {@code ByteString}
    */
   public static Output newOutput() {
-    return newOutput(32);
+    return new Output(CONCATENATE_BY_COPY_SIZE);
   }
 
   /**
    * Outputs to a {@code ByteString} instance. Call {@link #toByteString()} to
    * create the {@code ByteString} instance.
    */
-  public static final class Output extends FilterOutputStream {
-    private final ByteArrayOutputStream bout;
+  public static final class Output extends OutputStream {
+    // Implementation note.
+    // The public methods of this class must be synchronized.  ByteStrings
+    // are guaranteed to be immutable.  Without some sort of locking, it could
+    // be possible for one thread to call toByteSring(), while another thread
+    // is still modifying the underlying byte array.
+
+    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
+    // argument passed by user, indicating initial capacity.
+    private final int initialCapacity;
+    // ByteStrings to be concatenated to create the result
+    private final ArrayList<ByteString> flushedBuffers;
+    // Total number of bytes in the ByteStrings of flushedBuffers
+    private int flushedBuffersTotalBytes;
+    // Current buffer to which we are writing
+    private byte[] buffer;
+    // Location in buffer[] to which we write the next byte.
+    private int bufferPos;
 
     /**
-     * Constructs a new output with the given initial capacity.
+     * Creates a new ByteString output stream with the specified
+     * initial capacity.
+     *
+     * @param initialCapacity  the initial capacity of the output stream.
      */
-    private Output(final ByteArrayOutputStream bout) {
-      super(bout);
-      this.bout = bout;
+    Output(int initialCapacity) {
+      if (initialCapacity < 0) {
+        throw new IllegalArgumentException("Buffer size < 0");
+      }
+      this.initialCapacity = initialCapacity;
+      this.flushedBuffers = new ArrayList<ByteString>();
+      this.buffer = new byte[initialCapacity];
+    }
+
+    @Override
+    public synchronized void write(int b) {
+      if (bufferPos == buffer.length) {
+        flushFullBuffer(1);
+      }
+      buffer[bufferPos++] = (byte)b;
+    }
+
+    @Override
+    public synchronized void write(byte[] b, int offset, int length)  {
+      if (length <= buffer.length - bufferPos) {
+        // The bytes can fit into the current buffer.
+        System.arraycopy(b, offset, buffer, bufferPos, length);
+        bufferPos += length;
+      } else {
+        // Use up the current buffer
+        int copySize  = buffer.length - bufferPos;
+        System.arraycopy(b, offset, buffer, bufferPos, copySize);
+        offset += copySize;
+        length -= copySize;
+        // Flush the buffer, and get a new buffer at least big enough to cover
+        // what we still need to output
+        flushFullBuffer(length);
+        System.arraycopy(b, offset, buffer, 0 /* count */, length);
+        bufferPos = length;
+      }
+    }
+
+    /**
+     * Creates a byte string. Its size is the current size of this output
+     * stream and its output has been copied to it.
+     *
+     * @return  the current contents of this output stream, as a byte string.
+     */
+    public synchronized ByteString toByteString() {
+      flushLastBuffer();
+      return ByteString.copyFrom(flushedBuffers);
+    }
+
+    /**
+     * Writes the complete contents of this byte array output stream to
+     * the specified output stream argument.
+     *
+     * @param out the output stream to which to write the data.
+     * @throws IOException  if an I/O error occurs.
+     */
+    public void writeTo(OutputStream out) throws IOException {
+      ByteString[] cachedFlushBuffers;
+      byte[] cachedBuffer;
+      int cachedBufferPos;
+      synchronized (this) {
+        // Copy the information we need into local variables so as to hold
+        // the lock for as short a time as possible.
+        cachedFlushBuffers =
+            flushedBuffers.toArray(new ByteString[flushedBuffers.size()]);
+        cachedBuffer = buffer;
+        cachedBufferPos = bufferPos;
+      }
+      for (ByteString byteString : cachedFlushBuffers) {
+        byteString.writeTo(out);
+      }
+
+      out.write(Arrays.copyOf(cachedBuffer, cachedBufferPos));
+    }
+
+    /**
+     * Returns the current size of the output stream.
+     *
+     * @return  the current size of the output stream
+     */
+    public synchronized int size() {
+      return flushedBuffersTotalBytes + bufferPos;
+    }
+
+    /**
+     * Resets this stream, so that all currently accumulated output in the
+     * output stream is discarded. The output stream can be used again,
+     * reusing the already allocated buffer space.
+     */
+    public synchronized void reset() {
+      flushedBuffers.clear();
+      flushedBuffersTotalBytes = 0;
+      bufferPos = 0;
+    }
+
+    @Override
+    public String toString() {
+      return String.format("<ByteString.Output@%s size=%d>",
+          Integer.toHexString(System.identityHashCode(this)), size());
     }
 
     /**
-     * Creates a {@code ByteString} instance from this {@code Output}.
+     * Internal function used by writers.  The current buffer is full, and the
+     * writer needs a new buffer whose size is at least the specified minimum
+     * size.
      */
-    public ByteString toByteString() {
-      final byte[] byteArray = bout.toByteArray();
-      return new ByteString(byteArray);
+    private void flushFullBuffer(int minSize)  {
+      flushedBuffers.add(new LiteralByteString(buffer));
+      flushedBuffersTotalBytes += buffer.length;
+      // We want to increase our total capacity by 50%, but as a minimum,
+      // the new buffer should also at least be >= minSize and
+      // >= initial Capacity.
+      int newSize = Math.max(initialCapacity,
+          Math.max(minSize, flushedBuffersTotalBytes >>> 1));
+      buffer = new byte[newSize];
+      bufferPos = 0;
+    }
+
+    /**
+     * Internal function used by {@link #toByteString()}. The current buffer may
+     * or may not be full, but it needs to be flushed.
+     */
+    private void flushLastBuffer()  {
+      if (bufferPos < buffer.length) {
+        if (bufferPos > 0) {
+          byte[] bufferCopy = Arrays.copyOf(buffer, bufferPos);
+          flushedBuffers.add(new LiteralByteString(bufferCopy));
+        }
+        // We reuse this buffer for further writes.
+      } else {
+        // Buffer is completely full.  Huzzah.
+        flushedBuffers.add(new LiteralByteString(buffer));
+        // 99% of the time, we're not going to use this OutputStream again.
+        // We set buffer to an empty byte stream so that we're handling this
+        // case without wasting space.  In the rare case that more writes
+        // *do* occur, this empty buffer will be flushed and an appropriately
+        // sized new buffer will be created.
+        buffer = EMPTY_BYTE_ARRAY;
+      }
+      flushedBuffersTotalBytes += bufferPos;
+      bufferPos = 0;
     }
   }
 
   /**
-   * Constructs a new ByteString builder, which allows you to efficiently
-   * construct a {@code ByteString} by writing to a {@link CodedOutputStream}.
-   * Using this is much more efficient than calling {@code newOutput()} and
-   * wrapping that in a {@code CodedOutputStream}.
+   * Constructs a new {@code ByteString} builder, which allows you to
+   * efficiently construct a {@code ByteString} by writing to a {@link
+   * CodedOutputStream}. Using this is much more efficient than calling {@code
+   * newOutput()} and wrapping that in a {@code CodedOutputStream}.
    *
    * <p>This is package-private because it's a somewhat confusing interface.
    * Users can call {@link Message#toByteString()} instead of calling this
    * directly.
    *
-   * @param size The target byte size of the {@code ByteString}.  You must
-   *             write exactly this many bytes before building the result.
+   * @param size The target byte size of the {@code ByteString}.  You must write
+   *     exactly this many bytes before building the result.
+   * @return the builder
    */
-  static CodedBuilder newCodedBuilder(final int size) {
+  static CodedBuilder newCodedBuilder(int size) {
     return new CodedBuilder(size);
   }
 
@@ -382,7 +895,7 @@ public final class ByteString {
     private final CodedOutputStream output;
     private final byte[] buffer;
 
-    private CodedBuilder(final int size) {
+    private CodedBuilder(int size) {
       buffer = new byte[size];
       output = CodedOutputStream.newInstance(buffer);
     }
@@ -393,11 +906,57 @@ public final class ByteString {
       // We can be confident that the CodedOutputStream will not modify the
       // underlying bytes anymore because it already wrote all of them.  So,
       // no need to make a copy.
-      return new ByteString(buffer);
+      return new LiteralByteString(buffer);
     }
 
     public CodedOutputStream getCodedOutput() {
       return output;
     }
   }
+
+  // =================================================================
+  // Methods {@link RopeByteString} needs on instances, which aren't part of the
+  // public API.
+
+  /**
+   * Return the depth of the tree representing this {@code ByteString}, if any,
+   * whose root is this node. If this is a leaf node, return 0.
+   *
+   * @return tree depth or zero
+   */
+  protected abstract int getTreeDepth();
+
+  /**
+   * Return {@code true} if this ByteString is literal (a leaf node) or a
+   * flat-enough tree in the sense of {@link RopeByteString}.
+   *
+   * @return true if the tree is flat enough
+   */
+  protected abstract boolean isBalanced();
+
+  /**
+   * Return the cached hash code if available.
+   *
+   * @return value of cached hash code or 0 if not computed yet
+   */
+  protected abstract int peekCachedHashCode();
+
+  /**
+   * Compute the hash across the value bytes starting with the given hash, and
+   * return the result.  This is used to compute the hash across strings
+   * represented as a set of pieces by allowing the hash computation to be
+   * continued from piece to piece.
+   *
+   * @param h starting hash value
+   * @param offset offset into this value to start looking at data values
+   * @param length number of data values to include in the hash computation
+   * @return ending hash value
+   */
+  protected abstract int partialHash(int h, int offset, int length);
+
+  @Override
+  public String toString() {
+    return String.format("<ByteString@%s size=%d>",
+        Integer.toHexString(System.identityHashCode(this)), size());
+  }
 }
diff --git a/java/src/main/java/com/google/protobuf/CodedInputStream.java b/java/src/main/java/com/google/protobuf/CodedInputStream.java
index b3e08555..33417a7f 100644
--- a/java/src/main/java/com/google/protobuf/CodedInputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedInputStream.java
@@ -243,6 +243,23 @@ public final class CodedInputStream {
     --recursionDepth;
   }
 
+  /** Read a {@code group} field value from the stream. */
+  public <T extends MessageLite> T readGroup(
+      final int fieldNumber,
+      final Parser<T> parser,
+      final ExtensionRegistryLite extensionRegistry)
+      throws IOException {
+    if (recursionDepth >= recursionLimit) {
+      throw InvalidProtocolBufferException.recursionLimitExceeded();
+    }
+    ++recursionDepth;
+    T result = parser.parsePartialFrom(this, extensionRegistry);
+    checkLastTagWas(
+      WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_END_GROUP));
+    --recursionDepth;
+    return result;
+  }
+
   /**
    * Reads a {@code group} field value from the stream and merges it into the
    * given {@link UnknownFieldSet}.
@@ -278,6 +295,24 @@ public final class CodedInputStream {
     popLimit(oldLimit);
   }
 
+  /** Read an embedded message field value from the stream. */
+  public <T extends MessageLite> T readMessage(
+      final Parser<T> parser,
+      final ExtensionRegistryLite extensionRegistry)
+      throws IOException {
+    int length = readRawVarint32();
+    if (recursionDepth >= recursionLimit) {
+      throw InvalidProtocolBufferException.recursionLimitExceeded();
+    }
+    final int oldLimit = pushLimit(length);
+    ++recursionDepth;
+    T result = parser.parsePartialFrom(this, extensionRegistry);
+    checkLastTagWas(0);
+    --recursionDepth;
+    popLimit(oldLimit);
+    return result;
+  }
+
   /** Read a {@code bytes} field value from the stream. */
   public ByteString readBytes() throws IOException {
     final int size = readRawVarint32();
@@ -601,7 +636,7 @@ public final class CodedInputStream {
    * refreshing its buffer.  If you need to prevent reading past a certain
    * point in the underlying {@code InputStream} (e.g. because you expect it to
    * contain more data after the end of the message which you need to handle
-   * differently) then you must place a wrapper around you {@code InputStream}
+   * differently) then you must place a wrapper around your {@code InputStream}
    * which limits the amount of data that can be read from it.
    *
    * @return the old limit.
@@ -676,7 +711,7 @@ public final class CodedInputStream {
 
   /**
    * Called with {@code this.buffer} is empty to read more bytes from the
-   * input.  If {@code mustSucceed} is true, refillBuffer() gurantees that
+   * input.  If {@code mustSucceed} is true, refillBuffer() guarantees that
    * either there will be at least one byte in the buffer when it returns
    * or it will throw an exception.  If {@code mustSucceed} is false,
    * refillBuffer() returns false if no more bytes were available.
@@ -879,7 +914,7 @@ public final class CodedInputStream {
         refillBuffer(true);
       }
 
-      bufferPos = size - pos; 
+      bufferPos = size - pos;
     }
   }
 }
diff --git a/java/src/main/java/com/google/protobuf/CodedOutputStream.java b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
index ac5f2d30..ca24638d 100644
--- a/java/src/main/java/com/google/protobuf/CodedOutputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
@@ -30,10 +30,10 @@
 
 package com.google.protobuf;
 
-import java.io.OutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
 
 /**
  * Encodes and writes protocol message fields.
@@ -540,6 +540,15 @@ public final class CodedOutputStream {
   }
 
   /**
+   * Compute the number of bytes that would be needed to encode an
+   * embedded message in lazy field, including tag.
+   */
+  public static int computeLazyFieldSize(final int fieldNumber,
+                                         final LazyField value) {
+    return computeTagSize(fieldNumber) + computeLazyFieldSizeNoTag(value);
+  }
+
+  /**
    * Compute the number of bytes that would be needed to encode a
    * {@code uint32} field, including tag.
    */
@@ -614,6 +623,18 @@ public final class CodedOutputStream {
            computeBytesSize(WireFormat.MESSAGE_SET_MESSAGE, value);
   }
 
+  /**
+   * Compute the number of bytes that would be needed to encode an
+   * lazily parsed MessageSet extension field to the stream.  For
+   * historical reasons, the wire format differs from normal fields.
+   */
+  public static int computeLazyFieldMessageSetExtensionSize(
+      final int fieldNumber, final LazyField value) {
+    return computeTagSize(WireFormat.MESSAGE_SET_ITEM) * 2 +
+           computeUInt32Size(WireFormat.MESSAGE_SET_TYPE_ID, fieldNumber) +
+           computeLazyFieldSize(WireFormat.MESSAGE_SET_MESSAGE, value);
+  }
+  
   // -----------------------------------------------------------------
 
   /**
@@ -730,6 +751,15 @@ public final class CodedOutputStream {
   }
 
   /**
+   * Compute the number of bytes that would be needed to encode an embedded
+   * message stored in lazy field.
+   */
+  public static int computeLazyFieldSizeNoTag(final LazyField value) {
+    final int size = value.getSerializedSize();
+    return computeRawVarint32Size(size) + size;
+  }
+
+  /**
    * Compute the number of bytes that would be needed to encode a
    * {@code bytes} field.
    */
diff --git a/java/src/main/java/com/google/protobuf/Descriptors.java b/java/src/main/java/com/google/protobuf/Descriptors.java
index 2ee84594..a4913053 100644
--- a/java/src/main/java/com/google/protobuf/Descriptors.java
+++ b/java/src/main/java/com/google/protobuf/Descriptors.java
@@ -35,8 +35,10 @@ import com.google.protobuf.DescriptorProtos.*;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.io.UnsupportedEncodingException;
 
 /**
@@ -106,6 +108,11 @@ public final class Descriptors {
       return Collections.unmodifiableList(Arrays.asList(dependencies));
     }
 
+    /** Get a list of this file's public dependencies (public imports). */
+    public List<FileDescriptor> getPublicDependencies() {
+      return Collections.unmodifiableList(Arrays.asList(publicDependencies));
+    }
+
     /**
      * Find a message type in the file by name.  Does not find nested types.
      *
@@ -216,7 +223,7 @@ public final class Descriptors {
     public static FileDescriptor buildFrom(final FileDescriptorProto proto,
                                            final FileDescriptor[] dependencies)
                                     throws DescriptorValidationException {
-      // Building decsriptors involves two steps:  translating and linking.
+      // Building descriptors involves two steps:  translating and linking.
       // In the translation step (implemented by FileDescriptor's
       // constructor), we build an object tree mirroring the
       // FileDescriptorProto's tree and put all of the descriptors into the
@@ -317,12 +324,12 @@ public final class Descriptors {
      * {@link FileDescriptor#internalBuildGeneratedFileFrom}, the caller
      * provides a callback implementing this interface.  The callback is called
      * after the FileDescriptor has been constructed, in order to assign all
-     * the global variales defined in the generated code which point at parts
+     * the global variables defined in the generated code which point at parts
      * of the FileDescriptor.  The callback returns an ExtensionRegistry which
      * contains any extensions which might be used in the descriptor -- that
      * is, extensions of the various "Options" messages defined in
      * descriptor.proto.  The callback may also return null to indicate that
-     * no extensions are used in the decsriptor.
+     * no extensions are used in the descriptor.
      */
     public interface InternalDescriptorAssigner {
       ExtensionRegistry assignDescriptors(FileDescriptor root);
@@ -334,6 +341,7 @@ public final class Descriptors {
     private final ServiceDescriptor[] services;
     private final FieldDescriptor[] extensions;
     private final FileDescriptor[] dependencies;
+    private final FileDescriptor[] publicDependencies;
     private final DescriptorPool pool;
 
     private FileDescriptor(final FileDescriptorProto proto,
@@ -343,6 +351,17 @@ public final class Descriptors {
       this.pool = pool;
       this.proto = proto;
       this.dependencies = dependencies.clone();
+      this.publicDependencies =
+          new FileDescriptor[proto.getPublicDependencyCount()];
+      for (int i = 0; i < proto.getPublicDependencyCount(); i++) {
+        int index = proto.getPublicDependency(i);
+        if (index < 0 || index >= this.dependencies.length) {
+          throw new DescriptorValidationException(this,
+              "Invalid public dependency index.");
+        }
+        this.publicDependencies[i] =
+            this.dependencies[proto.getPublicDependency(i)];
+      }
 
       pool.addPackage(getPackage(), this);
 
@@ -390,7 +409,7 @@ public final class Descriptors {
      * in the original.  This method is needed for bootstrapping when a file
      * defines custom options.  The options may be defined in the file itself,
      * so we can't actually parse them until we've constructed the descriptors,
-     * but to construct the decsriptors we have to have parsed the descriptor
+     * but to construct the descriptors we have to have parsed the descriptor
      * protos.  So, we have to parse the descriptor protos a second time after
      * constructing the descriptors.
      */
@@ -641,7 +660,7 @@ public final class Descriptors {
                  FieldSet.FieldDescriptorLite<FieldDescriptor> {
     /**
      * Get the index of this descriptor within its parent.
-     * @see Descriptor#getIndex()
+     * @see Descriptors.Descriptor#getIndex()
      */
     public int getIndex() { return index; }
 
@@ -656,7 +675,7 @@ public final class Descriptors {
 
     /**
      * Get the field's fully-qualified name.
-     * @see Descriptor#getFullName()
+     * @see Descriptors.Descriptor#getFullName()
      */
     public String getFullName() { return fullName; }
 
@@ -943,7 +962,8 @@ public final class Descriptors {
     private void crossLink() throws DescriptorValidationException {
       if (proto.hasExtendee()) {
         final GenericDescriptor extendee =
-          file.pool.lookupSymbol(proto.getExtendee(), this);
+          file.pool.lookupSymbol(proto.getExtendee(), this,
+              DescriptorPool.SearchFilter.TYPES_ONLY);
         if (!(extendee instanceof Descriptor)) {
           throw new DescriptorValidationException(this,
               '\"' + proto.getExtendee() + "\" is not a message type.");
@@ -960,7 +980,8 @@ public final class Descriptors {
 
       if (proto.hasTypeName()) {
         final GenericDescriptor typeDescriptor =
-          file.pool.lookupSymbol(proto.getTypeName(), this);
+          file.pool.lookupSymbol(proto.getTypeName(), this,
+              DescriptorPool.SearchFilter.TYPES_ONLY);
 
         if (!proto.hasType()) {
           // Choose field type based on symbol.
@@ -1149,7 +1170,7 @@ public final class Descriptors {
       implements GenericDescriptor, Internal.EnumLiteMap<EnumValueDescriptor> {
     /**
      * Get the index of this descriptor within its parent.
-     * @see Descriptor#getIndex()
+     * @see Descriptors.Descriptor#getIndex()
      */
     public int getIndex() { return index; }
 
@@ -1161,7 +1182,7 @@ public final class Descriptors {
 
     /**
      * Get the type's fully-qualified name.
-     * @see Descriptor#getFullName()
+     * @see Descriptors.Descriptor#getFullName()
      */
     public String getFullName() { return fullName; }
 
@@ -1182,7 +1203,7 @@ public final class Descriptors {
     /**
      * Find an enum value by name.
      * @param name The unqualified name of the value (e.g. "FOO").
-     * @return the value's decsriptor, or {@code null} if not found.
+     * @return the value's descriptor, or {@code null} if not found.
      */
     public EnumValueDescriptor findValueByName(final String name) {
       final GenericDescriptor result =
@@ -1198,7 +1219,7 @@ public final class Descriptors {
      * Find an enum value by number.  If multiple enum values have the same
      * number, this returns the first defined value with that number.
      * @param number The value's number.
-     * @return the value's decsriptor, or {@code null} if not found.
+     * @return the value's descriptor, or {@code null} if not found.
      */
     public EnumValueDescriptor findValueByNumber(final int number) {
       return file.pool.enumValuesByNumber.get(
@@ -1261,7 +1282,7 @@ public final class Descriptors {
       implements GenericDescriptor, Internal.EnumLite {
     /**
      * Get the index of this descriptor within its parent.
-     * @see Descriptor#getIndex()
+     * @see Descriptors.Descriptor#getIndex()
      */
     public int getIndex() { return index; }
 
@@ -1276,7 +1297,7 @@ public final class Descriptors {
 
     /**
      * Get the value's fully-qualified name.
-     * @see Descriptor#getFullName()
+     * @see Descriptors.Descriptor#getFullName()
      */
     public String getFullName() { return fullName; }
 
@@ -1337,7 +1358,7 @@ public final class Descriptors {
 
     /**
      * Get the type's fully-qualified name.
-     * @see Descriptor#getFullName()
+     * @see Descriptors.Descriptor#getFullName()
      */
     public String getFullName() { return fullName; }
 
@@ -1355,7 +1376,7 @@ public final class Descriptors {
     /**
      * Find a method by name.
      * @param name The unqualified name of the method (e.g. "Foo").
-     * @return the method's decsriptor, or {@code null} if not found.
+     * @return the method's descriptor, or {@code null} if not found.
      */
     public MethodDescriptor findMethodByName(final String name) {
       final GenericDescriptor result =
@@ -1427,7 +1448,7 @@ public final class Descriptors {
 
     /**
      * Get the method's fully-qualified name.
-     * @see Descriptor#getFullName()
+     * @see Descriptors.Descriptor#getFullName()
      */
     public String getFullName() { return fullName; }
 
@@ -1475,7 +1496,8 @@ public final class Descriptors {
 
     private void crossLink() throws DescriptorValidationException {
       final GenericDescriptor input =
-        file.pool.lookupSymbol(proto.getInputType(), this);
+        file.pool.lookupSymbol(proto.getInputType(), this,
+            DescriptorPool.SearchFilter.TYPES_ONLY);
       if (!(input instanceof Descriptor)) {
         throw new DescriptorValidationException(this,
             '\"' + proto.getInputType() + "\" is not a message type.");
@@ -1483,7 +1505,8 @@ public final class Descriptors {
       inputType = (Descriptor)input;
 
       final GenericDescriptor output =
-        file.pool.lookupSymbol(proto.getOutputType(), this);
+        file.pool.lookupSymbol(proto.getOutputType(), this,
+            DescriptorPool.SearchFilter.TYPES_ONLY);
       if (!(output instanceof Descriptor)) {
         throw new DescriptorValidationException(this,
             '\"' + proto.getOutputType() + "\" is not a message type.");
@@ -1535,7 +1558,7 @@ public final class Descriptors {
     public String getProblemSymbolName() { return name; }
 
     /**
-     * Gets the the protocol message representation of the invalid descriptor.
+     * Gets the protocol message representation of the invalid descriptor.
      */
     public Message getProblemProto() { return proto; }
 
@@ -1590,14 +1613,22 @@ public final class Descriptors {
    * descriptors defined in a particular file.
    */
   private static final class DescriptorPool {
+    
+    /** Defines what subclass of descriptors to search in the descriptor pool. 
+     */
+    enum SearchFilter {
+      TYPES_ONLY, AGGREGATES_ONLY, ALL_SYMBOLS
+    }
+    
     DescriptorPool(final FileDescriptor[] dependencies) {
-      this.dependencies = new DescriptorPool[dependencies.length];
+      this.dependencies = new HashSet<FileDescriptor>();
 
-      for (int i = 0; i < dependencies.length; i++)  {
-        this.dependencies[i] = dependencies[i].pool;
+      for (int i = 0; i < dependencies.length; i++) {
+        this.dependencies.add(dependencies[i]);
+        importPublicDependencies(dependencies[i]);
       }
 
-      for (final FileDescriptor dependency : dependencies) {
+      for (final FileDescriptor dependency : this.dependencies) {
         try {
           addPackage(dependency.getPackage(), dependency);
         } catch (DescriptorValidationException e) {
@@ -1609,7 +1640,16 @@ public final class Descriptors {
       }
     }
 
-    private final DescriptorPool[] dependencies;
+    /** Find and put public dependencies of the file into dependencies set.*/
+    private void importPublicDependencies(final FileDescriptor file) {
+      for (FileDescriptor dependency : file.getPublicDependencies()) {
+        if (dependencies.add(dependency)) {
+          importPublicDependencies(dependency);
+        }
+      }
+    }
+
+    private final Set<FileDescriptor> dependencies;
 
     private final Map<String, GenericDescriptor> descriptorsByName =
       new HashMap<String, GenericDescriptor>();
@@ -1620,39 +1660,81 @@ public final class Descriptors {
 
     /** Find a generic descriptor by fully-qualified name. */
     GenericDescriptor findSymbol(final String fullName) {
+      return findSymbol(fullName, SearchFilter.ALL_SYMBOLS);
+    }
+    
+    /** Find a descriptor by fully-qualified name and given option to only 
+     * search valid field type descriptors. 
+     */
+    GenericDescriptor findSymbol(final String fullName,
+                                 final SearchFilter filter) {
       GenericDescriptor result = descriptorsByName.get(fullName);
       if (result != null) {
-        return result;
+        if ((filter==SearchFilter.ALL_SYMBOLS) ||
+            ((filter==SearchFilter.TYPES_ONLY) && isType(result)) ||
+            ((filter==SearchFilter.AGGREGATES_ONLY) && isAggregate(result))) {
+          return result;
+        }
       }
 
-      for (final DescriptorPool dependency : dependencies) {
-        result = dependency.descriptorsByName.get(fullName);
+      for (final FileDescriptor dependency : dependencies) {
+        result = dependency.pool.descriptorsByName.get(fullName);
         if (result != null) {
-          return result;
+          if ((filter==SearchFilter.ALL_SYMBOLS) ||
+              ((filter==SearchFilter.TYPES_ONLY) && isType(result)) ||
+              ((filter==SearchFilter.AGGREGATES_ONLY) && isAggregate(result))) {
+            return result;
+          }
         }
       }
 
       return null;
     }
 
+    /** Checks if the descriptor is a valid type for a message field. */
+    boolean isType(GenericDescriptor descriptor) {
+      return (descriptor instanceof Descriptor) || 
+        (descriptor instanceof EnumDescriptor);
+    }
+    
+    /** Checks if the descriptor is a valid namespace type. */
+    boolean isAggregate(GenericDescriptor descriptor) {
+      return (descriptor instanceof Descriptor) || 
+        (descriptor instanceof EnumDescriptor) || 
+        (descriptor instanceof PackageDescriptor) || 
+        (descriptor instanceof ServiceDescriptor);
+    }
+       
     /**
-     * Look up a descriptor by name, relative to some other descriptor.
+     * Look up a type descriptor by name, relative to some other descriptor.
      * The name may be fully-qualified (with a leading '.'),
      * partially-qualified, or unqualified.  C++-like name lookup semantics
      * are used to search for the matching descriptor.
      */
     GenericDescriptor lookupSymbol(final String name,
-                                   final GenericDescriptor relativeTo)
+                                   final GenericDescriptor relativeTo,
+                                   final DescriptorPool.SearchFilter filter)
                             throws DescriptorValidationException {
       // TODO(kenton):  This could be optimized in a number of ways.
 
       GenericDescriptor result;
       if (name.startsWith(".")) {
         // Fully-qualified name.
-        result = findSymbol(name.substring(1));
+        result = findSymbol(name.substring(1), filter);
       } else {
         // If "name" is a compound identifier, we want to search for the
         // first component of it, then search within it for the rest.
+        // If name is something like "Foo.Bar.baz", and symbols named "Foo" are
+        // defined in multiple parent scopes, we only want to find "Bar.baz" in
+        // the innermost one.  E.g., the following should produce an error:
+        //   message Bar { message Baz {} }
+        //   message Foo {
+        //     message Bar {
+        //     }
+        //     optional Bar.Baz baz = 1;
+        //   }
+        // So, we look for just "Foo" first, then look for "Bar.baz" within it
+        // if found.
         final int firstPartLength = name.indexOf('.');
         final String firstPart;
         if (firstPartLength == -1) {
@@ -1670,14 +1752,15 @@ public final class Descriptors {
           // Chop off the last component of the scope.
           final int dotpos = scopeToTry.lastIndexOf(".");
           if (dotpos == -1) {
-            result = findSymbol(name);
+            result = findSymbol(name, filter);
             break;
           } else {
             scopeToTry.setLength(dotpos + 1);
 
-            // Append firstPart and try to find.
+            // Append firstPart and try to find
             scopeToTry.append(firstPart);
-            result = findSymbol(scopeToTry.toString());
+            result = findSymbol(scopeToTry.toString(), 
+                DescriptorPool.SearchFilter.AGGREGATES_ONLY);
 
             if (result != null) {
               if (firstPartLength != -1) {
@@ -1686,7 +1769,7 @@ public final class Descriptors {
                 // searching parent scopes.
                 scopeToTry.setLength(dotpos + 1);
                 scopeToTry.append(name);
-                result = findSymbol(scopeToTry.toString());
+                result = findSymbol(scopeToTry.toString(), filter);
               }
               break;
             }
@@ -1817,7 +1900,7 @@ public final class Descriptors {
 
     /**
      * Adds a field to the fieldsByNumber table.  Throws an exception if a
-     * field with hte same containing type and number already exists.
+     * field with the same containing type and number already exists.
      */
     void addFieldByNumber(final FieldDescriptor field)
                    throws DescriptorValidationException {
diff --git a/java/src/main/java/com/google/protobuf/DynamicMessage.java b/java/src/main/java/com/google/protobuf/DynamicMessage.java
index c106b662..c0c9fc94 100644
--- a/java/src/main/java/com/google/protobuf/DynamicMessage.java
+++ b/java/src/main/java/com/google/protobuf/DynamicMessage.java
@@ -35,6 +35,7 @@ import com.google.protobuf.Descriptors.FieldDescriptor;
 
 import java.io.InputStream;
 import java.io.IOException;
+import java.util.Collections;
 import java.util.Map;
 
 /**
@@ -160,7 +161,9 @@ public final class DynamicMessage extends AbstractMessage {
     verifyContainingType(field);
     Object result = fields.getField(field);
     if (result == null) {
-      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+      if (field.isRepeated()) {
+        result = Collections.emptyList();
+      } else if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
         result = getDefaultInstance(field.getMessageType());
       } else {
         result = field.getDefaultValue();
@@ -198,10 +201,12 @@ public final class DynamicMessage extends AbstractMessage {
     return fields.isInitialized();
   }
 
+  @Override
   public boolean isInitialized() {
     return isInitialized(type, fields);
   }
 
+  @Override
   public void writeTo(CodedOutputStream output) throws IOException {
     if (type.getOptions().getMessageSetWireFormat()) {
       fields.writeMessageSetTo(output);
@@ -212,6 +217,7 @@ public final class DynamicMessage extends AbstractMessage {
     }
   }
 
+  @Override
   public int getSerializedSize() {
     int size = memoizedSize;
     if (size != -1) return size;
@@ -236,6 +242,26 @@ public final class DynamicMessage extends AbstractMessage {
     return newBuilderForType().mergeFrom(this);
   }
 
+  public Parser<DynamicMessage> getParserForType() {
+    return new AbstractParser<DynamicMessage>() {
+      public DynamicMessage parsePartialFrom(
+          CodedInputStream input,
+          ExtensionRegistryLite extensionRegistry)
+          throws InvalidProtocolBufferException {
+        Builder builder = newBuilder(type);
+        try {
+          builder.mergeFrom(input, extensionRegistry);
+        } catch (InvalidProtocolBufferException e) {
+          throw e.setUnfinishedMessage(builder.buildPartial());
+        } catch (IOException e) {
+          throw new InvalidProtocolBufferException(e.getMessage())
+              .setUnfinishedMessage(builder.buildPartial());
+        }
+        return builder.buildPartial();
+      }
+    };
+  }
+
   /** Verifies that the field is a field of this message. */
   private void verifyContainingType(FieldDescriptor field) {
     if (field.getContainingType() != type) {
@@ -264,14 +290,18 @@ public final class DynamicMessage extends AbstractMessage {
     // ---------------------------------------------------------------
     // Implementation of Message.Builder interface.
 
+    @Override
     public Builder clear() {
-      if (fields == null) {
-        throw new IllegalStateException("Cannot call clear() after build().");
+      if (fields.isImmutable()) {
+        fields = FieldSet.newFieldSet();
+      } else {
+        fields.clear();
       }
-      fields.clear();
+      unknownFields = UnknownFieldSet.getDefaultInstance();
       return this;
     }
 
+    @Override
     public Builder mergeFrom(Message other) {
       if (other instanceof DynamicMessage) {
         // This should be somewhat faster than calling super.mergeFrom().
@@ -280,6 +310,7 @@ public final class DynamicMessage extends AbstractMessage {
           throw new IllegalArgumentException(
             "mergeFrom(Message) can only merge messages of the same type.");
         }
+        ensureIsMutable();
         fields.mergeFrom(otherDynamicMessage.fields);
         mergeUnknownFields(otherDynamicMessage.unknownFields);
         return this;
@@ -289,8 +320,7 @@ public final class DynamicMessage extends AbstractMessage {
     }
 
     public DynamicMessage build() {
-      // If fields == null, we'll throw an appropriate exception later.
-      if (fields != null && !isInitialized()) {
+      if (!isInitialized()) {
         throw newUninitializedMessageException(
           new DynamicMessage(type, fields, unknownFields));
       }
@@ -312,21 +342,17 @@ public final class DynamicMessage extends AbstractMessage {
     }
 
     public DynamicMessage buildPartial() {
-      if (fields == null) {
-        throw new IllegalStateException(
-            "build() has already been called on this Builder.");
-      }
       fields.makeImmutable();
       DynamicMessage result =
         new DynamicMessage(type, fields, unknownFields);
-      fields = null;
-      unknownFields = null;
       return result;
     }
 
+    @Override
     public Builder clone() {
       Builder result = new Builder(type);
       result.fields.mergeFrom(fields);
+      result.mergeUnknownFields(unknownFields);
       return result;
     }
 
@@ -377,12 +403,14 @@ public final class DynamicMessage extends AbstractMessage {
 
     public Builder setField(FieldDescriptor field, Object value) {
       verifyContainingType(field);
+      ensureIsMutable();
       fields.setField(field, value);
       return this;
     }
 
     public Builder clearField(FieldDescriptor field) {
       verifyContainingType(field);
+      ensureIsMutable();
       fields.clearField(field);
       return this;
     }
@@ -400,12 +428,14 @@ public final class DynamicMessage extends AbstractMessage {
     public Builder setRepeatedField(FieldDescriptor field,
                                     int index, Object value) {
       verifyContainingType(field);
+      ensureIsMutable();
       fields.setRepeatedField(field, index, value);
       return this;
     }
 
     public Builder addRepeatedField(FieldDescriptor field, Object value) {
       verifyContainingType(field);
+      ensureIsMutable();
       fields.addRepeatedField(field, value);
       return this;
     }
@@ -419,6 +449,7 @@ public final class DynamicMessage extends AbstractMessage {
       return this;
     }
 
+    @Override
     public Builder mergeUnknownFields(UnknownFieldSet unknownFields) {
       this.unknownFields =
         UnknownFieldSet.newBuilder(this.unknownFields)
@@ -434,5 +465,18 @@ public final class DynamicMessage extends AbstractMessage {
           "FieldDescriptor does not match message type.");
       }
     }
+
+    private void ensureIsMutable() {
+      if (fields.isImmutable()) {
+        fields = fields.clone();
+      }
+    }
+
+    @Override
+    public com.google.protobuf.Message.Builder getFieldBuilder(FieldDescriptor field) {
+      // TODO(xiangl): need implementation for dynamic message
+      throw new UnsupportedOperationException(
+        "getFieldBuilder() called on a dynamic message type.");
+    }
   }
 }
diff --git a/java/src/main/java/com/google/protobuf/ExtensionRegistryLite.java b/java/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
index d5288dd8..1e1289d0 100644
--- a/java/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
+++ b/java/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
@@ -43,7 +43,7 @@ import java.util.Map;
  * make sense to mix the two, since if you have any regular types in your
  * program, you then require the full runtime and lose all the benefits of
  * the lite runtime, so you might as well make all your types be regular types.
- * However, in some cases (e.g. when depending on multiple third-patry libraries
+ * However, in some cases (e.g. when depending on multiple third-party libraries
  * where one uses lite types and one uses regular), you may find yourself
  * wanting to mix the two.  In this case things get more complicated.
  * <p>
@@ -71,6 +71,22 @@ import java.util.Map;
  * @author kenton@google.com Kenton Varda
  */
 public class ExtensionRegistryLite {
+
+  // Set true to enable lazy parsing feature for MessageSet.
+  //
+  // TODO(xiangl): Now we use a global flag to control whether enable lazy
+  // parsing feature for MessageSet, which may be too crude for some
+  // applications. Need to support this feature on smaller granularity.
+  private static volatile boolean eagerlyParseMessageSets = false;
+
+  public static boolean isEagerlyParseMessageSets() {
+    return eagerlyParseMessageSets;
+  }
+
+  public static void setEagerlyParseMessageSets(boolean isEagerlyParse) {
+    eagerlyParseMessageSets = isEagerlyParse;
+  }
+
   /** Construct a new, empty instance. */
   public static ExtensionRegistryLite newInstance() {
     return new ExtensionRegistryLite();
diff --git a/java/src/main/java/com/google/protobuf/FieldSet.java b/java/src/main/java/com/google/protobuf/FieldSet.java
index a85dbaa6..2663694f 100644
--- a/java/src/main/java/com/google/protobuf/FieldSet.java
+++ b/java/src/main/java/com/google/protobuf/FieldSet.java
@@ -30,12 +30,14 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.LazyField.LazyIterator;
+
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.io.IOException;
 
 /**
  * A class which represents an arbitrary set of fields of some message type.
@@ -68,6 +70,7 @@ final class FieldSet<FieldDescriptorType extends
 
   private final SmallSortedMap<FieldDescriptorType, Object> fields;
   private boolean isImmutable;
+  private boolean hasLazyField = false;
 
   /** Construct a new FieldSet. */
   private FieldSet() {
@@ -95,7 +98,7 @@ final class FieldSet<FieldDescriptorType extends
       FieldSet<T> emptySet() {
     return DEFAULT_INSTANCE;
   }
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("rawtypes")
   private static final FieldSet DEFAULT_INSTANCE = new FieldSet(true);
 
   /** Make this FieldSet immutable from this point forward. */
@@ -109,7 +112,7 @@ final class FieldSet<FieldDescriptorType extends
   }
 
   /**
-   * Retuns whether the FieldSet is immutable. This is true if it is the
+   * Returns whether the FieldSet is immutable. This is true if it is the
    * {@link #emptySet} or if {@link #makeImmutable} were called.
    *
    * @return whether the FieldSet is immutable.
@@ -139,6 +142,7 @@ final class FieldSet<FieldDescriptorType extends
       FieldDescriptorType descriptor = entry.getKey();
       clone.setField(descriptor, entry.getValue());
     }
+    clone.hasLazyField = hasLazyField;
     return clone;
   }
 
@@ -147,21 +151,52 @@ final class FieldSet<FieldDescriptorType extends
   /** See {@link Message.Builder#clear()}. */
   public void clear() {
     fields.clear();
+    hasLazyField = false;
   }
 
   /**
    * Get a simple map containing all the fields.
    */
   public Map<FieldDescriptorType, Object> getAllFields() {
+    if (hasLazyField) {
+      SmallSortedMap<FieldDescriptorType, Object> result =
+          SmallSortedMap.newFieldMap(16);
+      for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+        cloneFieldEntry(result, fields.getArrayEntryAt(i));
+      }
+      for (Map.Entry<FieldDescriptorType, Object> entry :
+          fields.getOverflowEntries()) {
+        cloneFieldEntry(result, entry);
+      }
+      if (fields.isImmutable()) {
+        result.makeImmutable();
+      }
+      return result;
+    }
     return fields.isImmutable() ? fields : Collections.unmodifiableMap(fields);
   }
 
+  private void cloneFieldEntry(Map<FieldDescriptorType, Object> map,
+      Map.Entry<FieldDescriptorType, Object> entry) {
+    FieldDescriptorType key = entry.getKey();
+    Object value = entry.getValue();
+    if (value instanceof LazyField) {
+      map.put(key, ((LazyField) value).getValue());
+    } else {
+      map.put(key, value);
+    }
+  }
+
   /**
    * Get an iterator to the field map. This iterator should not be leaked out
-   * of the protobuf library as it is not protected from mutation when
-   * fields is not immutable.
+   * of the protobuf library as it is not protected from mutation when fields
+   * is not immutable.
    */
   public Iterator<Map.Entry<FieldDescriptorType, Object>> iterator() {
+    if (hasLazyField) {
+      return new LazyIterator<FieldDescriptorType>(
+          fields.entrySet().iterator());
+    }
     return fields.entrySet().iterator();
   }
 
@@ -185,14 +220,18 @@ final class FieldSet<FieldDescriptorType extends
    * to the caller to fetch the field's default value.
    */
   public Object getField(final FieldDescriptorType descriptor) {
-    return fields.get(descriptor);
+    Object o = fields.get(descriptor);
+    if (o instanceof LazyField) {
+      return ((LazyField) o).getValue();
+    }
+    return o;
   }
 
   /**
    * Useful for implementing
    * {@link Message.Builder#setField(Descriptors.FieldDescriptor,Object)}.
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "rawtypes"})
   public void setField(final FieldDescriptorType descriptor,
                        Object value) {
     if (descriptor.isRepeated()) {
@@ -204,7 +243,7 @@ final class FieldSet<FieldDescriptorType extends
       // Wrap the contents in a new list so that the caller cannot change
       // the list's contents after setting it.
       final List newList = new ArrayList();
-      newList.addAll((List)value);
+      newList.addAll((List) value);
       for (final Object element : newList) {
         verifyType(descriptor.getLiteType(), element);
       }
@@ -213,6 +252,9 @@ final class FieldSet<FieldDescriptorType extends
       verifyType(descriptor.getLiteType(), value);
     }
 
+    if (value instanceof LazyField) {
+      hasLazyField = true;
+    }
     fields.put(descriptor, value);
   }
 
@@ -222,6 +264,9 @@ final class FieldSet<FieldDescriptorType extends
    */
   public void clearField(final FieldDescriptorType descriptor) {
     fields.remove(descriptor);
+    if (fields.isEmpty()) {
+      hasLazyField = false;
+    }
   }
 
   /**
@@ -234,7 +279,7 @@ final class FieldSet<FieldDescriptorType extends
         "getRepeatedField() can only be called on repeated fields.");
     }
 
-    final Object value = fields.get(descriptor);
+    final Object value = getField(descriptor);
     if (value == null) {
       return 0;
     } else {
@@ -253,7 +298,7 @@ final class FieldSet<FieldDescriptorType extends
         "getRepeatedField() can only be called on repeated fields.");
     }
 
-    final Object value = fields.get(descriptor);
+    final Object value = getField(descriptor);
 
     if (value == null) {
       throw new IndexOutOfBoundsException();
@@ -275,13 +320,13 @@ final class FieldSet<FieldDescriptorType extends
         "getRepeatedField() can only be called on repeated fields.");
     }
 
-    final Object list = fields.get(descriptor);
+    final Object list = getField(descriptor);
     if (list == null) {
       throw new IndexOutOfBoundsException();
     }
 
     verifyType(descriptor.getLiteType(), value);
-    ((List) list).set(index, value);
+    ((List<Object>) list).set(index, value);
   }
 
   /**
@@ -298,13 +343,13 @@ final class FieldSet<FieldDescriptorType extends
 
     verifyType(descriptor.getLiteType(), value);
 
-    final Object existingValue = fields.get(descriptor);
-    List list;
+    final Object existingValue = getField(descriptor);
+    List<Object> list;
     if (existingValue == null) {
-      list = new ArrayList();
+      list = new ArrayList<Object>();
       fields.put(descriptor, list);
     } else {
-      list = (List) existingValue;
+      list = (List<Object>) existingValue;
     }
 
     list.add(value);
@@ -338,7 +383,8 @@ final class FieldSet<FieldDescriptorType extends
         break;
       case MESSAGE:
         // TODO(kenton):  Caller must do type checking here, I guess.
-        isValid = value instanceof MessageLite;
+        isValid =
+            (value instanceof MessageLite) || (value instanceof LazyField);
         break;
     }
 
@@ -392,8 +438,16 @@ final class FieldSet<FieldDescriptorType extends
           }
         }
       } else {
-        if (!((MessageLite) entry.getValue()).isInitialized()) {
-          return false;
+        Object value = entry.getValue();
+        if (value instanceof MessageLite) {
+          if (!((MessageLite) value).isInitialized()) {
+            return false;
+          }
+        } else if (value instanceof LazyField) {
+          return true;
+        } else {
+          throw new IllegalArgumentException(
+              "Wrong object type used with protocol message reflection.");
         }
       }
     }
@@ -416,7 +470,8 @@ final class FieldSet<FieldDescriptorType extends
   }
 
   /**
-   * Like {@link #mergeFrom(Message)}, but merges from another {@link FieldSet}.
+   * Like {@link Message.Builder#mergeFrom(Message)}, but merges from another 
+   * {@link FieldSet}.
    */
   public void mergeFrom(final FieldSet<FieldDescriptorType> other) {
     for (int i = 0; i < other.fields.getNumArrayEntries(); i++) {
@@ -428,14 +483,17 @@ final class FieldSet<FieldDescriptorType extends
     }
   }
 
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "rawtypes"})
   private void mergeFromField(
       final Map.Entry<FieldDescriptorType, Object> entry) {
     final FieldDescriptorType descriptor = entry.getKey();
-    final Object otherValue = entry.getValue();
+    Object otherValue = entry.getValue();
+    if (otherValue instanceof LazyField) {
+      otherValue = ((LazyField) otherValue).getValue();
+    }
 
     if (descriptor.isRepeated()) {
-      Object value = fields.get(descriptor);
+      Object value = getField(descriptor);
       if (value == null) {
         // Our list is empty, but we still need to make a defensive copy of
         // the other list since we don't know if the other FieldSet is still
@@ -446,7 +504,7 @@ final class FieldSet<FieldDescriptorType extends
         ((List) value).addAll((List) otherValue);
       }
     } else if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE) {
-      Object value = fields.get(descriptor);
+      Object value = getField(descriptor);
       if (value == null) {
         fields.put(descriptor, otherValue);
       } else {
@@ -457,7 +515,6 @@ final class FieldSet<FieldDescriptorType extends
                 ((MessageLite) value).toBuilder(), (MessageLite) otherValue)
             .build());
       }
-
     } else {
       fields.put(descriptor, otherValue);
     }
@@ -646,7 +703,11 @@ final class FieldSet<FieldDescriptorType extends
         }
       }
     } else {
-      writeElement(output, type, number, value);
+      if (value instanceof LazyField) {
+        writeElement(output, type, number, ((LazyField) value).getValue());
+      } else {
+        writeElement(output, type, number, value);
+      }
     }
   }
 
@@ -686,12 +747,18 @@ final class FieldSet<FieldDescriptorType extends
   private int getMessageSetSerializedSize(
       final Map.Entry<FieldDescriptorType, Object> entry) {
     final FieldDescriptorType descriptor = entry.getKey();
-    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE &&
-        !descriptor.isRepeated() && !descriptor.isPacked()) {
-      return CodedOutputStream.computeMessageSetExtensionSize(
-          entry.getKey().getNumber(), (MessageLite) entry.getValue());
+    Object value = entry.getValue();
+    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE
+        && !descriptor.isRepeated() && !descriptor.isPacked()) {
+      if (value instanceof LazyField) {
+        return CodedOutputStream.computeLazyFieldMessageSetExtensionSize(
+            entry.getKey().getNumber(), (LazyField) value);
+      } else {
+        return CodedOutputStream.computeMessageSetExtensionSize(
+            entry.getKey().getNumber(), (MessageLite) value);
+      }
     } else {
-      return computeFieldSize(descriptor, entry.getValue());
+      return computeFieldSize(descriptor, value);
     }
   }
 
@@ -741,7 +808,6 @@ final class FieldSet<FieldDescriptorType extends
       case BOOL    : return CodedOutputStream.computeBoolSizeNoTag    ((Boolean    )value);
       case STRING  : return CodedOutputStream.computeStringSizeNoTag  ((String     )value);
       case GROUP   : return CodedOutputStream.computeGroupSizeNoTag   ((MessageLite)value);
-      case MESSAGE : return CodedOutputStream.computeMessageSizeNoTag ((MessageLite)value);
       case BYTES   : return CodedOutputStream.computeBytesSizeNoTag   ((ByteString )value);
       case UINT32  : return CodedOutputStream.computeUInt32SizeNoTag  ((Integer    )value);
       case SFIXED32: return CodedOutputStream.computeSFixed32SizeNoTag((Integer    )value);
@@ -749,6 +815,13 @@ final class FieldSet<FieldDescriptorType extends
       case SINT32  : return CodedOutputStream.computeSInt32SizeNoTag  ((Integer    )value);
       case SINT64  : return CodedOutputStream.computeSInt64SizeNoTag  ((Long       )value);
 
+      case MESSAGE:
+        if (value instanceof LazyField) {
+          return CodedOutputStream.computeLazyFieldSizeNoTag((LazyField) value);
+        } else {
+          return CodedOutputStream.computeMessageSizeNoTag((MessageLite) value);
+        }
+
       case ENUM:
         return CodedOutputStream.computeEnumSizeNoTag(
             ((Internal.EnumLite) value).getNumber());
diff --git a/java/src/main/java/com/google/protobuf/GeneratedMessage.java b/java/src/main/java/com/google/protobuf/GeneratedMessage.java
index b5eaded5..0c15ca84 100644
--- a/java/src/main/java/com/google/protobuf/GeneratedMessage.java
+++ b/java/src/main/java/com/google/protobuf/GeneratedMessage.java
@@ -58,8 +58,6 @@ public abstract class GeneratedMessage extends AbstractMessage
     implements Serializable {
   private static final long serialVersionUID = 1L;
 
-  private final UnknownFieldSet unknownFields;
-
   /**
    * For testing. Allows a test to disable the optimization that avoids using
    * field builders for nested messages until they are requested. By disabling
@@ -68,11 +66,14 @@ public abstract class GeneratedMessage extends AbstractMessage
   protected static boolean alwaysUseFieldBuilders = false;
 
   protected GeneratedMessage() {
-    this.unknownFields = UnknownFieldSet.getDefaultInstance();
   }
 
   protected GeneratedMessage(Builder<?> builder) {
-    this.unknownFields = builder.getUnknownFields();
+  }
+
+  public Parser<? extends Message> getParserForType() {
+    throw new UnsupportedOperationException(
+        "This is supposed to be overridden by subclasses.");
   }
 
  /**
@@ -175,8 +176,28 @@ public abstract class GeneratedMessage extends AbstractMessage
   }
 
   //@Override (Java 1.6 override semantics, but we must support 1.5)
-  public final UnknownFieldSet getUnknownFields() {
-    return unknownFields;
+  public UnknownFieldSet getUnknownFields() {
+    throw new UnsupportedOperationException(
+        "This is supposed to be overridden by subclasses.");
+  }
+
+  /**
+   * Called by subclasses to parse an unknown field.
+   * @return {@code true} unless the tag is an end-group tag.
+   */
+  protected boolean parseUnknownField(
+      CodedInputStream input,
+      UnknownFieldSet.Builder unknownFields,
+      ExtensionRegistryLite extensionRegistry,
+      int tag) throws IOException {
+    return unknownFields.mergeFieldFrom(tag, input);
+  }
+
+  /**
+   * Used by parsing constructors in generated classes.
+   */
+  protected void makeExtensionsImmutable() {
+    // Noop for messages without extensions.
   }
 
   protected abstract Message.Builder newBuilderForType(BuilderParent parent);
@@ -319,6 +340,11 @@ public abstract class GeneratedMessage extends AbstractMessage
     }
 
     //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public Message.Builder getFieldBuilder(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).getBuilder(this);
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
     public boolean hasField(final FieldDescriptor field) {
       return internalGetFieldAccessorTable().getField(field).has(this);
     }
@@ -626,6 +652,25 @@ public abstract class GeneratedMessage extends AbstractMessage
       return super.isInitialized() && extensionsAreInitialized();
     }
 
+    @Override
+    protected boolean parseUnknownField(
+        CodedInputStream input,
+        UnknownFieldSet.Builder unknownFields,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
+      return AbstractMessage.Builder.mergeFieldFrom(
+        input, unknownFields, extensionRegistry, getDescriptorForType(),
+        null, extensions, tag);
+    }
+
+    /**
+     * Used by parsing constructors in generated classes.
+     */
+    @Override
+    protected void makeExtensionsImmutable() {
+      extensions.makeImmutable();
+    }
+
     /**
      * Used by subclasses to serialize extensions.  Extension ranges may be
      * interleaved with field numbers, but we must write them in canonical
@@ -655,9 +700,21 @@ public abstract class GeneratedMessage extends AbstractMessage
           if (messageSetWireFormat && descriptor.getLiteJavaType() ==
                   WireFormat.JavaType.MESSAGE &&
               !descriptor.isRepeated()) {
-            output.writeMessageSetExtension(descriptor.getNumber(),
-                                            (Message) next.getValue());
+            if (next instanceof LazyField.LazyEntry<?>) {
+              output.writeRawMessageSetExtension(descriptor.getNumber(),
+                  ((LazyField.LazyEntry<?>) next).getField().toByteString());
+            } else {
+              output.writeMessageSetExtension(descriptor.getNumber(),
+                                              (Message) next.getValue());
+            }
           } else {
+            // TODO(xiangl): Taken care of following code, it may cause
+            // problem when we use LazyField for normal fields/extensions.
+            // Due to the optional field can be duplicated at the end of
+            // serialized bytes, which will make the serialized size change
+            // after lazy field parsed. So when we use LazyField globally,
+            // we need to change the following write method to write cached
+            // bytes directly rather than write the parsed message.
             FieldSet.writeField(descriptor, next.getValue(), output);
           }
           if (iter.hasNext()) {
@@ -974,7 +1031,8 @@ public abstract class GeneratedMessage extends AbstractMessage
         final ExtensionRegistryLite extensionRegistry,
         final int tag) throws IOException {
       return AbstractMessage.Builder.mergeFieldFrom(
-        input, unknownFields, extensionRegistry, this, tag);
+        input, unknownFields, extensionRegistry, getDescriptorForType(),
+        this, null, tag);
     }
 
     // ---------------------------------------------------------------
@@ -1405,39 +1463,72 @@ public abstract class GeneratedMessage extends AbstractMessage
         final String[] camelCaseNames,
         final Class<? extends GeneratedMessage> messageClass,
         final Class<? extends Builder> builderClass) {
+      this(descriptor, camelCaseNames);
+      ensureFieldAccessorsInitialized(messageClass, builderClass);
+    }
+
+    /**
+     * Construct a FieldAccessorTable for a particular message class without
+     * initializing FieldAccessors.
+     */
+    public FieldAccessorTable(
+        final Descriptor descriptor,
+        final String[] camelCaseNames) {
       this.descriptor = descriptor;
+      this.camelCaseNames = camelCaseNames;
       fields = new FieldAccessor[descriptor.getFields().size()];
+      initialized = false;
+    }
 
-      for (int i = 0; i < fields.length; i++) {
-        final FieldDescriptor field = descriptor.getFields().get(i);
-        if (field.isRepeated()) {
-          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
-            fields[i] = new RepeatedMessageFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
-          } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
-            fields[i] = new RepeatedEnumFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
-          } else {
-            fields[i] = new RepeatedFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
-          }
-        } else {
-          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
-            fields[i] = new SingularMessageFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
-          } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
-            fields[i] = new SingularEnumFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
+    /**
+     * Ensures the field accessors are initialized. This method is thread-safe.
+     *
+     * @param messageClass   The message type.
+     * @param builderClass   The builder type.
+     * @return this
+     */
+    public FieldAccessorTable ensureFieldAccessorsInitialized(
+        Class<? extends GeneratedMessage> messageClass,
+        Class<? extends Builder> builderClass) {
+      if (initialized) { return this; }
+      synchronized (this) {
+        if (initialized) { return this; }
+        for (int i = 0; i < fields.length; i++) {
+          FieldDescriptor field = descriptor.getFields().get(i);
+          if (field.isRepeated()) {
+            if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+              fields[i] = new RepeatedMessageFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+              fields[i] = new RepeatedEnumFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            } else {
+              fields[i] = new RepeatedFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            }
           } else {
-            fields[i] = new SingularFieldAccessor(
-              field, camelCaseNames[i], messageClass, builderClass);
+            if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+              fields[i] = new SingularMessageFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+              fields[i] = new SingularEnumFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            } else {
+              fields[i] = new SingularFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            }
           }
         }
+        initialized = true;
+        camelCaseNames = null;
+        return this;
       }
     }
 
     private final Descriptor descriptor;
     private final FieldAccessor[] fields;
+    private String[] camelCaseNames;
+    private volatile boolean initialized;
 
     /** Get the FieldAccessor for a particular field. */
     private FieldAccessor getField(final FieldDescriptor field) {
@@ -1472,6 +1563,7 @@ public abstract class GeneratedMessage extends AbstractMessage
       int getRepeatedCount(GeneratedMessage.Builder builder);
       void clear(Builder builder);
       Message.Builder newBuilder();
+      Message.Builder getBuilder(GeneratedMessage.Builder builder);
     }
 
     // ---------------------------------------------------------------
@@ -1551,6 +1643,10 @@ public abstract class GeneratedMessage extends AbstractMessage
         throw new UnsupportedOperationException(
           "newBuilderForField() called on a non-Message type.");
       }
+      public Message.Builder getBuilder(GeneratedMessage.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getFieldBuilder() called on a non-Message type.");
+      }
     }
 
     private static class RepeatedFieldAccessor implements FieldAccessor {
@@ -1573,8 +1669,6 @@ public abstract class GeneratedMessage extends AbstractMessage
                                    "get" + camelCaseName + "List");
         getMethodBuilder = getMethodOrDie(builderClass,
                                    "get" + camelCaseName + "List");
-
-
         getRepeatedMethod =
             getMethodOrDie(messageClass, "get" + camelCaseName, Integer.TYPE);
         getRepeatedMethodBuilder =
@@ -1625,11 +1719,11 @@ public abstract class GeneratedMessage extends AbstractMessage
       }
       public boolean has(final GeneratedMessage message) {
         throw new UnsupportedOperationException(
-          "hasField() called on a singular field.");
+          "hasField() called on a repeated field.");
       }
       public boolean has(GeneratedMessage.Builder builder) {
         throw new UnsupportedOperationException(
-          "hasField() called on a singular field.");
+          "hasField() called on a repeated field.");
       }
       public int getRepeatedCount(final GeneratedMessage message) {
         return (Integer) invokeOrDie(getCountMethod, message);
@@ -1644,6 +1738,10 @@ public abstract class GeneratedMessage extends AbstractMessage
         throw new UnsupportedOperationException(
           "newBuilderForField() called on a non-Message type.");
       }
+      public Message.Builder getBuilder(GeneratedMessage.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getFieldBuilder() called on a non-Message type.");
+      }
     }
 
     // ---------------------------------------------------------------
@@ -1753,9 +1851,12 @@ public abstract class GeneratedMessage extends AbstractMessage
         super(descriptor, camelCaseName, messageClass, builderClass);
 
         newBuilderMethod = getMethodOrDie(type, "newBuilder");
+        getBuilderMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName + "Builder");
       }
 
       private final Method newBuilderMethod;
+      private final Method getBuilderMethodBuilder;
 
       private Object coerceType(final Object value) {
         if (type.isInstance(value)) {
@@ -1766,7 +1867,7 @@ public abstract class GeneratedMessage extends AbstractMessage
           // DynamicMessage -- we should accept it.  In this case we can make
           // a copy of the message.
           return ((Message.Builder) invokeOrDie(newBuilderMethod, null))
-                  .mergeFrom((Message) value).build();
+                  .mergeFrom((Message) value).buildPartial();
         }
       }
 
@@ -1778,6 +1879,10 @@ public abstract class GeneratedMessage extends AbstractMessage
       public Message.Builder newBuilder() {
         return (Message.Builder) invokeOrDie(newBuilderMethod, null);
       }
+      @Override
+      public Message.Builder getBuilder(GeneratedMessage.Builder builder) {
+        return (Message.Builder) invokeOrDie(getBuilderMethodBuilder, builder);
+      }
     }
 
     private static final class RepeatedMessageFieldAccessor
@@ -1825,7 +1930,7 @@ public abstract class GeneratedMessage extends AbstractMessage
   /**
    * Replaces this object in the output stream with a serialized form.
    * Part of Java's serialization magic.  Generated sub-classes must override
-   * this method by calling <code>return super.writeReplace();</code>
+   * this method by calling {@code return super.writeReplace();}
    * @return a SerializedForm of this message
    */
   protected Object writeReplace() throws ObjectStreamException {
diff --git a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
index 1813e9b3..437e3412 100644
--- a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
+++ b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
@@ -55,6 +55,29 @@ public abstract class GeneratedMessageLite extends AbstractMessageLite
   protected GeneratedMessageLite(Builder builder) {
   }
 
+  public Parser<? extends MessageLite> getParserForType() {
+    throw new UnsupportedOperationException(
+        "This is supposed to be overridden by subclasses.");
+  }
+
+  /**
+   * Called by subclasses to parse an unknown field.
+   * @return {@code true} unless the tag is an end-group tag.
+   */
+  protected boolean parseUnknownField(
+      CodedInputStream input,
+      ExtensionRegistryLite extensionRegistry,
+      int tag) throws IOException {
+    return input.skipField(tag);
+  }
+
+  /**
+   * Used by parsing constructors in generated classes.
+   */
+  protected void makeExtensionsImmutable() {
+    // Noop for messages without extensions.
+  }
+
   @SuppressWarnings("unchecked")
   public abstract static class Builder<MessageType extends GeneratedMessageLite,
                                        BuilderType extends Builder>
@@ -86,9 +109,9 @@ public abstract class GeneratedMessageLite extends AbstractMessageLite
      * @return {@code true} unless the tag is an end-group tag.
      */
     protected boolean parseUnknownField(
-        final CodedInputStream input,
-        final ExtensionRegistryLite extensionRegistry,
-        final int tag) throws IOException {
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
       return input.skipField(tag);
     }
   }
@@ -194,6 +217,31 @@ public abstract class GeneratedMessageLite extends AbstractMessageLite
     }
 
     /**
+     * Called by subclasses to parse an unknown field or an extension.
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    @Override
+    protected boolean parseUnknownField(
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
+      return GeneratedMessageLite.parseUnknownField(
+          extensions,
+          getDefaultInstanceForType(),
+          input,
+          extensionRegistry,
+          tag);
+    }
+
+    /**
+     * Used by parsing constructors in generated classes.
+     */
+    @Override
+    protected void makeExtensionsImmutable() {
+      extensions.makeImmutable();
+    }
+
+    /**
      * Used by subclasses to serialize extensions.  Extension ranges may be
      * interleaved with field numbers, but we must write them in canonical
      * (sorted by field number) order.  ExtensionWriter helps us write
@@ -400,121 +448,139 @@ public abstract class GeneratedMessageLite extends AbstractMessageLite
      */
     @Override
     protected boolean parseUnknownField(
-        final CodedInputStream input,
-        final ExtensionRegistryLite extensionRegistry,
-        final int tag) throws IOException {
-      final int wireType = WireFormat.getTagWireType(tag);
-      final int fieldNumber = WireFormat.getTagFieldNumber(tag);
-
-      final GeneratedExtension<MessageType, ?> extension =
-        extensionRegistry.findLiteExtensionByNumber(
-            getDefaultInstanceForType(), fieldNumber);
-
-      boolean unknown = false;
-      boolean packed = false;
-      if (extension == null) {
-        unknown = true;  // Unknown field.
-      } else if (wireType == FieldSet.getWireFormatForFieldType(
-                   extension.descriptor.getLiteType(),
-                   false  /* isPacked */)) {
-        packed = false;  // Normal, unpacked value.
-      } else if (extension.descriptor.isRepeated &&
-                 extension.descriptor.type.isPackable() &&
-                 wireType == FieldSet.getWireFormatForFieldType(
-                   extension.descriptor.getLiteType(),
-                   true  /* isPacked */)) {
-        packed = true;  // Packed value.
-      } else {
-        unknown = true;  // Wrong wire type.
-      }
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
+      ensureExtensionsIsMutable();
+      return GeneratedMessageLite.parseUnknownField(
+          extensions,
+          getDefaultInstanceForType(),
+          input,
+          extensionRegistry,
+          tag);
+    }
 
-      if (unknown) {  // Unknown field or wrong wire type.  Skip.
-        return input.skipField(tag);
-      }
+    protected final void mergeExtensionFields(final MessageType other) {
+      ensureExtensionsIsMutable();
+      extensions.mergeFrom(((ExtendableMessage) other).extensions);
+    }
+  }
 
-      if (packed) {
-        final int length = input.readRawVarint32();
-        final int limit = input.pushLimit(length);
-        if (extension.descriptor.getLiteType() == WireFormat.FieldType.ENUM) {
-          while (input.getBytesUntilLimit() > 0) {
-            final int rawValue = input.readEnum();
-            final Object value =
-                extension.descriptor.getEnumType().findValueByNumber(rawValue);
-            if (value == null) {
-              // If the number isn't recognized as a valid value for this
-              // enum, drop it (don't even add it to unknownFields).
-              return true;
-            }
-            ensureExtensionsIsMutable();
-            extensions.addRepeatedField(extension.descriptor, value);
-          }
-        } else {
-          while (input.getBytesUntilLimit() > 0) {
-            final Object value =
-              FieldSet.readPrimitiveField(input,
-                                          extension.descriptor.getLiteType());
-            ensureExtensionsIsMutable();
-            extensions.addRepeatedField(extension.descriptor, value);
+  // -----------------------------------------------------------------
+
+  /**
+   * Parse an unknown field or an extension.
+   * @return {@code true} unless the tag is an end-group tag.
+   */
+  private static <MessageType extends MessageLite>
+      boolean parseUnknownField(
+          FieldSet<ExtensionDescriptor> extensions,
+          MessageType defaultInstance,
+          CodedInputStream input,
+          ExtensionRegistryLite extensionRegistry,
+          int tag) throws IOException {
+    int wireType = WireFormat.getTagWireType(tag);
+    int fieldNumber = WireFormat.getTagFieldNumber(tag);
+
+    GeneratedExtension<MessageType, ?> extension =
+      extensionRegistry.findLiteExtensionByNumber(
+          defaultInstance, fieldNumber);
+
+    boolean unknown = false;
+    boolean packed = false;
+    if (extension == null) {
+      unknown = true;  // Unknown field.
+    } else if (wireType == FieldSet.getWireFormatForFieldType(
+                 extension.descriptor.getLiteType(),
+                 false  /* isPacked */)) {
+      packed = false;  // Normal, unpacked value.
+    } else if (extension.descriptor.isRepeated &&
+               extension.descriptor.type.isPackable() &&
+               wireType == FieldSet.getWireFormatForFieldType(
+                 extension.descriptor.getLiteType(),
+                 true  /* isPacked */)) {
+      packed = true;  // Packed value.
+    } else {
+      unknown = true;  // Wrong wire type.
+    }
+
+    if (unknown) {  // Unknown field or wrong wire type.  Skip.
+      return input.skipField(tag);
+    }
+
+    if (packed) {
+      int length = input.readRawVarint32();
+      int limit = input.pushLimit(length);
+      if (extension.descriptor.getLiteType() == WireFormat.FieldType.ENUM) {
+        while (input.getBytesUntilLimit() > 0) {
+          int rawValue = input.readEnum();
+          Object value =
+              extension.descriptor.getEnumType().findValueByNumber(rawValue);
+          if (value == null) {
+            // If the number isn't recognized as a valid value for this
+            // enum, drop it (don't even add it to unknownFields).
+            return true;
           }
+          extensions.addRepeatedField(extension.descriptor, value);
         }
-        input.popLimit(limit);
       } else {
-        final Object value;
-        switch (extension.descriptor.getLiteJavaType()) {
-          case MESSAGE: {
-            MessageLite.Builder subBuilder = null;
-            if (!extension.descriptor.isRepeated()) {
-              MessageLite existingValue =
-                  (MessageLite) extensions.getField(extension.descriptor);
-              if (existingValue != null) {
-                subBuilder = existingValue.toBuilder();
-              }
-            }
-            if (subBuilder == null) {
-              subBuilder = extension.messageDefaultInstance.newBuilderForType();
-            }
-            if (extension.descriptor.getLiteType() ==
-                WireFormat.FieldType.GROUP) {
-              input.readGroup(extension.getNumber(),
-                              subBuilder, extensionRegistry);
-            } else {
-              input.readMessage(subBuilder, extensionRegistry);
+        while (input.getBytesUntilLimit() > 0) {
+          Object value =
+            FieldSet.readPrimitiveField(input,
+                                        extension.descriptor.getLiteType());
+          extensions.addRepeatedField(extension.descriptor, value);
+        }
+      }
+      input.popLimit(limit);
+    } else {
+      Object value;
+      switch (extension.descriptor.getLiteJavaType()) {
+        case MESSAGE: {
+          MessageLite.Builder subBuilder = null;
+          if (!extension.descriptor.isRepeated()) {
+            MessageLite existingValue =
+                (MessageLite) extensions.getField(extension.descriptor);
+            if (existingValue != null) {
+              subBuilder = existingValue.toBuilder();
             }
-            value = subBuilder.build();
-            break;
           }
-          case ENUM:
-            final int rawValue = input.readEnum();
-            value = extension.descriptor.getEnumType()
-                             .findValueByNumber(rawValue);
-            // If the number isn't recognized as a valid value for this enum,
-            // drop it.
-            if (value == null) {
-              return true;
-            }
-            break;
-          default:
-            value = FieldSet.readPrimitiveField(input,
-                extension.descriptor.getLiteType());
-            break;
-        }
-
-        if (extension.descriptor.isRepeated()) {
-          ensureExtensionsIsMutable();
-          extensions.addRepeatedField(extension.descriptor, value);
-        } else {
-          ensureExtensionsIsMutable();
-          extensions.setField(extension.descriptor, value);
+          if (subBuilder == null) {
+            subBuilder = extension.messageDefaultInstance.newBuilderForType();
+          }
+          if (extension.descriptor.getLiteType() ==
+              WireFormat.FieldType.GROUP) {
+            input.readGroup(extension.getNumber(),
+                            subBuilder, extensionRegistry);
+          } else {
+            input.readMessage(subBuilder, extensionRegistry);
+          }
+          value = subBuilder.build();
+          break;
         }
+        case ENUM:
+          int rawValue = input.readEnum();
+          value = extension.descriptor.getEnumType()
+                           .findValueByNumber(rawValue);
+          // If the number isn't recognized as a valid value for this enum,
+          // drop it.
+          if (value == null) {
+            return true;
+          }
+          break;
+        default:
+          value = FieldSet.readPrimitiveField(input,
+              extension.descriptor.getLiteType());
+          break;
       }
 
-      return true;
+      if (extension.descriptor.isRepeated()) {
+        extensions.addRepeatedField(extension.descriptor, value);
+      } else {
+        extensions.setField(extension.descriptor, value);
+      }
     }
 
-    protected final void mergeExtensionFields(final MessageType other) {
-      ensureExtensionsIsMutable();
-      extensions.mergeFrom(((ExtendableMessage) other).extensions);
-    }
+    return true;
   }
 
   // -----------------------------------------------------------------
@@ -722,7 +788,7 @@ public abstract class GeneratedMessageLite extends AbstractMessageLite
   /**
    * Replaces this object in the output stream with a serialized form.
    * Part of Java's serialization magic.  Generated sub-classes must override
-   * this method by calling <code>return super.writeReplace();</code>
+   * this method by calling {@code return super.writeReplace();}
    * @return a SerializedForm of this message
    */
   protected Object writeReplace() throws ObjectStreamException {
diff --git a/java/src/main/java/com/google/protobuf/Internal.java b/java/src/main/java/com/google/protobuf/Internal.java
index 05eab57a..81af2583 100644
--- a/java/src/main/java/com/google/protobuf/Internal.java
+++ b/java/src/main/java/com/google/protobuf/Internal.java
@@ -103,85 +103,32 @@ public class Internal {
    * Helper called by generated code to determine if a byte array is a valid
    * UTF-8 encoded string such that the original bytes can be converted to
    * a String object and then back to a byte array round tripping the bytes
-   * without loss.
-   * <p>
-   * This is inspired by UTF_8.java in sun.nio.cs.
+   * without loss.  More precisely, returns {@code true} whenever:
+   * <pre>   {@code
+   * Arrays.equals(byteString.toByteArray(),
+   *     new String(byteString.toByteArray(), "UTF-8").getBytes("UTF-8"))
+   * }</pre>
+   *
+   * <p>This method rejects "overlong" byte sequences, as well as
+   * 3-byte sequences that would map to a surrogate character, in
+   * accordance with the restricted definition of UTF-8 introduced in
+   * Unicode 3.1.  Note that the UTF-8 decoder included in Oracle's
+   * JDK has been modified to also reject "overlong" byte sequences,
+   * but currently (2011) still accepts 3-byte surrogate character
+   * byte sequences.
+   *
+   * <p>See the Unicode Standard,</br>
+   * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
+   * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
+   *
+   * <p>As of 2011-02, this method simply returns the result of {@link
+   * ByteString#isValidUtf8()}.  Calling that method directly is preferred.
    *
    * @param byteString the string to check
    * @return whether the byte array is round trippable
    */
   public static boolean isValidUtf8(ByteString byteString) {
-    int index = 0;
-    int size = byteString.size();
-    // To avoid the masking, we could change this to use bytes;
-    // Then X > 0xC2 gets turned into X < -0xC2; X < 0x80
-    // gets turned into X >= 0, etc.
-
-    while (index < size) {
-      int byte1 = byteString.byteAt(index++) & 0xFF;
-      if (byte1 < 0x80) {
-        // fast loop for single bytes
-        continue;
-
-        // we know from this point on that we have 2-4 byte forms
-      } else if (byte1 < 0xC2 || byte1 > 0xF4) {
-        // catch illegal first bytes: < C2 or > F4
-        return false;
-      }
-      if (index >= size) {
-        // fail if we run out of bytes
-        return false;
-      }
-      int byte2 = byteString.byteAt(index++) & 0xFF;
-      if (byte2 < 0x80 || byte2 > 0xBF) {
-        // general trail-byte test
-        return false;
-      }
-      if (byte1 <= 0xDF) {
-        // two-byte form; general trail-byte test is sufficient
-        continue;
-      }
-
-      // we know from this point on that we have 3 or 4 byte forms
-      if (index >= size) {
-        // fail if we run out of bytes
-        return false;
-      }
-      int byte3 = byteString.byteAt(index++) & 0xFF;
-      if (byte3 < 0x80 || byte3 > 0xBF) {
-        // general trail-byte test
-        return false;
-      }
-      if (byte1 <= 0xEF) {
-        // three-byte form. Vastly more frequent than four-byte forms
-        // The following has an extra test, but not worth restructuring
-        if (byte1 == 0xE0 && byte2 < 0xA0 ||
-            byte1 == 0xED && byte2 > 0x9F) {
-          // check special cases of byte2
-          return false;
-        }
-
-      } else {
-        // four-byte form
-
-        if (index >= size) {
-          // fail if we run out of bytes
-          return false;
-        }
-        int byte4 = byteString.byteAt(index++) & 0xFF;
-        if (byte4 < 0x80 || byte4 > 0xBF) {
-          // general trail-byte test
-          return false;
-        }
-        // The following has an extra test, but not worth restructuring
-        if (byte1 == 0xF0 && byte2 < 0x90 ||
-            byte1 == 0xF4 && byte2 > 0x8F) {
-          // check special cases of byte2
-          return false;
-        }
-      }
-    }
-    return true;
+    return byteString.isValidUtf8();
   }
 
   /**
diff --git a/java/src/main/java/com/google/protobuf/InvalidProtocolBufferException.java b/java/src/main/java/com/google/protobuf/InvalidProtocolBufferException.java
index 90f7ffbc..72d7ff7d 100644
--- a/java/src/main/java/com/google/protobuf/InvalidProtocolBufferException.java
+++ b/java/src/main/java/com/google/protobuf/InvalidProtocolBufferException.java
@@ -40,11 +40,32 @@ import java.io.IOException;
  */
 public class InvalidProtocolBufferException extends IOException {
   private static final long serialVersionUID = -1616151763072450476L;
+  private MessageLite unfinishedMessage = null;
 
   public InvalidProtocolBufferException(final String description) {
     super(description);
   }
 
+  /**
+   * Attaches an unfinished message to the exception to support best-effort
+   * parsing in {@code Parser} interface.
+   *
+   * @return this
+   */
+  public InvalidProtocolBufferException setUnfinishedMessage(
+      MessageLite unfinishedMessage) {
+    this.unfinishedMessage = unfinishedMessage;
+    return this;
+  }
+
+  /**
+   * Returns the unfinished message attached to the exception, or null if
+   * no message is attached.
+   */
+  public MessageLite getUnfinishedMessage() {
+    return unfinishedMessage;
+  }
+
   static InvalidProtocolBufferException truncatedMessage() {
     return new InvalidProtocolBufferException(
       "While parsing a protocol message, the input ended unexpectedly " +
diff --git a/java/src/main/java/com/google/protobuf/LazyField.java b/java/src/main/java/com/google/protobuf/LazyField.java
new file mode 100644
index 00000000..df9425eb
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/LazyField.java
@@ -0,0 +1,216 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.IOException;
+import java.util.Iterator;
+import java.util.Map.Entry;
+
+/**
+ * LazyField encapsulates the logic of lazily parsing message fields. It stores
+ * the message in a ByteString initially and then parse it on-demand.
+ *
+ * LazyField is thread-compatible e.g. concurrent read are safe, however,
+ * synchronizations are needed under read/write situations.
+ *
+ * Now LazyField is only used to lazily load MessageSet.
+ * TODO(xiangl): Use LazyField to lazily load all messages.
+ *
+ * @author xiangl@google.com (Xiang Li)
+ */
+class LazyField {
+
+  final private MessageLite defaultInstance;
+  final private ExtensionRegistryLite extensionRegistry;
+
+  // Mutable because it is initialized lazily.
+  private ByteString bytes;
+  private volatile MessageLite value;
+  private volatile boolean isDirty = false;
+
+  public LazyField(MessageLite defaultInstance,
+      ExtensionRegistryLite extensionRegistry, ByteString bytes) {
+    this.defaultInstance = defaultInstance;
+    this.extensionRegistry = extensionRegistry;
+    this.bytes = bytes;
+  }
+
+  public MessageLite getValue() {
+    ensureInitialized();
+    return value;
+  }
+
+  /**
+   * LazyField is not thread-safe for write access. Synchronizations are needed
+   * under read/write situations.
+   */
+  public MessageLite setValue(MessageLite value) {
+    MessageLite originalValue = this.value;
+    this.value = value;
+    bytes = null;
+    isDirty = true;
+    return originalValue;
+  }
+
+  /**
+   * Due to the optional field can be duplicated at the end of serialized
+   * bytes, which will make the serialized size changed after LazyField
+   * parsed. Be careful when using this method.
+   */
+  public int getSerializedSize() {
+    if (isDirty) {
+      return value.getSerializedSize();
+    }
+    return bytes.size();
+  }
+
+  public ByteString toByteString() {
+    if (!isDirty) {
+      return bytes;
+    }
+    synchronized (this) {
+      if (!isDirty) {
+        return bytes;
+      }
+      bytes = value.toByteString();
+      isDirty = false;
+      return bytes;
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    ensureInitialized();
+    return value.hashCode();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    ensureInitialized();
+    return value.equals(obj);
+  }
+
+  @Override
+  public String toString() {
+    ensureInitialized();
+    return value.toString();
+  }
+
+  private void ensureInitialized() {
+    if (value != null) {
+      return;
+    }
+    synchronized (this) {
+      if (value != null) {
+        return;
+      }
+      try {
+        if (bytes != null) {
+          value = defaultInstance.getParserForType()
+              .parseFrom(bytes, extensionRegistry);
+        }
+      } catch (IOException e) {
+        // TODO(xiangl): Refactory the API to support the exception thrown from
+        // lazily load messages.
+      }
+    }
+  }
+
+  // ====================================================
+
+  /**
+   * LazyEntry and LazyIterator are used to encapsulate the LazyField, when
+   * users iterate all fields from FieldSet.
+   */
+  static class LazyEntry<K> implements Entry<K, Object> {
+    private Entry<K, LazyField> entry;
+
+    private LazyEntry(Entry<K, LazyField> entry) {
+      this.entry = entry;
+    }
+
+    @Override
+    public K getKey() {
+      return entry.getKey();
+    }
+
+    @Override
+    public Object getValue() {
+      LazyField field = entry.getValue();
+      if (field == null) {
+        return null;
+      }
+      return field.getValue();
+    }
+
+    public LazyField getField() {
+      return entry.getValue();
+    }
+
+    @Override
+    public Object setValue(Object value) {
+      if (!(value instanceof MessageLite)) {
+        throw new IllegalArgumentException(
+            "LazyField now only used for MessageSet, "
+            + "and the value of MessageSet must be an instance of MessageLite");
+      }
+      return entry.getValue().setValue((MessageLite) value);
+    }
+  }
+
+  static class LazyIterator<K> implements Iterator<Entry<K, Object>> {
+    private Iterator<Entry<K, Object>> iterator;
+
+    public LazyIterator(Iterator<Entry<K, Object>> iterator) {
+      this.iterator = iterator;
+    }
+
+    @Override
+    public boolean hasNext() {
+      return iterator.hasNext();
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public Entry<K, Object> next() {
+      Entry<K, ?> entry = iterator.next();
+      if (entry.getValue() instanceof LazyField) {
+        return new LazyEntry<K>((Entry<K, LazyField>) entry);
+      }
+      return (Entry<K, Object>) entry;
+    }
+
+    @Override
+    public void remove() {
+      iterator.remove();
+    }
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/LazyStringArrayList.java b/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
index 1683a640..75c6a4b7 100644
--- a/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
+++ b/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
@@ -33,8 +33,9 @@ package com.google.protobuf;
 import java.util.List;
 import java.util.AbstractList;
 import java.util.ArrayList;
-import java.util.RandomAccess;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.RandomAccess;
 
 /**
  * An implementation of {@link LazyStringList} that wraps an ArrayList. Each
@@ -72,6 +73,11 @@ public class LazyStringArrayList extends AbstractList<String>
     list = new ArrayList<Object>();
   }
 
+  public LazyStringArrayList(LazyStringList from) {
+    list = new ArrayList<Object>(from.size());
+    addAll(from);
+  }
+
   public LazyStringArrayList(List<String> from) {
     list = new ArrayList<Object>(from);
   }
@@ -84,7 +90,7 @@ public class LazyStringArrayList extends AbstractList<String>
     } else {
       ByteString bs = (ByteString) o;
       String s = bs.toStringUtf8();
-      if (Internal.isValidUtf8(bs)) {
+      if (bs.isValidUtf8()) {
         list.set(index, s);
       }
       return s;
@@ -109,8 +115,21 @@ public class LazyStringArrayList extends AbstractList<String>
   }
 
   @Override
+  public boolean addAll(Collection<? extends String> c) {
+    // The default implementation of AbstractCollection.addAll(Collection)
+    // delegates to add(Object). This implementation instead delegates to
+    // addAll(int, Collection), which makes a special case for Collections
+    // which are instances of LazyStringList.
+    return addAll(size(), c);
+  }
+
+  @Override
   public boolean addAll(int index, Collection<? extends String> c) {
-    boolean ret = list.addAll(index, c);
+    // When copying from another LazyStringList, directly copy the underlying
+    // elements rather than forcing each element to be decoded to a String.
+    Collection<?> collection = c instanceof LazyStringList
+        ? ((LazyStringList) c).getUnderlyingElements() : c;
+    boolean ret = list.addAll(index, collection);
     modCount++;
     return ret;
   }
@@ -152,4 +171,9 @@ public class LazyStringArrayList extends AbstractList<String>
       return ((ByteString) o).toStringUtf8();
     }
   }
+
+  @Override
+  public List<?> getUnderlyingElements() {
+    return Collections.unmodifiableList(list);
+  }
 }
diff --git a/java/src/main/java/com/google/protobuf/LazyStringList.java b/java/src/main/java/com/google/protobuf/LazyStringList.java
index 97139ca6..630932fe 100644
--- a/java/src/main/java/com/google/protobuf/LazyStringList.java
+++ b/java/src/main/java/com/google/protobuf/LazyStringList.java
@@ -33,7 +33,7 @@ package com.google.protobuf;
 import java.util.List;
 
 /**
- * An interface extending List&lt;String&gt; that also provides access to the
+ * An interface extending {@code List<String>} that also provides access to the
  * items of the list as UTF8-encoded ByteString objects. This is used by the
  * protocol buffer implementation to support lazily converting bytes parsed
  * over the wire to String objects until needed and also increases the
@@ -41,9 +41,9 @@ import java.util.List;
  * ByteString is already cached.
  * <p>
  * This only adds additional methods that are required for the use in the
- * protocol buffer code in order to be able successfuly round trip byte arrays
+ * protocol buffer code in order to be able successfully round trip byte arrays
  * through parsing and serialization without conversion to strings. It's not
- * attempting to support the functionality of say List&ltByteString&gt, hence
+ * attempting to support the functionality of say {@code List<ByteString>}, hence
  * why only these two very specific methods are added.
  *
  * @author jonp@google.com (Jon Perlow)
@@ -56,7 +56,7 @@ public interface LazyStringList extends List<String> {
    * @param index index of the element to return
    * @return the element at the specified position in this list
    * @throws IndexOutOfBoundsException if the index is out of range
-   *         (<tt>index &lt; 0 || index &gt;= size()</tt>)
+   *         ({@code index < 0 || index >= size()})
    */
   ByteString getByteString(int index);
 
@@ -69,4 +69,13 @@ public interface LazyStringList extends List<String> {
    *         is not supported by this list
    */
   void add(ByteString element);
+
+  /**
+   * Returns an unmodifiable List of the underlying elements, each of
+   * which is either a {@code String} or its equivalent UTF-8 encoded
+   * {@code ByteString}. It is an error for the caller to modify the returned
+   * List, and attempting to do so will result in an
+   * {@link UnsupportedOperationException}.
+   */
+  List<?> getUnderlyingElements();
 }
diff --git a/java/src/main/java/com/google/protobuf/LiteralByteString.java b/java/src/main/java/com/google/protobuf/LiteralByteString.java
new file mode 100644
index 00000000..93c53dce
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/LiteralByteString.java
@@ -0,0 +1,349 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ * This class implements a {@link com.google.protobuf.ByteString} backed by a
+ * single array of bytes, contiguous in memory. It supports substring by
+ * pointing to only a sub-range of the underlying byte array, meaning that a
+ * substring will reference the full byte-array of the string it's made from,
+ * exactly as with {@link String}.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+class LiteralByteString extends ByteString {
+
+  protected final byte[] bytes;
+
+  /**
+   * Creates a {@code LiteralByteString} backed by the given array, without
+   * copying.
+   *
+   * @param bytes array to wrap
+   */
+  LiteralByteString(byte[] bytes) {
+    this.bytes = bytes;
+  }
+
+  @Override
+  public byte byteAt(int index) {
+    // Unlike most methods in this class, this one is a direct implementation
+    // ignoring the potential offset because we need to do range-checking in the
+    // substring case anyway.
+    return bytes[index];
+  }
+
+  @Override
+  public int size() {
+    return bytes.length;
+  }
+
+  // =================================================================
+  // ByteString -> substring
+
+  @Override
+  public ByteString substring(int beginIndex, int endIndex) {
+    if (beginIndex < 0) {
+      throw new IndexOutOfBoundsException(
+          "Beginning index: " + beginIndex + " < 0");
+    }
+    if (endIndex > size()) {
+      throw new IndexOutOfBoundsException("End index: " + endIndex + " > " +
+          size());
+    }
+    int substringLength = endIndex - beginIndex;
+    if (substringLength < 0) {
+      throw new IndexOutOfBoundsException(
+          "Beginning index larger than ending index: " + beginIndex + ", "
+              + endIndex);
+    }
+
+    ByteString result;
+    if (substringLength == 0) {
+      result = ByteString.EMPTY;
+    } else {
+      result = new BoundedByteString(bytes, getOffsetIntoBytes() + beginIndex,
+          substringLength);
+    }
+    return result;
+  }
+
+  // =================================================================
+  // ByteString -> byte[]
+
+  @Override
+  protected void copyToInternal(byte[] target, int sourceOffset, 
+      int targetOffset, int numberToCopy) {
+    // Optimized form, not for subclasses, since we don't call
+    // getOffsetIntoBytes() or check the 'numberToCopy' parameter.
+    System.arraycopy(bytes, sourceOffset, target, targetOffset, numberToCopy);
+  }
+
+  @Override
+  public void copyTo(ByteBuffer target) {
+    target.put(bytes, getOffsetIntoBytes(), size());  // Copies bytes
+  }
+
+  @Override
+  public ByteBuffer asReadOnlyByteBuffer() {
+    ByteBuffer byteBuffer =
+        ByteBuffer.wrap(bytes, getOffsetIntoBytes(), size());
+    return byteBuffer.asReadOnlyBuffer();
+  }
+
+  @Override
+  public List<ByteBuffer> asReadOnlyByteBufferList() {
+    // Return the ByteBuffer generated by asReadOnlyByteBuffer() as a singleton
+    List<ByteBuffer> result = new ArrayList<ByteBuffer>(1);
+    result.add(asReadOnlyByteBuffer());
+    return result;
+ }
+
+ @Override
+  public void writeTo(OutputStream outputStream) throws IOException {
+    outputStream.write(toByteArray());
+  }
+
+  @Override
+  public String toString(String charsetName)
+      throws UnsupportedEncodingException {
+    return new String(bytes, getOffsetIntoBytes(), size(), charsetName);
+  }
+
+  // =================================================================
+  // UTF-8 decoding
+
+  @Override
+  public boolean isValidUtf8() {
+    int offset = getOffsetIntoBytes();
+    return Utf8.isValidUtf8(bytes, offset, offset + size());
+  }
+
+  @Override
+  protected int partialIsValidUtf8(int state, int offset, int length) {
+    int index = getOffsetIntoBytes() + offset;
+    return Utf8.partialIsValidUtf8(state, bytes, index, index + length);
+  }
+
+  // =================================================================
+  // equals() and hashCode()
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof ByteString)) {
+      return false;
+    }
+
+    if (size() != ((ByteString) other).size()) {
+      return false;
+    }
+    if (size() == 0) {
+      return true;
+    }
+
+    if (other instanceof LiteralByteString) {
+      return equalsRange((LiteralByteString) other, 0, size());
+    } else if (other instanceof RopeByteString) {
+      return other.equals(this);
+    } else {
+      throw new IllegalArgumentException(
+          "Has a new type of ByteString been created? Found "
+              + other.getClass());
+    }
+  }
+
+  /**
+   * Check equality of the substring of given length of this object starting at
+   * zero with another {@code LiteralByteString} substring starting at offset.
+   *
+   * @param other  what to compare a substring in
+   * @param offset offset into other
+   * @param length number of bytes to compare
+   * @return true for equality of substrings, else false.
+   */
+  boolean equalsRange(LiteralByteString other, int offset, int length) {
+    if (length > other.size()) {
+      throw new IllegalArgumentException(
+          "Length too large: " + length + size());
+    }
+    if (offset + length > other.size()) {
+      throw new IllegalArgumentException(
+          "Ran off end of other: " + offset + ", " + length + ", " +
+              other.size());
+    }
+
+    byte[] thisBytes = bytes;
+    byte[] otherBytes = other.bytes;
+    int thisLimit = getOffsetIntoBytes() + length;
+    for (int thisIndex = getOffsetIntoBytes(), otherIndex =
+        other.getOffsetIntoBytes() + offset;
+        (thisIndex < thisLimit); ++thisIndex, ++otherIndex) {
+      if (thisBytes[thisIndex] != otherBytes[otherIndex]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Cached hash value.  Intentionally accessed via a data race, which
+   * is safe because of the Java Memory Model's "no out-of-thin-air values"
+   * guarantees for ints.
+   */
+  private int hash = 0;
+
+  /**
+   * Compute the hashCode using the traditional algorithm from {@link
+   * ByteString}.
+   *
+   * @return hashCode value
+   */
+  @Override
+  public int hashCode() {
+    int h = hash;
+
+    if (h == 0) {
+      int size = size();
+      h = partialHash(size, 0, size);
+      if (h == 0) {
+        h = 1;
+      }
+      hash = h;
+    }
+    return h;
+  }
+
+  @Override
+  protected int peekCachedHashCode() {
+    return hash;
+  }
+
+  @Override
+  protected int partialHash(int h, int offset, int length) {
+    byte[] thisBytes = bytes;
+    for (int i = getOffsetIntoBytes() + offset, limit = i + length; i < limit;
+        i++) {
+      h = h * 31 + thisBytes[i];
+    }
+    return h;
+  }
+
+  // =================================================================
+  // Input stream
+
+  @Override
+  public InputStream newInput() {
+    return new ByteArrayInputStream(bytes, getOffsetIntoBytes(),
+        size());  // No copy
+  }
+
+  @Override
+  public CodedInputStream newCodedInput() {
+    // We trust CodedInputStream not to modify the bytes, or to give anyone
+    // else access to them.
+    return CodedInputStream
+        .newInstance(bytes, getOffsetIntoBytes(), size());  // No copy
+  }
+
+  // =================================================================
+  // ByteIterator
+
+  @Override
+  public ByteIterator iterator() {
+    return new LiteralByteIterator();
+  }
+
+  private class LiteralByteIterator implements ByteIterator {
+    private int position;
+    private final int limit;
+
+    private LiteralByteIterator() {
+      position = 0;
+      limit = size();
+    }
+
+    public boolean hasNext() {
+      return (position < limit);
+    }
+
+    public Byte next() {
+      // Boxing calls Byte.valueOf(byte), which does not instantiate.
+      return nextByte();
+    }
+
+    public byte nextByte() {
+      try {
+        return bytes[position++];
+      } catch (ArrayIndexOutOfBoundsException e) {
+        throw new NoSuchElementException(e.getMessage());
+      }
+    }
+
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  // =================================================================
+  // Internal methods
+
+  @Override
+  protected int getTreeDepth() {
+    return 0;
+  }
+
+  @Override
+  protected boolean isBalanced() {
+    return true;
+  }
+
+  /**
+   * Offset into {@code bytes[]} to use, non-zero for substrings.
+   *
+   * @return always 0 for this class
+   */
+  protected int getOffsetIntoBytes() {
+    return 0;
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/Message.java b/java/src/main/java/com/google/protobuf/Message.java
index 67c4148e..2b881413 100644
--- a/java/src/main/java/com/google/protobuf/Message.java
+++ b/java/src/main/java/com/google/protobuf/Message.java
@@ -50,25 +50,28 @@ import java.util.Map;
  */
 public interface Message extends MessageLite, MessageOrBuilder {
 
+  // (From MessageLite, re-declared here only for return type covariance.)
+  Parser<? extends Message> getParserForType();
+
   // -----------------------------------------------------------------
   // Comparison and hashing
 
   /**
    * Compares the specified object with this message for equality.  Returns
-   * <tt>true</tt> if the given object is a message of the same type (as
+   * {@code true} if the given object is a message of the same type (as
    * defined by {@code getDescriptorForType()}) and has identical values for
    * all of its fields.  Subclasses must implement this; inheriting
    * {@code Object.equals()} is incorrect.
    *
    * @param other object to be compared for equality with this message
-   * @return <tt>true</tt> if the specified object is equal to this message
+   * @return {@code true} if the specified object is equal to this message
    */
   @Override
   boolean equals(Object other);
 
   /**
    * Returns the hash code value for this message.  The hash code of a message
-   * should mix the message's type (object identity of the decsriptor) with its
+   * should mix the message's type (object identity of the descriptor) with its
    * contents (known and unknown field values).  Subclasses must implement this;
    * inheriting {@code Object.hashCode()} is incorrect.
    *
@@ -83,7 +86,8 @@ public interface Message extends MessageLite, MessageOrBuilder {
 
   /**
    * Converts the message to a string in protocol buffer text format. This is
-   * just a trivial wrapper around {@link TextFormat#printToString(Message)}.
+   * just a trivial wrapper around {@link
+   * TextFormat#printToString(MessageOrBuilder)}.
    */
   @Override
   String toString();
@@ -145,6 +149,24 @@ public interface Message extends MessageLite, MessageOrBuilder {
     Builder newBuilderForField(Descriptors.FieldDescriptor field);
 
     /**
+     * Get a nested builder instance for the given field.
+     * <p>
+     * Normally, we hold a reference to the immutable message object for the
+     * message type field. Some implementations(the generated message builders),
+     * however, can also hold a reference to the builder object (a nested
+     * builder) for the field.
+     * <p>
+     * If the field is already backed up by a nested builder, the nested builder
+     * will be returned. Otherwise, a new field builder will be created and
+     * returned. The original message field (if exist) will be merged into the
+     * field builder, which will then be nested into its parent builder.
+     * <p>
+     * NOTE: implementations that do not support nested builders will throw
+     * <code>UnsupportedException</code>.
+     */
+    Builder getFieldBuilder(Descriptors.FieldDescriptor field);
+
+    /**
      * Sets a field to the given value.  The value must be of the correct type
      * for this field, i.e. the same type that
      * {@link Message#getField(Descriptors.FieldDescriptor)} would return.
diff --git a/java/src/main/java/com/google/protobuf/MessageLite.java b/java/src/main/java/com/google/protobuf/MessageLite.java
index 31b8256e..e5b9a47b 100644
--- a/java/src/main/java/com/google/protobuf/MessageLite.java
+++ b/java/src/main/java/com/google/protobuf/MessageLite.java
@@ -79,6 +79,12 @@ public interface MessageLite extends MessageLiteOrBuilder {
    */
   int getSerializedSize();
 
+
+  /**
+   * Gets the parser for a message of the same type as this message.
+   */
+  Parser<? extends MessageLite> getParserForType();
+
   // -----------------------------------------------------------------
   // Convenience methods.
 
@@ -144,11 +150,8 @@ public interface MessageLite extends MessageLiteOrBuilder {
     Builder clear();
 
     /**
-     * Construct the final message.  Once this is called, the Builder is no
-     * longer valid, and calling any other method will result in undefined
-     * behavior and may throw a NullPointerException.  If you need to continue
-     * working with the builder after calling {@code build()}, {@code clone()}
-     * it first.
+     * Constructs the message based on the state of the Builder. Subsequent
+     * changes to the Builder will not affect the returned message.
      * @throws UninitializedMessageException The message is missing one or more
      *         required fields (i.e. {@link #isInitialized()} returns false).
      *         Use {@link #buildPartial()} to bypass this check.
@@ -158,11 +161,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
     /**
      * Like {@link #build()}, but does not throw an exception if the message
      * is missing required fields.  Instead, a partial message is returned.
-     * Once this is called, the Builder is no longer valid, and calling any
-     * will result in undefined behavior and may throw a NullPointerException.
-     *
-     * If you need to continue working with the builder after calling
-     * {@code buildPartial()}, {@code clone()} it first.
+     * Subsequent changes to the Builder will not affect the returned message.
      */
     MessageLite buildPartial();
 
@@ -174,7 +173,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
 
     /**
      * Parses a message of this type from the input and merges it with this
-     * message, as if using {@link Builder#mergeFrom(MessageLite)}.
+     * message.
      *
      * <p>Warning:  This does not verify that all required fields are present in
      * the input message.  If you call {@link #build()} without setting all
@@ -184,11 +183,6 @@ public interface MessageLite extends MessageLiteOrBuilder {
      * <ul>
      *   <li>Call {@link #isInitialized()} to verify that all required fields
      *       are set before building.
-     *   <li>Parse the message separately using one of the static
-     *       {@code parseFrom} methods, then use {@link #mergeFrom(MessageLite)}
-     *       to merge it with this one.  {@code parseFrom} will throw an
-     *       {@link InvalidProtocolBufferException} (an {@code IOException})
-     *       if some required fields are missing.
      *   <li>Use {@code buildPartial()} to build, which ignores missing
      *       required fields.
      * </ul>
@@ -225,7 +219,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
     /**
      * Parse {@code data} as a message of this type and merge it with the
      * message being built.  This is just a small wrapper around
-     * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}.
+     * {@link #mergeFrom(CodedInputStream,ExtensionRegistryLite)}.
      *
      * @return this
      */
@@ -255,7 +249,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
     /**
      * Parse {@code data} as a message of this type and merge it with the
      * message being built.  This is just a small wrapper around
-     * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}.
+     * {@link #mergeFrom(CodedInputStream,ExtensionRegistryLite)}.
      *
      * @return this
      */
@@ -266,7 +260,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
     /**
      * Parse {@code data} as a message of this type and merge it with the
      * message being built.  This is just a small wrapper around
-     * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}.
+     * {@link #mergeFrom(CodedInputStream,ExtensionRegistryLite)}.
      *
      * @return this
      */
@@ -293,7 +287,7 @@ public interface MessageLite extends MessageLiteOrBuilder {
     /**
      * Parse a message of this type from {@code input} and merge it with the
      * message being built.  This is just a small wrapper around
-     * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}.
+     * {@link #mergeFrom(CodedInputStream,ExtensionRegistryLite)}.
      *
      * @return this
      */
@@ -308,9 +302,9 @@ public interface MessageLite extends MessageLiteOrBuilder {
      * {@link MessageLite#writeDelimitedTo(OutputStream)} to write messages in
      * this format.
      *
-     * @returns True if successful, or false if the stream is at EOF when the
-     *          method starts.  Any other error (including reaching EOF during
-     *          parsing) will cause an exception to be thrown.
+     * @return True if successful, or false if the stream is at EOF when the
+     *         method starts.  Any other error (including reaching EOF during
+     *         parsing) will cause an exception to be thrown.
      */
     boolean mergeDelimitedFrom(InputStream input)
                                throws IOException;
diff --git a/java/src/main/java/com/google/protobuf/MessageLiteOrBuilder.java b/java/src/main/java/com/google/protobuf/MessageLiteOrBuilder.java
index 7cc72e9c..05b2b161 100644
--- a/java/src/main/java/com/google/protobuf/MessageLiteOrBuilder.java
+++ b/java/src/main/java/com/google/protobuf/MessageLiteOrBuilder.java
@@ -52,6 +52,8 @@ public interface MessageLiteOrBuilder {
   /**
    * Returns true if all required fields in the message and all embedded
    * messages are set, false otherwise.
+   *
+   * <p>See also: {@link MessageOrBuilder#getInitializationErrorString()}
    */
   boolean isInitialized();
 
diff --git a/java/src/main/java/com/google/protobuf/MessageOrBuilder.java b/java/src/main/java/com/google/protobuf/MessageOrBuilder.java
index 0132e7ca..bf62d45e 100644
--- a/java/src/main/java/com/google/protobuf/MessageOrBuilder.java
+++ b/java/src/main/java/com/google/protobuf/MessageOrBuilder.java
@@ -30,6 +30,7 @@
 
 package com.google.protobuf;
 
+import java.util.List;
 import java.util.Map;
 
 /**
@@ -45,6 +46,24 @@ public interface MessageOrBuilder extends MessageLiteOrBuilder {
   Message getDefaultInstanceForType();
 
   /**
+   * Returns a list of field paths (e.g. "foo.bar.baz") of required fields
+   * which are not set in this message.  You should call
+   * {@link MessageLiteOrBuilder#isInitialized()} first to check if there
+   * are any missing fields, as that method is likely to be much faster
+   * than this one even when the message is fully-initialized.
+   */
+  List<String> findInitializationErrors();
+
+  /**
+   * Returns a comma-delimited list of required fields which are not set
+   * in this message object.  You should call
+   * {@link MessageLiteOrBuilder#isInitialized()} first to check if there
+   * are any missing fields, as that method is likely to be much faster
+   * than this one even when the message is fully-initialized.
+   */
+  String getInitializationErrorString();
+
+  /**
    * Get the message's type's descriptor.  This differs from the
    * {@code getDescriptor()} method of generated message classes in that
    * this method is an abstract method of the {@code Message} interface
@@ -80,7 +99,7 @@ public interface MessageOrBuilder extends MessageLiteOrBuilder {
   /**
    * Obtains the value of the given field, or the default value if it is
    * not set.  For primitive fields, the boxed primitive value is returned.
-   * For enum fields, the EnumValueDescriptor for the value is returend. For
+   * For enum fields, the EnumValueDescriptor for the value is returned. For
    * embedded message fields, the sub-message is returned.  For repeated
    * fields, a java.util.List is returned.
    */
@@ -98,7 +117,7 @@ public interface MessageOrBuilder extends MessageLiteOrBuilder {
   /**
    * Gets an element of a repeated field.  For primitive fields, the boxed
    * primitive value is returned.  For enum fields, the EnumValueDescriptor
-   * for the value is returend. For embedded message fields, the sub-message
+   * for the value is returned. For embedded message fields, the sub-message
    * is returned.
    * @throws IllegalArgumentException The field is not a repeated field, or
    *           {@code field.getContainingType() != getDescriptorForType()}.
diff --git a/java/src/main/java/com/google/protobuf/Parser.java b/java/src/main/java/com/google/protobuf/Parser.java
new file mode 100644
index 00000000..7d8e8217
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/Parser.java
@@ -0,0 +1,259 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.InputStream;
+
+/**
+ * Abstract interface for parsing Protocol Messages.
+ *
+ * @author liujisi@google.com (Pherl Liu)
+ */
+public interface Parser<MessageType> {
+  /**
+   * Parses a message of {@code MessageType} from the input.
+   *
+   * <p>Note:  The caller should call
+   * {@link CodedInputStream#checkLastTagWas(int)} after calling this to
+   * verify that the last tag seen was the appropriate end-group tag,
+   * or zero for EOF.
+   */
+  public MessageType parseFrom(CodedInputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(CodedInputStream)}, but also parses extensions.
+   * The extensions that you want to be able to parse must be registered in
+   * {@code extensionRegistry}. Extensions not in the registry will be treated
+   * as unknown fields.
+   */
+  public MessageType parseFrom(CodedInputStream input,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(CodedInputStream)}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialFrom(CodedInputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(CodedInputStream input, ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialFrom(CodedInputStream input,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  // ---------------------------------------------------------------
+  // Convenience methods.
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around {@link #parseFrom(CodedInputStream)}.
+   */
+  public MessageType parseFrom(ByteString data)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around
+   * {@link #parseFrom(CodedInputStream, ExtensionRegistryLite)}.
+   */
+  public MessageType parseFrom(ByteString data,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(ByteString)}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialFrom(ByteString data)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(ByteString, ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialFrom(ByteString data,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around {@link #parseFrom(CodedInputStream)}.
+   */
+  public MessageType parseFrom(byte[] data, int off, int len)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around
+   * {@link #parseFrom(CodedInputStream, ExtensionRegistryLite)}.
+   */
+  public MessageType parseFrom(byte[] data, int off, int len,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around {@link #parseFrom(CodedInputStream)}.
+   */
+  public MessageType parseFrom(byte[] data)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses {@code data} as a message of {@code MessageType}.
+   * This is just a small wrapper around
+   * {@link #parseFrom(CodedInputStream, ExtensionRegistryLite)}.
+   */
+  public MessageType parseFrom(byte[] data,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(byte[], int, int)}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialFrom(byte[] data, int off, int len)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(ByteString, ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialFrom(byte[] data, int off, int len,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(byte[])}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialFrom(byte[] data)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(byte[], ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialFrom(byte[] data,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parse a message of {@code MessageType} from {@code input}.
+   * This is just a small wrapper around {@link #parseFrom(CodedInputStream)}.
+   * Note that this method always reads the <i>entire</i> input (unless it
+   * throws an exception).  If you want it to stop earlier, you will need to
+   * wrap your input in some wrapper stream that limits reading.  Or, use
+   * {@link MessageLite#writeDelimitedTo(java.io.OutputStream)} to write your
+   * message and {@link #parseDelimitedFrom(InputStream)} to read it.
+   * <p>
+   * Despite usually reading the entire input, this does not close the stream.
+   */
+  public MessageType parseFrom(InputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Parses a message of {@code MessageType} from {@code input}.
+   * This is just a small wrapper around
+   * {@link #parseFrom(CodedInputStream, ExtensionRegistryLite)}.
+   */
+  public MessageType parseFrom(InputStream input,
+                               ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(InputStream)}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialFrom(InputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(InputStream, ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialFrom(InputStream input,
+                                      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseFrom(InputStream)}, but does not read util EOF.
+   * Instead, the size of message (encoded as a varint) is read first,
+   * then the message data. Use
+   * {@link MessageLite#writeDelimitedTo(java.io.OutputStream)} to write
+   * messages in this format.
+   *
+   * @return True if successful, or false if the stream is at EOF when the
+   *         method starts. Any other error (including reaching EOF during
+   *         parsing) will cause an exception to be thrown.
+   */
+  public MessageType parseDelimitedFrom(InputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseDelimitedFrom(InputStream)} but supporting extensions.
+   */
+  public MessageType parseDelimitedFrom(InputStream input,
+                                        ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseDelimitedFrom(InputStream)}, but does not throw an
+   * exception if the message is missing required fields. Instead, a partial
+   * message is returned.
+   */
+  public MessageType parsePartialDelimitedFrom(InputStream input)
+      throws InvalidProtocolBufferException;
+
+  /**
+   * Like {@link #parseDelimitedFrom(InputStream, ExtensionRegistryLite)},
+   * but does not throw an exception if the message is missing required fields.
+   * Instead, a partial message is returned.
+   */
+  public MessageType parsePartialDelimitedFrom(
+      InputStream input,
+      ExtensionRegistryLite extensionRegistry)
+      throws InvalidProtocolBufferException;
+}
diff --git a/java/src/main/java/com/google/protobuf/RepeatedFieldBuilder.java b/java/src/main/java/com/google/protobuf/RepeatedFieldBuilder.java
index 0024f791..65d9270d 100644
--- a/java/src/main/java/com/google/protobuf/RepeatedFieldBuilder.java
+++ b/java/src/main/java/com/google/protobuf/RepeatedFieldBuilder.java
@@ -37,22 +37,22 @@ import java.util.Collections;
 import java.util.List;
 
 /**
- * <code>RepeatedFieldBuilder</code> implements a structure that a protocol
+ * {@code RepeatedFieldBuilder} implements a structure that a protocol
  * message uses to hold a repeated field of other protocol messages. It supports
  * the classical use case of adding immutable {@link Message}'s to the
  * repeated field and is highly optimized around this (no extra memory
  * allocations and sharing of immutable arrays).
  * <br>
  * It also supports the additional use case of adding a {@link Message.Builder}
- * to the repeated field and deferring conversion of that <code>Builder</code>
- * to an immutable <code>Message</code>. In this way, it's possible to maintain
- * a tree of <code>Builder</code>'s that acts as a fully read/write data
+ * to the repeated field and deferring conversion of that {@code Builder}
+ * to an immutable {@code Message}. In this way, it's possible to maintain
+ * a tree of {@code Builder}'s that acts as a fully read/write data
  * structure.
  * <br>
  * Logically, one can think of a tree of builders as converting the entire tree
  * to messages when build is called on the root or when any method is called
  * that desires a Message instead of a Builder. In terms of the implementation,
- * the <code>SingleFieldBuilder</code> and <code>RepeatedFieldBuilder</code>
+ * the {@code SingleFieldBuilder} and {@code RepeatedFieldBuilder}
  * classes cache messages that were created so that messages only need to be
  * created when some change occured in its builder or a builder for one of its
  * descendants.
@@ -192,7 +192,7 @@ public class RepeatedFieldBuilder
 
   /**
    * Get the message at the specified index. If the message is currently stored
-   * as a <code>Builder</code>, it is converted to a <code>Message</code> by
+   * as a {@code Builder}, it is converted to a {@code Message} by
    * calling {@link Message.Builder#buildPartial} on it.
    *
    * @param index the index of the message to get
@@ -204,7 +204,7 @@ public class RepeatedFieldBuilder
 
   /**
    * Get the message at the specified index. If the message is currently stored
-   * as a <code>Builder</code>, it is converted to a <code>Message</code> by
+   * as a {@code Builder}, it is converted to a {@code Message} by
    * calling {@link Message.Builder#buildPartial} on it.
    *
    * @param index the index of the message to get
diff --git a/java/src/main/java/com/google/protobuf/RopeByteString.java b/java/src/main/java/com/google/protobuf/RopeByteString.java
new file mode 100644
index 00000000..8d44d117
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/RopeByteString.java
@@ -0,0 +1,945 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.io.ByteArrayInputStream;
+import java.nio.ByteBuffer;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ * Class to represent {@code ByteStrings} formed by concatenation of other
+ * ByteStrings, without copying the data in the pieces. The concatenation is
+ * represented as a tree whose leaf nodes are each a {@link LiteralByteString}.
+ *
+ * <p>Most of the operation here is inspired by the now-famous paper <a
+ * href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
+ * BAP95 </a> Ropes: an Alternative to Strings hans-j. boehm, russ atkinson and
+ * michael plass
+ *
+ * <p>The algorithms described in the paper have been implemented for character
+ * strings in {@link com.google.common.string.Rope} and in the c++ class {@code
+ * cord.cc}.
+ *
+ * <p>Fundamentally the Rope algorithm represents the collection of pieces as a
+ * binary tree. BAP95 uses a Fibonacci bound relating depth to a minimum
+ * sequence length, sequences that are too short relative to their depth cause a
+ * tree rebalance.  More precisely, a tree of depth d is "balanced" in the
+ * terminology of BAP95 if its length is at least F(d+2), where F(n) is the
+ * n-the Fibonacci number. Thus for depths 0, 1, 2, 3, 4, 5,... we have minimum
+ * lengths 1, 2, 3, 5, 8, 13,...
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+class RopeByteString extends ByteString {
+
+  /**
+   * BAP95. Let Fn be the nth Fibonacci number. A {@link RopeByteString} of
+   * depth n is "balanced", i.e flat enough, if its length is at least Fn+2,
+   * e.g. a "balanced" {@link RopeByteString} of depth 1 must have length at
+   * least 2, of depth 4 must have length >= 8, etc.
+   *
+   * <p>There's nothing special about using the Fibonacci numbers for this, but
+   * they are a reasonable sequence for encapsulating the idea that we are OK
+   * with longer strings being encoded in deeper binary trees.
+   *
+   * <p>For 32-bit integers, this array has length 46.
+   */
+  private static final int[] minLengthByDepth;
+
+  static {
+    // Dynamically generate the list of Fibonacci numbers the first time this
+    // class is accessed.
+    List<Integer> numbers = new ArrayList<Integer>();
+
+    // we skip the first Fibonacci number (1).  So instead of: 1 1 2 3 5 8 ...
+    // we have: 1 2 3 5 8 ...
+    int f1 = 1;
+    int f2 = 1;
+
+    // get all the values until we roll over.
+    while (f2 > 0) {
+      numbers.add(f2);
+      int temp = f1 + f2;
+      f1 = f2;
+      f2 = temp;
+    }
+
+    // we include this here so that we can index this array to [x + 1] in the
+    // loops below.
+    numbers.add(Integer.MAX_VALUE);
+    minLengthByDepth = new int[numbers.size()];
+    for (int i = 0; i < minLengthByDepth.length; i++) {
+      // unbox all the values
+      minLengthByDepth[i] = numbers.get(i);
+    }
+  }
+
+  private final int totalLength;
+  private final ByteString left;
+  private final ByteString right;
+  private final int leftLength;
+  private final int treeDepth;
+
+  /**
+   * Create a new RopeByteString, which can be thought of as a new tree node, by
+   * recording references to the two given strings.
+   *
+   * @param left  string on the left of this node, should have {@code size() >
+   *              0}
+   * @param right string on the right of this node, should have {@code size() >
+   *              0}
+   */
+  private RopeByteString(ByteString left, ByteString right) {
+    this.left = left;
+    this.right = right;
+    leftLength = left.size();
+    totalLength = leftLength + right.size();
+    treeDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1;
+  }
+
+  /**
+   * Concatenate the given strings while performing various optimizations to
+   * slow the growth rate of tree depth and tree node count. The result is
+   * either a {@link LiteralByteString} or a {@link RopeByteString}
+   * depending on which optimizations, if any, were applied.
+   *
+   * <p>Small pieces of length less than {@link
+   * ByteString#CONCATENATE_BY_COPY_SIZE} may be copied by value here, as in
+   * BAP95.  Large pieces are referenced without copy.
+   *
+   * @param left  string on the left
+   * @param right string on the right
+   * @return concatenation representing the same sequence as the given strings
+   */
+  static ByteString concatenate(ByteString left, ByteString right) {
+    ByteString result;
+    RopeByteString leftRope =
+        (left instanceof RopeByteString) ? (RopeByteString) left : null;
+    if (right.size() == 0) {
+      result = left;
+    } else if (left.size() == 0) {
+      result = right;
+    } else {
+      int newLength = left.size() + right.size();
+      if (newLength < ByteString.CONCATENATE_BY_COPY_SIZE) {
+        // Optimization from BAP95: For short (leaves in paper, but just short
+        // here) total length, do a copy of data to a new leaf.
+        result = concatenateBytes(left, right);
+      } else if (leftRope != null
+          && leftRope.right.size() + right.size() < CONCATENATE_BY_COPY_SIZE) {
+        // Optimization from BAP95: As an optimization of the case where the
+        // ByteString is constructed by repeated concatenate, recognize the case
+        // where a short string is concatenated to a left-hand node whose
+        // right-hand branch is short.  In the paper this applies to leaves, but
+        // we just look at the length here. This has the advantage of shedding
+        // references to unneeded data when substrings have been taken.
+        //
+        // When we recognize this case, we do a copy of the data and create a
+        // new parent node so that the depth of the result is the same as the
+        // given left tree.
+        ByteString newRight = concatenateBytes(leftRope.right, right);
+        result = new RopeByteString(leftRope.left, newRight);
+      } else if (leftRope != null
+          && leftRope.left.getTreeDepth() > leftRope.right.getTreeDepth()
+          && leftRope.getTreeDepth() > right.getTreeDepth()) {
+        // Typically for concatenate-built strings the left-side is deeper than
+        // the right.  This is our final attempt to concatenate without
+        // increasing the tree depth.  We'll redo the the node on the RHS.  This
+        // is yet another optimization for building the string by repeatedly
+        // concatenating on the right.
+        ByteString newRight = new RopeByteString(leftRope.right, right);
+        result = new RopeByteString(leftRope.left, newRight);
+      } else {
+        // Fine, we'll add a node and increase the tree depth--unless we
+        // rebalance ;^)
+        int newDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1;
+        if (newLength >= minLengthByDepth[newDepth]) {
+          // The tree is shallow enough, so don't rebalance
+          result = new RopeByteString(left, right);
+        } else {
+          result = new Balancer().balance(left, right);
+        }
+      }
+    }
+    return result;
+  }
+
+  /**
+   * Concatenates two strings by copying data values. This is called in a few
+   * cases in order to reduce the growth of the number of tree nodes.
+   *
+   * @param left  string on the left
+   * @param right string on the right
+   * @return string formed by copying data bytes
+   */
+  private static LiteralByteString concatenateBytes(ByteString left,
+      ByteString right) {
+    int leftSize = left.size();
+    int rightSize = right.size();
+    byte[] bytes = new byte[leftSize + rightSize];
+    left.copyTo(bytes, 0, 0, leftSize);
+    right.copyTo(bytes, 0, leftSize, rightSize);
+    return new LiteralByteString(bytes);  // Constructor wraps bytes
+  }
+
+  /**
+   * Create a new RopeByteString for testing only while bypassing all the
+   * defenses of {@link #concatenate(ByteString, ByteString)}. This allows
+   * testing trees of specific structure. We are also able to insert empty
+   * leaves, though these are dis-allowed, so that we can make sure the
+   * implementation can withstand their presence.
+   *
+   * @param left  string on the left of this node
+   * @param right string on the right of this node
+   * @return an unsafe instance for testing only
+   */
+  static RopeByteString newInstanceForTest(ByteString left, ByteString right) {
+    return new RopeByteString(left, right);
+  }
+
+  /**
+   * Gets the byte at the given index.
+   * Throws {@link ArrayIndexOutOfBoundsException} for backwards-compatibility
+   * reasons although it would more properly be {@link
+   * IndexOutOfBoundsException}.
+   *
+   * @param index index of byte
+   * @return the value
+   * @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size
+   */
+  @Override
+  public byte byteAt(int index) {
+    if (index < 0) {
+      throw new ArrayIndexOutOfBoundsException("Index < 0: " + index);
+    }
+    if (index > totalLength) {
+      throw new ArrayIndexOutOfBoundsException(
+          "Index > length: " + index + ", " + totalLength);
+    }
+
+    byte result;
+    // Find the relevant piece by recursive descent
+    if (index < leftLength) {
+      result = left.byteAt(index);
+    } else {
+      result = right.byteAt(index - leftLength);
+    }
+    return result;
+  }
+
+  @Override
+  public int size() {
+    return totalLength;
+  }
+
+  // =================================================================
+  // Pieces
+
+  @Override
+  protected int getTreeDepth() {
+    return treeDepth;
+  }
+
+  /**
+   * Determines if the tree is balanced according to BAP95, which means the tree
+   * is flat-enough with respect to the bounds. Note that this definition of
+   * balanced is one where sub-trees of balanced trees are not necessarily
+   * balanced.
+   *
+   * @return true if the tree is balanced
+   */
+  @Override
+  protected boolean isBalanced() {
+    return totalLength >= minLengthByDepth[treeDepth];
+  }
+
+  /**
+   * Takes a substring of this one. This involves recursive descent along the
+   * left and right edges of the substring, and referencing any wholly contained
+   * segments in between. Any leaf nodes entirely uninvolved in the substring
+   * will not be referenced by the substring.
+   *
+   * <p>Substrings of {@code length < 2} should result in at most a single
+   * recursive call chain, terminating at a leaf node. Thus the result will be a
+   * {@link LiteralByteString}. {@link #RopeByteString(ByteString,
+   * ByteString)}.
+   *
+   * @param beginIndex start at this index
+   * @param endIndex   the last character is the one before this index
+   * @return substring leaf node or tree
+   */
+  @Override
+  public ByteString substring(int beginIndex, int endIndex) {
+    if (beginIndex < 0) {
+      throw new IndexOutOfBoundsException(
+          "Beginning index: " + beginIndex + " < 0");
+    }
+    if (endIndex > totalLength) {
+      throw new IndexOutOfBoundsException(
+          "End index: " + endIndex + " > " + totalLength);
+    }
+    int substringLength = endIndex - beginIndex;
+    if (substringLength < 0) {
+      throw new IndexOutOfBoundsException(
+          "Beginning index larger than ending index: " + beginIndex + ", "
+              + endIndex);
+    }
+
+    ByteString result;
+    if (substringLength == 0) {
+      // Empty substring
+      result = ByteString.EMPTY;
+    } else if (substringLength == totalLength) {
+      // The whole string
+      result = this;
+    } else {
+      // Proper substring
+      if (endIndex <= leftLength) {
+        // Substring on the left
+        result = left.substring(beginIndex, endIndex);
+      } else if (beginIndex >= leftLength) {
+        // Substring on the right
+        result = right
+            .substring(beginIndex - leftLength, endIndex - leftLength);
+      } else {
+        // Split substring
+        ByteString leftSub = left.substring(beginIndex);
+        ByteString rightSub = right.substring(0, endIndex - leftLength);
+        // Intentionally not rebalancing, since in many cases these two
+        // substrings will already be less deep than the top-level
+        // RopeByteString we're taking a substring of.
+        result = new RopeByteString(leftSub, rightSub);
+      }
+    }
+    return result;
+  }
+
+  // =================================================================
+  // ByteString -> byte[]
+
+  @Override
+  protected void copyToInternal(byte[] target, int sourceOffset,
+      int targetOffset, int numberToCopy) {
+   if (sourceOffset + numberToCopy <= leftLength) {
+      left.copyToInternal(target, sourceOffset, targetOffset, numberToCopy);
+    } else if (sourceOffset >= leftLength) {
+      right.copyToInternal(target, sourceOffset - leftLength, targetOffset,
+          numberToCopy);
+    } else {
+      int leftLength = this.leftLength - sourceOffset;
+      left.copyToInternal(target, sourceOffset, targetOffset, leftLength);
+      right.copyToInternal(target, 0, targetOffset + leftLength,
+          numberToCopy - leftLength);
+    }
+  }
+
+  @Override
+  public void copyTo(ByteBuffer target) {
+    left.copyTo(target);
+    right.copyTo(target);
+  }
+
+  @Override
+  public ByteBuffer asReadOnlyByteBuffer() {
+    ByteBuffer byteBuffer = ByteBuffer.wrap(toByteArray());
+    return byteBuffer.asReadOnlyBuffer();
+  }
+
+  @Override
+  public List<ByteBuffer> asReadOnlyByteBufferList() {
+    // Walk through the list of LiteralByteString's that make up this
+    // rope, and add each one as a read-only ByteBuffer.
+    List<ByteBuffer> result = new ArrayList<ByteBuffer>();
+    PieceIterator pieces = new PieceIterator(this);
+    while (pieces.hasNext()) {
+      LiteralByteString byteString = pieces.next();
+      result.add(byteString.asReadOnlyByteBuffer());
+    }
+    return result;
+  }
+
+  @Override
+  public void writeTo(OutputStream outputStream) throws IOException {
+    left.writeTo(outputStream);
+    right.writeTo(outputStream);
+  }
+
+  @Override
+  public String toString(String charsetName)
+      throws UnsupportedEncodingException {
+    return new String(toByteArray(), charsetName);
+  }
+
+  // =================================================================
+  // UTF-8 decoding
+
+  @Override
+  public boolean isValidUtf8() {
+    int leftPartial = left.partialIsValidUtf8(Utf8.COMPLETE, 0, leftLength);
+    int state = right.partialIsValidUtf8(leftPartial, 0, right.size());
+    return state == Utf8.COMPLETE;
+  }
+
+  @Override
+  protected int partialIsValidUtf8(int state, int offset, int length) {
+    int toIndex = offset + length;
+    if (toIndex <= leftLength) {
+      return left.partialIsValidUtf8(state, offset, length);
+    } else if (offset >= leftLength) {
+      return right.partialIsValidUtf8(state, offset - leftLength, length);
+    } else {
+      int leftLength = this.leftLength - offset;
+      int leftPartial = left.partialIsValidUtf8(state, offset, leftLength);
+      return right.partialIsValidUtf8(leftPartial, 0, length - leftLength);
+    }
+  }
+
+  // =================================================================
+  // equals() and hashCode()
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof ByteString)) {
+      return false;
+    }
+
+    ByteString otherByteString = (ByteString) other;
+    if (totalLength != otherByteString.size()) {
+      return false;
+    }
+    if (totalLength == 0) {
+      return true;
+    }
+
+    // You don't really want to be calling equals on long strings, but since
+    // we cache the hashCode, we effectively cache inequality. We use the cached
+    // hashCode if it's already computed.  It's arguable we should compute the
+    // hashCode here, and if we're going to be testing a bunch of byteStrings,
+    // it might even make sense.
+    if (hash != 0) {
+      int cachedOtherHash = otherByteString.peekCachedHashCode();
+      if (cachedOtherHash != 0 && hash != cachedOtherHash) {
+        return false;
+      }
+    }
+
+    return equalsFragments(otherByteString);
+  }
+
+  /**
+   * Determines if this string is equal to another of the same length by
+   * iterating over the leaf nodes. On each step of the iteration, the
+   * overlapping segments of the leaves are compared.
+   *
+   * @param other string of the same length as this one
+   * @return true if the values of this string equals the value of the given
+   *         one
+   */
+  private boolean equalsFragments(ByteString other) {
+    int thisOffset = 0;
+    Iterator<LiteralByteString> thisIter = new PieceIterator(this);
+    LiteralByteString thisString = thisIter.next();
+
+    int thatOffset = 0;
+    Iterator<LiteralByteString> thatIter = new PieceIterator(other);
+    LiteralByteString thatString = thatIter.next();
+
+    int pos = 0;
+    while (true) {
+      int thisRemaining = thisString.size() - thisOffset;
+      int thatRemaining = thatString.size() - thatOffset;
+      int bytesToCompare = Math.min(thisRemaining, thatRemaining);
+
+      // At least one of the offsets will be zero
+      boolean stillEqual = (thisOffset == 0)
+          ? thisString.equalsRange(thatString, thatOffset, bytesToCompare)
+          : thatString.equalsRange(thisString, thisOffset, bytesToCompare);
+      if (!stillEqual) {
+        return false;
+      }
+
+      pos += bytesToCompare;
+      if (pos >= totalLength) {
+        if (pos == totalLength) {
+          return true;
+        }
+        throw new IllegalStateException();
+      }
+      // We always get to the end of at least one of the pieces
+      if (bytesToCompare == thisRemaining) { // If reached end of this
+        thisOffset = 0;
+        thisString = thisIter.next();
+      } else {
+        thisOffset += bytesToCompare;
+      }
+      if (bytesToCompare == thatRemaining) { // If reached end of that
+        thatOffset = 0;
+        thatString = thatIter.next();
+      } else {
+        thatOffset += bytesToCompare;
+      }
+    }
+  }
+
+  /**
+   * Cached hash value.  Intentionally accessed via a data race, which is safe
+   * because of the Java Memory Model's "no out-of-thin-air values" guarantees
+   * for ints.
+   */
+  private int hash = 0;
+
+  @Override
+  public int hashCode() {
+    int h = hash;
+
+    if (h == 0) {
+      h = totalLength;
+      h = partialHash(h, 0, totalLength);
+      if (h == 0) {
+        h = 1;
+      }
+      hash = h;
+    }
+    return h;
+  }
+
+  @Override
+  protected int peekCachedHashCode() {
+    return hash;
+  }
+
+  @Override
+  protected int partialHash(int h, int offset, int length) {
+    int toIndex = offset + length;
+    if (toIndex <= leftLength) {
+      return left.partialHash(h, offset, length);
+    } else if (offset >= leftLength) {
+      return right.partialHash(h, offset - leftLength, length);
+    } else {
+      int leftLength = this.leftLength - offset;
+      int leftPartial = left.partialHash(h, offset, leftLength);
+      return right.partialHash(leftPartial, 0, length - leftLength);
+    }
+  }
+
+  // =================================================================
+  // Input stream
+
+  @Override
+  public CodedInputStream newCodedInput() {
+    return CodedInputStream.newInstance(new RopeInputStream());
+  }
+
+  @Override
+  public InputStream newInput() {
+    return new RopeInputStream();
+  }
+
+  /**
+   * This class implements the balancing algorithm of BAP95. In the paper the
+   * authors use an array to keep track of pieces, while here we use a stack.
+   * The tree is balanced by traversing subtrees in left to right order, and the
+   * stack always contains the part of the string we've traversed so far.
+   *
+   * <p>One surprising aspect of the algorithm is the result of balancing is not
+   * necessarily balanced, though it is nearly balanced.  For details, see
+   * BAP95.
+   */
+  private static class Balancer {
+    // Stack containing the part of the string, starting from the left, that
+    // we've already traversed.  The final string should be the equivalent of
+    // concatenating the strings on the stack from bottom to top.
+    private final Deque<ByteString> prefixesStack =
+        new ArrayDeque<ByteString>(minLengthByDepth.length);
+
+    private ByteString balance(ByteString left, ByteString right) {
+      doBalance(left);
+      doBalance(right);
+
+      // Sweep stack to gather the result
+      ByteString partialString = prefixesStack.pop();
+      while (!prefixesStack.isEmpty()) {
+        ByteString newLeft = prefixesStack.pop();
+        partialString = new RopeByteString(newLeft, partialString);
+      }
+      // We should end up with a RopeByteString since at a minimum we will
+      // create one from concatenating left and right
+      return partialString;
+    }
+
+    private void doBalance(ByteString root) {
+      // BAP95: Insert balanced subtrees whole. This means the result might not
+      // be balanced, leading to repeated rebalancings on concatenate. However,
+      // these rebalancings are shallow due to ignoring balanced subtrees, and
+      // relatively few calls to insert() result.
+      if (root.isBalanced()) {
+        insert(root);
+      } else if (root instanceof RopeByteString) {
+        RopeByteString rbs = (RopeByteString) root;
+        doBalance(rbs.left);
+        doBalance(rbs.right);
+      } else {
+        throw new IllegalArgumentException(
+            "Has a new type of ByteString been created? Found " +
+                root.getClass());
+      }
+    }
+
+    /**
+     * Push a string on the balance stack (BAP95).  BAP95 uses an array and
+     * calls the elements in the array 'bins'.  We instead use a stack, so the
+     * 'bins' of lengths are represented by differences between the elements of
+     * minLengthByDepth.
+     *
+     * <p>If the length bin for our string, and all shorter length bins, are
+     * empty, we just push it on the stack.  Otherwise, we need to start
+     * concatenating, putting the given string in the "middle" and continuing
+     * until we land in an empty length bin that matches the length of our
+     * concatenation.
+     *
+     * @param byteString string to place on the balance stack
+     */
+    private void insert(ByteString byteString) {
+      int depthBin = getDepthBinForLength(byteString.size());
+      int binEnd = minLengthByDepth[depthBin + 1];
+
+      // BAP95: Concatenate all trees occupying bins representing the length of
+      // our new piece or of shorter pieces, to the extent that is possible.
+      // The goal is to clear the bin which our piece belongs in, but that may
+      // not be entirely possible if there aren't enough longer bins occupied.
+      if (prefixesStack.isEmpty() || prefixesStack.peek().size() >= binEnd) {
+        prefixesStack.push(byteString);
+      } else {
+        int binStart = minLengthByDepth[depthBin];
+
+        // Concatenate the subtrees of shorter length
+        ByteString newTree = prefixesStack.pop();
+        while (!prefixesStack.isEmpty()
+            && prefixesStack.peek().size() < binStart) {
+          ByteString left = prefixesStack.pop();
+          newTree = new RopeByteString(left, newTree);
+        }
+
+        // Concatenate the given string
+        newTree = new RopeByteString(newTree, byteString);
+
+        // Continue concatenating until we land in an empty bin
+        while (!prefixesStack.isEmpty()) {
+          depthBin = getDepthBinForLength(newTree.size());
+          binEnd = minLengthByDepth[depthBin + 1];
+          if (prefixesStack.peek().size() < binEnd) {
+            ByteString left = prefixesStack.pop();
+            newTree = new RopeByteString(left, newTree);
+          } else {
+            break;
+          }
+        }
+        prefixesStack.push(newTree);
+      }
+    }
+
+    private int getDepthBinForLength(int length) {
+      int depth = Arrays.binarySearch(minLengthByDepth, length);
+      if (depth < 0) {
+        // It wasn't an exact match, so convert to the index of the containing
+        // fragment, which is one less even than the insertion point.
+        int insertionPoint = -(depth + 1);
+        depth = insertionPoint - 1;
+      }
+
+      return depth;
+    }
+  }
+
+  /**
+   * This class is a continuable tree traversal, which keeps the state
+   * information which would exist on the stack in a recursive traversal instead
+   * on a stack of "Bread Crumbs". The maximum depth of the stack in this
+   * iterator is the same as the depth of the tree being traversed.
+   *
+   * <p>This iterator is used to implement
+   * {@link RopeByteString#equalsFragments(ByteString)}.
+   */
+  private static class PieceIterator implements Iterator<LiteralByteString> {
+
+    private final Deque<RopeByteString> breadCrumbs =
+        new ArrayDeque<RopeByteString>(minLengthByDepth.length);
+    private LiteralByteString next;
+
+    private PieceIterator(ByteString root) {
+      next = getLeafByLeft(root);
+    }
+
+    private LiteralByteString getLeafByLeft(ByteString root) {
+      ByteString pos = root;
+      while (pos instanceof RopeByteString) {
+        RopeByteString rbs = (RopeByteString) pos;
+        breadCrumbs.push(rbs);
+        pos = rbs.left;
+      }
+      return (LiteralByteString) pos;
+    }
+
+    private LiteralByteString getNextNonEmptyLeaf() {
+      while (true) {
+        // Almost always, we go through this loop exactly once.  However, if
+        // we discover an empty string in the rope, we toss it and try again.
+        if (breadCrumbs.isEmpty()) {
+          return null;
+        } else {
+          LiteralByteString result = getLeafByLeft(breadCrumbs.pop().right);
+          if (!result.isEmpty()) {
+            return result;
+          }
+        }
+      }
+    }
+
+    public boolean hasNext() {
+      return next != null;
+    }
+
+    /**
+     * Returns the next item and advances one {@code LiteralByteString}.
+     *
+     * @return next non-empty LiteralByteString or {@code null}
+     */
+    public LiteralByteString next() {
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
+      LiteralByteString result = next;
+      next = getNextNonEmptyLeaf();
+      return result;
+    }
+
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  // =================================================================
+  // ByteIterator
+
+  @Override
+  public ByteIterator iterator() {
+    return new RopeByteIterator();
+  }
+
+  private class RopeByteIterator implements ByteString.ByteIterator {
+
+    private final PieceIterator pieces;
+    private ByteIterator bytes;
+    int bytesRemaining;
+
+    private RopeByteIterator() {
+      pieces = new PieceIterator(RopeByteString.this);
+      bytes = pieces.next().iterator();
+      bytesRemaining = size();
+    }
+
+    public boolean hasNext() {
+      return (bytesRemaining > 0);
+    }
+
+    public Byte next() {
+      return nextByte(); // Does not instantiate a Byte
+    }
+
+    public byte nextByte() {
+      if (!bytes.hasNext()) {
+        bytes = pieces.next().iterator();
+      }
+      --bytesRemaining;
+      return bytes.nextByte();
+    }
+
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  /**
+   * This class is the {@link RopeByteString} equivalent for
+   * {@link ByteArrayInputStream}.
+   */
+  private class RopeInputStream extends InputStream {
+    // Iterates through the pieces of the rope
+    private PieceIterator pieceIterator;
+    // The current piece
+    private LiteralByteString currentPiece;
+    // The size of the current piece
+    private int currentPieceSize;
+    // The index of the next byte to read in the current piece
+    private int currentPieceIndex;
+    // The offset of the start of the current piece in the rope byte string
+    private int currentPieceOffsetInRope;
+    // Offset in the buffer at which user called mark();
+    private int mark;
+
+    public RopeInputStream() {
+      initialize();
+    }
+
+    @Override
+    public int read(byte b[], int offset, int length)  {
+      if (b == null) {
+        throw new NullPointerException();
+      } else if (offset < 0 || length < 0 || length > b.length - offset) {
+        throw new IndexOutOfBoundsException();
+      }
+      return readSkipInternal(b, offset, length);
+    }
+
+    @Override
+    public long skip(long length) {
+      if (length < 0) {
+        throw new IndexOutOfBoundsException();
+      } else if (length > Integer.MAX_VALUE) {
+        length = Integer.MAX_VALUE;
+      }
+      return readSkipInternal(null, 0, (int) length);
+    }
+
+    /**
+     * Internal implementation of read and skip.  If b != null, then read the
+     * next {@code length} bytes into the buffer {@code b} at
+     * offset {@code offset}.  If b == null, then skip the next {@code length)
+     * bytes.
+     * <p>
+     * This method assumes that all error checking has already happened.
+     * <p>
+     * Returns the actual number of bytes read or skipped.
+     */
+    private int readSkipInternal(byte b[], int offset, int length)  {
+      int bytesRemaining = length;
+      while (bytesRemaining > 0) {
+        advanceIfCurrentPieceFullyRead();
+        if (currentPiece == null) {
+          if (bytesRemaining == length) {
+             // We didn't manage to read anything
+             return -1;
+           }
+          break;
+        } else {
+          // Copy the bytes from this piece.
+          int currentPieceRemaining = currentPieceSize - currentPieceIndex;
+          int count = Math.min(currentPieceRemaining, bytesRemaining);
+          if (b != null) {
+            currentPiece.copyTo(b, currentPieceIndex, offset, count);
+            offset += count;
+          }
+          currentPieceIndex += count;
+          bytesRemaining -= count;
+        }
+      }
+       // Return the number of bytes read.
+      return length - bytesRemaining;
+    }
+
+    @Override
+    public int read() throws IOException {
+      advanceIfCurrentPieceFullyRead();
+      if (currentPiece == null) {
+        return -1;
+      } else {
+        return currentPiece.byteAt(currentPieceIndex++) & 0xFF;
+      }
+    }
+
+    @Override
+    public int available() throws IOException {
+      int bytesRead = currentPieceOffsetInRope + currentPieceIndex;
+      return RopeByteString.this.size() - bytesRead;
+    }
+
+    @Override
+    public boolean markSupported() {
+      return true;
+    }
+
+    @Override
+    public void mark(int readAheadLimit) {
+      // Set the mark to our position in the byte string
+      mark = currentPieceOffsetInRope + currentPieceIndex;
+    }
+
+    @Override
+    public synchronized void reset() {
+      // Just reinitialize and skip the specified number of bytes.
+      initialize();
+      readSkipInternal(null, 0, mark);
+    }
+
+    /** Common initialization code used by both the constructor and reset() */
+    private void initialize() {
+      pieceIterator = new PieceIterator(RopeByteString.this);
+      currentPiece = pieceIterator.next();
+      currentPieceSize = currentPiece.size();
+      currentPieceIndex = 0;
+      currentPieceOffsetInRope = 0;
+    }
+
+    /**
+     * Skips to the next piece if we have read all the data in the current
+     * piece.  Sets currentPiece to null if we have reached the end of the
+     * input.
+     */
+    private void advanceIfCurrentPieceFullyRead() {
+      if (currentPiece != null && currentPieceIndex == currentPieceSize) {
+        // Generally, we can only go through this loop at most once, since
+        // empty strings can't end up in a rope.  But better to test.
+        currentPieceOffsetInRope += currentPieceSize;
+        currentPieceIndex = 0;
+        if (pieceIterator.hasNext()) {
+          currentPiece = pieceIterator.next();
+          currentPieceSize = currentPiece.size();
+        } else {
+          currentPiece = null;
+          currentPieceSize = 0;
+        }
+      }
+    }
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/SingleFieldBuilder.java b/java/src/main/java/com/google/protobuf/SingleFieldBuilder.java
index d4475f66..4bfc9f34 100644
--- a/java/src/main/java/com/google/protobuf/SingleFieldBuilder.java
+++ b/java/src/main/java/com/google/protobuf/SingleFieldBuilder.java
@@ -31,21 +31,21 @@
 package com.google.protobuf;
 
 /**
- * <code>SingleFieldBuilder</code> implements a structure that a protocol
+ * {@code SingleFieldBuilder} implements a structure that a protocol
  * message uses to hold a single field of another protocol message. It supports
  * the classical use case of setting an immutable {@link Message} as the value
  * of the field and is highly optimized around this.
  * <br>
  * It also supports the additional use case of setting a {@link Message.Builder}
- * as the field and deferring conversion of that <code>Builder</code>
- * to an immutable <code>Message</code>. In this way, it's possible to maintain
- * a tree of <code>Builder</code>'s that acts as a fully read/write data
+ * as the field and deferring conversion of that {@code Builder}
+ * to an immutable {@code Message}. In this way, it's possible to maintain
+ * a tree of {@code Builder}'s that acts as a fully read/write data
  * structure.
  * <br>
  * Logically, one can think of a tree of builders as converting the entire tree
  * to messages when build is called on the root or when any method is called
  * that desires a Message instead of a Builder. In terms of the implementation,
- * the <code>SingleFieldBuilder</code> and <code>RepeatedFieldBuilder</code>
+ * the {@code SingleFieldBuilder} and {@code RepeatedFieldBuilder}
  * classes cache messages that were created so that messages only need to be
  * created when some change occured in its builder or a builder for one of its
  * descendants.
@@ -99,7 +99,7 @@ public class SingleFieldBuilder
 
   /**
    * Get the message for the field. If the message is currently stored
-   * as a <code>Builder</code>, it is converted to a <code>Message</code> by
+   * as a {@code Builder}, it is converted to a {@code Message} by
    * calling {@link Message.Builder#buildPartial} on it. If no message has
    * been set, returns the default instance of the message.
    *
diff --git a/java/src/main/java/com/google/protobuf/SmallSortedMap.java b/java/src/main/java/com/google/protobuf/SmallSortedMap.java
index 1cf270f3..c6cad6af 100644
--- a/java/src/main/java/com/google/protobuf/SmallSortedMap.java
+++ b/java/src/main/java/com/google/protobuf/SmallSortedMap.java
@@ -51,14 +51,14 @@ import java.util.SortedMap;
  * remaining entries are stored in an overflow map. Iteration over the entries
  * in the map should be done as follows:
  *
- * <pre>
- * for (int i = 0; i &lt; fieldMap.getNumArrayEntries(); i++) {
+ * <pre>   {@code
+ * for (int i = 0; i < fieldMap.getNumArrayEntries(); i++) {
  *   process(fieldMap.getArrayEntryAt(i));
  * }
- * for (Map.Entry&lt;K, V&gt; entry : fieldMap.getOverflowEntries()) {
+ * for (Map.Entry<K, V> entry : fieldMap.getOverflowEntries()) {
  *   process(entry);
  * }
- * </pre>
+ * }</pre>
  *
  * The resulting iteration is in order of ascending field tag number. The
  * object returned by {@link #entrySet()} adheres to the same contract but is
@@ -394,7 +394,7 @@ class SmallSortedMap<K extends Comparable<K>, V> extends AbstractMap<K, V> {
 
   /**
    * Entry implementation that implements Comparable in order to support
-   * binary search witin the entry array. Also checks mutability in
+   * binary search within the entry array. Also checks mutability in
    * {@link #setValue()}.
    */
   private class Entry implements Map.Entry<K, V>, Comparable<Entry> {
diff --git a/java/src/main/java/com/google/protobuf/TextFormat.java b/java/src/main/java/com/google/protobuf/TextFormat.java
index d5fbdabf..ed462899 100644
--- a/java/src/main/java/com/google/protobuf/TextFormat.java
+++ b/java/src/main/java/com/google/protobuf/TextFormat.java
@@ -55,15 +55,18 @@ import java.util.regex.Pattern;
 public final class TextFormat {
   private TextFormat() {}
 
-  private static final Printer DEFAULT_PRINTER = new Printer(false);
-  private static final Printer SINGLE_LINE_PRINTER = new Printer(true);
+  private static final Printer DEFAULT_PRINTER = new Printer();
+  private static final Printer SINGLE_LINE_PRINTER =
+      (new Printer()).setSingleLineMode(true);
+  private static final Printer UNICODE_PRINTER =
+      (new Printer()).setEscapeNonAscii(false);
 
   /**
    * Outputs a textual representation of the Protocol Message supplied into
    * the parameter output. (This representation is the new version of the
    * classic "ProtocolPrinter" output from the original Protocol Buffer system)
    */
-  public static void print(final Message message, final Appendable output)
+  public static void print(final MessageOrBuilder message, final Appendable output)
                            throws IOException {
     DEFAULT_PRINTER.print(message, new TextGenerator(output));
   }
@@ -79,7 +82,7 @@ public final class TextFormat {
    * Generates a human readable form of this message, useful for debugging and
    * other purposes, with no newline characters.
    */
-  public static String shortDebugString(final Message message) {
+  public static String shortDebugString(final MessageOrBuilder message) {
     try {
       final StringBuilder sb = new StringBuilder();
       SINGLE_LINE_PRINTER.print(message, new TextGenerator(sb));
@@ -109,7 +112,7 @@ public final class TextFormat {
    * Like {@code print()}, but writes directly to a {@code String} and
    * returns it.
    */
-  public static String printToString(final Message message) {
+  public static String printToString(final MessageOrBuilder message) {
     try {
       final StringBuilder text = new StringBuilder();
       print(message, text);
@@ -133,6 +136,34 @@ public final class TextFormat {
     }
   }
 
+  /**
+   * Same as {@code printToString()}, except that non-ASCII characters
+   * in string type fields are not escaped in backslash+octals.
+   */
+  public static String printToUnicodeString(final MessageOrBuilder message) {
+    try {
+      final StringBuilder text = new StringBuilder();
+      UNICODE_PRINTER.print(message, new TextGenerator(text));
+      return text.toString();
+    } catch (IOException e) {
+      throw new IllegalStateException(e);
+    }
+  }
+
+  /**
+   * Same as {@code printToString()}, except that non-ASCII characters
+   * in string type fields are not escaped in backslash+octals.
+   */
+  public static String printToUnicodeString(final UnknownFieldSet fields) {
+    try {
+      final StringBuilder text = new StringBuilder();
+      UNICODE_PRINTER.printUnknownFields(fields, new TextGenerator(text));
+      return text.toString();
+    } catch (IOException e) {
+      throw new IllegalStateException(e);
+    }
+  }
+
   public static void printField(final FieldDescriptor field,
                                 final Object value,
                                 final Appendable output)
@@ -216,13 +247,26 @@ public final class TextFormat {
   /** Helper class for converting protobufs to text. */
   private static final class Printer {
     /** Whether to omit newlines from the output. */
-    final boolean singleLineMode;
+    boolean singleLineMode = false;
+
+    /** Whether to escape non ASCII characters with backslash and octal. */
+    boolean escapeNonAscii = true;
+
+    private Printer() {}
 
-    private Printer(final boolean singleLineMode) {
+    /** Setter of singleLineMode */
+    private Printer setSingleLineMode(boolean singleLineMode) {
       this.singleLineMode = singleLineMode;
+      return this;
+    }
+
+    /** Setter of escapeNonAscii */
+    private Printer setEscapeNonAscii(boolean escapeNonAscii) {
+      this.escapeNonAscii = escapeNonAscii;
+      return this;
     }
 
-    private void print(final Message message, final TextGenerator generator)
+    private void print(final MessageOrBuilder message, final TextGenerator generator)
         throws IOException {
       for (Map.Entry<FieldDescriptor, Object> field
           : message.getAllFields().entrySet()) {
@@ -339,7 +383,9 @@ public final class TextFormat {
 
         case STRING:
           generator.print("\"");
-          generator.print(escapeText((String) value));
+          generator.print(escapeNonAscii ?
+              escapeText((String) value) :
+              (String) value);
           generator.print("\"");
           break;
 
@@ -541,7 +587,7 @@ public final class TextFormat {
     private int previousLine = 0;
     private int previousColumn = 0;
 
-    // We use possesive quantifiers (*+ and ++) because otherwise the Java
+    // We use possessive quantifiers (*+ and ++) because otherwise the Java
     // regex matcher has stack overflows on large inputs.
     private static final Pattern WHITESPACE =
       Pattern.compile("(\\s|(#.*$))++", Pattern.MULTILINE);
@@ -864,7 +910,7 @@ public final class TextFormat {
     public ParseException parseException(final String description) {
       // Note:  People generally prefer one-based line and column numbers.
       return new ParseException(
-        (line + 1) + ":" + (column + 1) + ": " + description);
+        line + 1, column + 1, description);
     }
 
     /**
@@ -875,7 +921,7 @@ public final class TextFormat {
         final String description) {
       // Note:  People generally prefer one-based line and column numbers.
       return new ParseException(
-        (previousLine + 1) + ":" + (previousColumn + 1) + ": " + description);
+        previousLine + 1, previousColumn + 1, description);
     }
 
     /**
@@ -900,8 +946,45 @@ public final class TextFormat {
   public static class ParseException extends IOException {
     private static final long serialVersionUID = 3196188060225107702L;
 
+    private final int line;
+    private final int column;
+
+    /** Create a new instance, with -1 as the line and column numbers. */
     public ParseException(final String message) {
-      super(message);
+      this(-1, -1, message);
+    }
+
+    /**
+     * Create a new instance
+     *
+     * @param line the line number where the parse error occurred,
+     * using 1-offset.
+     * @param column the column number where the parser error occurred,
+     * using 1-offset.
+     */
+    public ParseException(final int line, final int column,
+        final String message) {
+      super(Integer.toString(line) + ":" + column + ": " + message);
+      this.line = line;
+      this.column = column;
+    }
+
+    /**
+     * Return the line where the parse exception occurred, or -1 when
+     * none is provided. The value is specified as 1-offset, so the first
+     * line is line 1.
+     */
+    public int getLine() {
+      return line;
+    }
+
+    /**
+     * Return the column where the parse exception occurred, or -1 when
+     * none is provided. The value is specified as 1-offset, so the first
+     * line is line 1.
+     */
+    public int getColumn() {
+      return column;
     }
   }
 
@@ -1073,7 +1156,7 @@ public final class TextFormat {
         mergeField(tokenizer, extensionRegistry, subBuilder);
       }
 
-      value = subBuilder.build();
+      value = subBuilder.buildPartial();
 
     } else {
       tokenizer.consume(":");
@@ -1212,7 +1295,7 @@ public final class TextFormat {
    */
   static ByteString unescapeBytes(final CharSequence charString)
       throws InvalidEscapeSequenceException {
-    // First convert the Java characater sequence to UTF-8 bytes.
+    // First convert the Java character sequence to UTF-8 bytes.
     ByteString input = ByteString.copyFromUtf8(charString.toString());
     // Then unescape certain byte sequences introduced by ASCII '\\'.  The valid
     // escapes can all be expressed with ASCII characters, so it is safe to
@@ -1349,7 +1432,7 @@ public final class TextFormat {
   /**
    * Parse a 32-bit signed integer from the text.  Unlike the Java standard
    * {@code Integer.parseInt()}, this function recognizes the prefixes "0x"
-   * and "0" to signify hexidecimal and octal numbers, respectively.
+   * and "0" to signify hexadecimal and octal numbers, respectively.
    */
   static int parseInt32(final String text) throws NumberFormatException {
     return (int) parseInteger(text, true, false);
@@ -1358,7 +1441,7 @@ public final class TextFormat {
   /**
    * Parse a 32-bit unsigned integer from the text.  Unlike the Java standard
    * {@code Integer.parseInt()}, this function recognizes the prefixes "0x"
-   * and "0" to signify hexidecimal and octal numbers, respectively.  The
+   * and "0" to signify hexadecimal and octal numbers, respectively.  The
    * result is coerced to a (signed) {@code int} when returned since Java has
    * no unsigned integer type.
    */
@@ -1369,7 +1452,7 @@ public final class TextFormat {
   /**
    * Parse a 64-bit signed integer from the text.  Unlike the Java standard
    * {@code Integer.parseInt()}, this function recognizes the prefixes "0x"
-   * and "0" to signify hexidecimal and octal numbers, respectively.
+   * and "0" to signify hexadecimal and octal numbers, respectively.
    */
   static long parseInt64(final String text) throws NumberFormatException {
     return parseInteger(text, true, true);
@@ -1378,7 +1461,7 @@ public final class TextFormat {
   /**
    * Parse a 64-bit unsigned integer from the text.  Unlike the Java standard
    * {@code Integer.parseInt()}, this function recognizes the prefixes "0x"
-   * and "0" to signify hexidecimal and octal numbers, respectively.  The
+   * and "0" to signify hexadecimal and octal numbers, respectively.  The
    * result is coerced to a (signed) {@code long} when returned since Java has
    * no unsigned long type.
    */
diff --git a/java/src/main/java/com/google/protobuf/UnknownFieldSet.java b/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
index 26a15d00..45e2e6e4 100644
--- a/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -46,7 +46,7 @@ import java.util.TreeMap;
  * {@code UnknownFieldSet} is used to keep track of fields which were seen when
  * parsing a protocol message but whose field numbers or types are unrecognized.
  * This most frequently occurs when new fields are added to a message type
- * and then messages containing those feilds are read by old software that was
+ * and then messages containing those fields are read by old software that was
  * compiled before the new types were added.
  *
  * <p>Every {@link Message} contains an {@code UnknownFieldSet} (and every
@@ -468,7 +468,7 @@ public final class UnknownFieldSet implements MessageLite {
     /**
      * Parse a single field from {@code input} and merge it into this set.
      * @param tag The field's tag number, which was already parsed.
-     * @return {@code false} if the tag is an engroup tag.
+     * @return {@code false} if the tag is an end group tag.
      */
     public boolean mergeFieldFrom(final int tag, final CodedInputStream input)
                                   throws IOException {
@@ -950,4 +950,29 @@ public final class UnknownFieldSet implements MessageLite {
       }
     }
   }
+
+  /**
+   * Parser to implement MessageLite interface.
+   */
+  public static final class Parser extends AbstractParser<UnknownFieldSet> {
+    public UnknownFieldSet parsePartialFrom(
+        CodedInputStream input, ExtensionRegistryLite extensionRegistry)
+        throws InvalidProtocolBufferException {
+      Builder builder = newBuilder();
+      try {
+        builder.mergeFrom(input);
+      } catch (InvalidProtocolBufferException e) {
+        throw e.setUnfinishedMessage(builder.buildPartial());
+      } catch (IOException e) {
+        throw new InvalidProtocolBufferException(e.getMessage())
+            .setUnfinishedMessage(builder.buildPartial());
+      }
+      return builder.buildPartial();
+    }
+  }
+
+  private static final Parser PARSER = new Parser();
+  public final Parser getParserForType() {
+    return PARSER;
+  }
 }
diff --git a/java/src/main/java/com/google/protobuf/UnmodifiableLazyStringList.java b/java/src/main/java/com/google/protobuf/UnmodifiableLazyStringList.java
index 83e5c796..f80f0968 100644
--- a/java/src/main/java/com/google/protobuf/UnmodifiableLazyStringList.java
+++ b/java/src/main/java/com/google/protobuf/UnmodifiableLazyStringList.java
@@ -32,6 +32,7 @@ package com.google.protobuf;
 
 import java.util.AbstractList;
 import java.util.RandomAccess;
+import java.util.List;
 import java.util.ListIterator;
 import java.util.Iterator;
 
@@ -143,4 +144,10 @@ public class UnmodifiableLazyStringList extends AbstractList<String>
       }
     };
   }
+
+  @Override
+  public List<?> getUnderlyingElements() {
+    // The returned value is already unmodifiable.
+    return list.getUnderlyingElements();
+  }
 }
diff --git a/java/src/main/java/com/google/protobuf/Utf8.java b/java/src/main/java/com/google/protobuf/Utf8.java
new file mode 100644
index 00000000..388f7fc5
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/Utf8.java
@@ -0,0 +1,349 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+/**
+ * A set of low-level, high-performance static utility methods related
+ * to the UTF-8 character encoding.  This class has no dependencies
+ * outside of the core JDK libraries.
+ *
+ * <p>There are several variants of UTF-8.  The one implemented by
+ * this class is the restricted definition of UTF-8 introduced in
+ * Unicode 3.1, which mandates the rejection of "overlong" byte
+ * sequences as well as rejection of 3-byte surrogate codepoint byte
+ * sequences.  Note that the UTF-8 decoder included in Oracle's JDK
+ * has been modified to also reject "overlong" byte sequences, but (as
+ * of 2011) still accepts 3-byte surrogate codepoint byte sequences.
+ *
+ * <p>The byte sequences considered valid by this class are exactly
+ * those that can be roundtrip converted to Strings and back to bytes
+ * using the UTF-8 charset, without loss: <pre> {@code
+ * Arrays.equals(bytes, new String(bytes, "UTF-8").getBytes("UTF-8"))
+ * }</pre>
+ *
+ * <p>See the Unicode Standard,</br>
+ * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
+ * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
+ *
+ * <p>This class supports decoding of partial byte sequences, so that the
+ * bytes in a complete UTF-8 byte sequences can be stored in multiple
+ * segments.  Methods typically return {@link #MALFORMED} if the partial
+ * byte sequence is definitely not well-formed, {@link #COMPLETE} if it is
+ * well-formed in the absence of additional input, or if the byte sequence
+ * apparently terminated in the middle of a character, an opaque integer
+ * "state" value containing enough information to decode the character when
+ * passed to a subsequent invocation of a partial decoding method.
+ *
+ * @author martinrb@google.com (Martin Buchholz)
+ */
+final class Utf8 {
+  private Utf8() {}
+
+  /**
+   * State value indicating that the byte sequence is well-formed and
+   * complete (no further bytes are needed to complete a character).
+   */
+  public static final int COMPLETE = 0;
+
+  /**
+   * State value indicating that the byte sequence is definitely not
+   * well-formed.
+   */
+  public static final int MALFORMED = -1;
+
+  // Other state values include the partial bytes of the incomplete
+  // character to be decoded in the simplest way: we pack the bytes
+  // into the state int in little-endian order.  For example:
+  //
+  // int state = byte1 ^ (byte2 << 8) ^ (byte3 << 16);
+  //
+  // Such a state is unpacked thus (note the ~ operation for byte2 to
+  // undo byte1's sign-extension bits):
+  //
+  // int byte1 = (byte) state;
+  // int byte2 = (byte) ~(state >> 8);
+  // int byte3 = (byte) (state >> 16);
+  //
+  // We cannot store a zero byte in the state because it would be
+  // indistinguishable from the absence of a byte.  But we don't need
+  // to, because partial bytes must always be negative.  When building
+  // a state, we ensure that byte1 is negative and subsequent bytes
+  // are valid trailing bytes.
+
+  /**
+   * Returns {@code true} if the given byte array is a well-formed
+   * UTF-8 byte sequence.
+   *
+   * <p>This is a convenience method, equivalent to a call to {@code
+   * isValidUtf8(bytes, 0, bytes.length)}.
+   */
+  public static boolean isValidUtf8(byte[] bytes) {
+    return isValidUtf8(bytes, 0, bytes.length);
+  }
+
+  /**
+   * Returns {@code true} if the given byte array slice is a
+   * well-formed UTF-8 byte sequence.  The range of bytes to be
+   * checked extends from index {@code index}, inclusive, to {@code
+   * limit}, exclusive.
+   *
+   * <p>This is a convenience method, equivalent to {@code
+   * partialIsValidUtf8(bytes, index, limit) == Utf8.COMPLETE}.
+   */
+  public static boolean isValidUtf8(byte[] bytes, int index, int limit) {
+    return partialIsValidUtf8(bytes, index, limit) == COMPLETE;
+  }
+
+  /**
+   * Tells whether the given byte array slice is a well-formed,
+   * malformed, or incomplete UTF-8 byte sequence.  The range of bytes
+   * to be checked extends from index {@code index}, inclusive, to
+   * {@code limit}, exclusive.
+   *
+   * @param state either {@link Utf8#COMPLETE} (if this is the initial decoding
+   * operation) or the value returned from a call to a partial decoding method
+   * for the previous bytes
+   *
+   * @return {@link #MALFORMED} if the partial byte sequence is
+   * definitely not well-formed, {@link #COMPLETE} if it is well-formed
+   * (no additional input needed), or if the byte sequence is
+   * "incomplete", i.e. apparently terminated in the middle of a character,
+   * an opaque integer "state" value containing enough information to
+   * decode the character when passed to a subsequent invocation of a
+   * partial decoding method.
+   */
+  public static int partialIsValidUtf8(
+      int state, byte[] bytes, int index, int limit) {
+    if (state != COMPLETE) {
+      // The previous decoding operation was incomplete (or malformed).
+      // We look for a well-formed sequence consisting of bytes from
+      // the previous decoding operation (stored in state) together
+      // with bytes from the array slice.
+      //
+      // We expect such "straddler characters" to be rare.
+
+      if (index >= limit) {  // No bytes? No progress.
+        return state;
+      }
+      int byte1 = (byte) state;
+      // byte1 is never ASCII.
+      if (byte1 < (byte) 0xE0) {
+        // two-byte form
+
+        // Simultaneously checks for illegal trailing-byte in
+        // leading position and overlong 2-byte form.
+        if (byte1 < (byte) 0xC2 ||
+            // byte2 trailing-byte test
+            bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      } else if (byte1 < (byte) 0xF0) {
+        // three-byte form
+
+        // Get byte2 from saved state or array
+        int byte2 = (byte) ~(state >> 8);
+        if (byte2 == 0) {
+          byte2 = bytes[index++];
+          if (index >= limit) {
+            return incompleteStateFor(byte1, byte2);
+          }
+        }
+        if (byte2 > (byte) 0xBF ||
+            // overlong? 5 most significant bits must not all be zero
+            (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) ||
+            // illegal surrogate codepoint?
+            (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) ||
+            // byte3 trailing-byte test
+            bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      } else {
+        // four-byte form
+
+        // Get byte2 and byte3 from saved state or array
+        int byte2 = (byte) ~(state >> 8);
+        int byte3 = 0;
+        if (byte2 == 0) {
+          byte2 = bytes[index++];
+          if (index >= limit) {
+            return incompleteStateFor(byte1, byte2);
+          }
+        } else {
+          byte3 = (byte) (state >> 16);
+        }
+        if (byte3 == 0) {
+          byte3 = bytes[index++];
+          if (index >= limit) {
+            return incompleteStateFor(byte1, byte2, byte3);
+          }
+        }
+
+        // If we were called with state == MALFORMED, then byte1 is 0xFF,
+        // which never occurs in well-formed UTF-8, and so we will return
+        // MALFORMED again below.
+
+        if (byte2 > (byte) 0xBF ||
+            // Check that 1 <= plane <= 16.  Tricky optimized form of:
+            // if (byte1 > (byte) 0xF4 ||
+            //     byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 ||
+            //     byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F)
+            (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 ||
+            // byte3 trailing-byte test
+            byte3 > (byte) 0xBF ||
+            // byte4 trailing-byte test
+             bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      }
+    }
+
+    return partialIsValidUtf8(bytes, index, limit);
+  }
+
+  /**
+   * Tells whether the given byte array slice is a well-formed,
+   * malformed, or incomplete UTF-8 byte sequence.  The range of bytes
+   * to be checked extends from index {@code index}, inclusive, to
+   * {@code limit}, exclusive.
+   *
+   * <p>This is a convenience method, equivalent to a call to {@code
+   * partialIsValidUtf8(Utf8.COMPLETE, bytes, index, limit)}.
+   *
+   * @return {@link #MALFORMED} if the partial byte sequence is
+   * definitely not well-formed, {@link #COMPLETE} if it is well-formed
+   * (no additional input needed), or if the byte sequence is
+   * "incomplete", i.e. apparently terminated in the middle of a character,
+   * an opaque integer "state" value containing enough information to
+   * decode the character when passed to a subsequent invocation of a
+   * partial decoding method.
+   */
+  public static int partialIsValidUtf8(
+      byte[] bytes, int index, int limit) {
+    // Optimize for 100% ASCII.
+    // Hotspot loves small simple top-level loops like this.
+    while (index < limit && bytes[index] >= 0) {
+      index++;
+    }
+
+    return (index >= limit) ? COMPLETE :
+        partialIsValidUtf8NonAscii(bytes, index, limit);
+  }
+
+  private static int partialIsValidUtf8NonAscii(
+      byte[] bytes, int index, int limit) {
+    for (;;) {
+      int byte1, byte2;
+
+      // Optimize for interior runs of ASCII bytes.
+      do {
+        if (index >= limit) {
+          return COMPLETE;
+        }
+      } while ((byte1 = bytes[index++]) >= 0);
+
+      if (byte1 < (byte) 0xE0) {
+        // two-byte form
+
+        if (index >= limit) {
+          return byte1;
+        }
+
+        // Simultaneously checks for illegal trailing-byte in
+        // leading position and overlong 2-byte form.
+        if (byte1 < (byte) 0xC2 ||
+            bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      } else if (byte1 < (byte) 0xF0) {
+        // three-byte form
+
+        if (index >= limit - 1) { // incomplete sequence
+          return incompleteStateFor(bytes, index, limit);
+        }
+        if ((byte2 = bytes[index++]) > (byte) 0xBF ||
+            // overlong? 5 most significant bits must not all be zero
+            (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) ||
+            // check for illegal surrogate codepoints
+            (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) ||
+            // byte3 trailing-byte test
+            bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      } else {
+        // four-byte form
+
+        if (index >= limit - 2) {  // incomplete sequence
+          return incompleteStateFor(bytes, index, limit);
+        }
+        if ((byte2 = bytes[index++]) > (byte) 0xBF ||
+            // Check that 1 <= plane <= 16.  Tricky optimized form of:
+            // if (byte1 > (byte) 0xF4 ||
+            //     byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 ||
+            //     byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F)
+            (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 ||
+            // byte3 trailing-byte test
+            bytes[index++] > (byte) 0xBF ||
+            // byte4 trailing-byte test
+            bytes[index++] > (byte) 0xBF) {
+          return MALFORMED;
+        }
+      }
+    }
+  }
+
+  private static int incompleteStateFor(int byte1) {
+    return (byte1 > (byte) 0xF4) ?
+        MALFORMED : byte1;
+  }
+
+  private static int incompleteStateFor(int byte1, int byte2) {
+    return (byte1 > (byte) 0xF4 ||
+            byte2 > (byte) 0xBF) ?
+        MALFORMED : byte1 ^ (byte2 << 8);
+  }
+
+  private static int incompleteStateFor(int byte1, int byte2, int byte3) {
+    return (byte1 > (byte) 0xF4 ||
+            byte2 > (byte) 0xBF ||
+            byte3 > (byte) 0xBF) ?
+        MALFORMED : byte1 ^ (byte2 << 8) ^ (byte3 << 16);
+  }
+
+  private static int incompleteStateFor(byte[] bytes, int index, int limit) {
+    int byte1 = bytes[index - 1];
+    switch (limit - index) {
+      case 0: return incompleteStateFor(byte1);
+      case 1: return incompleteStateFor(byte1, bytes[index]);
+      case 2: return incompleteStateFor(byte1, bytes[index], bytes[index + 1]);
+      default: throw new AssertionError();
+    }
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/WireFormat.java b/java/src/main/java/com/google/protobuf/WireFormat.java
index a30f2a3c..dd2d6310 100644
--- a/java/src/main/java/com/google/protobuf/WireFormat.java
+++ b/java/src/main/java/com/google/protobuf/WireFormat.java
@@ -146,7 +146,7 @@ public final class WireFormat {
     public boolean isPackable() { return true; }
   }
 
-  // Field numbers for feilds in MessageSet wire format.
+  // Field numbers for fields in MessageSet wire format.
   static final int MESSAGE_SET_ITEM    = 1;
   static final int MESSAGE_SET_TYPE_ID = 2;
   static final int MESSAGE_SET_MESSAGE = 3;
diff --git a/java/src/test/java/com/google/protobuf/AbstractMessageTest.java b/java/src/test/java/com/google/protobuf/AbstractMessageTest.java
index d53ce8d7..3d05cb7d 100644
--- a/java/src/test/java/com/google/protobuf/AbstractMessageTest.java
+++ b/java/src/test/java/com/google/protobuf/AbstractMessageTest.java
@@ -30,6 +30,7 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.Descriptors.FieldDescriptor;
 import protobuf_unittest.UnittestOptimizeFor.TestOptimizedForSize;
 import protobuf_unittest.UnittestProto;
 import protobuf_unittest.UnittestProto.ForeignMessage;
@@ -167,6 +168,13 @@ public class AbstractMessageTest extends TestCase {
         wrappedBuilder.setUnknownFields(unknownFields);
         return this;
       }
+      @Override
+      public Message.Builder getFieldBuilder(FieldDescriptor field) {
+        return wrappedBuilder.getFieldBuilder(field);
+      }
+    }
+    public Parser<? extends Message> getParserForType() {
+      return wrappedMessage.getParserForType();
     }
   }
 
@@ -220,6 +228,34 @@ public class AbstractMessageTest extends TestCase {
     TestUtil.assertAllFieldsSet((TestAllTypes) message.wrappedMessage);
   }
 
+  public void testParsingUninitialized() throws Exception {
+    TestRequiredForeign.Builder builder = TestRequiredForeign.newBuilder();
+    builder.getOptionalMessageBuilder().setDummy2(10);
+    ByteString bytes = builder.buildPartial().toByteString();
+    Message.Builder abstractMessageBuilder =
+        new AbstractMessageWrapper.Builder(TestRequiredForeign.newBuilder());
+    // mergeFrom() should not throw initialization error.
+    abstractMessageBuilder.mergeFrom(bytes).buildPartial();
+    try {
+      abstractMessageBuilder.mergeFrom(bytes).build();
+      fail();
+    } catch (UninitializedMessageException ex) {
+      // pass
+    }
+
+    // test DynamicMessage directly.
+    Message.Builder dynamicMessageBuilder = DynamicMessage.newBuilder(
+        TestRequiredForeign.getDescriptor());
+    // mergeFrom() should not throw initialization error.
+    dynamicMessageBuilder.mergeFrom(bytes).buildPartial();
+    try {
+      dynamicMessageBuilder.mergeFrom(bytes).build();
+      fail();
+    } catch (UninitializedMessageException ex) {
+      // pass
+    }
+  }
+
   public void testPackedSerialization() throws Exception {
     Message abstractMessage =
         new AbstractMessageWrapper(TestUtil.getPackedSet());
@@ -298,12 +334,16 @@ public class AbstractMessageTest extends TestCase {
       new AbstractMessageWrapper.Builder(builder);
 
     assertFalse(abstractBuilder.isInitialized());
+    assertEquals("a, b, c", abstractBuilder.getInitializationErrorString());
     builder.setA(1);
     assertFalse(abstractBuilder.isInitialized());
+    assertEquals("b, c", abstractBuilder.getInitializationErrorString());
     builder.setB(1);
     assertFalse(abstractBuilder.isInitialized());
+    assertEquals("c", abstractBuilder.getInitializationErrorString());
     builder.setC(1);
     assertTrue(abstractBuilder.isInitialized());
+    assertEquals("", abstractBuilder.getInitializationErrorString());
   }
 
   public void testForeignIsInitialized() throws Exception {
@@ -312,18 +352,27 @@ public class AbstractMessageTest extends TestCase {
       new AbstractMessageWrapper.Builder(builder);
 
     assertTrue(abstractBuilder.isInitialized());
+    assertEquals("", abstractBuilder.getInitializationErrorString());
 
     builder.setOptionalMessage(TEST_REQUIRED_UNINITIALIZED);
     assertFalse(abstractBuilder.isInitialized());
+    assertEquals(
+        "optional_message.a, optional_message.b, optional_message.c",
+        abstractBuilder.getInitializationErrorString());
 
     builder.setOptionalMessage(TEST_REQUIRED_INITIALIZED);
     assertTrue(abstractBuilder.isInitialized());
+    assertEquals("", abstractBuilder.getInitializationErrorString());
 
     builder.addRepeatedMessage(TEST_REQUIRED_UNINITIALIZED);
     assertFalse(abstractBuilder.isInitialized());
+    assertEquals(
+        "repeated_message[0].a, repeated_message[0].b, repeated_message[0].c",
+        abstractBuilder.getInitializationErrorString());
 
     builder.setRepeatedMessage(0, TEST_REQUIRED_INITIALIZED);
     assertTrue(abstractBuilder.isInitialized());
+    assertEquals("", abstractBuilder.getInitializationErrorString());
   }
 
   // -----------------------------------------------------------------
@@ -421,7 +470,7 @@ public class AbstractMessageTest extends TestCase {
 
 
   /**
-   * Asserts that the given proto has symetric equals and hashCode methods.
+   * Asserts that the given proto has symmetric equals and hashCode methods.
    */
   private void checkEqualsIsConsistent(Message message) {
     // Object should be equal to itself.
diff --git a/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java b/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java
new file mode 100644
index 00000000..20fa2dff
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java
@@ -0,0 +1,68 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * This class tests {@link BoundedByteString}, which extends {@link LiteralByteString},
+ * by inheriting the tests from {@link LiteralByteStringTest}.  The only method which
+ * is strange enough that it needs to be overridden here is {@link #testToString()}.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+public class BoundedByteStringTest extends LiteralByteStringTest {
+
+  @Override
+  protected void setUp() throws Exception {
+    classUnderTest = "BoundedByteString";
+    byte[] sourceBytes = ByteStringTest.getTestBytes(2341, 11337766L);
+    int from = 100;
+    int to = sourceBytes.length - 100;
+    stringUnderTest = ByteString.copyFrom(sourceBytes).substring(from, to);
+    referenceBytes = new byte[to - from];
+    System.arraycopy(sourceBytes, from, referenceBytes, 0, to - from);
+    expectedHashCode = 727575887;
+  }
+
+  @Override
+  public void testToString() throws UnsupportedEncodingException {
+    String testString = "I love unicode \u1234\u5678 characters";
+    LiteralByteString unicode = new LiteralByteString(testString.getBytes(UTF_8));
+    ByteString chopped = unicode.substring(2, unicode.size() - 6);
+    assertEquals(classUnderTest + ".substring() must have the expected type",
+        classUnderTest, getActualClassName(chopped));
+
+    String roundTripString = chopped.toString(UTF_8);
+    assertEquals(classUnderTest + " unicode bytes must match",
+        testString.substring(2, testString.length() - 6), roundTripString);
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/ByteStringTest.java b/java/src/test/java/com/google/protobuf/ByteStringTest.java
new file mode 100644
index 00000000..7a1d6823
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/ByteStringTest.java
@@ -0,0 +1,692 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.ByteString.Output;
+
+import junit.framework.TestCase;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Random;
+
+/**
+ * Test methods with implementations in {@link ByteString}, plus do some top-level "integration"
+ * tests.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+public class ByteStringTest extends TestCase {
+
+  private static final String UTF_16 = "UTF-16";
+
+  static byte[] getTestBytes(int size, long seed) {
+    Random random = new Random(seed);
+    byte[] result = new byte[size];
+    random.nextBytes(result);
+    return result;
+  }
+
+  private byte[] getTestBytes(int size) {
+    return getTestBytes(size, 445566L);
+  }
+
+  private byte[] getTestBytes() {
+    return getTestBytes(1000);
+  }
+
+  // Compare the entire left array with a subset of the right array.
+  private boolean isArrayRange(byte[] left, byte[] right, int rightOffset, int length) {
+    boolean stillEqual = (left.length == length);
+    for (int i = 0; (stillEqual && i < length); ++i) {
+      stillEqual = (left[i] == right[rightOffset + i]);
+    }
+    return stillEqual;
+  }
+
+  // Returns true only if the given two arrays have identical contents.
+  private boolean isArray(byte[] left, byte[] right) {
+    return left.length == right.length && isArrayRange(left, right, 0, left.length);
+  }
+
+  public void testSubstring_BeginIndex() {
+    byte[] bytes = getTestBytes();
+    ByteString substring = ByteString.copyFrom(bytes).substring(500);
+    assertTrue("substring must contain the tail of the string",
+        isArrayRange(substring.toByteArray(), bytes, 500, bytes.length - 500));
+  }
+
+  public void testCopyFrom_BytesOffsetSize() {
+    byte[] bytes = getTestBytes();
+    ByteString byteString = ByteString.copyFrom(bytes, 500, 200);
+    assertTrue("copyFrom sub-range must contain the expected bytes",
+        isArrayRange(byteString.toByteArray(), bytes, 500, 200));
+  }
+
+  public void testCopyFrom_Bytes() {
+    byte[] bytes = getTestBytes();
+    ByteString byteString = ByteString.copyFrom(bytes);
+    assertTrue("copyFrom must contain the expected bytes",
+        isArray(byteString.toByteArray(), bytes));
+  }
+
+  public void testCopyFrom_ByteBufferSize() {
+    byte[] bytes = getTestBytes();
+    ByteBuffer byteBuffer = ByteBuffer.allocate(bytes.length);
+    byteBuffer.put(bytes);
+    byteBuffer.position(500);
+    ByteString byteString = ByteString.copyFrom(byteBuffer, 200);
+    assertTrue("copyFrom byteBuffer sub-range must contain the expected bytes",
+        isArrayRange(byteString.toByteArray(), bytes, 500, 200));
+  }
+
+  public void testCopyFrom_ByteBuffer() {
+    byte[] bytes = getTestBytes();
+    ByteBuffer byteBuffer = ByteBuffer.allocate(bytes.length);
+    byteBuffer.put(bytes);
+    byteBuffer.position(500);
+    ByteString byteString = ByteString.copyFrom(byteBuffer);
+    assertTrue("copyFrom byteBuffer sub-range must contain the expected bytes",
+        isArrayRange(byteString.toByteArray(), bytes, 500, bytes.length - 500));
+  }
+
+  public void testCopyFrom_StringEncoding() throws UnsupportedEncodingException {
+    String testString = "I love unicode \u1234\u5678 characters";
+    ByteString byteString = ByteString.copyFrom(testString, UTF_16);
+    byte[] testBytes = testString.getBytes(UTF_16);
+    assertTrue("copyFrom string must respect the charset",
+        isArrayRange(byteString.toByteArray(), testBytes, 0, testBytes.length));
+  }
+
+  public void testCopyFrom_Utf8() throws UnsupportedEncodingException {
+    String testString = "I love unicode \u1234\u5678 characters";
+    ByteString byteString = ByteString.copyFromUtf8(testString);
+    byte[] testBytes = testString.getBytes("UTF-8");
+    assertTrue("copyFromUtf8 string must respect the charset",
+        isArrayRange(byteString.toByteArray(), testBytes, 0, testBytes.length));
+  }
+
+  public void testCopyFrom_Iterable() {
+    byte[] testBytes = getTestBytes(77777, 113344L);
+    final List<ByteString> pieces = makeConcretePieces(testBytes);
+    // Call copyFrom() on a Collection
+    ByteString byteString = ByteString.copyFrom(pieces);
+    assertTrue("copyFrom a List must contain the expected bytes",
+        isArrayRange(byteString.toByteArray(), testBytes, 0, testBytes.length));
+    // Call copyFrom on an iteration that's not a collection
+    ByteString byteStringAlt = ByteString.copyFrom(new Iterable<ByteString>() {
+      public Iterator<ByteString> iterator() {
+        return pieces.iterator();
+      }
+    });
+    assertEquals("copyFrom from an Iteration must contain the expected bytes",
+        byteString, byteStringAlt);
+  }
+
+  public void testCopyTo_TargetOffset() {
+    byte[] bytes = getTestBytes();
+    ByteString byteString = ByteString.copyFrom(bytes);
+    byte[] target = new byte[bytes.length + 1000];
+    byteString.copyTo(target, 400);
+    assertTrue("copyFrom byteBuffer sub-range must contain the expected bytes",
+        isArrayRange(bytes, target, 400, bytes.length));
+  }
+
+  public void testReadFrom_emptyStream() throws IOException {
+    ByteString byteString =
+        ByteString.readFrom(new ByteArrayInputStream(new byte[0]));
+    assertSame("reading an empty stream must result in the EMPTY constant "
+        + "byte string", ByteString.EMPTY, byteString);
+  }
+
+  public void testReadFrom_smallStream() throws IOException {
+    assertReadFrom(getTestBytes(10));
+  }
+
+  public void testReadFrom_mutating() throws IOException {
+    byte[] capturedArray = null;
+    EvilInputStream eis = new EvilInputStream();
+    ByteString byteString = ByteString.readFrom(eis);
+
+    capturedArray = eis.capturedArray;
+    byte[] originalValue = byteString.toByteArray();
+    for (int x = 0; x < capturedArray.length; ++x) {
+      capturedArray[x] = (byte) 0;
+    }
+
+    byte[] newValue = byteString.toByteArray();
+    assertTrue("copyFrom byteBuffer must not grant access to underlying array",
+        Arrays.equals(originalValue, newValue));
+  }
+
+  // Tests sizes that are near the rope copy-out threshold.
+  public void testReadFrom_mediumStream() throws IOException {
+    assertReadFrom(getTestBytes(ByteString.CONCATENATE_BY_COPY_SIZE - 1));
+    assertReadFrom(getTestBytes(ByteString.CONCATENATE_BY_COPY_SIZE));
+    assertReadFrom(getTestBytes(ByteString.CONCATENATE_BY_COPY_SIZE + 1));
+    assertReadFrom(getTestBytes(200));
+  }
+
+  // Tests sizes that are over multi-segment rope threshold.
+  public void testReadFrom_largeStream() throws IOException {
+    assertReadFrom(getTestBytes(0x100));
+    assertReadFrom(getTestBytes(0x101));
+    assertReadFrom(getTestBytes(0x110));
+    assertReadFrom(getTestBytes(0x1000));
+    assertReadFrom(getTestBytes(0x1001));
+    assertReadFrom(getTestBytes(0x1010));
+    assertReadFrom(getTestBytes(0x10000));
+    assertReadFrom(getTestBytes(0x10001));
+    assertReadFrom(getTestBytes(0x10010));
+  }
+
+  // Tests sizes that are near the read buffer size.
+  public void testReadFrom_byteBoundaries() throws IOException {
+    final int min = ByteString.MIN_READ_FROM_CHUNK_SIZE;
+    final int max = ByteString.MAX_READ_FROM_CHUNK_SIZE;
+
+    assertReadFrom(getTestBytes(min - 1));
+    assertReadFrom(getTestBytes(min));
+    assertReadFrom(getTestBytes(min + 1));
+
+    assertReadFrom(getTestBytes(min * 2 - 1));
+    assertReadFrom(getTestBytes(min * 2));
+    assertReadFrom(getTestBytes(min * 2 + 1));
+
+    assertReadFrom(getTestBytes(min * 4 - 1));
+    assertReadFrom(getTestBytes(min * 4));
+    assertReadFrom(getTestBytes(min * 4 + 1));
+
+    assertReadFrom(getTestBytes(min * 8 - 1));
+    assertReadFrom(getTestBytes(min * 8));
+    assertReadFrom(getTestBytes(min * 8 + 1));
+
+    assertReadFrom(getTestBytes(max - 1));
+    assertReadFrom(getTestBytes(max));
+    assertReadFrom(getTestBytes(max + 1));
+
+    assertReadFrom(getTestBytes(max * 2 - 1));
+    assertReadFrom(getTestBytes(max * 2));
+    assertReadFrom(getTestBytes(max * 2 + 1));
+  }
+
+  // Tests that IOExceptions propagate through ByteString.readFrom().
+  public void testReadFrom_IOExceptions() {
+    try {
+      ByteString.readFrom(new FailStream());
+      fail("readFrom must throw the underlying IOException");
+
+    } catch (IOException e) {
+      assertEquals("readFrom must throw the expected exception",
+                   "synthetic failure", e.getMessage());
+    }
+  }
+
+  // Tests that ByteString.readFrom works with streams that don't
+  // always fill their buffers.
+  public void testReadFrom_reluctantStream() throws IOException {
+    final byte[] data = getTestBytes(0x1000);
+
+    ByteString byteString = ByteString.readFrom(new ReluctantStream(data));
+    assertTrue("readFrom byte stream must contain the expected bytes",
+        isArray(byteString.toByteArray(), data));
+
+    // Same test as above, but with some specific chunk sizes.
+    assertReadFromReluctantStream(data, 100);
+    assertReadFromReluctantStream(data, 248);
+    assertReadFromReluctantStream(data, 249);
+    assertReadFromReluctantStream(data, 250);
+    assertReadFromReluctantStream(data, 251);
+    assertReadFromReluctantStream(data, 0x1000);
+    assertReadFromReluctantStream(data, 0x1001);
+  }
+
+  // Fails unless ByteString.readFrom reads the bytes correctly from a
+  // reluctant stream with the given chunkSize parameter.
+  private void assertReadFromReluctantStream(byte[] bytes, int chunkSize)
+      throws IOException {
+    ByteString b = ByteString.readFrom(new ReluctantStream(bytes), chunkSize);
+    assertTrue("readFrom byte stream must contain the expected bytes",
+        isArray(b.toByteArray(), bytes));
+  }
+
+  // Tests that ByteString.readFrom works with streams that implement
+  // available().
+  public void testReadFrom_available() throws IOException {
+    final byte[] data = getTestBytes(0x1001);
+
+    ByteString byteString = ByteString.readFrom(new AvailableStream(data));
+    assertTrue("readFrom byte stream must contain the expected bytes",
+        isArray(byteString.toByteArray(), data));
+  }
+
+  // Fails unless ByteString.readFrom reads the bytes correctly.
+  private void assertReadFrom(byte[] bytes) throws IOException {
+    ByteString byteString =
+        ByteString.readFrom(new ByteArrayInputStream(bytes));
+    assertTrue("readFrom byte stream must contain the expected bytes",
+        isArray(byteString.toByteArray(), bytes));
+  }
+
+  // A stream that fails when read.
+  private static final class FailStream extends InputStream {
+    @Override public int read() throws IOException {
+      throw new IOException("synthetic failure");
+    }
+  }
+
+  // A stream that simulates blocking by only producing 250 characters
+  // per call to read(byte[]).
+  private static class ReluctantStream extends InputStream {
+    protected final byte[] data;
+    protected int pos = 0;
+
+    public ReluctantStream(byte[] data) {
+      this.data = data;
+    }
+
+    @Override public int read() {
+      if (pos == data.length) {
+        return -1;
+      } else {
+        return data[pos++];
+      }
+    }
+
+    @Override public int read(byte[] buf) {
+      return read(buf, 0, buf.length);
+    }
+
+    @Override public int read(byte[] buf, int offset, int size) {
+      if (pos == data.length) {
+        return -1;
+      }
+      int count = Math.min(Math.min(size, data.length - pos), 250);
+      System.arraycopy(data, pos, buf, offset, count);
+      pos += count;
+      return count;
+    }
+  }
+
+  // Same as above, but also implements available().
+  private static final class AvailableStream extends ReluctantStream {
+    public AvailableStream(byte[] data) {
+      super(data);
+    }
+
+    @Override public int available() {
+      return Math.min(250, data.length - pos);
+    }
+  }
+
+  // A stream which exposes the byte array passed into read(byte[], int, int).
+  private static class EvilInputStream extends InputStream {
+    public byte[] capturedArray = null;
+
+    @Override
+    public int read(byte[] buf, int off, int len) {
+      if (capturedArray != null) {
+        return -1;
+      } else {
+        capturedArray = buf;
+        for (int x = 0; x < len; ++x) {
+          buf[x] = (byte) x;
+        }
+        return len;
+      }
+    }
+
+    @Override
+    public int read() {
+      // Purposefully do nothing.
+      return -1;
+    }
+  }
+  
+  // A stream which exposes the byte array passed into write(byte[], int, int).
+  private static class EvilOutputStream extends OutputStream {
+    public byte[] capturedArray = null;
+
+    @Override
+    public void write(byte[] buf, int off, int len) {
+      if (capturedArray == null) {
+        capturedArray = buf;
+      }
+    }
+
+    @Override
+    public void write(int ignored) {
+      // Purposefully do nothing.
+    }
+  }
+
+  public void testToStringUtf8() throws UnsupportedEncodingException {
+    String testString = "I love unicode \u1234\u5678 characters";
+    byte[] testBytes = testString.getBytes("UTF-8");
+    ByteString byteString = ByteString.copyFrom(testBytes);
+    assertEquals("copyToStringUtf8 must respect the charset",
+        testString, byteString.toStringUtf8());
+  }
+
+  public void testNewOutput_InitialCapacity() throws IOException {
+    byte[] bytes = getTestBytes();
+    ByteString.Output output = ByteString.newOutput(bytes.length + 100);
+    output.write(bytes);
+    ByteString byteString = output.toByteString();
+    assertTrue(
+        "String built from newOutput(int) must contain the expected bytes",
+        isArrayRange(bytes, byteString.toByteArray(), 0, bytes.length));
+  }
+
+  // Test newOutput() using a variety of buffer sizes and a variety of (fixed)
+  // write sizes
+  public void testNewOutput_ArrayWrite() throws IOException {
+    byte[] bytes = getTestBytes();
+    int length = bytes.length;
+    int[] bufferSizes = {128, 256, length / 2, length - 1, length, length + 1,
+                         2 * length, 3 * length};
+    int[] writeSizes = {1, 4, 5, 7, 23, bytes.length};
+
+    for (int bufferSize : bufferSizes) {
+      for (int writeSize : writeSizes) {
+        // Test writing the entire output writeSize bytes at a time.
+        ByteString.Output output = ByteString.newOutput(bufferSize);
+        for (int i = 0; i < length; i += writeSize) {
+          output.write(bytes, i, Math.min(writeSize, length - i));
+        }
+        ByteString byteString = output.toByteString();
+        assertTrue("String built from newOutput() must contain the expected bytes",
+            isArrayRange(bytes, byteString.toByteArray(), 0, bytes.length));
+      }
+    }
+  }
+
+  // Test newOutput() using a variety of buffer sizes, but writing all the
+  // characters using write(byte);
+  public void testNewOutput_WriteChar() throws IOException {
+    byte[] bytes = getTestBytes();
+    int length = bytes.length;
+    int[] bufferSizes = {0, 1, 128, 256, length / 2,
+                         length - 1, length, length + 1,
+                         2 * length, 3 * length};
+    for (int bufferSize : bufferSizes) {
+      ByteString.Output output = ByteString.newOutput(bufferSize);
+      for (byte byteValue : bytes) {
+        output.write(byteValue);
+      }
+      ByteString byteString = output.toByteString();
+      assertTrue("String built from newOutput() must contain the expected bytes",
+          isArrayRange(bytes, byteString.toByteArray(), 0, bytes.length));
+    }
+  }
+
+  // Test newOutput() in which we write the bytes using a variety of methods
+  // and sizes, and in which we repeatedly call toByteString() in the middle.
+  public void testNewOutput_Mixed() throws IOException {
+    Random rng = new Random(1);
+    byte[] bytes = getTestBytes();
+    int length = bytes.length;
+    int[] bufferSizes = {0, 1, 128, 256, length / 2,
+                         length - 1, length, length + 1,
+                         2 * length, 3 * length};
+
+    for (int bufferSize : bufferSizes) {
+      // Test writing the entire output using a mixture of write sizes and
+      // methods;
+      ByteString.Output output = ByteString.newOutput(bufferSize);
+      int position = 0;
+      while (position < bytes.length) {
+        if (rng.nextBoolean()) {
+          int count = 1 + rng.nextInt(bytes.length - position);
+          output.write(bytes, position, count);
+          position += count;
+        } else {
+          output.write(bytes[position]);
+          position++;
+        }
+        assertEquals("size() returns the right value", position, output.size());
+        assertTrue("newOutput() substring must have correct bytes",
+            isArrayRange(output.toByteString().toByteArray(),
+                bytes, 0, position));
+      }
+      ByteString byteString = output.toByteString();
+      assertTrue("String built from newOutput() must contain the expected bytes",
+          isArrayRange(bytes, byteString.toByteArray(), 0, bytes.length));
+    }
+  }
+  
+  public void testNewOutputEmpty() throws IOException {
+    // Make sure newOutput() correctly builds empty byte strings
+    ByteString byteString = ByteString.newOutput().toByteString();
+    assertEquals(ByteString.EMPTY, byteString);
+  }
+  
+  public void testNewOutput_Mutating() throws IOException {
+    Output os = ByteString.newOutput(5);
+    os.write(new byte[] {1, 2, 3, 4, 5});
+    EvilOutputStream eos = new EvilOutputStream();
+    os.writeTo(eos);
+    byte[] capturedArray = eos.capturedArray;
+    ByteString byteString = os.toByteString();
+    byte[] oldValue = byteString.toByteArray();
+    Arrays.fill(capturedArray, (byte) 0);
+    byte[] newValue = byteString.toByteArray();
+    assertTrue("Output must not provide access to the underlying byte array",
+        Arrays.equals(oldValue, newValue));
+  }
+
+  public void testNewCodedBuilder() throws IOException {
+    byte[] bytes = getTestBytes();
+    ByteString.CodedBuilder builder = ByteString.newCodedBuilder(bytes.length);
+    builder.getCodedOutput().writeRawBytes(bytes);
+    ByteString byteString = builder.build();
+    assertTrue("String built from newCodedBuilder() must contain the expected bytes",
+        isArrayRange(bytes, byteString.toByteArray(), 0, bytes.length));
+  }
+
+  public void testSubstringParity() {
+    byte[] bigBytes = getTestBytes(2048 * 1024, 113344L);
+    int start = 512 * 1024 - 3333;
+    int end   = 512 * 1024 + 7777;
+    ByteString concreteSubstring = ByteString.copyFrom(bigBytes).substring(start, end);
+    boolean ok = true;
+    for (int i = start; ok && i < end; ++i) {
+      ok = (bigBytes[i] == concreteSubstring.byteAt(i - start));
+    }
+    assertTrue("Concrete substring didn't capture the right bytes", ok);
+
+    ByteString literalString = ByteString.copyFrom(bigBytes, start, end - start);
+    assertTrue("Substring must be equal to literal string",
+        concreteSubstring.equals(literalString));
+    assertEquals("Substring must have same hashcode as literal string",
+        literalString.hashCode(), concreteSubstring.hashCode());
+  }
+
+  public void testCompositeSubstring() {
+    byte[] referenceBytes = getTestBytes(77748, 113344L);
+
+    List<ByteString> pieces = makeConcretePieces(referenceBytes);
+    ByteString listString = ByteString.copyFrom(pieces);
+
+    int from = 1000;
+    int to = 40000;
+    ByteString compositeSubstring = listString.substring(from, to);
+    byte[] substringBytes = compositeSubstring.toByteArray();
+    boolean stillEqual = true;
+    for (int i = 0; stillEqual && i < to - from; ++i) {
+      stillEqual = referenceBytes[from + i] == substringBytes[i];
+    }
+    assertTrue("Substring must return correct bytes", stillEqual);
+
+    stillEqual = true;
+    for (int i = 0; stillEqual && i < to - from; ++i) {
+      stillEqual = referenceBytes[from + i] == compositeSubstring.byteAt(i);
+    }
+    assertTrue("Substring must support byteAt() correctly", stillEqual);
+
+    ByteString literalSubstring = ByteString.copyFrom(referenceBytes, from, to - from);
+    assertTrue("Composite substring must equal a literal substring over the same bytes",
+        compositeSubstring.equals(literalSubstring));
+    assertTrue("Literal substring must equal a composite substring over the same bytes",
+        literalSubstring.equals(compositeSubstring));
+
+    assertEquals("We must get the same hashcodes for composite and literal substrings",
+        literalSubstring.hashCode(), compositeSubstring.hashCode());
+
+    assertFalse("We can't be equal to a proper substring",
+        compositeSubstring.equals(literalSubstring.substring(0, literalSubstring.size() - 1)));
+  }
+
+  public void testCopyFromList() {
+    byte[] referenceBytes = getTestBytes(77748, 113344L);
+    ByteString literalString = ByteString.copyFrom(referenceBytes);
+
+    List<ByteString> pieces = makeConcretePieces(referenceBytes);
+    ByteString listString = ByteString.copyFrom(pieces);
+
+    assertTrue("Composite string must be equal to literal string",
+        listString.equals(literalString));
+    assertEquals("Composite string must have same hashcode as literal string",
+        literalString.hashCode(), listString.hashCode());
+  }
+
+  public void testConcat() {
+    byte[] referenceBytes = getTestBytes(77748, 113344L);
+    ByteString literalString = ByteString.copyFrom(referenceBytes);
+
+    List<ByteString> pieces = makeConcretePieces(referenceBytes);
+
+    Iterator<ByteString> iter = pieces.iterator();
+    ByteString concatenatedString = iter.next();
+    while (iter.hasNext()) {
+      concatenatedString = concatenatedString.concat(iter.next());
+    }
+
+    assertTrue("Concatenated string must be equal to literal string",
+        concatenatedString.equals(literalString));
+    assertEquals("Concatenated string must have same hashcode as literal string",
+        literalString.hashCode(), concatenatedString.hashCode());
+  }
+
+  /**
+   * Test the Rope implementation can deal with Empty nodes, even though we
+   * guard against them. See also {@link LiteralByteStringTest#testConcat_empty()}.
+   */
+  public void testConcat_empty() {
+    byte[] referenceBytes = getTestBytes(7748, 113344L);
+    ByteString literalString = ByteString.copyFrom(referenceBytes);
+
+    ByteString duo = RopeByteString.newInstanceForTest(literalString, literalString);
+    ByteString temp = RopeByteString.newInstanceForTest(
+        RopeByteString.newInstanceForTest(literalString, ByteString.EMPTY),
+        RopeByteString.newInstanceForTest(ByteString.EMPTY, literalString));
+    ByteString quintet = RopeByteString.newInstanceForTest(temp, ByteString.EMPTY);
+
+    assertTrue("String with concatenated nulls must equal simple concatenate",
+        duo.equals(quintet));
+    assertEquals("String with concatenated nulls have same hashcode as simple concatenate",
+        duo.hashCode(), quintet.hashCode());
+
+    ByteString.ByteIterator duoIter = duo.iterator();
+    ByteString.ByteIterator quintetIter = quintet.iterator();
+    boolean stillEqual = true;
+    while (stillEqual && quintetIter.hasNext()) {
+      stillEqual = (duoIter.nextByte() == quintetIter.nextByte());
+    }
+    assertTrue("We must get the same characters by iterating", stillEqual);
+    assertFalse("Iterator must be exhausted", duoIter.hasNext());
+    try {
+      duoIter.nextByte();
+      fail("Should have thrown an exception.");
+    } catch (NoSuchElementException e) {
+      // This is success
+    }
+    try {
+      quintetIter.nextByte();
+      fail("Should have thrown an exception.");
+    } catch (NoSuchElementException e) {
+      // This is success
+    }
+
+    // Test that even if we force empty strings in as rope leaves in this
+    // configuration, we always get a (possibly Bounded) LiteralByteString
+    // for a length 1 substring.
+    //
+    // It is possible, using the testing factory method to create deeply nested
+    // trees of empty leaves, to make a string that will fail this test.
+    for (int i = 1; i < duo.size(); ++i) {
+      assertTrue("Substrings of size() < 2 must not be RopeByteStrings",
+          duo.substring(i - 1, i) instanceof LiteralByteString);
+    }
+    for (int i = 1; i < quintet.size(); ++i) {
+      assertTrue("Substrings of size() < 2 must not be RopeByteStrings",
+          quintet.substring(i - 1, i) instanceof LiteralByteString);
+    }
+  }
+
+  public void testStartsWith() {
+    byte[] bytes = getTestBytes(1000, 1234L);
+    ByteString string = ByteString.copyFrom(bytes);
+    ByteString prefix = ByteString.copyFrom(bytes, 0, 500);
+    ByteString suffix = ByteString.copyFrom(bytes, 400, 600);
+    assertTrue(string.startsWith(ByteString.EMPTY));
+    assertTrue(string.startsWith(string));
+    assertTrue(string.startsWith(prefix));
+    assertFalse(string.startsWith(suffix));
+    assertFalse(prefix.startsWith(suffix));
+    assertFalse(suffix.startsWith(prefix));
+    assertFalse(ByteString.EMPTY.startsWith(prefix));
+    assertTrue(ByteString.EMPTY.startsWith(ByteString.EMPTY));
+  }
+
+  static List<ByteString> makeConcretePieces(byte[] referenceBytes) {
+    List<ByteString> pieces = new ArrayList<ByteString>();
+    // Starting length should be small enough that we'll do some concatenating by
+    // copying if we just concatenate all these pieces together.
+    for (int start = 0, length = 16; start < referenceBytes.length; start += length) {
+      length = (length << 1) - 1;
+      if (start + length > referenceBytes.length) {
+        length = referenceBytes.length - start;
+      }
+      pieces.add(ByteString.copyFrom(referenceBytes, start, length));
+    }
+    return pieces;
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
index 74476e36..86255029 100644
--- a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
+++ b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
@@ -30,8 +30,10 @@
 
 package com.google.protobuf;
 
+import protobuf_unittest.UnittestProto.SparseEnumMessage;
 import protobuf_unittest.UnittestProto.TestAllTypes;
 import protobuf_unittest.UnittestProto.TestPackedTypes;
+import protobuf_unittest.UnittestProto.TestSparseEnum;
 
 import junit.framework.TestCase;
 
@@ -302,17 +304,14 @@ public class CodedOutputStreamTest extends TestCase {
   }
 
   /** Test writing a message containing a negative enum value. This used to
-   * fail because the size was not properly computed as a sign-extended varint. */
+   * fail because the size was not properly computed as a sign-extended varint.
+   */
   public void testWriteMessageWithNegativeEnumValue() throws Exception {
-    protobuf_unittest.UnittestProto.SparseEnumMessage message =
-        protobuf_unittest.UnittestProto.SparseEnumMessage.newBuilder()
-        .setSparseEnum(protobuf_unittest.UnittestProto.TestSparseEnum.SPARSE_E)
-        .build();
+    SparseEnumMessage message = SparseEnumMessage.newBuilder()
+        .setSparseEnum(TestSparseEnum.SPARSE_E) .build();
     assertTrue(message.getSparseEnum().getNumber() < 0);
     byte[] rawBytes = message.toByteArray();
-    protobuf_unittest.UnittestProto.SparseEnumMessage message2 =
-        protobuf_unittest.UnittestProto.SparseEnumMessage.parseFrom(rawBytes);
-    assertEquals(protobuf_unittest.UnittestProto.TestSparseEnum.SPARSE_E,
-                 message2.getSparseEnum());
+    SparseEnumMessage message2 = SparseEnumMessage.parseFrom(rawBytes);
+    assertEquals(TestSparseEnum.SPARSE_E, message2.getSparseEnum());
   }
 }
diff --git a/java/src/test/java/com/google/protobuf/DescriptorsTest.java b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
index 65d06e32..9c310919 100644
--- a/java/src/test/java/com/google/protobuf/DescriptorsTest.java
+++ b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
@@ -31,6 +31,8 @@
 package com.google.protobuf;
 
 import com.google.protobuf.DescriptorProtos.DescriptorProto;
+import com.google.protobuf.DescriptorProtos.EnumDescriptorProto;
+import com.google.protobuf.DescriptorProtos.EnumValueDescriptorProto;
 import com.google.protobuf.DescriptorProtos.FieldDescriptorProto;
 import com.google.protobuf.DescriptorProtos.FileDescriptorProto;
 import com.google.protobuf.Descriptors.DescriptorValidationException;
@@ -60,6 +62,7 @@ import junit.framework.TestCase;
 
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 
 /**
  * Unit test for {@link Descriptors}.
@@ -426,7 +429,7 @@ public class DescriptorsTest extends TestCase {
         UnittestEnormousDescriptor.getDescriptor()
           .toProto().getSerializedSize() > 65536);
   }
-  
+
   /**
    * Tests that the DescriptorValidationException works as intended.
    */
@@ -445,7 +448,7 @@ public class DescriptorsTest extends TestCase {
         .build())
       .build();
     try {
-      Descriptors.FileDescriptor.buildFrom(fileDescriptorProto, 
+      Descriptors.FileDescriptor.buildFrom(fileDescriptorProto,
           new FileDescriptor[0]);
       fail("DescriptorValidationException expected");
     } catch (DescriptorValidationException e) {
@@ -457,4 +460,189 @@ public class DescriptorsTest extends TestCase {
       assertTrue(e.getCause().getMessage().indexOf("invalid") != -1);
     }
   }
+
+  /**
+   * Tests the translate/crosslink for an example where a message field's name
+   * and type name are the same.
+   */
+  public void testDescriptorComplexCrosslink() throws Exception {
+    FileDescriptorProto fileDescriptorProto = FileDescriptorProto.newBuilder()
+      .setName("foo.proto")
+      .addMessageType(DescriptorProto.newBuilder()
+        .setName("Foo")
+        .addField(FieldDescriptorProto.newBuilder()
+          .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)
+          .setType(FieldDescriptorProto.Type.TYPE_INT32)
+          .setName("foo")
+          .setNumber(1)
+          .build())
+        .build())
+      .addMessageType(DescriptorProto.newBuilder()
+        .setName("Bar")
+        .addField(FieldDescriptorProto.newBuilder()
+          .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)
+          .setTypeName("Foo")
+          .setName("Foo")
+          .setNumber(1)
+          .build())
+        .build())
+      .build();
+    // translate and crosslink
+    FileDescriptor file =
+      Descriptors.FileDescriptor.buildFrom(fileDescriptorProto, 
+          new FileDescriptor[0]);
+    // verify resulting descriptors
+    assertNotNull(file);
+    List<Descriptor> msglist = file.getMessageTypes();
+    assertNotNull(msglist);
+    assertTrue(msglist.size() == 2);
+    boolean barFound = false;
+    for (Descriptor desc : msglist) {
+      if (desc.getName().equals("Bar")) {
+        barFound = true;
+        assertNotNull(desc.getFields());
+        List<FieldDescriptor> fieldlist = desc.getFields();
+        assertNotNull(fieldlist);
+        assertTrue(fieldlist.size() == 1);
+        assertTrue(fieldlist.get(0).getType() == FieldDescriptor.Type.MESSAGE);
+        assertTrue(fieldlist.get(0).getMessageType().getName().equals("Foo"));
+      }
+    }
+    assertTrue(barFound);
+  }
+  
+  public void testInvalidPublicDependency() throws Exception {
+    FileDescriptorProto fooProto = FileDescriptorProto.newBuilder()
+        .setName("foo.proto") .build();
+    FileDescriptorProto barProto = FileDescriptorProto.newBuilder()
+        .setName("boo.proto")
+        .addDependency("foo.proto")
+        .addPublicDependency(1)  // Error, should be 0.
+        .build();
+    FileDescriptor fooFile = Descriptors.FileDescriptor.buildFrom(fooProto,
+        new FileDescriptor[0]);
+    try {
+      Descriptors.FileDescriptor.buildFrom(barProto,
+          new FileDescriptor[] {fooFile});
+      fail("DescriptorValidationException expected");
+    } catch (DescriptorValidationException e) {
+      assertTrue(
+          e.getMessage().indexOf("Invalid public dependency index.") != -1);
+    }
+  }
+
+  public void testHiddenDependency() throws Exception {
+    FileDescriptorProto barProto = FileDescriptorProto.newBuilder()
+        .setName("bar.proto")
+        .addMessageType(DescriptorProto.newBuilder().setName("Bar"))
+        .build();
+    FileDescriptorProto forwardProto = FileDescriptorProto.newBuilder()
+        .setName("forward.proto")
+        .addDependency("bar.proto")
+        .build();
+    FileDescriptorProto fooProto = FileDescriptorProto.newBuilder()
+        .setName("foo.proto")
+        .addDependency("forward.proto")
+        .addMessageType(DescriptorProto.newBuilder()
+            .setName("Foo")
+            .addField(FieldDescriptorProto.newBuilder()
+                .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)
+                .setTypeName("Bar")
+                .setName("bar")
+                .setNumber(1)))
+        .build();
+    FileDescriptor barFile = Descriptors.FileDescriptor.buildFrom(
+        barProto, new FileDescriptor[0]);
+    FileDescriptor forwardFile = Descriptors.FileDescriptor.buildFrom(
+        forwardProto, new FileDescriptor[] {barFile});
+
+    try {
+      Descriptors.FileDescriptor.buildFrom(
+          fooProto, new FileDescriptor[] {forwardFile});
+      fail("DescriptorValidationException expected");
+    } catch (DescriptorValidationException e) {
+      assertTrue(e.getMessage().indexOf("Bar") != -1);
+      assertTrue(e.getMessage().indexOf("is not defined") != -1);
+    }
+  }
+
+  public void testPublicDependency() throws Exception {
+    FileDescriptorProto barProto = FileDescriptorProto.newBuilder()
+        .setName("bar.proto")
+        .addMessageType(DescriptorProto.newBuilder().setName("Bar"))
+        .build();
+    FileDescriptorProto forwardProto = FileDescriptorProto.newBuilder()
+        .setName("forward.proto")
+        .addDependency("bar.proto")
+        .addPublicDependency(0)
+        .build();
+    FileDescriptorProto fooProto = FileDescriptorProto.newBuilder()
+        .setName("foo.proto")
+        .addDependency("forward.proto")
+        .addMessageType(DescriptorProto.newBuilder()
+            .setName("Foo")
+            .addField(FieldDescriptorProto.newBuilder()
+                .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)
+                .setTypeName("Bar")
+                .setName("bar")
+                .setNumber(1)))
+        .build();
+    FileDescriptor barFile = Descriptors.FileDescriptor.buildFrom(
+        barProto, new FileDescriptor[0]);
+    FileDescriptor forwardFile = Descriptors.FileDescriptor.buildFrom(
+        forwardProto, new FileDescriptor[]{barFile});
+    Descriptors.FileDescriptor.buildFrom(
+        fooProto, new FileDescriptor[] {forwardFile});
+  }
+  
+  /**
+   * Tests the translate/crosslink for an example with a more complex namespace
+   * referencing.
+   */
+  public void testComplexNamespacePublicDependency() throws Exception {
+    FileDescriptorProto fooProto = FileDescriptorProto.newBuilder()
+        .setName("bar.proto")
+        .setPackage("a.b.c.d.bar.shared")
+        .addEnumType(EnumDescriptorProto.newBuilder()
+            .setName("MyEnum")
+            .addValue(EnumValueDescriptorProto.newBuilder()
+                .setName("BLAH")
+                .setNumber(1)))
+        .build();
+    FileDescriptorProto barProto = FileDescriptorProto.newBuilder()
+        .setName("foo.proto")
+        .addDependency("bar.proto")
+        .setPackage("a.b.c.d.foo.shared")
+        .addMessageType(DescriptorProto.newBuilder()
+            .setName("MyMessage")
+            .addField(FieldDescriptorProto.newBuilder()
+                .setLabel(FieldDescriptorProto.Label.LABEL_REPEATED)
+                .setTypeName("bar.shared.MyEnum")
+                .setName("MyField")
+                .setNumber(1)))
+        .build();
+    // translate and crosslink
+    FileDescriptor fooFile = Descriptors.FileDescriptor.buildFrom(
+        fooProto, new FileDescriptor[0]);
+    FileDescriptor barFile = Descriptors.FileDescriptor.buildFrom(
+        barProto, new FileDescriptor[]{fooFile});
+    // verify resulting descriptors
+    assertNotNull(barFile);
+    List<Descriptor> msglist = barFile.getMessageTypes();
+    assertNotNull(msglist);
+    assertTrue(msglist.size() == 1);
+    Descriptor desc = msglist.get(0);
+    if (desc.getName().equals("MyMessage")) {
+      assertNotNull(desc.getFields());
+      List<FieldDescriptor> fieldlist = desc.getFields();
+      assertNotNull(fieldlist);
+      assertTrue(fieldlist.size() == 1);
+      FieldDescriptor field = fieldlist.get(0);
+      assertTrue(field.getType() == FieldDescriptor.Type.ENUM);
+      assertTrue(field.getEnumType().getName().equals("MyEnum"));
+      assertTrue(field.getEnumType().getFile().getName().equals("bar.proto"));
+      assertTrue(field.getEnumType().getFile().getPackage().equals(
+          "a.b.c.d.bar.shared"));
+    }   
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/DynamicMessageTest.java b/java/src/test/java/com/google/protobuf/DynamicMessageTest.java
index aabccda2..990e8ca6 100644
--- a/java/src/test/java/com/google/protobuf/DynamicMessageTest.java
+++ b/java/src/test/java/com/google/protobuf/DynamicMessageTest.java
@@ -30,8 +30,9 @@
 
 package com.google.protobuf;
 
-import protobuf_unittest.UnittestProto.TestAllTypes;
 import protobuf_unittest.UnittestProto.TestAllExtensions;
+import protobuf_unittest.UnittestProto.TestAllTypes;
+import protobuf_unittest.UnittestProto.TestEmptyMessage;
 import protobuf_unittest.UnittestProto.TestPackedTypes;
 
 import junit.framework.TestCase;
@@ -61,28 +62,44 @@ public class DynamicMessageTest extends TestCase {
     reflectionTester.assertAllFieldsSetViaReflection(message);
   }
 
-  public void testDoubleBuildError() throws Exception {
+  public void testSettersAfterBuild() throws Exception {
     Message.Builder builder =
       DynamicMessage.newBuilder(TestAllTypes.getDescriptor());
+    Message firstMessage = builder.build();
+    // double build()
     builder.build();
-    try {
-      builder.build();
-      fail("Should have thrown exception.");
-    } catch (IllegalStateException e) {
-      // Success.
-    }
+    // clear() after build()
+    builder.clear();
+    // setters after build()
+    reflectionTester.setAllFieldsViaReflection(builder);
+    Message message = builder.build();
+    reflectionTester.assertAllFieldsSetViaReflection(message);
+    // repeated setters after build()
+    reflectionTester.modifyRepeatedFieldsViaReflection(builder);
+    message = builder.build();
+    reflectionTester.assertRepeatedFieldsModifiedViaReflection(message);
+    // firstMessage shouldn't have been modified.
+    reflectionTester.assertClearViaReflection(firstMessage);
   }
 
-  public void testClearAfterBuildError() throws Exception {
+  public void testUnknownFields() throws Exception {
     Message.Builder builder =
-      DynamicMessage.newBuilder(TestAllTypes.getDescriptor());
-    builder.build();
-    try {
-      builder.clear();
-      fail("Should have thrown exception.");
-    } catch (IllegalStateException e) {
-      // Success.
-    }
+        DynamicMessage.newBuilder(TestEmptyMessage.getDescriptor());
+    builder.setUnknownFields(UnknownFieldSet.newBuilder()
+        .addField(1, UnknownFieldSet.Field.newBuilder().addVarint(1).build())
+        .addField(2, UnknownFieldSet.Field.newBuilder().addFixed32(1).build())
+        .build());
+    Message message = builder.build();
+    assertEquals(2, message.getUnknownFields().asMap().size());
+    // clone() with unknown fields
+    Message.Builder newBuilder = builder.clone();
+    assertEquals(2, newBuilder.getUnknownFields().asMap().size());
+    // clear() with unknown fields
+    newBuilder.clear();
+    assertTrue(newBuilder.getUnknownFields().asMap().isEmpty());
+    // serialize/parse with unknown fields
+    newBuilder.mergeFrom(message.toByteString());
+    assertEquals(2, newBuilder.getUnknownFields().asMap().size());
   }
 
   public void testDynamicMessageSettersRejectNull() throws Exception {
@@ -167,6 +184,23 @@ public class DynamicMessageTest extends TestCase {
     Message message2 =
       DynamicMessage.parseFrom(TestAllTypes.getDescriptor(), rawBytes);
     reflectionTester.assertAllFieldsSetViaReflection(message2);
+
+    // Test Parser interface.
+    Message message3 = message2.getParserForType().parseFrom(rawBytes);
+    reflectionTester.assertAllFieldsSetViaReflection(message3);
+  }
+
+  public void testDynamicMessageExtensionParsing() throws Exception {
+    ByteString rawBytes = TestUtil.getAllExtensionsSet().toByteString();
+    Message message = DynamicMessage.parseFrom(
+        TestAllExtensions.getDescriptor(), rawBytes,
+        TestUtil.getExtensionRegistry());
+    extensionsReflectionTester.assertAllFieldsSetViaReflection(message);
+
+    // Test Parser interface.
+    Message message2 = message.getParserForType().parseFrom(
+        rawBytes, TestUtil.getExtensionRegistry());
+    extensionsReflectionTester.assertAllFieldsSetViaReflection(message2);
   }
 
   public void testDynamicMessagePackedSerialization() throws Exception {
@@ -194,6 +228,10 @@ public class DynamicMessageTest extends TestCase {
     Message message2 =
       DynamicMessage.parseFrom(TestPackedTypes.getDescriptor(), rawBytes);
     packedReflectionTester.assertPackedFieldsSetViaReflection(message2);
+
+    // Test Parser interface.
+    Message message3 = message2.getParserForType().parseFrom(rawBytes);
+    packedReflectionTester.assertPackedFieldsSetViaReflection(message3);
   }
 
   public void testDynamicMessageCopy() throws Exception {
diff --git a/java/src/test/java/com/google/protobuf/GeneratedMessageTest.java b/java/src/test/java/com/google/protobuf/GeneratedMessageTest.java
index acb22355..bf9db75b 100644
--- a/java/src/test/java/com/google/protobuf/GeneratedMessageTest.java
+++ b/java/src/test/java/com/google/protobuf/GeneratedMessageTest.java
@@ -30,6 +30,8 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.UnittestLite.TestAllExtensionsLite;
 import com.google.protobuf.test.UnittestImport;
 import protobuf_unittest.EnumWithNoOuter;
@@ -53,6 +55,7 @@ import protobuf_unittest.UnittestProto.ForeignMessage;
 import protobuf_unittest.UnittestProto.ForeignMessageOrBuilder;
 import protobuf_unittest.UnittestProto.TestAllExtensions;
 import protobuf_unittest.UnittestProto.TestAllTypes;
+import protobuf_unittest.UnittestProto.TestAllTypes.NestedMessage;
 import protobuf_unittest.UnittestProto.TestAllTypesOrBuilder;
 import protobuf_unittest.UnittestProto.TestExtremeDefaultValues;
 import protobuf_unittest.UnittestProto.TestPackedTypes;
@@ -180,6 +183,33 @@ public class GeneratedMessageTest extends TestCase {
     assertIsUnmodifiable(value.getRepeatedFloatList());
   }
 
+  public void testParsedMessagesAreImmutable() throws Exception {
+    TestAllTypes value = TestAllTypes.PARSER.parseFrom(
+        TestUtil.getAllSet().toByteString());
+    assertIsUnmodifiable(value.getRepeatedInt32List());
+    assertIsUnmodifiable(value.getRepeatedInt64List());
+    assertIsUnmodifiable(value.getRepeatedUint32List());
+    assertIsUnmodifiable(value.getRepeatedUint64List());
+    assertIsUnmodifiable(value.getRepeatedSint32List());
+    assertIsUnmodifiable(value.getRepeatedSint64List());
+    assertIsUnmodifiable(value.getRepeatedFixed32List());
+    assertIsUnmodifiable(value.getRepeatedFixed64List());
+    assertIsUnmodifiable(value.getRepeatedSfixed32List());
+    assertIsUnmodifiable(value.getRepeatedSfixed64List());
+    assertIsUnmodifiable(value.getRepeatedFloatList());
+    assertIsUnmodifiable(value.getRepeatedDoubleList());
+    assertIsUnmodifiable(value.getRepeatedBoolList());
+    assertIsUnmodifiable(value.getRepeatedStringList());
+    assertIsUnmodifiable(value.getRepeatedBytesList());
+    assertIsUnmodifiable(value.getRepeatedGroupList());
+    assertIsUnmodifiable(value.getRepeatedNestedMessageList());
+    assertIsUnmodifiable(value.getRepeatedForeignMessageList());
+    assertIsUnmodifiable(value.getRepeatedImportMessageList());
+    assertIsUnmodifiable(value.getRepeatedNestedEnumList());
+    assertIsUnmodifiable(value.getRepeatedForeignEnumList());
+    assertIsUnmodifiable(value.getRepeatedImportEnumList());
+  }
+
   private void assertIsUnmodifiable(List<?> list) {
     if (list == Collections.emptyList()) {
       // OKAY -- Need to check this b/c EmptyList allows you to call clear.
@@ -881,7 +911,7 @@ public class GeneratedMessageTest extends TestCase {
     builder.setOptionalNestedMessage(nestedMessage1);
     assertEquals(3, mockParent.getInvalidationCount());
 
-    // primitive repated
+    // primitive repeated
     builder.buildPartial();
     builder.addRepeatedInt32(2);
     builder.addRepeatedInt32(3);
@@ -977,4 +1007,140 @@ public class GeneratedMessageTest extends TestCase {
     assertSame(b1, messageOrBuilderList.get(1));
     assertSame(m2, messageOrBuilderList.get(2));
   }
+
+  public void testGetFieldBuilder() {
+    Descriptor descriptor = TestAllTypes.getDescriptor();
+
+    FieldDescriptor fieldDescriptor =
+        descriptor.findFieldByName("optional_nested_message");
+    FieldDescriptor foreignFieldDescriptor =
+        descriptor.findFieldByName("optional_foreign_message");
+    FieldDescriptor importFieldDescriptor =
+        descriptor.findFieldByName("optional_import_message");
+
+    // Mutate the message with new field builder
+    // Mutate nested message
+    TestAllTypes.Builder builder1 = TestAllTypes.newBuilder();
+    Message.Builder fieldBuilder1 = builder1.newBuilderForField(fieldDescriptor)
+        .mergeFrom((Message) builder1.getField(fieldDescriptor));
+    FieldDescriptor subFieldDescriptor1 =
+        fieldBuilder1.getDescriptorForType().findFieldByName("bb");
+    fieldBuilder1.setField(subFieldDescriptor1, 1);
+    builder1.setField(fieldDescriptor, fieldBuilder1.build());
+
+    // Mutate foreign message
+    Message.Builder foreignFieldBuilder1 = builder1.newBuilderForField(
+        foreignFieldDescriptor)
+        .mergeFrom((Message) builder1.getField(foreignFieldDescriptor));
+    FieldDescriptor subForeignFieldDescriptor1 =
+        foreignFieldBuilder1.getDescriptorForType().findFieldByName("c");
+    foreignFieldBuilder1.setField(subForeignFieldDescriptor1, 2);
+    builder1.setField(foreignFieldDescriptor, foreignFieldBuilder1.build());
+
+    // Mutate import message
+    Message.Builder importFieldBuilder1 = builder1.newBuilderForField(
+        importFieldDescriptor)
+        .mergeFrom((Message) builder1.getField(importFieldDescriptor));
+    FieldDescriptor subImportFieldDescriptor1 =
+        importFieldBuilder1.getDescriptorForType().findFieldByName("d");
+    importFieldBuilder1.setField(subImportFieldDescriptor1, 3);
+    builder1.setField(importFieldDescriptor, importFieldBuilder1.build());
+
+    Message newMessage1 = builder1.build();
+
+    // Mutate the message with existing field builder
+    // Mutate nested message
+    TestAllTypes.Builder builder2 = TestAllTypes.newBuilder();
+    Message.Builder fieldBuilder2 = builder2.getFieldBuilder(fieldDescriptor);
+    FieldDescriptor subFieldDescriptor2 =
+        fieldBuilder2.getDescriptorForType().findFieldByName("bb");
+    fieldBuilder2.setField(subFieldDescriptor2, 1);
+    builder2.setField(fieldDescriptor, fieldBuilder2.build());
+
+    // Mutate foreign message
+    Message.Builder foreignFieldBuilder2 = builder2.newBuilderForField(
+        foreignFieldDescriptor)
+        .mergeFrom((Message) builder2.getField(foreignFieldDescriptor));
+    FieldDescriptor subForeignFieldDescriptor2 =
+        foreignFieldBuilder2.getDescriptorForType().findFieldByName("c");
+    foreignFieldBuilder2.setField(subForeignFieldDescriptor2, 2);
+    builder2.setField(foreignFieldDescriptor, foreignFieldBuilder2.build());
+
+    // Mutate import message
+    Message.Builder importFieldBuilder2 = builder2.newBuilderForField(
+        importFieldDescriptor)
+        .mergeFrom((Message) builder2.getField(importFieldDescriptor));
+    FieldDescriptor subImportFieldDescriptor2 =
+        importFieldBuilder2.getDescriptorForType().findFieldByName("d");
+    importFieldBuilder2.setField(subImportFieldDescriptor2, 3);
+    builder2.setField(importFieldDescriptor, importFieldBuilder2.build());
+
+    Message newMessage2 = builder2.build();
+
+    // These two messages should be equal.
+    assertEquals(newMessage1, newMessage2);
+  }
+
+  public void testGetFieldBuilderWithInitializedValue() {
+    Descriptor descriptor = TestAllTypes.getDescriptor();
+    FieldDescriptor fieldDescriptor =
+        descriptor.findFieldByName("optional_nested_message");
+
+    // Before setting field, builder is initialized by default value. 
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    NestedMessage.Builder fieldBuilder =
+        (NestedMessage.Builder) builder.getFieldBuilder(fieldDescriptor);
+    assertEquals(0, fieldBuilder.getBb());
+
+    // Setting field value with new field builder instance.
+    builder = TestAllTypes.newBuilder();
+    NestedMessage.Builder newFieldBuilder =
+        builder.getOptionalNestedMessageBuilder();
+    newFieldBuilder.setBb(2);
+    // Then get the field builder instance by getFieldBuilder().
+    fieldBuilder =
+        (NestedMessage.Builder) builder.getFieldBuilder(fieldDescriptor);
+    // It should contain new value.
+    assertEquals(2, fieldBuilder.getBb());
+    // These two builder should be equal.
+    assertSame(fieldBuilder, newFieldBuilder);
+  }
+
+  public void testGetFieldBuilderNotSupportedException() {
+    Descriptor descriptor = TestAllTypes.getDescriptor();
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    try {
+      builder.getFieldBuilder(descriptor.findFieldByName("optional_int32"));
+      fail("Exception was not thrown");
+    } catch (UnsupportedOperationException e) {
+      // We expect this exception.
+    }
+    try {
+      builder.getFieldBuilder(
+          descriptor.findFieldByName("optional_nested_enum"));
+      fail("Exception was not thrown");
+    } catch (UnsupportedOperationException e) {
+      // We expect this exception.
+    }
+    try {
+      builder.getFieldBuilder(descriptor.findFieldByName("repeated_int32"));
+      fail("Exception was not thrown");
+    } catch (UnsupportedOperationException e) {
+      // We expect this exception.
+    }
+    try {
+      builder.getFieldBuilder(
+          descriptor.findFieldByName("repeated_nested_enum"));
+      fail("Exception was not thrown");
+    } catch (UnsupportedOperationException e) {
+      // We expect this exception.
+    }
+    try {
+      builder.getFieldBuilder(
+          descriptor.findFieldByName("repeated_nested_message"));
+      fail("Exception was not thrown");
+    } catch (UnsupportedOperationException e) {
+      // We expect this exception.
+    }
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/IsValidUtf8Test.java b/java/src/test/java/com/google/protobuf/IsValidUtf8Test.java
new file mode 100644
index 00000000..b204b604
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/IsValidUtf8Test.java
@@ -0,0 +1,180 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.IsValidUtf8TestUtil.Shard;
+
+import junit.framework.TestCase;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * Tests cases for {@link ByteString#isValidUtf8()}. This includes three
+ * brute force tests that actually test every permutation of one byte, two byte,
+ * and three byte sequences to ensure that the method produces the right result
+ * for every possible byte encoding where "right" means it's consistent with
+ * java's UTF-8 string encoding/decoding such that the method returns true for
+ * any sequence that will round trip when converted to a String and then back to
+ * bytes and will return false for any sequence that will not round trip.
+ * See also {@link IsValidUtf8FourByteTest}. It also includes some
+ * other more targeted tests.
+ *
+ * @author jonp@google.com (Jon Perlow)
+ * @author martinrb@google.com (Martin Buchholz)
+ */
+public class IsValidUtf8Test extends TestCase {
+
+  /**
+   * Tests that round tripping of all two byte permutations work.
+   */
+  public void testIsValidUtf8_1Byte() throws UnsupportedEncodingException {
+    IsValidUtf8TestUtil.testBytes(1,
+        IsValidUtf8TestUtil.EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT);
+  }
+
+  /**
+   * Tests that round tripping of all two byte permutations work.
+   */
+  public void testIsValidUtf8_2Bytes() throws UnsupportedEncodingException {
+    IsValidUtf8TestUtil.testBytes(2,
+        IsValidUtf8TestUtil.EXPECTED_TWO_BYTE_ROUNDTRIPPABLE_COUNT);
+  }
+
+  /**
+   * Tests that round tripping of all three byte permutations work.
+   */
+  public void testIsValidUtf8_3Bytes() throws UnsupportedEncodingException {
+    IsValidUtf8TestUtil.testBytes(3,
+        IsValidUtf8TestUtil.EXPECTED_THREE_BYTE_ROUNDTRIPPABLE_COUNT);
+  }
+
+  /**
+   * Tests that round tripping of a sample of four byte permutations work.
+   * All permutations are prohibitively expensive to test for automated runs;
+   * {@link IsValidUtf8FourByteTest} is used for full coverage. This method
+   * tests specific four-byte cases.
+   */
+  public void testIsValidUtf8_4BytesSamples()
+      throws UnsupportedEncodingException {
+    // Valid 4 byte.
+    assertValidUtf8(0xF0, 0xA4, 0xAD, 0xA2);
+
+    // Bad trailing bytes
+    assertInvalidUtf8(0xF0, 0xA4, 0xAD, 0x7F);
+    assertInvalidUtf8(0xF0, 0xA4, 0xAD, 0xC0);
+
+    // Special cases for byte2
+    assertInvalidUtf8(0xF0, 0x8F, 0xAD, 0xA2);
+    assertInvalidUtf8(0xF4, 0x90, 0xAD, 0xA2);
+  }
+
+  /**
+   * Tests some hard-coded test cases.
+   */
+  public void testSomeSequences() {
+    // Empty
+    assertTrue(asBytes("").isValidUtf8());
+
+    // One-byte characters, including control characters
+    assertTrue(asBytes("\u0000abc\u007f").isValidUtf8());
+
+    // Two-byte characters
+    assertTrue(asBytes("\u00a2\u00a2").isValidUtf8());
+
+    // Three-byte characters
+    assertTrue(asBytes("\u020ac\u020ac").isValidUtf8());
+
+    // Four-byte characters
+    assertTrue(asBytes("\u024B62\u024B62").isValidUtf8());
+
+    // Mixed string
+    assertTrue(
+        asBytes("a\u020ac\u00a2b\\u024B62u020acc\u00a2de\u024B62")
+        .isValidUtf8());
+
+    // Not a valid string
+    assertInvalidUtf8(-1, 0, -1, 0);
+  }
+
+  private byte[] toByteArray(int... bytes) {
+    byte[] realBytes = new byte[bytes.length];
+    for (int i = 0; i < bytes.length; i++) {
+      realBytes[i] = (byte) bytes[i];
+    }
+    return realBytes;
+  }
+
+  private ByteString toByteString(int... bytes) {
+    return ByteString.copyFrom(toByteArray(bytes));
+  }
+
+  private void assertValidUtf8(int[] bytes, boolean not) {
+    byte[] realBytes = toByteArray(bytes);
+    assertTrue(not ^ Utf8.isValidUtf8(realBytes));
+    assertTrue(not ^ Utf8.isValidUtf8(realBytes, 0, bytes.length));
+    ByteString lit = ByteString.copyFrom(realBytes);
+    ByteString sub = lit.substring(0, bytes.length);
+    assertTrue(not ^ lit.isValidUtf8());
+    assertTrue(not ^ sub.isValidUtf8());
+    ByteString[] ropes = {
+      RopeByteString.newInstanceForTest(ByteString.EMPTY, lit),
+      RopeByteString.newInstanceForTest(ByteString.EMPTY, sub),
+      RopeByteString.newInstanceForTest(lit, ByteString.EMPTY),
+      RopeByteString.newInstanceForTest(sub, ByteString.EMPTY),
+      RopeByteString.newInstanceForTest(sub, lit)
+    };
+    for (ByteString rope : ropes) {
+      assertTrue(not ^ rope.isValidUtf8());
+    }
+  }
+
+  private void assertValidUtf8(int... bytes) {
+    assertValidUtf8(bytes, false);
+  }
+
+  private void assertInvalidUtf8(int... bytes) {
+    assertValidUtf8(bytes, true);
+  }
+
+  private static ByteString asBytes(String s) {
+    return ByteString.copyFromUtf8(s);
+  }
+
+  public void testShardsHaveExpectedRoundTrippables() {
+    // A sanity check.
+    int actual = 0;
+    for (Shard shard : IsValidUtf8TestUtil.FOUR_BYTE_SHARDS) {
+      actual += shard.expected;
+    }
+    assertEquals(IsValidUtf8TestUtil.EXPECTED_FOUR_BYTE_ROUNDTRIPPABLE_COUNT,
+        actual);
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/IsValidUtf8TestUtil.java b/java/src/test/java/com/google/protobuf/IsValidUtf8TestUtil.java
new file mode 100644
index 00000000..4cb3d5b9
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/IsValidUtf8TestUtil.java
@@ -0,0 +1,421 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import static junit.framework.Assert.*;
+
+import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Random;
+import java.util.logging.Logger;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.Charset;
+import java.nio.charset.CodingErrorAction;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.CoderResult;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+
+/**
+ * Shared testing code for {@link IsValidUtf8Test} and
+ * {@link IsValidUtf8FourByteTest}.
+ *
+ * @author jonp@google.com (Jon Perlow)
+ * @author martinrb@google.com (Martin Buchholz)
+ */
+class IsValidUtf8TestUtil {
+  private static Logger logger = Logger.getLogger(
+      IsValidUtf8TestUtil.class.getName());
+
+  // 128 - [chars 0x0000 to 0x007f]
+  static long ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS = 0x007f - 0x0000 + 1;
+
+  // 128
+  static long EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT =
+      ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS;
+
+  // 1920 [chars 0x0080 to 0x07FF]
+  static long TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS = 0x07FF - 0x0080 + 1;
+
+  // 18,304
+  static long EXPECTED_TWO_BYTE_ROUNDTRIPPABLE_COUNT =
+      // Both bytes are one byte characters
+      (long) Math.pow(EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT, 2) +
+      // The possible number of two byte characters
+      TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS;
+
+  // 2048
+  static long THREE_BYTE_SURROGATES = 2 * 1024;
+
+  // 61,440 [chars 0x0800 to 0xFFFF, minus surrogates]
+  static long THREE_BYTE_ROUNDTRIPPABLE_CHARACTERS =
+      0xFFFF - 0x0800 + 1 - THREE_BYTE_SURROGATES;
+
+  // 2,650,112
+  static long EXPECTED_THREE_BYTE_ROUNDTRIPPABLE_COUNT =
+      // All one byte characters
+      (long) Math.pow(EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT, 3) +
+      // One two byte character and a one byte character
+      2 * TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS *
+          ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS +
+       // Three byte characters
+      THREE_BYTE_ROUNDTRIPPABLE_CHARACTERS;
+
+  // 1,048,576 [chars 0x10000L to 0x10FFFF]
+  static long FOUR_BYTE_ROUNDTRIPPABLE_CHARACTERS = 0x10FFFF - 0x10000L + 1;
+
+  // 289,571,839
+  static long EXPECTED_FOUR_BYTE_ROUNDTRIPPABLE_COUNT =
+      // All one byte characters
+      (long) Math.pow(EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT, 4) +
+      // One and three byte characters
+      2 * THREE_BYTE_ROUNDTRIPPABLE_CHARACTERS *
+          ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS +
+      // Two two byte characters
+      TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS * TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS +
+      // Permutations of one and two byte characters
+      3 * TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS *
+          ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS *
+          ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS +
+      // Four byte characters
+      FOUR_BYTE_ROUNDTRIPPABLE_CHARACTERS;
+
+  static class Shard {
+    final long index;
+    final long start;
+    final long lim;
+    final long expected;
+
+
+    public Shard(long index, long start, long lim, long expected) {
+      assertTrue(start < lim);
+      this.index = index;
+      this.start = start;
+      this.lim = lim;
+      this.expected = expected;
+    }
+  }
+
+  static final long[] FOUR_BYTE_SHARDS_EXPECTED_ROUNTRIPPABLES =
+      generateFourByteShardsExpectedRunnables();
+
+  private static long[] generateFourByteShardsExpectedRunnables() {
+    long[] expected = new long[128];
+
+    // 0-63 are all 5300224
+    for (int i = 0; i <= 63; i++) {
+      expected[i] = 5300224;
+    }
+
+    // 97-111 are all 2342912
+    for (int i = 97; i <= 111; i++) {
+     expected[i] = 2342912;
+    }
+
+    // 113-117 are all 1048576
+    for (int i = 113; i <= 117; i++) {
+      expected[i] = 1048576;
+    }
+
+    // One offs
+    expected[112] = 786432;
+    expected[118] = 786432;
+    expected[119] = 1048576;
+    expected[120] = 458752;
+    expected[121] = 524288;
+    expected[122] = 65536;
+
+    // Anything not assigned was the default 0.
+    return expected;
+  }
+
+  static final List<Shard> FOUR_BYTE_SHARDS = generateFourByteShards(
+      128, FOUR_BYTE_SHARDS_EXPECTED_ROUNTRIPPABLES);
+
+
+  private static List<Shard> generateFourByteShards(
+      int numShards, long[] expected) {
+    assertEquals(numShards, expected.length);
+    List<Shard> shards = new ArrayList<Shard>(numShards);
+    long LIM = 1L << 32;
+    long increment = LIM / numShards;
+    assertTrue(LIM % numShards == 0);
+    for (int i = 0; i < numShards; i++) {
+      shards.add(new Shard(i,
+          increment * i,
+          increment * (i + 1),
+          expected[i]));
+    }
+    return shards;
+  }
+
+  /**
+   * Helper to run the loop to test all the permutations for the number of bytes
+   * specified.
+   *
+   * @param numBytes the number of bytes in the byte array
+   * @param expectedCount the expected number of roundtrippable permutations
+   */
+  static void testBytes(int numBytes, long expectedCount)
+      throws UnsupportedEncodingException {
+    testBytes(numBytes, expectedCount, 0, -1);
+  }
+
+  /**
+   * Helper to run the loop to test all the permutations for the number of bytes
+   * specified. This overload is useful for debugging to get the loop to start
+   * at a certain character.
+   *
+   * @param numBytes the number of bytes in the byte array
+   * @param expectedCount the expected number of roundtrippable permutations
+   * @param start the starting bytes encoded as a long as big-endian
+   * @param lim the limit of bytes to process encoded as a long as big-endian,
+   *     or -1 to mean the max limit for numBytes
+   */
+  static void testBytes(int numBytes, long expectedCount, long start, long lim)
+      throws UnsupportedEncodingException {
+    Random rnd = new Random();
+    byte[] bytes = new byte[numBytes];
+
+    if (lim == -1) {
+      lim = 1L << (numBytes * 8);
+    }
+    long count = 0;
+    long countRoundTripped = 0;
+    for (long byteChar = start; byteChar < lim; byteChar++) {
+      long tmpByteChar = byteChar;
+      for (int i = 0; i < numBytes; i++) {
+        bytes[bytes.length - i - 1] = (byte) tmpByteChar;
+        tmpByteChar = tmpByteChar >> 8;
+      }
+      ByteString bs = ByteString.copyFrom(bytes);
+      boolean isRoundTrippable = bs.isValidUtf8();
+      String s = new String(bytes, "UTF-8");
+      byte[] bytesReencoded = s.getBytes("UTF-8");
+      boolean bytesEqual = Arrays.equals(bytes, bytesReencoded);
+
+      if (bytesEqual != isRoundTrippable) {
+        outputFailure(byteChar, bytes, bytesReencoded);
+      }
+
+      // Check agreement with static Utf8 methods.
+      assertEquals(isRoundTrippable, Utf8.isValidUtf8(bytes));
+      assertEquals(isRoundTrippable, Utf8.isValidUtf8(bytes, 0, numBytes));
+
+      // Test partial sequences.
+      // Partition numBytes into three segments (not necessarily non-empty).
+      int i = rnd.nextInt(numBytes);
+      int j = rnd.nextInt(numBytes);
+      if (j < i) {
+        int tmp = i; i = j; j = tmp;
+      }
+      int state1 = Utf8.partialIsValidUtf8(Utf8.COMPLETE, bytes, 0, i);
+      int state2 = Utf8.partialIsValidUtf8(state1, bytes, i, j);
+      int state3 = Utf8.partialIsValidUtf8(state2, bytes, j, numBytes);
+      if (isRoundTrippable != (state3 == Utf8.COMPLETE)) {
+        System.out.printf("state=%04x %04x %04x i=%d j=%d%n",
+                          state1, state2, state3, i, j);
+        outputFailure(byteChar, bytes, bytesReencoded);
+      }
+      assertEquals(isRoundTrippable, (state3 == Utf8.COMPLETE));
+
+      // Test ropes built out of small partial sequences
+      ByteString rope = RopeByteString.newInstanceForTest(
+          bs.substring(0, i),
+          RopeByteString.newInstanceForTest(
+              bs.substring(i, j),
+              bs.substring(j, numBytes)));
+      assertSame(RopeByteString.class, rope.getClass());
+
+      ByteString[] byteStrings = { bs, bs.substring(0, numBytes), rope };
+      for (ByteString x : byteStrings) {
+        assertEquals(isRoundTrippable,
+                     x.isValidUtf8());
+        assertEquals(state3,
+                     x.partialIsValidUtf8(Utf8.COMPLETE, 0, numBytes));
+
+        assertEquals(state1,
+                     x.partialIsValidUtf8(Utf8.COMPLETE, 0, i));
+        assertEquals(state1,
+                     x.substring(0, i).partialIsValidUtf8(Utf8.COMPLETE, 0, i));
+        assertEquals(state2,
+                     x.partialIsValidUtf8(state1, i, j - i));
+        assertEquals(state2,
+                     x.substring(i, j).partialIsValidUtf8(state1, 0, j - i));
+        assertEquals(state3,
+                     x.partialIsValidUtf8(state2, j, numBytes - j));
+        assertEquals(state3,
+                     x.substring(j, numBytes)
+                     .partialIsValidUtf8(state2, 0, numBytes - j));
+      }
+
+      // ByteString reduplication should not affect its UTF-8 validity.
+      ByteString ropeADope =
+          RopeByteString.newInstanceForTest(bs, bs.substring(0, numBytes));
+      assertEquals(isRoundTrippable, ropeADope.isValidUtf8());
+
+      if (isRoundTrippable) {
+        countRoundTripped++;
+      }
+      count++;
+      if (byteChar != 0 && byteChar % 1000000L == 0) {
+        logger.info("Processed " + (byteChar / 1000000L) +
+            " million characters");
+      }
+    }
+    logger.info("Round tripped " + countRoundTripped + " of " + count);
+    assertEquals(expectedCount, countRoundTripped);
+  }
+
+  /**
+   * Variation of {@link #testBytes} that does less allocation using the
+   * low-level encoders/decoders directly. Checked in because it's useful for
+   * debugging when trying to process bytes faster, but since it doesn't use the
+   * actual String class, it's possible for incompatibilities to develop
+   * (although unlikely).
+   *
+   * @param numBytes the number of bytes in the byte array
+   * @param expectedCount the expected number of roundtrippable permutations
+   * @param start the starting bytes encoded as a long as big-endian
+   * @param lim the limit of bytes to process encoded as a long as big-endian,
+   *     or -1 to mean the max limit for numBytes
+   */
+  void testBytesUsingByteBuffers(
+      int numBytes, long expectedCount, long start, long lim)
+      throws UnsupportedEncodingException {
+    CharsetDecoder decoder = Charset.forName("UTF-8").newDecoder()
+        .onMalformedInput(CodingErrorAction.REPLACE)
+        .onUnmappableCharacter(CodingErrorAction.REPLACE);
+    CharsetEncoder encoder = Charset.forName("UTF-8").newEncoder()
+        .onMalformedInput(CodingErrorAction.REPLACE)
+        .onUnmappableCharacter(CodingErrorAction.REPLACE);
+    byte[] bytes = new byte[numBytes];
+    int maxChars = (int) (decoder.maxCharsPerByte() * numBytes) + 1;
+    char[] charsDecoded =
+        new char[(int) (decoder.maxCharsPerByte() * numBytes) + 1];
+    int maxBytes = (int) (encoder.maxBytesPerChar() * maxChars) + 1;
+    byte[] bytesReencoded = new byte[maxBytes];
+
+    ByteBuffer bb = ByteBuffer.wrap(bytes);
+    CharBuffer cb = CharBuffer.wrap(charsDecoded);
+    ByteBuffer bbReencoded = ByteBuffer.wrap(bytesReencoded);
+    if (lim == -1) {
+      lim = 1L << (numBytes * 8);
+    }
+    long count = 0;
+    long countRoundTripped = 0;
+    for (long byteChar = start; byteChar < lim; byteChar++) {
+      bb.rewind();
+      bb.limit(bytes.length);
+      cb.rewind();
+      cb.limit(charsDecoded.length);
+      bbReencoded.rewind();
+      bbReencoded.limit(bytesReencoded.length);
+      encoder.reset();
+      decoder.reset();
+      long tmpByteChar = byteChar;
+      for (int i = 0; i < bytes.length; i++) {
+        bytes[bytes.length - i - 1] = (byte) tmpByteChar;
+        tmpByteChar = tmpByteChar >> 8;
+      }
+      boolean isRoundTrippable = ByteString.copyFrom(bytes).isValidUtf8();
+      CoderResult result = decoder.decode(bb, cb, true);
+      assertFalse(result.isError());
+      result = decoder.flush(cb);
+      assertFalse(result.isError());
+
+      int charLen = cb.position();
+      cb.rewind();
+      cb.limit(charLen);
+      result = encoder.encode(cb, bbReencoded, true);
+      assertFalse(result.isError());
+      result = encoder.flush(bbReencoded);
+      assertFalse(result.isError());
+
+      boolean bytesEqual = true;
+      int bytesLen = bbReencoded.position();
+      if (bytesLen != numBytes) {
+        bytesEqual = false;
+      } else {
+        for (int i = 0; i < numBytes; i++) {
+          if (bytes[i] != bytesReencoded[i]) {
+            bytesEqual = false;
+            break;
+          }
+        }
+      }
+      if (bytesEqual != isRoundTrippable) {
+        outputFailure(byteChar, bytes, bytesReencoded, bytesLen);
+      }
+
+      count++;
+      if (isRoundTrippable) {
+        countRoundTripped++;
+      }
+      if (byteChar != 0 && byteChar % 1000000 == 0) {
+        logger.info("Processed " + (byteChar / 1000000) +
+            " million characters");
+      }
+    }
+    logger.info("Round tripped " + countRoundTripped + " of " + count);
+    assertEquals(expectedCount, countRoundTripped);
+  }
+
+  private static void outputFailure(long byteChar, byte[] bytes, byte[] after) {
+    outputFailure(byteChar, bytes, after, after.length);
+  }
+
+  private static void outputFailure(long byteChar, byte[] bytes, byte[] after,
+      int len) {
+    fail("Failure: (" + Long.toHexString(byteChar) + ") " +
+        toHexString(bytes) + " => " + toHexString(after, len));
+  }
+
+  private static String toHexString(byte[] b) {
+    return toHexString(b, b.length);
+  }
+
+  private static String toHexString(byte[] b, int len) {
+    StringBuilder s = new StringBuilder();
+    s.append("\"");
+    for (int i = 0; i < len; i++) {
+      if (i > 0) {
+        s.append(" ");
+      }
+      s.append(String.format("%02x", b[i] & 0xFF));
+    }
+    s.append("\"");
+    return s.toString();
+  }
+
+}
diff --git a/java/src/test/java/com/google/protobuf/LazyStringArrayListTest.java b/java/src/test/java/com/google/protobuf/LazyStringArrayListTest.java
index 4dcdc74d..d500595f 100644
--- a/java/src/test/java/com/google/protobuf/LazyStringArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/LazyStringArrayListTest.java
@@ -32,6 +32,9 @@ package com.google.protobuf;
 
 import junit.framework.TestCase;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Tests for {@link LazyStringArrayList}.
  *
@@ -115,4 +118,45 @@ public class LazyStringArrayListTest extends TestCase {
     assertSame(aPrimeByteString, list.getByteString(0));
     assertSame(bPrimeByteString, list.getByteString(1));
   }
+
+  public void testCopyConstructorCopiesByReference() {
+    LazyStringArrayList list1 = new LazyStringArrayList();
+    list1.add(STRING_A);
+    list1.add(BYTE_STRING_B);
+    list1.add(BYTE_STRING_C);
+
+    LazyStringArrayList list2 = new LazyStringArrayList(list1);
+    assertEquals(3, list2.size());
+    assertSame(STRING_A, list2.get(0));
+    assertSame(BYTE_STRING_B, list2.getByteString(1));
+    assertSame(BYTE_STRING_C, list2.getByteString(2));
+  }
+
+  public void testListCopyConstructor() {
+    List<String> list1 = new ArrayList<String>();
+    list1.add(STRING_A);
+    list1.add(STRING_B);
+    list1.add(STRING_C);
+
+    LazyStringArrayList list2 = new LazyStringArrayList(list1);
+    assertEquals(3, list2.size());
+    assertSame(STRING_A, list2.get(0));
+    assertSame(STRING_B, list2.get(1));
+    assertSame(STRING_C, list2.get(2));
+  }
+
+  public void testAddAllCopiesByReferenceIfPossible() {
+    LazyStringArrayList list1 = new LazyStringArrayList();
+    list1.add(STRING_A);
+    list1.add(BYTE_STRING_B);
+    list1.add(BYTE_STRING_C);
+
+    LazyStringArrayList list2 = new LazyStringArrayList();
+    list2.addAll(list1);
+
+    assertEquals(3, list2.size());
+    assertSame(STRING_A, list2.get(0));
+    assertSame(BYTE_STRING_B, list2.getByteString(1));
+    assertSame(BYTE_STRING_C, list2.getByteString(2));
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/LazyStringEndToEndTest.java b/java/src/test/java/com/google/protobuf/LazyStringEndToEndTest.java
index e6870b51..fe9599e3 100644
--- a/java/src/test/java/com/google/protobuf/LazyStringEndToEndTest.java
+++ b/java/src/test/java/com/google/protobuf/LazyStringEndToEndTest.java
@@ -50,6 +50,19 @@ public class LazyStringEndToEndTest extends TestCase {
           114, 4, -1, 0, -1, 0, -30, 2, 4, -1,
           0, -1, 0, -30, 2, 4, -1, 0, -1, 0, });
 
+  private ByteString encodedTestAllTypes;
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    this.encodedTestAllTypes = UnittestProto.TestAllTypes.newBuilder()
+        .setOptionalString("foo")
+        .addRepeatedString("bar")
+        .addRepeatedString("baz")
+        .build()
+        .toByteString();
+  }
+
   /**
    * Tests that an invalid UTF8 string will roundtrip through a parse
    * and serialization.
@@ -112,4 +125,19 @@ public class LazyStringEndToEndTest extends TestCase {
     assertSame(bPrime, proto.getRepeatedString(0));
     assertSame(cPrime, proto.getRepeatedString(1));
   }
+
+  public void testNoStringCachingIfOnlyBytesAccessed() throws Exception {
+    UnittestProto.TestAllTypes proto =
+        UnittestProto.TestAllTypes.parseFrom(encodedTestAllTypes);
+    ByteString optional = proto.getOptionalStringBytes();
+    assertSame(optional, proto.getOptionalStringBytes());
+    assertSame(optional, proto.toBuilder().getOptionalStringBytes());
+
+    ByteString repeated0 = proto.getRepeatedStringBytes(0);
+    ByteString repeated1 = proto.getRepeatedStringBytes(1);
+    assertSame(repeated0, proto.getRepeatedStringBytes(0));
+    assertSame(repeated1, proto.getRepeatedStringBytes(1));
+    assertSame(repeated0, proto.toBuilder().getRepeatedStringBytes(0));
+    assertSame(repeated1, proto.toBuilder().getRepeatedStringBytes(1));
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java b/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java
new file mode 100644
index 00000000..deee1eea
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java
@@ -0,0 +1,396 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import junit.framework.TestCase;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ * Test {@link LiteralByteString} by setting up a reference string in {@link #setUp()}.
+ * This class is designed to be extended for testing extensions of {@link LiteralByteString}
+ * such as {@link BoundedByteString}, see {@link BoundedByteStringTest}.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+public class LiteralByteStringTest extends TestCase {
+  protected static final String UTF_8 = "UTF-8";
+
+  protected String classUnderTest;
+  protected byte[] referenceBytes;
+  protected ByteString stringUnderTest;
+  protected int expectedHashCode;
+
+  @Override
+  protected void setUp() throws Exception {
+    classUnderTest = "LiteralByteString";
+    referenceBytes = ByteStringTest.getTestBytes(1234, 11337766L);
+    stringUnderTest = ByteString.copyFrom(referenceBytes);
+    expectedHashCode = 331161852;
+  }
+
+  public void testExpectedType() {
+    String actualClassName = getActualClassName(stringUnderTest);
+    assertEquals(classUnderTest + " should match type exactly", classUnderTest, actualClassName);
+  }
+
+  protected String getActualClassName(Object object) {
+    String actualClassName = object.getClass().getName();
+    actualClassName = actualClassName.substring(actualClassName.lastIndexOf('.') + 1);
+    return actualClassName;
+  }
+
+  public void testByteAt() {
+    boolean stillEqual = true;
+    for (int i = 0; stillEqual && i < referenceBytes.length; ++i) {
+      stillEqual = (referenceBytes[i] == stringUnderTest.byteAt(i));
+    }
+    assertTrue(classUnderTest + " must capture the right bytes", stillEqual);
+  }
+
+  public void testByteIterator() {
+    boolean stillEqual = true;
+    ByteString.ByteIterator iter = stringUnderTest.iterator();
+    for (int i = 0; stillEqual && i < referenceBytes.length; ++i) {
+      stillEqual = (iter.hasNext() && referenceBytes[i] == iter.nextByte());
+    }
+    assertTrue(classUnderTest + " must capture the right bytes", stillEqual);
+    assertFalse(classUnderTest + " must have exhausted the itertor", iter.hasNext());
+
+    try {
+      iter.nextByte();
+      fail("Should have thrown an exception.");
+    } catch (NoSuchElementException e) {
+      // This is success
+    }
+  }
+
+  public void testByteIterable() {
+    boolean stillEqual = true;
+    int j = 0;
+    for (byte quantum : stringUnderTest) {
+      stillEqual = (referenceBytes[j] == quantum);
+      ++j;
+    }
+    assertTrue(classUnderTest + " must capture the right bytes as Bytes", stillEqual);
+    assertEquals(classUnderTest + " iterable character count", referenceBytes.length, j);
+  }
+
+  public void testSize() {
+    assertEquals(classUnderTest + " must have the expected size", referenceBytes.length,
+        stringUnderTest.size());
+  }
+
+  public void testGetTreeDepth() {
+    assertEquals(classUnderTest + " must have depth 0", 0, stringUnderTest.getTreeDepth());
+  }
+
+  public void testIsBalanced() {
+    assertTrue(classUnderTest + " is technically balanced", stringUnderTest.isBalanced());
+  }
+
+  public void testCopyTo_ByteArrayOffsetLength() {
+    int destinationOffset = 50;
+    int length = 100;
+    byte[] destination = new byte[destinationOffset + length];
+    int sourceOffset = 213;
+    stringUnderTest.copyTo(destination, sourceOffset, destinationOffset, length);
+    boolean stillEqual = true;
+    for (int i = 0; stillEqual && i < length; ++i) {
+      stillEqual = referenceBytes[i + sourceOffset] == destination[i + destinationOffset];
+    }
+    assertTrue(classUnderTest + ".copyTo(4 arg) must give the expected bytes", stillEqual);
+  }
+
+  public void testCopyTo_ByteArrayOffsetLengthErrors() {
+    int destinationOffset = 50;
+    int length = 100;
+    byte[] destination = new byte[destinationOffset + length];
+
+    try {
+      // Copy one too many bytes
+      stringUnderTest.copyTo(destination, stringUnderTest.size() + 1 - length,
+          destinationOffset, length);
+      fail("Should have thrown an exception when copying too many bytes of a "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative sourceOffset
+      stringUnderTest.copyTo(destination, -1, destinationOffset, length);
+      fail("Should have thrown an exception when given a negative sourceOffset in "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative destinationOffset
+      stringUnderTest.copyTo(destination, 0, -1, length);
+      fail("Should have thrown an exception when given a negative destinationOffset in "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative size
+      stringUnderTest.copyTo(destination, 0, 0, -1);
+      fail("Should have thrown an exception when given a negative size in "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal too-large sourceOffset
+      stringUnderTest.copyTo(destination, 2 * stringUnderTest.size(), 0, length);
+      fail("Should have thrown an exception when the destinationOffset is too large in "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal too-large destinationOffset
+      stringUnderTest.copyTo(destination, 0, 2 * destination.length, length);
+      fail("Should have thrown an exception when the destinationOffset is too large in "
+          + classUnderTest);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+  }
+
+  public void testCopyTo_ByteBuffer() {
+    ByteBuffer myBuffer = ByteBuffer.allocate(referenceBytes.length);
+    stringUnderTest.copyTo(myBuffer);
+    assertTrue(classUnderTest + ".copyTo(ByteBuffer) must give back the same bytes",
+        Arrays.equals(referenceBytes, myBuffer.array()));
+  }
+
+  public void testAsReadOnlyByteBuffer() {
+    ByteBuffer byteBuffer = stringUnderTest.asReadOnlyByteBuffer();
+    byte[] roundTripBytes = new byte[referenceBytes.length];
+    assertTrue(byteBuffer.remaining() == referenceBytes.length);
+    assertTrue(byteBuffer.isReadOnly());
+    byteBuffer.get(roundTripBytes);
+    assertTrue(classUnderTest + ".asReadOnlyByteBuffer() must give back the same bytes",
+        Arrays.equals(referenceBytes, roundTripBytes));
+  }
+
+  public void testAsReadOnlyByteBufferList() {
+    List<ByteBuffer> byteBuffers = stringUnderTest.asReadOnlyByteBufferList();
+    int bytesSeen = 0;
+    byte[] roundTripBytes = new byte[referenceBytes.length];
+    for (ByteBuffer byteBuffer : byteBuffers) {
+      int thisLength = byteBuffer.remaining();
+      assertTrue(byteBuffer.isReadOnly());
+      assertTrue(bytesSeen + thisLength <= referenceBytes.length);
+      byteBuffer.get(roundTripBytes, bytesSeen, thisLength);
+      bytesSeen += thisLength;
+    }
+    assertTrue(bytesSeen == referenceBytes.length);
+    assertTrue(classUnderTest + ".asReadOnlyByteBufferTest() must give back the same bytes",
+        Arrays.equals(referenceBytes, roundTripBytes));
+  }
+
+  public void testToByteArray() {
+    byte[] roundTripBytes = stringUnderTest.toByteArray();
+    assertTrue(classUnderTest + ".toByteArray() must give back the same bytes",
+        Arrays.equals(referenceBytes, roundTripBytes));
+  }
+
+  public void testWriteTo() throws IOException {
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+    stringUnderTest.writeTo(bos);
+    byte[] roundTripBytes = bos.toByteArray();
+    assertTrue(classUnderTest + ".writeTo() must give back the same bytes",
+        Arrays.equals(referenceBytes, roundTripBytes));
+  }
+  
+  public void testWriteTo_mutating() throws IOException {
+    OutputStream os = new OutputStream() {
+      @Override
+      public void write(byte[] b, int off, int len) {
+        for (int x = 0; x < len; ++x) {
+          b[off + x] = (byte) 0;
+        }
+      }
+
+      @Override
+      public void write(int b) {
+        // Purposefully left blank.
+      }
+    };
+
+    stringUnderTest.writeTo(os);
+    byte[] newBytes = stringUnderTest.toByteArray();
+    assertTrue(classUnderTest + ".writeTo() must not grant access to underlying array",
+        Arrays.equals(referenceBytes, newBytes));
+  }
+
+  public void testNewOutput() throws IOException {
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+    ByteString.Output output = ByteString.newOutput();
+    stringUnderTest.writeTo(output);
+    assertEquals("Output Size returns correct result",
+        output.size(), stringUnderTest.size());
+    output.writeTo(bos);
+    assertTrue("Output.writeTo() must give back the same bytes",
+        Arrays.equals(referenceBytes, bos.toByteArray()));
+
+    // write the output stream to itself! This should cause it to double
+    output.writeTo(output);
+    assertEquals("Writing an output stream to itself is successful",
+        stringUnderTest.concat(stringUnderTest), output.toByteString());
+
+    output.reset();
+    assertEquals("Output.reset() resets the output", 0, output.size());
+    assertEquals("Output.reset() resets the output",
+        ByteString.EMPTY, output.toByteString());
+    
+  }
+
+  public void testToString() throws UnsupportedEncodingException {
+    String testString = "I love unicode \u1234\u5678 characters";
+    LiteralByteString unicode = new LiteralByteString(testString.getBytes(UTF_8));
+    String roundTripString = unicode.toString(UTF_8);
+    assertEquals(classUnderTest + " unicode must match", testString, roundTripString);
+  }
+
+  public void testEquals() {
+    assertEquals(classUnderTest + " must not equal null", false, stringUnderTest.equals(null));
+    assertEquals(classUnderTest + " must equal self", stringUnderTest, stringUnderTest);
+    assertFalse(classUnderTest + " must not equal the empty string",
+        stringUnderTest.equals(ByteString.EMPTY));
+    assertEquals(classUnderTest + " empty strings must be equal",
+        new LiteralByteString(new byte[]{}), stringUnderTest.substring(55, 55));
+    assertEquals(classUnderTest + " must equal another string with the same value",
+        stringUnderTest, new LiteralByteString(referenceBytes));
+
+    byte[] mungedBytes = new byte[referenceBytes.length];
+    System.arraycopy(referenceBytes, 0, mungedBytes, 0, referenceBytes.length);
+    mungedBytes[mungedBytes.length - 5] ^= 0xFF;
+    assertFalse(classUnderTest + " must not equal every string with the same length",
+        stringUnderTest.equals(new LiteralByteString(mungedBytes)));
+  }
+
+  public void testHashCode() {
+    int hash = stringUnderTest.hashCode();
+    assertEquals(classUnderTest + " must have expected hashCode", expectedHashCode, hash);
+  }
+
+  public void testPeekCachedHashCode() {
+    assertEquals(classUnderTest + ".peekCachedHashCode() should return zero at first", 0,
+        stringUnderTest.peekCachedHashCode());
+    stringUnderTest.hashCode();
+    assertEquals(classUnderTest + ".peekCachedHashCode should return zero at first",
+        expectedHashCode, stringUnderTest.peekCachedHashCode());
+  }
+
+  public void testPartialHash() {
+    // partialHash() is more strenuously tested elsewhere by testing hashes of substrings.
+    // This test would fail if the expected hash were 1.  It's not.
+    int hash = stringUnderTest.partialHash(stringUnderTest.size(), 0, stringUnderTest.size());
+    assertEquals(classUnderTest + ".partialHash() must yield expected hashCode",
+        expectedHashCode, hash);
+  }
+
+  public void testNewInput() throws IOException {
+    InputStream input = stringUnderTest.newInput();
+    assertEquals("InputStream.available() returns correct value",
+        stringUnderTest.size(), input.available());
+    boolean stillEqual = true;
+    for (byte referenceByte : referenceBytes) {
+      int expectedInt = (referenceByte & 0xFF);
+      stillEqual = (expectedInt == input.read());
+    }
+    assertEquals("InputStream.available() returns correct value",
+        0, input.available());
+    assertTrue(classUnderTest + " must give the same bytes from the InputStream", stillEqual);
+    assertEquals(classUnderTest + " InputStream must now be exhausted", -1, input.read());
+  }
+
+  public void testNewInput_skip() throws IOException {
+    InputStream input = stringUnderTest.newInput();
+    int stringSize = stringUnderTest.size();
+    int nearEndIndex = stringSize * 2 / 3;
+    long skipped1 = input.skip(nearEndIndex);
+    assertEquals("InputStream.skip()", skipped1, nearEndIndex);
+    assertEquals("InputStream.available()",
+        stringSize - skipped1, input.available());
+    assertTrue("InputStream.mark() is available", input.markSupported());
+    input.mark(0);
+    assertEquals("InputStream.skip(), read()",
+        stringUnderTest.byteAt(nearEndIndex) & 0xFF, input.read());
+    assertEquals("InputStream.available()",
+                 stringSize - skipped1 - 1, input.available());
+    long skipped2 = input.skip(stringSize);
+    assertEquals("InputStream.skip() incomplete",
+        skipped2, stringSize - skipped1 - 1);
+    assertEquals("InputStream.skip(), no more input", 0, input.available());
+    assertEquals("InputStream.skip(), no more input", -1, input.read());
+    input.reset();
+    assertEquals("InputStream.reset() succeded",
+                 stringSize - skipped1, input.available());
+    assertEquals("InputStream.reset(), read()",
+        stringUnderTest.byteAt(nearEndIndex) & 0xFF, input.read());
+  }
+
+  public void testNewCodedInput() throws IOException {
+    CodedInputStream cis = stringUnderTest.newCodedInput();
+    byte[] roundTripBytes = cis.readRawBytes(referenceBytes.length);
+    assertTrue(classUnderTest + " must give the same bytes back from the CodedInputStream",
+        Arrays.equals(referenceBytes, roundTripBytes));
+    assertTrue(classUnderTest + " CodedInputStream must now be exhausted", cis.isAtEnd());
+  }
+
+  /**
+   * Make sure we keep things simple when concatenating with empty. See also
+   * {@link ByteStringTest#testConcat_empty()}.
+   */
+  public void testConcat_empty() {
+    assertSame(classUnderTest + " concatenated with empty must give " + classUnderTest,
+        stringUnderTest.concat(ByteString.EMPTY), stringUnderTest);
+    assertSame("empty concatenated with " + classUnderTest + " must give " + classUnderTest,
+        ByteString.EMPTY.concat(stringUnderTest), stringUnderTest);
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/MessageTest.java b/java/src/test/java/com/google/protobuf/MessageTest.java
index c2f47eb2..747fed75 100644
--- a/java/src/test/java/com/google/protobuf/MessageTest.java
+++ b/java/src/test/java/com/google/protobuf/MessageTest.java
@@ -38,6 +38,8 @@ import protobuf_unittest.UnittestProto.ForeignMessage;
 
 import junit.framework.TestCase;
 
+import java.util.List;
+
 /**
  * Misc. unit tests for message operations that apply to both generated
  * and dynamic messages.
@@ -310,4 +312,42 @@ public class MessageTest extends TestCase {
       assertEquals("Message missing required fields: a, b, c", e.getMessage());
     }
   }
+  
+  /** Test reading unset repeated message from DynamicMessage. */
+  public void testDynamicRepeatedMessageNull() throws Exception {
+    Descriptors.Descriptor descriptor = TestRequired.getDescriptor();
+    DynamicMessage result =
+      DynamicMessage.newBuilder(TestAllTypes.getDescriptor())
+        .mergeFrom(DynamicMessage.newBuilder(MERGE_SOURCE).build())
+        .build();
+
+    assertTrue(result.getField(result.getDescriptorForType()
+        .findFieldByName("repeated_foreign_message")) instanceof List<?>);
+    assertEquals(result.getRepeatedFieldCount(result.getDescriptorForType()
+        .findFieldByName("repeated_foreign_message")), 0);
+  }
+  
+  /** Test reading repeated message from DynamicMessage. */
+  public void testDynamicRepeatedMessageNotNull() throws Exception {
+
+    TestAllTypes REPEATED_NESTED =
+      TestAllTypes.newBuilder()
+        .setOptionalInt32(1)
+        .setOptionalString("foo")
+        .setOptionalForeignMessage(ForeignMessage.getDefaultInstance())
+        .addRepeatedString("bar")
+        .addRepeatedForeignMessage(ForeignMessage.getDefaultInstance())
+        .addRepeatedForeignMessage(ForeignMessage.getDefaultInstance())
+        .build();
+    Descriptors.Descriptor descriptor = TestRequired.getDescriptor();
+    DynamicMessage result =
+      DynamicMessage.newBuilder(TestAllTypes.getDescriptor())
+        .mergeFrom(DynamicMessage.newBuilder(REPEATED_NESTED).build())
+        .build();
+
+    assertTrue(result.getField(result.getDescriptorForType()
+        .findFieldByName("repeated_foreign_message")) instanceof List<?>);
+    assertEquals(result.getRepeatedFieldCount(result.getDescriptorForType()
+        .findFieldByName("repeated_foreign_message")), 2);
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/ParserTest.java b/java/src/test/java/com/google/protobuf/ParserTest.java
new file mode 100644
index 00000000..396902cf
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/ParserTest.java
@@ -0,0 +1,375 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.UnittestLite.TestAllTypesLite;
+import com.google.protobuf.UnittestLite.TestPackedExtensionsLite;
+import com.google.protobuf.UnittestLite.TestParsingMergeLite;
+import com.google.protobuf.UnittestLite;
+import protobuf_unittest.UnittestOptimizeFor.TestOptimizedForSize;
+import protobuf_unittest.UnittestOptimizeFor.TestRequiredOptimizedForSize;
+import protobuf_unittest.UnittestOptimizeFor;
+import protobuf_unittest.UnittestProto.ForeignMessage;
+import protobuf_unittest.UnittestProto.TestAllTypes;
+import protobuf_unittest.UnittestProto.TestEmptyMessage;
+import protobuf_unittest.UnittestProto.TestRequired;
+import protobuf_unittest.UnittestProto.TestParsingMerge;
+import protobuf_unittest.UnittestProto;
+
+import junit.framework.TestCase;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * Unit test for {@link Parser}.
+ *
+ * @author liujisi@google.com (Pherl Liu)
+ */
+public class ParserTest extends TestCase {
+  public void testGeneratedMessageParserSingleton() throws Exception {
+    for (int i = 0; i < 10; i++) {
+      assertEquals(TestAllTypes.PARSER,
+                   TestUtil.getAllSet().getParserForType());
+    }
+  }
+
+  private void assertRoundTripEquals(MessageLite message,
+                                     ExtensionRegistryLite registry)
+      throws Exception {
+    final byte[] data = message.toByteArray();
+    final int offset = 20;
+    final int length = data.length;
+    final int padding = 30;
+    Parser<? extends MessageLite> parser = message.getParserForType();
+    assertMessageEquals(message, parser.parseFrom(data, registry));
+    assertMessageEquals(message, parser.parseFrom(
+        generatePaddingArray(data, offset, padding),
+        offset, length, registry));
+    assertMessageEquals(message, parser.parseFrom(
+        message.toByteString(), registry));
+    assertMessageEquals(message, parser.parseFrom(
+        new ByteArrayInputStream(data), registry));
+    assertMessageEquals(message, parser.parseFrom(
+        CodedInputStream.newInstance(data), registry));
+  }
+
+  private void assertRoundTripEquals(MessageLite message) throws Exception {
+    final byte[] data = message.toByteArray();
+    final int offset = 20;
+    final int length = data.length;
+    final int padding = 30;
+    Parser<? extends MessageLite> parser = message.getParserForType();
+    assertMessageEquals(message, parser.parseFrom(data));
+    assertMessageEquals(message, parser.parseFrom(
+        generatePaddingArray(data, offset, padding),
+        offset, length));
+    assertMessageEquals(message, parser.parseFrom(message.toByteString()));
+    assertMessageEquals(message, parser.parseFrom(
+        new ByteArrayInputStream(data)));
+    assertMessageEquals(message, parser.parseFrom(
+        CodedInputStream.newInstance(data)));
+  }
+
+  private void assertMessageEquals(MessageLite expected, MessageLite actual)
+      throws Exception {
+    if (expected instanceof Message) {
+      assertEquals(expected, actual);
+    } else {
+      assertEquals(expected.toByteString(), actual.toByteString());
+    }
+  }
+
+  private byte[] generatePaddingArray(byte[] data, int offset, int padding) {
+    byte[] result = new byte[offset + data.length + padding];
+    System.arraycopy(data, 0, result, offset, data.length);
+    return result;
+  }
+
+  public void testNormalMessage() throws Exception {
+    assertRoundTripEquals(TestUtil.getAllSet());
+  }
+
+  public void testParsePartial() throws Exception {
+    Parser<TestRequired> parser = TestRequired.PARSER;
+    final String errorString =
+        "Should throw exceptions when the parsed message isn't initialized.";
+
+    // TestRequired.b and TestRequired.c are not set.
+    TestRequired partialMessage = TestRequired.newBuilder()
+        .setA(1).buildPartial();
+
+    // parsePartialFrom should pass.
+    byte[] data = partialMessage.toByteArray();
+    assertEquals(partialMessage, parser.parsePartialFrom(data));
+    assertEquals(partialMessage, parser.parsePartialFrom(
+        partialMessage.toByteString()));
+    assertEquals(partialMessage, parser.parsePartialFrom(
+        new ByteArrayInputStream(data)));
+    assertEquals(partialMessage, parser.parsePartialFrom(
+        CodedInputStream.newInstance(data)));
+
+    // parseFrom(ByteArray)
+    try {
+      parser.parseFrom(partialMessage.toByteArray());
+      fail(errorString);
+    } catch (InvalidProtocolBufferException e) {
+      // pass.
+    }
+
+    // parseFrom(ByteString)
+    try {
+      parser.parseFrom(partialMessage.toByteString());
+      fail(errorString);
+    } catch (InvalidProtocolBufferException e) {
+      // pass.
+    }
+
+    // parseFrom(InputStream)
+    try {
+      parser.parseFrom(new ByteArrayInputStream(partialMessage.toByteArray()));
+      fail(errorString);
+    } catch (IOException e) {
+      // pass.
+    }
+
+    // parseFrom(CodedInputStream)
+    try {
+      parser.parseFrom(CodedInputStream.newInstance(
+          partialMessage.toByteArray()));
+      fail(errorString);
+    } catch (IOException e) {
+      // pass.
+    }
+  }
+
+  public void testParseExtensions() throws Exception {
+    assertRoundTripEquals(TestUtil.getAllExtensionsSet(),
+                          TestUtil.getExtensionRegistry());
+    assertRoundTripEquals(TestUtil.getAllLiteExtensionsSet(),
+                          TestUtil.getExtensionRegistryLite());
+  }
+
+  public void testParsePacked() throws Exception {
+    assertRoundTripEquals(TestUtil.getPackedSet());
+    assertRoundTripEquals(TestUtil.getPackedExtensionsSet(),
+                          TestUtil.getExtensionRegistry());
+    assertRoundTripEquals(TestUtil.getLitePackedExtensionsSet(),
+                          TestUtil.getExtensionRegistryLite());
+  }
+
+  public void testParseDelimitedTo() throws Exception {
+    // Write normal Message.
+    TestAllTypes normalMessage = TestUtil.getAllSet();
+    ByteArrayOutputStream output = new ByteArrayOutputStream();
+    normalMessage.writeDelimitedTo(output);
+
+    // Write MessageLite with packed extension fields.
+    TestPackedExtensionsLite packedMessage =
+        TestUtil.getLitePackedExtensionsSet();
+    packedMessage.writeDelimitedTo(output);
+
+    InputStream input = new ByteArrayInputStream(output.toByteArray());
+    assertMessageEquals(
+        normalMessage,
+        normalMessage.getParserForType().parseDelimitedFrom(input));
+    assertMessageEquals(
+        packedMessage,
+        packedMessage.getParserForType().parseDelimitedFrom(
+            input, TestUtil.getExtensionRegistryLite()));
+  }
+
+  public void testParseUnknownFields() throws Exception {
+    // All fields will be treated as unknown fields in emptyMessage.
+    TestEmptyMessage emptyMessage = TestEmptyMessage.PARSER.parseFrom(
+        TestUtil.getAllSet().toByteString());
+    assertEquals(
+        TestUtil.getAllSet().toByteString(),
+        emptyMessage.toByteString());
+  }
+
+  public void testOptimizeForSize() throws Exception {
+    TestOptimizedForSize.Builder builder = TestOptimizedForSize.newBuilder();
+    builder.setI(12).setMsg(ForeignMessage.newBuilder().setC(34).build());
+    builder.setExtension(TestOptimizedForSize.testExtension, 56);
+    builder.setExtension(TestOptimizedForSize.testExtension2,
+        TestRequiredOptimizedForSize.newBuilder().setX(78).build());
+
+    TestOptimizedForSize message = builder.build();
+    ExtensionRegistry registry = ExtensionRegistry.newInstance();
+    UnittestOptimizeFor.registerAllExtensions(registry);
+
+    assertRoundTripEquals(message, registry);
+  }
+
+  /** Helper method for {@link #testParsingMerge()}.*/
+  private void assertMessageMerged(TestAllTypes allTypes)
+      throws Exception {
+    assertEquals(3, allTypes.getOptionalInt32());
+    assertEquals(2, allTypes.getOptionalInt64());
+    assertEquals("hello", allTypes.getOptionalString());
+  }
+
+  /** Helper method for {@link #testParsingMergeLite()}.*/
+  private void assertMessageMerged(TestAllTypesLite allTypes)
+      throws Exception {
+    assertEquals(3, allTypes.getOptionalInt32());
+    assertEquals(2, allTypes.getOptionalInt64());
+    assertEquals("hello", allTypes.getOptionalString());
+  }
+
+  public void testParsingMerge() throws Exception {
+    // Build messages.
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    TestAllTypes msg1 = builder.setOptionalInt32(1).build();
+    builder.clear();
+    TestAllTypes msg2 = builder.setOptionalInt64(2).build();
+    builder.clear();
+    TestAllTypes msg3 = builder.setOptionalInt32(3)
+        .setOptionalString("hello").build();
+
+    // Build groups.
+    TestParsingMerge.RepeatedFieldsGenerator.Group1 optionalG1 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg1).build();
+    TestParsingMerge.RepeatedFieldsGenerator.Group1 optionalG2 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg2).build();
+    TestParsingMerge.RepeatedFieldsGenerator.Group1 optionalG3 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg3).build();
+    TestParsingMerge.RepeatedFieldsGenerator.Group2 repeatedG1 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg1).build();
+    TestParsingMerge.RepeatedFieldsGenerator.Group2 repeatedG2 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg2).build();
+    TestParsingMerge.RepeatedFieldsGenerator.Group2 repeatedG3 =
+        TestParsingMerge.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg3).build();
+
+    // Assign and serialize RepeatedFieldsGenerator.
+    ByteString data = TestParsingMerge.RepeatedFieldsGenerator.newBuilder()
+        .addField1(msg1).addField1(msg2).addField1(msg3)
+        .addField2(msg1).addField2(msg2).addField2(msg3)
+        .addField3(msg1).addField3(msg2).addField3(msg3)
+        .addGroup1(optionalG1).addGroup1(optionalG2).addGroup1(optionalG3)
+        .addGroup2(repeatedG1).addGroup2(repeatedG2).addGroup2(repeatedG3)
+        .addExt1(msg1).addExt1(msg2).addExt1(msg3)
+        .addExt2(msg1).addExt2(msg2).addExt2(msg3)
+        .build().toByteString();
+
+    // Parse TestParsingMerge.
+    ExtensionRegistry registry = ExtensionRegistry.newInstance();
+    UnittestProto.registerAllExtensions(registry);
+    TestParsingMerge parsingMerge =
+        TestParsingMerge.PARSER.parseFrom(data, registry);
+
+    // Required and optional fields should be merged.
+    assertMessageMerged(parsingMerge.getRequiredAllTypes());
+    assertMessageMerged(parsingMerge.getOptionalAllTypes());
+    assertMessageMerged(
+        parsingMerge.getOptionalGroup().getOptionalGroupAllTypes());
+    assertMessageMerged(parsingMerge.getExtension(
+        TestParsingMerge.optionalExt));
+
+    // Repeated fields should not be merged.
+    assertEquals(3, parsingMerge.getRepeatedAllTypesCount());
+    assertEquals(3, parsingMerge.getRepeatedGroupCount());
+    assertEquals(3, parsingMerge.getExtensionCount(
+        TestParsingMerge.repeatedExt));
+  }
+
+  public void testParsingMergeLite() throws Exception {
+    // Build messages.
+    TestAllTypesLite.Builder builder =
+        TestAllTypesLite.newBuilder();
+    TestAllTypesLite msg1 = builder.setOptionalInt32(1).build();
+    builder.clear();
+    TestAllTypesLite msg2 = builder.setOptionalInt64(2).build();
+    builder.clear();
+    TestAllTypesLite msg3 = builder.setOptionalInt32(3)
+        .setOptionalString("hello").build();
+
+    // Build groups.
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group1 optionalG1 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg1).build();
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group1 optionalG2 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg2).build();
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group1 optionalG3 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group1.newBuilder()
+        .setField1(msg3).build();
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group2 repeatedG1 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg1).build();
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group2 repeatedG2 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg2).build();
+    TestParsingMergeLite.RepeatedFieldsGenerator.Group2 repeatedG3 =
+        TestParsingMergeLite.RepeatedFieldsGenerator.Group2.newBuilder()
+        .setField1(msg3).build();
+
+    // Assign and serialize RepeatedFieldsGenerator.
+    ByteString data = TestParsingMergeLite.RepeatedFieldsGenerator.newBuilder()
+        .addField1(msg1).addField1(msg2).addField1(msg3)
+        .addField2(msg1).addField2(msg2).addField2(msg3)
+        .addField3(msg1).addField3(msg2).addField3(msg3)
+        .addGroup1(optionalG1).addGroup1(optionalG2).addGroup1(optionalG3)
+        .addGroup2(repeatedG1).addGroup2(repeatedG2).addGroup2(repeatedG3)
+        .addExt1(msg1).addExt1(msg2).addExt1(msg3)
+        .addExt2(msg1).addExt2(msg2).addExt2(msg3)
+        .build().toByteString();
+
+    // Parse TestParsingMergeLite.
+    ExtensionRegistry registry = ExtensionRegistry.newInstance();
+    UnittestLite.registerAllExtensions(registry);
+    TestParsingMergeLite parsingMerge =
+        TestParsingMergeLite.PARSER.parseFrom(data, registry);
+
+    // Required and optional fields should be merged.
+    assertMessageMerged(parsingMerge.getRequiredAllTypes());
+    assertMessageMerged(parsingMerge.getOptionalAllTypes());
+    assertMessageMerged(
+        parsingMerge.getOptionalGroup().getOptionalGroupAllTypes());
+    assertMessageMerged(parsingMerge.getExtension(
+        TestParsingMergeLite.optionalExt));
+
+    // Repeated fields should not be merged.
+    assertEquals(3, parsingMerge.getRepeatedAllTypesCount());
+    assertEquals(3, parsingMerge.getRepeatedGroupCount());
+    assertEquals(3, parsingMerge.getExtensionCount(
+        TestParsingMergeLite.repeatedExt));
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java b/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java
new file mode 100644
index 00000000..06707a2f
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java
@@ -0,0 +1,97 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.UnsupportedEncodingException;
+import java.util.Iterator;
+
+/**
+ * This class tests {@link RopeByteString#substring(int, int)} by inheriting the tests from
+ * {@link LiteralByteStringTest}.  Only a couple of methods are overridden.  
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+public class RopeByteStringSubstringTest extends LiteralByteStringTest {
+
+  @Override
+  protected void setUp() throws Exception {
+    classUnderTest = "RopeByteString";
+    byte[] sourceBytes = ByteStringTest.getTestBytes(22341, 22337766L);
+    Iterator<ByteString> iter = ByteStringTest.makeConcretePieces(sourceBytes).iterator();
+    ByteString sourceString = iter.next();
+    while (iter.hasNext()) {
+      sourceString = sourceString.concat(iter.next());
+    }
+
+    int from = 1130;
+    int to = sourceBytes.length - 5555;
+    stringUnderTest = sourceString.substring(from, to);
+    referenceBytes = new byte[to - from];
+    System.arraycopy(sourceBytes, from, referenceBytes, 0, to - from);
+    expectedHashCode = -1259260680;
+  }
+
+  @Override
+  public void testGetTreeDepth() {
+    assertEquals(classUnderTest + " must have the expected tree depth",
+        3, stringUnderTest.getTreeDepth());
+  }
+
+  @Override
+  public void testToString() throws UnsupportedEncodingException {
+    String sourceString = "I love unicode \u1234\u5678 characters";
+    ByteString sourceByteString = ByteString.copyFromUtf8(sourceString);
+    int copies = 250;
+
+    // By building the RopeByteString by concatenating, this is actually a fairly strenuous test.
+    StringBuilder builder = new StringBuilder(copies * sourceString.length());
+    ByteString unicode = ByteString.EMPTY;
+    for (int i = 0; i < copies; ++i) {
+      builder.append(sourceString);
+      unicode = RopeByteString.concatenate(unicode, sourceByteString);
+    }
+    String testString = builder.toString();
+
+    // Do the substring part
+    testString = testString.substring(2, testString.length() - 6);
+    unicode = unicode.substring(2, unicode.size() - 6);
+
+    assertEquals(classUnderTest + " from string must have the expected type",
+        classUnderTest, getActualClassName(unicode));
+    String roundTripString = unicode.toString(UTF_8);
+    assertEquals(classUnderTest + " unicode bytes must match",
+        testString, roundTripString);
+    ByteString flatString = ByteString.copyFromUtf8(testString);
+    assertEquals(classUnderTest + " string must equal the flat string", flatString, unicode);
+    assertEquals(classUnderTest + " string must must have same hashCode as the flat string",
+        flatString.hashCode(), unicode.hashCode());
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/RopeByteStringTest.java b/java/src/test/java/com/google/protobuf/RopeByteStringTest.java
new file mode 100644
index 00000000..15f660d9
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/RopeByteStringTest.java
@@ -0,0 +1,115 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.UnsupportedEncodingException;
+import java.util.Arrays;
+import java.util.Iterator;
+
+/**
+ * This class tests {@link RopeByteString} by inheriting the tests from
+ * {@link LiteralByteStringTest}.  Only a couple of methods are overridden.
+ * 
+ * <p>A full test of the result of {@link RopeByteString#substring(int, int)} is found in the
+ * separate class {@link RopeByteStringSubstringTest}.
+ *
+ * @author carlanton@google.com (Carl Haverl)
+ */
+public class RopeByteStringTest extends LiteralByteStringTest {
+
+  @Override
+  protected void setUp() throws Exception {
+    classUnderTest = "RopeByteString";
+    referenceBytes = ByteStringTest.getTestBytes(22341, 22337766L);
+    Iterator<ByteString> iter = ByteStringTest.makeConcretePieces(referenceBytes).iterator();
+    stringUnderTest = iter.next();
+    while (iter.hasNext()) {
+      stringUnderTest = stringUnderTest.concat(iter.next());
+    }
+    expectedHashCode = -1214197238;
+  }
+
+  @Override
+  public void testGetTreeDepth() {
+    assertEquals(classUnderTest + " must have the expected tree depth",
+        4, stringUnderTest.getTreeDepth());
+  }
+
+  public void testBalance() {
+    int numberOfPieces = 10000;
+    int pieceSize = 64;
+    byte[] testBytes = ByteStringTest.getTestBytes(numberOfPieces * pieceSize, 113377L);
+
+    // Build up a big ByteString from smaller pieces to force a rebalance
+    ByteString concatenated = ByteString.EMPTY;
+    for (int i = 0; i < numberOfPieces; ++i) {
+      concatenated = concatenated.concat(ByteString.copyFrom(testBytes, i * pieceSize, pieceSize));
+    }
+
+    assertEquals(classUnderTest + " from string must have the expected type",
+        classUnderTest, getActualClassName(concatenated));
+    assertTrue(classUnderTest + " underlying bytes must match after balancing",
+        Arrays.equals(testBytes, concatenated.toByteArray()));
+    ByteString testString = ByteString.copyFrom(testBytes);
+    assertTrue(classUnderTest + " balanced string must equal flat string",
+        concatenated.equals(testString));
+    assertTrue(classUnderTest + " flat string must equal balanced string",
+        testString.equals(concatenated));
+    assertEquals(classUnderTest + " balanced string must have same hash code as flat string",
+        testString.hashCode(), concatenated.hashCode());
+  }
+
+  @Override
+  public void testToString() throws UnsupportedEncodingException {
+    String sourceString = "I love unicode \u1234\u5678 characters";
+    ByteString sourceByteString = ByteString.copyFromUtf8(sourceString);
+    int copies = 250;
+
+    // By building the RopeByteString by concatenating, this is actually a fairly strenuous test.
+    StringBuilder builder = new StringBuilder(copies * sourceString.length());
+    ByteString unicode = ByteString.EMPTY;
+    for (int i = 0; i < copies; ++i) {
+      builder.append(sourceString);
+      unicode = RopeByteString.concatenate(unicode, sourceByteString);
+    }
+    String testString = builder.toString();
+
+    assertEquals(classUnderTest + " from string must have the expected type",
+        classUnderTest, getActualClassName(unicode));
+    String roundTripString = unicode.toString(UTF_8);
+    assertEquals(classUnderTest + " unicode bytes must match",
+        testString, roundTripString);
+    ByteString flatString = ByteString.copyFromUtf8(testString);
+    assertEquals(classUnderTest + " string must equal the flat string", flatString, unicode);
+    assertEquals(classUnderTest + " string must must have same hashCode as the flat string",
+        flatString.hashCode(), unicode.hashCode());
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/TestBadIdentifiers.java b/java/src/test/java/com/google/protobuf/TestBadIdentifiers.java
index 6feec4e6..382acf0f 100644
--- a/java/src/test/java/com/google/protobuf/TestBadIdentifiers.java
+++ b/java/src/test/java/com/google/protobuf/TestBadIdentifiers.java
@@ -35,7 +35,7 @@ import junit.framework.TestCase;
 /**
  * Tests that proto2 api generation doesn't cause compile errors when
  * compiling protocol buffers that have names that would otherwise conflict
- * if not fully qualified (like @Deprecated and @Override). 
+ * if not fully qualified (like @Deprecated and @Override).
  *
  * @author jonp@google.com (Jon Perlow)
  */
@@ -45,5 +45,19 @@ public class TestBadIdentifiers extends TestCase {
     // If this compiles, it means the generation was correct.
     TestBadIdentifiersProto.Deprecated.newBuilder();
     TestBadIdentifiersProto.Override.newBuilder();
-  } 
+  }
+
+  public void testGetDescriptor() {
+    Descriptors.FileDescriptor fileDescriptor =
+        TestBadIdentifiersProto.getDescriptor();
+    String descriptorField = TestBadIdentifiersProto.Descriptor
+        .getDefaultInstance().getDescriptor();
+    Descriptors.Descriptor protoDescriptor = TestBadIdentifiersProto.Descriptor
+        .getDefaultInstance().getDescriptorForType();
+    String nestedDescriptorField = TestBadIdentifiersProto.Descriptor
+        .NestedDescriptor.getDefaultInstance().getDescriptor();
+    Descriptors.Descriptor nestedProtoDescriptor = TestBadIdentifiersProto
+        .Descriptor.NestedDescriptor.getDefaultInstance()
+        .getDescriptorForType();
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/TestUtil.java b/java/src/test/java/com/google/protobuf/TestUtil.java
index 9109f419..76f5c602 100644
--- a/java/src/test/java/com/google/protobuf/TestUtil.java
+++ b/java/src/test/java/com/google/protobuf/TestUtil.java
@@ -72,14 +72,16 @@ import static protobuf_unittest.UnittestProto.optionalBoolExtension;
 import static protobuf_unittest.UnittestProto.optionalStringExtension;
 import static protobuf_unittest.UnittestProto.optionalBytesExtension;
 import static protobuf_unittest.UnittestProto.optionalGroupExtension;
-import static protobuf_unittest.UnittestProto.optionalNestedMessageExtension;
+import static protobuf_unittest.UnittestProto.optionalCordExtension;
+import static protobuf_unittest.UnittestProto.optionalForeignEnumExtension;
 import static protobuf_unittest.UnittestProto.optionalForeignMessageExtension;
+import static protobuf_unittest.UnittestProto.optionalImportEnumExtension;
 import static protobuf_unittest.UnittestProto.optionalImportMessageExtension;
 import static protobuf_unittest.UnittestProto.optionalNestedEnumExtension;
-import static protobuf_unittest.UnittestProto.optionalForeignEnumExtension;
-import static protobuf_unittest.UnittestProto.optionalImportEnumExtension;
+import static protobuf_unittest.UnittestProto.optionalNestedMessageExtension;
+import static protobuf_unittest.UnittestProto.optionalPublicImportMessageExtension;
+import static protobuf_unittest.UnittestProto.optionalLazyMessageExtension;
 import static protobuf_unittest.UnittestProto.optionalStringPieceExtension;
-import static protobuf_unittest.UnittestProto.optionalCordExtension;
 
 import static protobuf_unittest.UnittestProto.repeatedInt32Extension;
 import static protobuf_unittest.UnittestProto.repeatedInt64Extension;
@@ -100,6 +102,7 @@ import static protobuf_unittest.UnittestProto.repeatedGroupExtension;
 import static protobuf_unittest.UnittestProto.repeatedNestedMessageExtension;
 import static protobuf_unittest.UnittestProto.repeatedForeignMessageExtension;
 import static protobuf_unittest.UnittestProto.repeatedImportMessageExtension;
+import static protobuf_unittest.UnittestProto.repeatedLazyMessageExtension;
 import static protobuf_unittest.UnittestProto.repeatedNestedEnumExtension;
 import static protobuf_unittest.UnittestProto.repeatedForeignEnumExtension;
 import static protobuf_unittest.UnittestProto.repeatedImportEnumExtension;
@@ -162,11 +165,13 @@ import static com.google.protobuf.UnittestLite.optionalStringExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalBytesExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalGroupExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalNestedMessageExtensionLite;
+import static com.google.protobuf.UnittestLite.optionalForeignEnumExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalForeignMessageExtensionLite;
+import static com.google.protobuf.UnittestLite.optionalImportEnumExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalImportMessageExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalNestedEnumExtensionLite;
-import static com.google.protobuf.UnittestLite.optionalForeignEnumExtensionLite;
-import static com.google.protobuf.UnittestLite.optionalImportEnumExtensionLite;
+import static com.google.protobuf.UnittestLite.optionalPublicImportMessageExtensionLite;
+import static com.google.protobuf.UnittestLite.optionalLazyMessageExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalStringPieceExtensionLite;
 import static com.google.protobuf.UnittestLite.optionalCordExtensionLite;
 
@@ -189,6 +194,7 @@ import static com.google.protobuf.UnittestLite.repeatedGroupExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedNestedMessageExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedForeignMessageExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedImportMessageExtensionLite;
+import static com.google.protobuf.UnittestLite.repeatedLazyMessageExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedNestedEnumExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedForeignEnumExtensionLite;
 import static com.google.protobuf.UnittestLite.repeatedImportEnumExtensionLite;
@@ -222,8 +228,9 @@ import protobuf_unittest.UnittestProto.TestPackedTypes;
 import protobuf_unittest.UnittestProto.TestUnpackedTypes;
 import protobuf_unittest.UnittestProto.ForeignMessage;
 import protobuf_unittest.UnittestProto.ForeignEnum;
-import com.google.protobuf.test.UnittestImport.ImportMessage;
 import com.google.protobuf.test.UnittestImport.ImportEnum;
+import com.google.protobuf.test.UnittestImport.ImportMessage;
+import com.google.protobuf.test.UnittestImportPublic.PublicImportMessage;
 
 import com.google.protobuf.UnittestLite.TestAllTypesLite;
 import com.google.protobuf.UnittestLite.TestAllExtensionsLite;
@@ -231,8 +238,9 @@ import com.google.protobuf.UnittestLite.TestAllExtensionsLiteOrBuilder;
 import com.google.protobuf.UnittestLite.TestPackedExtensionsLite;
 import com.google.protobuf.UnittestLite.ForeignMessageLite;
 import com.google.protobuf.UnittestLite.ForeignEnumLite;
-import com.google.protobuf.UnittestImportLite.ImportMessageLite;
 import com.google.protobuf.UnittestImportLite.ImportEnumLite;
+import com.google.protobuf.UnittestImportLite.ImportMessageLite;
+import com.google.protobuf.UnittestImportPublicLite.PublicImportMessageLite;
 
 import junit.framework.Assert;
 
@@ -242,7 +250,7 @@ import java.io.RandomAccessFile;
 
 /**
  * Contains methods for setting all fields of {@code TestAllTypes} to
- * some vaules as well as checking that all the fields are set to those values.
+ * some values as well as checking that all the fields are set to those values.
  * These are useful for testing various protocol message features, e.g.
  * set all fields of a message, serialize it, parse it, and check that all
  * fields are set.
@@ -275,6 +283,16 @@ public final class TestUtil {
   }
 
   /**
+   * Get a {@code TestAllTypes.Builder} with all fields set as they would be by
+   * {@link #setAllFields(TestAllTypes.Builder)}.
+   */
+  public static TestAllTypes.Builder getAllSetBuilder() {
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    setAllFields(builder);
+    return builder;
+  }
+
+  /**
    * Get a {@code TestAllExtensions} with all fields set as they would be by
    * {@link #setAllExtensions(TestAllExtensions.Builder)}.
    */
@@ -344,6 +362,10 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(119).build());
     message.setOptionalImportMessage(
       ImportMessage.newBuilder().setD(120).build());
+    message.setOptionalPublicImportMessage(
+      PublicImportMessage.newBuilder().setE(126).build());
+    message.setOptionalLazyMessage(
+      TestAllTypes.NestedMessage.newBuilder().setBb(127).build());
 
     message.setOptionalNestedEnum (TestAllTypes.NestedEnum.BAZ);
     message.setOptionalForeignEnum(ForeignEnum.FOREIGN_BAZ);
@@ -378,6 +400,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(219).build());
     message.addRepeatedImportMessage(
       ImportMessage.newBuilder().setD(220).build());
+    message.addRepeatedLazyMessage(
+      TestAllTypes.NestedMessage.newBuilder().setBb(227).build());
 
     message.addRepeatedNestedEnum (TestAllTypes.NestedEnum.BAR);
     message.addRepeatedForeignEnum(ForeignEnum.FOREIGN_BAR);
@@ -411,6 +435,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(319).build());
     message.addRepeatedImportMessage(
       ImportMessage.newBuilder().setD(320).build());
+    message.addRepeatedLazyMessage(
+      TestAllTypes.NestedMessage.newBuilder().setBb(327).build());
 
     message.addRepeatedNestedEnum (TestAllTypes.NestedEnum.BAZ);
     message.addRepeatedForeignEnum(ForeignEnum.FOREIGN_BAZ);
@@ -476,6 +502,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(519).build());
     message.setRepeatedImportMessage(1,
       ImportMessage.newBuilder().setD(520).build());
+    message.setRepeatedLazyMessage(1,
+      TestAllTypes.NestedMessage.newBuilder().setBb(527).build());
 
     message.setRepeatedNestedEnum (1, TestAllTypes.NestedEnum.FOO);
     message.setRepeatedForeignEnum(1, ForeignEnum.FOREIGN_FOO);
@@ -541,10 +569,12 @@ public final class TestUtil {
     Assert.assertEquals("115", message.getOptionalString  ());
     Assert.assertEquals(toBytes("116"), message.getOptionalBytes());
 
-    Assert.assertEquals(117, message.getOptionalGroup         ().getA());
-    Assert.assertEquals(118, message.getOptionalNestedMessage ().getBb());
-    Assert.assertEquals(119, message.getOptionalForeignMessage().getC());
-    Assert.assertEquals(120, message.getOptionalImportMessage ().getD());
+    Assert.assertEquals(117, message.getOptionalGroup              ().getA());
+    Assert.assertEquals(118, message.getOptionalNestedMessage      ().getBb());
+    Assert.assertEquals(119, message.getOptionalForeignMessage     ().getC());
+    Assert.assertEquals(120, message.getOptionalImportMessage      ().getD());
+    Assert.assertEquals(126, message.getOptionalPublicImportMessage().getE());
+    Assert.assertEquals(127, message.getOptionalLazyMessage        ().getBb());
 
     Assert.assertEquals(TestAllTypes.NestedEnum.BAZ, message.getOptionalNestedEnum());
     Assert.assertEquals(ForeignEnum.FOREIGN_BAZ, message.getOptionalForeignEnum());
@@ -575,6 +605,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getRepeatedNestedMessageCount ());
     Assert.assertEquals(2, message.getRepeatedForeignMessageCount());
     Assert.assertEquals(2, message.getRepeatedImportMessageCount ());
+    Assert.assertEquals(2, message.getRepeatedLazyMessageCount   ());
     Assert.assertEquals(2, message.getRepeatedNestedEnumCount    ());
     Assert.assertEquals(2, message.getRepeatedForeignEnumCount   ());
     Assert.assertEquals(2, message.getRepeatedImportEnumCount    ());
@@ -602,6 +633,7 @@ public final class TestUtil {
     Assert.assertEquals(218, message.getRepeatedNestedMessage (0).getBb());
     Assert.assertEquals(219, message.getRepeatedForeignMessage(0).getC());
     Assert.assertEquals(220, message.getRepeatedImportMessage (0).getD());
+    Assert.assertEquals(227, message.getRepeatedLazyMessage   (0).getBb());
 
     Assert.assertEquals(TestAllTypes.NestedEnum.BAR, message.getRepeatedNestedEnum (0));
     Assert.assertEquals(ForeignEnum.FOREIGN_BAR, message.getRepeatedForeignEnum(0));
@@ -630,6 +662,7 @@ public final class TestUtil {
     Assert.assertEquals(318, message.getRepeatedNestedMessage (1).getBb());
     Assert.assertEquals(319, message.getRepeatedForeignMessage(1).getC());
     Assert.assertEquals(320, message.getRepeatedImportMessage (1).getD());
+    Assert.assertEquals(327, message.getRepeatedLazyMessage   (1).getBb());
 
     Assert.assertEquals(TestAllTypes.NestedEnum.BAZ, message.getRepeatedNestedEnum (1));
     Assert.assertEquals(ForeignEnum.FOREIGN_BAZ, message.getRepeatedForeignEnum(1));
@@ -741,15 +774,19 @@ public final class TestUtil {
     Assert.assertEquals(ByteString.EMPTY, message.getOptionalBytes());
 
     // Embedded messages should also be clear.
-    Assert.assertFalse(message.getOptionalGroup         ().hasA());
-    Assert.assertFalse(message.getOptionalNestedMessage ().hasBb());
-    Assert.assertFalse(message.getOptionalForeignMessage().hasC());
-    Assert.assertFalse(message.getOptionalImportMessage ().hasD());
-
-    Assert.assertEquals(0, message.getOptionalGroup         ().getA());
-    Assert.assertEquals(0, message.getOptionalNestedMessage ().getBb());
-    Assert.assertEquals(0, message.getOptionalForeignMessage().getC());
-    Assert.assertEquals(0, message.getOptionalImportMessage ().getD());
+    Assert.assertFalse(message.getOptionalGroup              ().hasA());
+    Assert.assertFalse(message.getOptionalNestedMessage      ().hasBb());
+    Assert.assertFalse(message.getOptionalForeignMessage     ().hasC());
+    Assert.assertFalse(message.getOptionalImportMessage      ().hasD());
+    Assert.assertFalse(message.getOptionalPublicImportMessage().hasE());
+    Assert.assertFalse(message.getOptionalLazyMessage        ().hasBb());
+
+    Assert.assertEquals(0, message.getOptionalGroup              ().getA());
+    Assert.assertEquals(0, message.getOptionalNestedMessage      ().getBb());
+    Assert.assertEquals(0, message.getOptionalForeignMessage     ().getC());
+    Assert.assertEquals(0, message.getOptionalImportMessage      ().getD());
+    Assert.assertEquals(0, message.getOptionalPublicImportMessage().getE());
+    Assert.assertEquals(0, message.getOptionalLazyMessage        ().getBb());
 
     // Enums without defaults are set to the first value in the enum.
     Assert.assertEquals(TestAllTypes.NestedEnum.FOO, message.getOptionalNestedEnum ());
@@ -780,6 +817,7 @@ public final class TestUtil {
     Assert.assertEquals(0, message.getRepeatedNestedMessageCount ());
     Assert.assertEquals(0, message.getRepeatedForeignMessageCount());
     Assert.assertEquals(0, message.getRepeatedImportMessageCount ());
+    Assert.assertEquals(0, message.getRepeatedLazyMessageCount   ());
     Assert.assertEquals(0, message.getRepeatedNestedEnumCount    ());
     Assert.assertEquals(0, message.getRepeatedForeignEnumCount   ());
     Assert.assertEquals(0, message.getRepeatedImportEnumCount    ());
@@ -868,6 +906,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getRepeatedNestedMessageCount ());
     Assert.assertEquals(2, message.getRepeatedForeignMessageCount());
     Assert.assertEquals(2, message.getRepeatedImportMessageCount ());
+    Assert.assertEquals(2, message.getRepeatedLazyMessageCount   ());
     Assert.assertEquals(2, message.getRepeatedNestedEnumCount    ());
     Assert.assertEquals(2, message.getRepeatedForeignEnumCount   ());
     Assert.assertEquals(2, message.getRepeatedImportEnumCount    ());
@@ -895,6 +934,7 @@ public final class TestUtil {
     Assert.assertEquals(218, message.getRepeatedNestedMessage (0).getBb());
     Assert.assertEquals(219, message.getRepeatedForeignMessage(0).getC());
     Assert.assertEquals(220, message.getRepeatedImportMessage (0).getD());
+    Assert.assertEquals(227, message.getRepeatedLazyMessage   (0).getBb());
 
     Assert.assertEquals(TestAllTypes.NestedEnum.BAR, message.getRepeatedNestedEnum (0));
     Assert.assertEquals(ForeignEnum.FOREIGN_BAR, message.getRepeatedForeignEnum(0));
@@ -924,6 +964,7 @@ public final class TestUtil {
     Assert.assertEquals(518, message.getRepeatedNestedMessage (1).getBb());
     Assert.assertEquals(519, message.getRepeatedForeignMessage(1).getC());
     Assert.assertEquals(520, message.getRepeatedImportMessage (1).getD());
+    Assert.assertEquals(527, message.getRepeatedLazyMessage   (1).getBb());
 
     Assert.assertEquals(TestAllTypes.NestedEnum.FOO, message.getRepeatedNestedEnum (1));
     Assert.assertEquals(ForeignEnum.FOREIGN_FOO, message.getRepeatedForeignEnum(1));
@@ -1210,6 +1251,10 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(119).build());
     message.setExtension(optionalImportMessageExtension,
       ImportMessage.newBuilder().setD(120).build());
+    message.setExtension(optionalPublicImportMessageExtension,
+      PublicImportMessage.newBuilder().setE(126).build());
+    message.setExtension(optionalLazyMessageExtension,
+      TestAllTypes.NestedMessage.newBuilder().setBb(127).build());
 
     message.setExtension(optionalNestedEnumExtension, TestAllTypes.NestedEnum.BAZ);
     message.setExtension(optionalForeignEnumExtension, ForeignEnum.FOREIGN_BAZ);
@@ -1244,6 +1289,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(219).build());
     message.addExtension(repeatedImportMessageExtension,
       ImportMessage.newBuilder().setD(220).build());
+    message.addExtension(repeatedLazyMessageExtension,
+      TestAllTypes.NestedMessage.newBuilder().setBb(227).build());
 
     message.addExtension(repeatedNestedEnumExtension, TestAllTypes.NestedEnum.BAR);
     message.addExtension(repeatedForeignEnumExtension, ForeignEnum.FOREIGN_BAR);
@@ -1277,6 +1324,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(319).build());
     message.addExtension(repeatedImportMessageExtension,
       ImportMessage.newBuilder().setD(320).build());
+    message.addExtension(repeatedLazyMessageExtension,
+      TestAllTypes.NestedMessage.newBuilder().setBb(327).build());
 
     message.addExtension(repeatedNestedEnumExtension, TestAllTypes.NestedEnum.BAZ);
     message.addExtension(repeatedForeignEnumExtension, ForeignEnum.FOREIGN_BAZ);
@@ -1343,6 +1392,8 @@ public final class TestUtil {
       ForeignMessage.newBuilder().setC(519).build());
     message.setExtension(repeatedImportMessageExtension, 1,
       ImportMessage.newBuilder().setD(520).build());
+    message.setExtension(repeatedLazyMessageExtension, 1,
+      TestAllTypes.NestedMessage.newBuilder().setBb(527).build());
 
     message.setExtension(repeatedNestedEnumExtension , 1, TestAllTypes.NestedEnum.FOO);
     message.setExtension(repeatedForeignEnumExtension, 1, ForeignEnum.FOREIGN_FOO);
@@ -1409,10 +1460,12 @@ public final class TestUtil {
     assertEqualsExactType("115", message.getExtension(optionalStringExtension  ));
     assertEqualsExactType(toBytes("116"), message.getExtension(optionalBytesExtension));
 
-    assertEqualsExactType(117, message.getExtension(optionalGroupExtension         ).getA());
-    assertEqualsExactType(118, message.getExtension(optionalNestedMessageExtension ).getBb());
-    assertEqualsExactType(119, message.getExtension(optionalForeignMessageExtension).getC());
-    assertEqualsExactType(120, message.getExtension(optionalImportMessageExtension ).getD());
+    assertEqualsExactType(117, message.getExtension(optionalGroupExtension              ).getA());
+    assertEqualsExactType(118, message.getExtension(optionalNestedMessageExtension      ).getBb());
+    assertEqualsExactType(119, message.getExtension(optionalForeignMessageExtension     ).getC());
+    assertEqualsExactType(120, message.getExtension(optionalImportMessageExtension      ).getD());
+    assertEqualsExactType(126, message.getExtension(optionalPublicImportMessageExtension).getE());
+    assertEqualsExactType(127, message.getExtension(optionalLazyMessageExtension        ).getBb());
 
     assertEqualsExactType(TestAllTypes.NestedEnum.BAZ,
       message.getExtension(optionalNestedEnumExtension));
@@ -1446,6 +1499,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedMessageExtension ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignMessageExtension));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportMessageExtension ));
+    Assert.assertEquals(2, message.getExtensionCount(repeatedLazyMessageExtension   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedEnumExtension    ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignEnumExtension   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportEnumExtension    ));
@@ -1473,6 +1527,7 @@ public final class TestUtil {
     assertEqualsExactType(218, message.getExtension(repeatedNestedMessageExtension , 0).getBb());
     assertEqualsExactType(219, message.getExtension(repeatedForeignMessageExtension, 0).getC());
     assertEqualsExactType(220, message.getExtension(repeatedImportMessageExtension , 0).getD());
+    assertEqualsExactType(227, message.getExtension(repeatedLazyMessageExtension   , 0).getBb());
 
     assertEqualsExactType(TestAllTypes.NestedEnum.BAR,
       message.getExtension(repeatedNestedEnumExtension, 0));
@@ -1504,6 +1559,7 @@ public final class TestUtil {
     assertEqualsExactType(318, message.getExtension(repeatedNestedMessageExtension , 1).getBb());
     assertEqualsExactType(319, message.getExtension(repeatedForeignMessageExtension, 1).getC());
     assertEqualsExactType(320, message.getExtension(repeatedImportMessageExtension , 1).getD());
+    assertEqualsExactType(327, message.getExtension(repeatedLazyMessageExtension   , 1).getBb());
 
     assertEqualsExactType(TestAllTypes.NestedEnum.BAZ,
       message.getExtension(repeatedNestedEnumExtension, 1));
@@ -1664,6 +1720,7 @@ public final class TestUtil {
     Assert.assertEquals(0, message.getExtensionCount(repeatedNestedMessageExtension ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedForeignMessageExtension));
     Assert.assertEquals(0, message.getExtensionCount(repeatedImportMessageExtension ));
+    Assert.assertEquals(0, message.getExtensionCount(repeatedLazyMessageExtension   ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedNestedEnumExtension    ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedForeignEnumExtension   ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedImportEnumExtension    ));
@@ -1692,6 +1749,7 @@ public final class TestUtil {
     Assert.assertEquals(0, message.getExtension(repeatedNestedMessageExtension ).size());
     Assert.assertEquals(0, message.getExtension(repeatedForeignMessageExtension).size());
     Assert.assertEquals(0, message.getExtension(repeatedImportMessageExtension ).size());
+    Assert.assertEquals(0, message.getExtension(repeatedLazyMessageExtension   ).size());
     Assert.assertEquals(0, message.getExtension(repeatedNestedEnumExtension    ).size());
     Assert.assertEquals(0, message.getExtension(repeatedForeignEnumExtension   ).size());
     Assert.assertEquals(0, message.getExtension(repeatedImportEnumExtension    ).size());
@@ -1783,6 +1841,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedMessageExtension ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignMessageExtension));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportMessageExtension ));
+    Assert.assertEquals(2, message.getExtensionCount(repeatedLazyMessageExtension   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedEnumExtension    ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignEnumExtension   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportEnumExtension    ));
@@ -1810,6 +1869,7 @@ public final class TestUtil {
     assertEqualsExactType(218, message.getExtension(repeatedNestedMessageExtension , 0).getBb());
     assertEqualsExactType(219, message.getExtension(repeatedForeignMessageExtension, 0).getC());
     assertEqualsExactType(220, message.getExtension(repeatedImportMessageExtension , 0).getD());
+    assertEqualsExactType(227, message.getExtension(repeatedLazyMessageExtension   , 0).getBb());
 
     assertEqualsExactType(TestAllTypes.NestedEnum.BAR,
       message.getExtension(repeatedNestedEnumExtension, 0));
@@ -1842,6 +1902,7 @@ public final class TestUtil {
     assertEqualsExactType(518, message.getExtension(repeatedNestedMessageExtension , 1).getBb());
     assertEqualsExactType(519, message.getExtension(repeatedForeignMessageExtension, 1).getC());
     assertEqualsExactType(520, message.getExtension(repeatedImportMessageExtension , 1).getD());
+    assertEqualsExactType(527, message.getExtension(repeatedLazyMessageExtension   , 1).getBb());
 
     assertEqualsExactType(TestAllTypes.NestedEnum.FOO,
       message.getExtension(repeatedNestedEnumExtension, 1));
@@ -1965,6 +2026,10 @@ public final class TestUtil {
       ForeignMessageLite.newBuilder().setC(119).build());
     message.setExtension(optionalImportMessageExtensionLite,
       ImportMessageLite.newBuilder().setD(120).build());
+    message.setExtension(optionalPublicImportMessageExtensionLite,
+      PublicImportMessageLite.newBuilder().setE(126).build());
+    message.setExtension(optionalLazyMessageExtensionLite,
+      TestAllTypesLite.NestedMessage.newBuilder().setBb(127).build());
 
     message.setExtension(optionalNestedEnumExtensionLite, TestAllTypesLite.NestedEnum.BAZ);
     message.setExtension(optionalForeignEnumExtensionLite, ForeignEnumLite.FOREIGN_LITE_BAZ);
@@ -1999,6 +2064,8 @@ public final class TestUtil {
       ForeignMessageLite.newBuilder().setC(219).build());
     message.addExtension(repeatedImportMessageExtensionLite,
       ImportMessageLite.newBuilder().setD(220).build());
+    message.addExtension(repeatedLazyMessageExtensionLite,
+      TestAllTypesLite.NestedMessage.newBuilder().setBb(227).build());
 
     message.addExtension(repeatedNestedEnumExtensionLite, TestAllTypesLite.NestedEnum.BAR);
     message.addExtension(repeatedForeignEnumExtensionLite, ForeignEnumLite.FOREIGN_LITE_BAR);
@@ -2032,6 +2099,8 @@ public final class TestUtil {
       ForeignMessageLite.newBuilder().setC(319).build());
     message.addExtension(repeatedImportMessageExtensionLite,
       ImportMessageLite.newBuilder().setD(320).build());
+    message.addExtension(repeatedLazyMessageExtensionLite,
+      TestAllTypesLite.NestedMessage.newBuilder().setBb(327).build());
 
     message.addExtension(repeatedNestedEnumExtensionLite, TestAllTypesLite.NestedEnum.BAZ);
     message.addExtension(repeatedForeignEnumExtensionLite, ForeignEnumLite.FOREIGN_LITE_BAZ);
@@ -2098,6 +2167,8 @@ public final class TestUtil {
       ForeignMessageLite.newBuilder().setC(519).build());
     message.setExtension(repeatedImportMessageExtensionLite, 1,
       ImportMessageLite.newBuilder().setD(520).build());
+    message.setExtension(repeatedLazyMessageExtensionLite, 1,
+      TestAllTypesLite.NestedMessage.newBuilder().setBb(527).build());
 
     message.setExtension(repeatedNestedEnumExtensionLite , 1, TestAllTypesLite.NestedEnum.FOO);
     message.setExtension(repeatedForeignEnumExtensionLite, 1, ForeignEnumLite.FOREIGN_LITE_FOO);
@@ -2168,6 +2239,9 @@ public final class TestUtil {
     assertEqualsExactType(118, message.getExtension(optionalNestedMessageExtensionLite ).getBb());
     assertEqualsExactType(119, message.getExtension(optionalForeignMessageExtensionLite).getC());
     assertEqualsExactType(120, message.getExtension(optionalImportMessageExtensionLite ).getD());
+    assertEqualsExactType(126, message.getExtension(
+        optionalPublicImportMessageExtensionLite).getE());
+    assertEqualsExactType(127, message.getExtension(optionalLazyMessageExtensionLite).getBb());
 
     assertEqualsExactType(TestAllTypesLite.NestedEnum.BAZ,
       message.getExtension(optionalNestedEnumExtensionLite));
@@ -2201,6 +2275,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedMessageExtensionLite ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignMessageExtensionLite));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportMessageExtensionLite ));
+    Assert.assertEquals(2, message.getExtensionCount(repeatedLazyMessageExtensionLite   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedEnumExtensionLite    ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignEnumExtensionLite   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportEnumExtensionLite    ));
@@ -2228,6 +2303,7 @@ public final class TestUtil {
     assertEqualsExactType(218, message.getExtension(repeatedNestedMessageExtensionLite ,0).getBb());
     assertEqualsExactType(219, message.getExtension(repeatedForeignMessageExtensionLite,0).getC());
     assertEqualsExactType(220, message.getExtension(repeatedImportMessageExtensionLite ,0).getD());
+    assertEqualsExactType(227, message.getExtension(repeatedLazyMessageExtensionLite   ,0).getBb());
 
     assertEqualsExactType(TestAllTypesLite.NestedEnum.BAR,
       message.getExtension(repeatedNestedEnumExtensionLite, 0));
@@ -2259,6 +2335,7 @@ public final class TestUtil {
     assertEqualsExactType(318, message.getExtension(repeatedNestedMessageExtensionLite ,1).getBb());
     assertEqualsExactType(319, message.getExtension(repeatedForeignMessageExtensionLite,1).getC());
     assertEqualsExactType(320, message.getExtension(repeatedImportMessageExtensionLite ,1).getD());
+    assertEqualsExactType(327, message.getExtension(repeatedLazyMessageExtensionLite   ,1).getBb());
 
     assertEqualsExactType(TestAllTypesLite.NestedEnum.BAZ,
       message.getExtension(repeatedNestedEnumExtensionLite, 1));
@@ -2348,10 +2425,12 @@ public final class TestUtil {
     Assert.assertFalse(message.hasExtension(optionalStringExtensionLite  ));
     Assert.assertFalse(message.hasExtension(optionalBytesExtensionLite   ));
 
-    Assert.assertFalse(message.hasExtension(optionalGroupExtensionLite         ));
-    Assert.assertFalse(message.hasExtension(optionalNestedMessageExtensionLite ));
-    Assert.assertFalse(message.hasExtension(optionalForeignMessageExtensionLite));
-    Assert.assertFalse(message.hasExtension(optionalImportMessageExtensionLite ));
+    Assert.assertFalse(message.hasExtension(optionalGroupExtensionLite              ));
+    Assert.assertFalse(message.hasExtension(optionalNestedMessageExtensionLite      ));
+    Assert.assertFalse(message.hasExtension(optionalForeignMessageExtensionLite     ));
+    Assert.assertFalse(message.hasExtension(optionalImportMessageExtensionLite      ));
+    Assert.assertFalse(message.hasExtension(optionalPublicImportMessageExtensionLite));
+    Assert.assertFalse(message.hasExtension(optionalLazyMessageExtensionLite        ));
 
     Assert.assertFalse(message.hasExtension(optionalNestedEnumExtensionLite ));
     Assert.assertFalse(message.hasExtension(optionalForeignEnumExtensionLite));
@@ -2378,15 +2457,20 @@ public final class TestUtil {
     assertEqualsExactType(ByteString.EMPTY, message.getExtension(optionalBytesExtensionLite));
 
     // Embedded messages should also be clear.
-    Assert.assertFalse(message.getExtension(optionalGroupExtensionLite         ).hasA());
-    Assert.assertFalse(message.getExtension(optionalNestedMessageExtensionLite ).hasBb());
-    Assert.assertFalse(message.getExtension(optionalForeignMessageExtensionLite).hasC());
-    Assert.assertFalse(message.getExtension(optionalImportMessageExtensionLite ).hasD());
+    Assert.assertFalse(message.getExtension(optionalGroupExtensionLite              ).hasA());
+    Assert.assertFalse(message.getExtension(optionalNestedMessageExtensionLite      ).hasBb());
+    Assert.assertFalse(message.getExtension(optionalForeignMessageExtensionLite     ).hasC());
+    Assert.assertFalse(message.getExtension(optionalImportMessageExtensionLite      ).hasD());
+    Assert.assertFalse(message.getExtension(optionalPublicImportMessageExtensionLite).hasE());
+    Assert.assertFalse(message.getExtension(optionalLazyMessageExtensionLite        ).hasBb());
 
     assertEqualsExactType(0, message.getExtension(optionalGroupExtensionLite         ).getA());
     assertEqualsExactType(0, message.getExtension(optionalNestedMessageExtensionLite ).getBb());
     assertEqualsExactType(0, message.getExtension(optionalForeignMessageExtensionLite).getC());
     assertEqualsExactType(0, message.getExtension(optionalImportMessageExtensionLite ).getD());
+    assertEqualsExactType(0, message.getExtension(
+        optionalPublicImportMessageExtensionLite).getE());
+    assertEqualsExactType(0, message.getExtension(optionalLazyMessageExtensionLite   ).getBb());
 
     // Enums without defaults are set to the first value in the enum.
     assertEqualsExactType(TestAllTypesLite.NestedEnum.FOO,
@@ -2420,6 +2504,7 @@ public final class TestUtil {
     Assert.assertEquals(0, message.getExtensionCount(repeatedNestedMessageExtensionLite ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedForeignMessageExtensionLite));
     Assert.assertEquals(0, message.getExtensionCount(repeatedImportMessageExtensionLite ));
+    Assert.assertEquals(0, message.getExtensionCount(repeatedLazyMessageExtensionLite   ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedNestedEnumExtensionLite    ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedForeignEnumExtensionLite   ));
     Assert.assertEquals(0, message.getExtensionCount(repeatedImportEnumExtensionLite    ));
@@ -2511,6 +2596,7 @@ public final class TestUtil {
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedMessageExtensionLite ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignMessageExtensionLite));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportMessageExtensionLite ));
+    Assert.assertEquals(2, message.getExtensionCount(repeatedLazyMessageExtensionLite   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedNestedEnumExtensionLite    ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedForeignEnumExtensionLite   ));
     Assert.assertEquals(2, message.getExtensionCount(repeatedImportEnumExtensionLite    ));
@@ -2538,6 +2624,7 @@ public final class TestUtil {
     assertEqualsExactType(218, message.getExtension(repeatedNestedMessageExtensionLite ,0).getBb());
     assertEqualsExactType(219, message.getExtension(repeatedForeignMessageExtensionLite,0).getC());
     assertEqualsExactType(220, message.getExtension(repeatedImportMessageExtensionLite ,0).getD());
+    assertEqualsExactType(227, message.getExtension(repeatedLazyMessageExtensionLite   ,0).getBb());
 
     assertEqualsExactType(TestAllTypesLite.NestedEnum.BAR,
       message.getExtension(repeatedNestedEnumExtensionLite, 0));
@@ -2570,6 +2657,7 @@ public final class TestUtil {
     assertEqualsExactType(518, message.getExtension(repeatedNestedMessageExtensionLite ,1).getBb());
     assertEqualsExactType(519, message.getExtension(repeatedForeignMessageExtensionLite,1).getC());
     assertEqualsExactType(520, message.getExtension(repeatedImportMessageExtensionLite ,1).getD());
+    assertEqualsExactType(527, message.getExtension(repeatedLazyMessageExtensionLite   ,1).getBb());
 
     assertEqualsExactType(TestAllTypesLite.NestedEnum.FOO,
       message.getExtension(repeatedNestedEnumExtensionLite, 1));
@@ -2674,18 +2762,21 @@ public final class TestUtil {
 
     private final Descriptors.FileDescriptor file;
     private final Descriptors.FileDescriptor importFile;
+    private final Descriptors.FileDescriptor publicImportFile;
 
     private final Descriptors.Descriptor optionalGroup;
     private final Descriptors.Descriptor repeatedGroup;
     private final Descriptors.Descriptor nestedMessage;
     private final Descriptors.Descriptor foreignMessage;
     private final Descriptors.Descriptor importMessage;
+    private final Descriptors.Descriptor publicImportMessage;
 
     private final Descriptors.FieldDescriptor groupA;
     private final Descriptors.FieldDescriptor repeatedGroupA;
     private final Descriptors.FieldDescriptor nestedB;
     private final Descriptors.FieldDescriptor foreignC;
     private final Descriptors.FieldDescriptor importD;
+    private final Descriptors.FieldDescriptor importE;
 
     private final Descriptors.EnumDescriptor nestedEnum;
     private final Descriptors.EnumDescriptor foreignEnum;
@@ -2722,6 +2813,7 @@ public final class TestUtil {
       this.file = baseDescriptor.getFile();
       Assert.assertEquals(1, file.getDependencies().size());
       this.importFile = file.getDependencies().get(0);
+      this.publicImportFile = importFile.getDependencies().get(0);
 
       Descriptors.Descriptor testAllTypes;
       if (baseDescriptor.getName() == "TestAllTypes") {
@@ -2748,6 +2840,8 @@ public final class TestUtil {
       this.nestedMessage = testAllTypes.findNestedTypeByName("NestedMessage");
       this.foreignMessage = file.findMessageTypeByName("ForeignMessage");
       this.importMessage = importFile.findMessageTypeByName("ImportMessage");
+      this.publicImportMessage = publicImportFile.findMessageTypeByName(
+          "PublicImportMessage");
 
       this.nestedEnum = testAllTypes.findEnumTypeByName("NestedEnum");
       this.foreignEnum = file.findEnumTypeByName("ForeignEnum");
@@ -2765,6 +2859,7 @@ public final class TestUtil {
       this.nestedB  = nestedMessage .findFieldByName("bb");
       this.foreignC = foreignMessage.findFieldByName("c");
       this.importD  = importMessage .findFieldByName("d");
+      this.importE  = publicImportMessage.findFieldByName("e");
       this.nestedFoo = nestedEnum.findValueByName("FOO");
       this.nestedBar = nestedEnum.findValueByName("BAR");
       this.nestedBaz = nestedEnum.findValueByName("BAZ");
@@ -2783,6 +2878,7 @@ public final class TestUtil {
       Assert.assertNotNull(nestedB       );
       Assert.assertNotNull(foreignC      );
       Assert.assertNotNull(importD       );
+      Assert.assertNotNull(importE       );
       Assert.assertNotNull(nestedFoo     );
       Assert.assertNotNull(nestedBar     );
       Assert.assertNotNull(nestedBaz     );
@@ -2863,6 +2959,12 @@ public final class TestUtil {
       message.setField(f("optional_import_message"),
         newBuilderForField(message, f("optional_import_message"))
                .setField(importD, 120).build());
+      message.setField(f("optional_public_import_message"),
+        newBuilderForField(message, f("optional_public_import_message"))
+               .setField(importE, 126).build());
+      message.setField(f("optional_lazy_message"),
+        newBuilderForField(message, f("optional_lazy_message"))
+               .setField(nestedB, 127).build());
 
       message.setField(f("optional_nested_enum" ),  nestedBaz);
       message.setField(f("optional_foreign_enum"), foreignBaz);
@@ -2901,6 +3003,9 @@ public final class TestUtil {
       message.addRepeatedField(f("repeated_import_message"),
         newBuilderForField(message, f("repeated_import_message"))
                .setField(importD, 220).build());
+      message.addRepeatedField(f("repeated_lazy_message"),
+        newBuilderForField(message, f("repeated_lazy_message"))
+               .setField(nestedB, 227).build());
 
       message.addRepeatedField(f("repeated_nested_enum" ),  nestedBar);
       message.addRepeatedField(f("repeated_foreign_enum"), foreignBar);
@@ -2938,6 +3043,9 @@ public final class TestUtil {
       message.addRepeatedField(f("repeated_import_message"),
         newBuilderForField(message, f("repeated_import_message"))
                .setField(importD, 320).build());
+      message.addRepeatedField(f("repeated_lazy_message"),
+        newBuilderForField(message, f("repeated_lazy_message"))
+               .setField(nestedB, 327).build());
 
       message.addRepeatedField(f("repeated_nested_enum" ),  nestedBaz);
       message.addRepeatedField(f("repeated_foreign_enum"), foreignBaz);
@@ -3008,6 +3116,9 @@ public final class TestUtil {
       message.setRepeatedField(f("repeated_import_message"), 1,
         newBuilderForField(message, f("repeated_import_message"))
                .setField(importD, 520).build());
+      message.setRepeatedField(f("repeated_lazy_message"), 1,
+        newBuilderForField(message, f("repeated_lazy_message"))
+               .setField(nestedB, 527).build());
 
       message.setRepeatedField(f("repeated_nested_enum" ), 1,  nestedFoo);
       message.setRepeatedField(f("repeated_foreign_enum"), 1, foreignFoo);
@@ -3092,6 +3203,12 @@ public final class TestUtil {
       Assert.assertEquals(120,
         ((Message)message.getField(f("optional_import_message")))
                          .getField(importD));
+      Assert.assertEquals(126,
+        ((Message)message.getField(f("optional_public_import_message")))
+                         .getField(importE));
+      Assert.assertEquals(127,
+        ((Message)message.getField(f("optional_lazy_message")))
+                         .getField(nestedB));
 
       Assert.assertEquals( nestedBaz, message.getField(f("optional_nested_enum" )));
       Assert.assertEquals(foreignBaz, message.getField(f("optional_foreign_enum")));
@@ -3122,6 +3239,7 @@ public final class TestUtil {
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_nested_message" )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_foreign_message")));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_import_message" )));
+      Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_lazy_message" )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_nested_enum"    )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_foreign_enum"   )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_import_enum"    )));
@@ -3157,6 +3275,9 @@ public final class TestUtil {
       Assert.assertEquals(220,
         ((Message)message.getRepeatedField(f("repeated_import_message"), 0))
                          .getField(importD));
+      Assert.assertEquals(227,
+        ((Message)message.getRepeatedField(f("repeated_lazy_message"), 0))
+                         .getField(nestedB));
 
       Assert.assertEquals( nestedBar, message.getRepeatedField(f("repeated_nested_enum" ),0));
       Assert.assertEquals(foreignBar, message.getRepeatedField(f("repeated_foreign_enum"),0));
@@ -3193,6 +3314,9 @@ public final class TestUtil {
       Assert.assertEquals(320,
         ((Message)message.getRepeatedField(f("repeated_import_message"), 1))
                          .getField(importD));
+      Assert.assertEquals(327,
+        ((Message)message.getRepeatedField(f("repeated_lazy_message"), 1))
+                         .getField(nestedB));
 
       Assert.assertEquals( nestedBaz, message.getRepeatedField(f("repeated_nested_enum" ),1));
       Assert.assertEquals(foreignBaz, message.getRepeatedField(f("repeated_foreign_enum"),1));
@@ -3316,6 +3440,12 @@ public final class TestUtil {
       Assert.assertFalse(
         ((Message)message.getField(f("optional_import_message")))
                          .hasField(importD));
+      Assert.assertFalse(
+        ((Message)message.getField(f("optional_public_import_message")))
+                         .hasField(importE));
+      Assert.assertFalse(
+        ((Message)message.getField(f("optional_lazy_message")))
+                         .hasField(nestedB));
 
       Assert.assertEquals(0,
         ((Message)message.getField(f("optionalgroup"))).getField(groupA));
@@ -3328,6 +3458,12 @@ public final class TestUtil {
       Assert.assertEquals(0,
         ((Message)message.getField(f("optional_import_message")))
                          .getField(importD));
+      Assert.assertEquals(0,
+        ((Message)message.getField(f("optional_public_import_message")))
+                         .getField(importE));
+      Assert.assertEquals(0,
+        ((Message)message.getField(f("optional_lazy_message")))
+                         .getField(nestedB));
 
       // Enums without defaults are set to the first value in the enum.
       Assert.assertEquals( nestedFoo, message.getField(f("optional_nested_enum" )));
@@ -3358,6 +3494,7 @@ public final class TestUtil {
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_nested_message" )));
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_foreign_message")));
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_import_message" )));
+      Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_lazy_message"   )));
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_nested_enum"    )));
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_foreign_enum"   )));
       Assert.assertEquals(0, message.getRepeatedFieldCount(f("repeated_import_enum"    )));
@@ -3442,6 +3579,7 @@ public final class TestUtil {
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_nested_message" )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_foreign_message")));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_import_message" )));
+      Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_lazy_message"   )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_nested_enum"    )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_foreign_enum"   )));
       Assert.assertEquals(2, message.getRepeatedFieldCount(f("repeated_import_enum"    )));
@@ -3477,6 +3615,9 @@ public final class TestUtil {
       Assert.assertEquals(220,
         ((Message)message.getRepeatedField(f("repeated_import_message"), 0))
                          .getField(importD));
+      Assert.assertEquals(227,
+        ((Message)message.getRepeatedField(f("repeated_lazy_message"), 0))
+                         .getField(nestedB));
 
       Assert.assertEquals( nestedBar, message.getRepeatedField(f("repeated_nested_enum" ),0));
       Assert.assertEquals(foreignBar, message.getRepeatedField(f("repeated_foreign_enum"),0));
@@ -3513,6 +3654,9 @@ public final class TestUtil {
       Assert.assertEquals(520,
         ((Message)message.getRepeatedField(f("repeated_import_message"), 1))
                          .getField(importD));
+      Assert.assertEquals(527,
+        ((Message)message.getRepeatedField(f("repeated_lazy_message"), 1))
+                         .getField(nestedB));
 
       Assert.assertEquals( nestedFoo, message.getRepeatedField(f("repeated_nested_enum" ),1));
       Assert.assertEquals(foreignFoo, message.getRepeatedField(f("repeated_foreign_enum"),1));
diff --git a/java/src/test/java/com/google/protobuf/TextFormatTest.java b/java/src/test/java/com/google/protobuf/TextFormatTest.java
index 47690d1f..5323d70e 100644
--- a/java/src/test/java/com/google/protobuf/TextFormatTest.java
+++ b/java/src/test/java/com/google/protobuf/TextFormatTest.java
@@ -121,6 +121,18 @@ public class TextFormatTest extends TestCase {
     assertEquals(allFieldsSetText, javaText);
   }
 
+  /** Print TestAllTypes as Builder and compare with golden file. */
+  public void testPrintMessageBuilder() throws Exception {
+    String javaText = TextFormat.printToString(TestUtil.getAllSetBuilder());
+
+    // Java likes to add a trailing ".0" to floats and doubles.  C printf
+    // (with %g format) does not.  Our golden files are used for both
+    // C++ and Java TextFormat classes, so we need to conform.
+    javaText = javaText.replace(".0\n", "\n");
+
+    assertEquals(allFieldsSetText, javaText);
+  }
+
   /** Print TestAllExtensions and compare with golden file. */
   public void testPrintExtensions() throws Exception {
     String javaText = TextFormat.printToString(TestUtil.getAllExtensionsSet());
@@ -749,4 +761,26 @@ public class TextFormatTest extends TestCase {
         + " 0xabcdef1234567890",
         TextFormat.shortDebugString(makeUnknownFieldSet()));
   }
+
+  public void testPrintToUnicodeString() {
+    assertEquals(
+        "optional_string: \"abc\u3042efg\"\n" +
+        "optional_bytes: \"\\343\\201\\202\"\n" +
+        "repeated_string: \"\u3093XYZ\"\n",
+        TextFormat.printToUnicodeString(TestAllTypes.newBuilder()
+            .setOptionalString("abc\u3042efg")
+            .setOptionalBytes(bytes(0xe3, 0x81, 0x82))
+            .addRepeatedString("\u3093XYZ")
+            .build()));
+  }
+
+  public void testPrintToUnicodeString_unknown() {
+    assertEquals(
+        "1: \"\\343\\201\\202\"\n",
+        TextFormat.printToUnicodeString(UnknownFieldSet.newBuilder()
+            .addField(1,
+                UnknownFieldSet.Field.newBuilder()
+                .addLengthDelimited(bytes(0xe3, 0x81, 0x82)).build())
+            .build()));
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/WireFormatTest.java b/java/src/test/java/com/google/protobuf/WireFormatTest.java
index 5ea1dd6a..94f62134 100644
--- a/java/src/test/java/com/google/protobuf/WireFormatTest.java
+++ b/java/src/test/java/com/google/protobuf/WireFormatTest.java
@@ -34,6 +34,7 @@ import junit.framework.TestCase;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
+import java.util.List;
 
 import protobuf_unittest.UnittestProto;
 import protobuf_unittest.UnittestProto.TestAllExtensions;
@@ -328,7 +329,17 @@ public class WireFormatTest extends TestCase {
   private static final int TYPE_ID_2 =
     TestMessageSetExtension2.getDescriptor().getExtensions().get(0).getNumber();
 
-  public void testSerializeMessageSet() throws Exception {
+  public void testSerializeMessageSetEagerly() throws Exception {
+    testSerializeMessageSetWithFlag(true);
+  }
+
+  public void testSerializeMessageSetNotEagerly() throws Exception {
+    testSerializeMessageSetWithFlag(false);
+  }
+
+  private void testSerializeMessageSetWithFlag(boolean eagerParsing)
+      throws Exception {
+    ExtensionRegistryLite.setEagerlyParseMessageSets(eagerParsing);
     // Set up a TestMessageSet with two known messages and an unknown one.
     TestMessageSet messageSet =
       TestMessageSet.newBuilder()
@@ -372,7 +383,17 @@ public class WireFormatTest extends TestCase {
     assertEquals("bar", raw.getItem(2).getMessage().toStringUtf8());
   }
 
-  public void testParseMessageSet() throws Exception {
+  public void testParseMessageSetEagerly() throws Exception {
+    testParseMessageSetWithFlag(true);
+  }
+
+  public void testParseMessageSetNotEagerly()throws Exception {
+    testParseMessageSetWithFlag(false);
+  }
+
+  private void testParseMessageSetWithFlag(boolean eagerParsing)
+      throws Exception {
+    ExtensionRegistryLite.setEagerlyParseMessageSets(eagerParsing);
     ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
     extensionRegistry.add(TestMessageSetExtension1.messageSetExtension);
     extensionRegistry.add(TestMessageSetExtension2.messageSetExtension);
@@ -424,4 +445,136 @@ public class WireFormatTest extends TestCase {
     assertEquals(1, field.getLengthDelimitedList().size());
     assertEquals("bar", field.getLengthDelimitedList().get(0).toStringUtf8());
   }
+
+  public void testParseMessageSetExtensionEagerly() throws Exception {
+    testParseMessageSetExtensionWithFlag(true);
+  }
+
+  public void testParseMessageSetExtensionNotEagerly() throws Exception {
+    testParseMessageSetExtensionWithFlag(false);
+  }
+
+  private void testParseMessageSetExtensionWithFlag(boolean eagerParsing)
+      throws Exception {
+    ExtensionRegistryLite.setEagerlyParseMessageSets(eagerParsing);
+    ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
+    extensionRegistry.add(TestMessageSetExtension1.messageSetExtension);
+
+    // Set up a RawMessageSet with a known messages.
+    int TYPE_ID_1 =
+        TestMessageSetExtension1
+            .getDescriptor().getExtensions().get(0).getNumber();
+    RawMessageSet raw =
+      RawMessageSet.newBuilder()
+        .addItem(
+          RawMessageSet.Item.newBuilder()
+            .setTypeId(TYPE_ID_1)
+            .setMessage(
+              TestMessageSetExtension1.newBuilder()
+                .setI(123)
+                .build().toByteString())
+            .build())
+        .build();
+
+    ByteString data = raw.toByteString();
+
+    // Parse as a TestMessageSet and check the contents.
+    TestMessageSet messageSet =
+        TestMessageSet.parseFrom(data, extensionRegistry);
+    assertEquals(123, messageSet.getExtension(
+        TestMessageSetExtension1.messageSetExtension).getI());
+  }
+
+  public void testMergeLazyMessageSetExtensionEagerly() throws Exception {
+    testMergeLazyMessageSetExtensionWithFlag(true);
+  }
+
+  public void testMergeLazyMessageSetExtensionNotEagerly() throws Exception {
+    testMergeLazyMessageSetExtensionWithFlag(false);
+  }
+
+  private void testMergeLazyMessageSetExtensionWithFlag(boolean eagerParsing)
+      throws Exception {
+    ExtensionRegistryLite.setEagerlyParseMessageSets(eagerParsing);
+    ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
+    extensionRegistry.add(TestMessageSetExtension1.messageSetExtension);
+
+    // Set up a RawMessageSet with a known messages.
+    int TYPE_ID_1 =
+        TestMessageSetExtension1
+            .getDescriptor().getExtensions().get(0).getNumber();
+    RawMessageSet raw =
+      RawMessageSet.newBuilder()
+        .addItem(
+          RawMessageSet.Item.newBuilder()
+            .setTypeId(TYPE_ID_1)
+            .setMessage(
+              TestMessageSetExtension1.newBuilder()
+                .setI(123)
+                .build().toByteString())
+            .build())
+        .build();
+
+    ByteString data = raw.toByteString();
+
+    // Parse as a TestMessageSet and store value into lazy field
+    TestMessageSet messageSet =
+        TestMessageSet.parseFrom(data, extensionRegistry);
+    // Merge lazy field check the contents.
+    messageSet =
+        messageSet.toBuilder().mergeFrom(data, extensionRegistry).build();
+    assertEquals(123, messageSet.getExtension(
+        TestMessageSetExtension1.messageSetExtension).getI());
+  }
+
+  public void testMergeMessageSetExtensionEagerly() throws Exception {
+    testMergeMessageSetExtensionWithFlag(true);
+  }
+
+  public void testMergeMessageSetExtensionNotEagerly() throws Exception {
+    testMergeMessageSetExtensionWithFlag(false);
+  }
+
+  private void testMergeMessageSetExtensionWithFlag(boolean eagerParsing)
+      throws Exception {
+    ExtensionRegistryLite.setEagerlyParseMessageSets(eagerParsing);
+    ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
+    extensionRegistry.add(TestMessageSetExtension1.messageSetExtension);
+
+    // Set up a RawMessageSet with a known messages.
+    int TYPE_ID_1 =
+        TestMessageSetExtension1
+            .getDescriptor().getExtensions().get(0).getNumber();
+    RawMessageSet raw =
+      RawMessageSet.newBuilder()
+        .addItem(
+          RawMessageSet.Item.newBuilder()
+            .setTypeId(TYPE_ID_1)
+            .setMessage(
+              TestMessageSetExtension1.newBuilder()
+                .setI(123)
+                .build().toByteString())
+            .build())
+        .build();
+
+    // Serialize RawMessageSet unnormally (message value before type id)
+    ByteString.CodedBuilder out = ByteString.newCodedBuilder(
+        raw.getSerializedSize());
+    CodedOutputStream output = out.getCodedOutput();
+    List<RawMessageSet.Item> items = raw.getItemList();
+    for (int i = 0; i < items.size(); i++) {
+      RawMessageSet.Item item = items.get(i);
+      output.writeTag(1, WireFormat.WIRETYPE_START_GROUP);
+      output.writeBytes(3, item.getMessage());
+      output.writeInt32(2, item.getTypeId());
+      output.writeTag(1, WireFormat.WIRETYPE_END_GROUP);
+    }
+    ByteString data = out.build();
+
+    // Merge bytes into TestMessageSet and check the contents.
+    TestMessageSet messageSet =
+        TestMessageSet.newBuilder().mergeFrom(data, extensionRegistry).build();
+    assertEquals(123, messageSet.getExtension(
+        TestMessageSetExtension1.messageSetExtension).getI());
+  }
 }
diff --git a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
index 9610e9d5..6e67d97a 100644
--- a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
+++ b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
@@ -46,6 +46,23 @@ option java_outer_classname = "TestBadIdentifiersProto";
 message TestMessage {
 }
 
+message Descriptor {
+  option no_standard_descriptor_accessor = true;
+  optional string descriptor = 1;
+  message NestedDescriptor {
+    option no_standard_descriptor_accessor = true;
+    optional string descriptor = 1;
+  }
+  optional NestedDescriptor nested_descriptor = 2;
+}
+
+message Parser {
+  enum ParserEnum {
+    PARSER = 1;
+  }
+  optional ParserEnum parser = 1;
+}
+
 message Deprecated {
   enum TestEnum {
     FOO = 1;
@@ -62,6 +79,7 @@ message Override {
 
 message Object {
   optional int32 object = 1;
+  optional string string_object = 2;
 }
 
 message String {
diff --git a/python/google/protobuf/descriptor.py b/python/google/protobuf/descriptor.py
index cf609bee..eb13eda5 100755
--- a/python/google/protobuf/descriptor.py
+++ b/python/google/protobuf/descriptor.py
@@ -39,13 +39,20 @@ from google.protobuf.internal import api_implementation
 
 
 if api_implementation.Type() == 'cpp':
-  from google.protobuf.internal import cpp_message
+  if api_implementation.Version() == 2:
+    from google.protobuf.internal.cpp import _message
+  else:
+    from google.protobuf.internal import cpp_message
 
 
 class Error(Exception):
   """Base error for this module."""
 
 
+class TypeTransformationError(Error):
+  """Error transforming between python proto type and corresponding C++ type."""
+
+
 class DescriptorBase(object):
 
   """Descriptors base class.
@@ -72,6 +79,18 @@ class DescriptorBase(object):
     # Does this descriptor have non-default options?
     self.has_options = options is not None
 
+  def _SetOptions(self, options, options_class_name):
+    """Sets the descriptor's options
+
+    This function is used in generated proto2 files to update descriptor
+    options. It must not be used outside proto2.
+    """
+    self._options = options
+    self._options_class_name = options_class_name
+
+    # Does this descriptor have non-default options?
+    self.has_options = options is not None
+
   def GetOptions(self):
     """Retrieves descriptor options.
 
@@ -250,6 +269,24 @@ class Descriptor(_NestedDescriptorBase):
     self._serialized_start = serialized_start
     self._serialized_end = serialized_end
 
+  def EnumValueName(self, enum, value):
+    """Returns the string name of an enum value.
+
+    This is just a small helper method to simplify a common operation.
+
+    Args:
+      enum: string name of the Enum.
+      value: int, value of the enum.
+
+    Returns:
+      string name of the enum value.
+
+    Raises:
+      KeyError if either the Enum doesn't exist or the value is not a valid
+        value for the enum.
+    """
+    return self.enum_types_by_name[enum].values_by_number[value].name
+
   def CopyToProto(self, proto):
     """Copies this to a descriptor_pb2.DescriptorProto.
 
@@ -275,7 +312,7 @@ class FieldDescriptor(DescriptorBase):
 
   """Descriptor for a single field in a .proto file.
 
-  A FieldDescriptor instance has the following attriubtes:
+  A FieldDescriptor instance has the following attributes:
 
     name: (str) Name of this field, exactly as it appears in .proto.
     full_name: (str) Name of this field, including containing scope.  This is
@@ -358,6 +395,27 @@ class FieldDescriptor(DescriptorBase):
   CPPTYPE_MESSAGE     = 10
   MAX_CPPTYPE         = 10
 
+  _PYTHON_TO_CPP_PROTO_TYPE_MAP = {
+      TYPE_DOUBLE: CPPTYPE_DOUBLE,
+      TYPE_FLOAT: CPPTYPE_FLOAT,
+      TYPE_ENUM: CPPTYPE_ENUM,
+      TYPE_INT64: CPPTYPE_INT64,
+      TYPE_SINT64: CPPTYPE_INT64,
+      TYPE_SFIXED64: CPPTYPE_INT64,
+      TYPE_UINT64: CPPTYPE_UINT64,
+      TYPE_FIXED64: CPPTYPE_UINT64,
+      TYPE_INT32: CPPTYPE_INT32,
+      TYPE_SFIXED32: CPPTYPE_INT32,
+      TYPE_SINT32: CPPTYPE_INT32,
+      TYPE_UINT32: CPPTYPE_UINT32,
+      TYPE_FIXED32: CPPTYPE_UINT32,
+      TYPE_BYTES: CPPTYPE_STRING,
+      TYPE_STRING: CPPTYPE_STRING,
+      TYPE_BOOL: CPPTYPE_BOOL,
+      TYPE_MESSAGE: CPPTYPE_MESSAGE,
+      TYPE_GROUP: CPPTYPE_MESSAGE
+      }
+
   # Must be consistent with C++ FieldDescriptor::Label enum in
   # descriptor.h.
   #
@@ -395,12 +453,38 @@ class FieldDescriptor(DescriptorBase):
     self.extension_scope = extension_scope
     if api_implementation.Type() == 'cpp':
       if is_extension:
-        self._cdescriptor = cpp_message.GetExtensionDescriptor(full_name)
+        if api_implementation.Version() == 2:
+          self._cdescriptor = _message.GetExtensionDescriptor(full_name)
+        else:
+          self._cdescriptor = cpp_message.GetExtensionDescriptor(full_name)
       else:
-        self._cdescriptor = cpp_message.GetFieldDescriptor(full_name)
+        if api_implementation.Version() == 2:
+          self._cdescriptor = _message.GetFieldDescriptor(full_name)
+        else:
+          self._cdescriptor = cpp_message.GetFieldDescriptor(full_name)
     else:
       self._cdescriptor = None
 
+  @staticmethod
+  def ProtoTypeToCppProtoType(proto_type):
+    """Converts from a Python proto type to a C++ Proto Type.
+
+    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
+    'C++' datatype - and they're not the same. This helper method should
+    translate from one to another.
+
+    Args:
+      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
+    Returns:
+      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
+    Raises:
+      TypeTransformationError: when the Python proto type isn't known.
+    """
+    try:
+      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
+    except KeyError:
+      raise TypeTransformationError('Unknown proto_type: %s' % proto_type)
+
 
 class EnumDescriptor(_NestedDescriptorBase):
 
@@ -577,7 +661,10 @@ class FileDescriptor(DescriptorBase):
     self.serialized_pb = serialized_pb
     if (api_implementation.Type() == 'cpp' and
         self.serialized_pb is not None):
-      cpp_message.BuildFile(self.serialized_pb)
+      if api_implementation.Version() == 2:
+        _message.BuildFile(self.serialized_pb)
+      else:
+        cpp_message.BuildFile(self.serialized_pb)
 
   def CopyToProto(self, proto):
     """Copies this to a descriptor_pb2.FileDescriptorProto.
@@ -596,3 +683,31 @@ def _ParseOptions(message, string):
   """
   message.ParseFromString(string)
   return message
+
+
+def MakeDescriptor(desc_proto, package=''):
+  """Make a protobuf Descriptor given a DescriptorProto protobuf.
+
+  Args:
+    desc_proto: The descriptor_pb2.DescriptorProto protobuf message.
+    package: Optional package name for the new message Descriptor (string).
+
+  Returns:
+    A Descriptor for protobuf messages.
+  """
+  full_message_name = [desc_proto.name]
+  if package: full_message_name.insert(0, package)
+  fields = []
+  for field_proto in desc_proto.field:
+    full_name = '.'.join(full_message_name + [field_proto.name])
+    field = FieldDescriptor(
+        field_proto.name, full_name, field_proto.number - 1,
+        field_proto.number, field_proto.type,
+        FieldDescriptor.ProtoTypeToCppProtoType(field_proto.type),
+        field_proto.label, None, None, None, None, False, None,
+        has_default_value=False)
+    fields.append(field)
+
+  desc_name = '.'.join(full_message_name)
+  return Descriptor(desc_proto.name, desc_name, None, None, fields,
+                    [], [], [])
diff --git a/python/google/protobuf/descriptor_database.py b/python/google/protobuf/descriptor_database.py
new file mode 100644
index 00000000..8665d3c5
--- /dev/null
+++ b/python/google/protobuf/descriptor_database.py
@@ -0,0 +1,120 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides a container for DescriptorProtos."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+
+class DescriptorDatabase(object):
+  """A container accepting FileDescriptorProtos and maps DescriptorProtos."""
+
+  def __init__(self):
+    self._file_desc_protos_by_file = {}
+    self._file_desc_protos_by_symbol = {}
+
+  def Add(self, file_desc_proto):
+    """Adds the FileDescriptorProto and its types to this database.
+
+    Args:
+      file_desc_proto: The FileDescriptorProto to add.
+    """
+
+    self._file_desc_protos_by_file[file_desc_proto.name] = file_desc_proto
+    package = file_desc_proto.package
+    for message in file_desc_proto.message_type:
+      self._file_desc_protos_by_symbol.update(
+          (name, file_desc_proto) for name in _ExtractSymbols(message, package))
+    for enum in file_desc_proto.enum_type:
+      self._file_desc_protos_by_symbol[
+          '.'.join((package, enum.name))] = file_desc_proto
+
+  def FindFileByName(self, name):
+    """Finds the file descriptor proto by file name.
+
+    Typically the file name is a relative path ending to a .proto file. The
+    proto with the given name will have to have been added to this database
+    using the Add method or else an error will be raised.
+
+    Args:
+      name: The file name to find.
+
+    Returns:
+      The file descriptor proto matching the name.
+
+    Raises:
+      KeyError if no file by the given name was added.
+    """
+
+    return self._file_desc_protos_by_file[name]
+
+  def FindFileContainingSymbol(self, symbol):
+    """Finds the file descriptor proto containing the specified symbol.
+
+    The symbol should be a fully qualified name including the file descriptor's
+    package and any containing messages. Some examples:
+
+    'some.package.name.Message'
+    'some.package.name.Message.NestedEnum'
+
+    The file descriptor proto containing the specified symbol must be added to
+    this database using the Add method or else an error will be raised.
+
+    Args:
+      symbol: The fully qualified symbol name.
+
+    Returns:
+      The file descriptor proto containing the symbol.
+
+    Raises:
+      KeyError if no file contains the specified symbol.
+    """
+
+    return self._file_desc_protos_by_symbol[symbol]
+
+
+def _ExtractSymbols(desc_proto, package):
+  """Pulls out all the symbols from a descriptor proto.
+
+  Args:
+    desc_proto: The proto to extract symbols from.
+    package: The package containing the descriptor type.
+
+  Yields:
+    The fully qualified name found in the descriptor.
+  """
+
+  message_name = '.'.join((package, desc_proto.name))
+  yield message_name
+  for nested_type in desc_proto.nested_type:
+    for symbol in _ExtractSymbols(nested_type, message_name):
+      yield symbol
+    for enum_type in desc_proto.enum_type:
+      yield '.'.join((message_name, enum_type.name))
diff --git a/python/google/protobuf/descriptor_pool.py b/python/google/protobuf/descriptor_pool.py
new file mode 100644
index 00000000..8f1f4457
--- /dev/null
+++ b/python/google/protobuf/descriptor_pool.py
@@ -0,0 +1,527 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides DescriptorPool to use as a container for proto2 descriptors.
+
+The DescriptorPool is used in conjection with a DescriptorDatabase to maintain
+a collection of protocol buffer descriptors for use when dynamically creating
+message types at runtime.
+
+For most applications protocol buffers should be used via modules generated by
+the protocol buffer compiler tool. This should only be used when the type of
+protocol buffers used in an application or library cannot be predetermined.
+
+Below is a straightforward example on how to use this class:
+
+  pool = DescriptorPool()
+  file_descriptor_protos = [ ... ]
+  for file_descriptor_proto in file_descriptor_protos:
+    pool.Add(file_descriptor_proto)
+  my_message_descriptor = pool.FindMessageTypeByName('some.package.MessageType')
+
+The message descriptor can be used in conjunction with the message_factory
+module in order to create a protocol buffer class that can be encoded and
+decoded.
+"""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+from google.protobuf import descriptor_pb2
+from google.protobuf import descriptor
+from google.protobuf import descriptor_database
+
+
+class DescriptorPool(object):
+  """A collection of protobufs dynamically constructed by descriptor protos."""
+
+  def __init__(self, descriptor_db=None):
+    """Initializes a Pool of proto buffs.
+
+    The descriptor_db argument to the constructor is provided to allow
+    specialized file descriptor proto lookup code to be triggered on demand. An
+    example would be an implementation which will read and compile a file
+    specified in a call to FindFileByName() and not require the call to Add()
+    at all. Results from this database will be cached internally here as well.
+
+    Args:
+      descriptor_db: A secondary source of file descriptors.
+    """
+
+    self._internal_db = descriptor_database.DescriptorDatabase()
+    self._descriptor_db = descriptor_db
+    self._descriptors = {}
+    self._enum_descriptors = {}
+    self._file_descriptors = {}
+
+  def Add(self, file_desc_proto):
+    """Adds the FileDescriptorProto and its types to this pool.
+
+    Args:
+      file_desc_proto: The FileDescriptorProto to add.
+    """
+
+    self._internal_db.Add(file_desc_proto)
+
+  def FindFileByName(self, file_name):
+    """Gets a FileDescriptor by file name.
+
+    Args:
+      file_name: The path to the file to get a descriptor for.
+
+    Returns:
+      A FileDescriptor for the named file.
+
+    Raises:
+      KeyError: if the file can not be found in the pool.
+    """
+
+    try:
+      file_proto = self._internal_db.FindFileByName(file_name)
+    except KeyError as error:
+      if self._descriptor_db:
+        file_proto = self._descriptor_db.FindFileByName(file_name)
+      else:
+        raise error
+    if not file_proto:
+      raise KeyError('Cannot find a file named %s' % file_name)
+    return self._ConvertFileProtoToFileDescriptor(file_proto)
+
+  def FindFileContainingSymbol(self, symbol):
+    """Gets the FileDescriptor for the file containing the specified symbol.
+
+    Args:
+      symbol: The name of the symbol to search for.
+
+    Returns:
+      A FileDescriptor that contains the specified symbol.
+
+    Raises:
+      KeyError: if the file can not be found in the pool.
+    """
+
+    try:
+      file_proto = self._internal_db.FindFileContainingSymbol(symbol)
+    except KeyError as error:
+      if self._descriptor_db:
+        file_proto = self._descriptor_db.FindFileContainingSymbol(symbol)
+      else:
+        raise error
+    if not file_proto:
+      raise KeyError('Cannot find a file containing %s' % symbol)
+    return self._ConvertFileProtoToFileDescriptor(file_proto)
+
+  def FindMessageTypeByName(self, full_name):
+    """Loads the named descriptor from the pool.
+
+    Args:
+      full_name: The full name of the descriptor to load.
+
+    Returns:
+      The descriptor for the named type.
+    """
+
+    full_name = full_name.lstrip('.')  # fix inconsistent qualified name formats
+    if full_name not in self._descriptors:
+      self.FindFileContainingSymbol(full_name)
+    return self._descriptors[full_name]
+
+  def FindEnumTypeByName(self, full_name):
+    """Loads the named enum descriptor from the pool.
+
+    Args:
+      full_name: The full name of the enum descriptor to load.
+
+    Returns:
+      The enum descriptor for the named type.
+    """
+
+    full_name = full_name.lstrip('.')  # fix inconsistent qualified name formats
+    if full_name not in self._enum_descriptors:
+      self.FindFileContainingSymbol(full_name)
+    return self._enum_descriptors[full_name]
+
+  def _ConvertFileProtoToFileDescriptor(self, file_proto):
+    """Creates a FileDescriptor from a proto or returns a cached copy.
+
+    This method also has the side effect of loading all the symbols found in
+    the file into the appropriate dictionaries in the pool.
+
+    Args:
+      file_proto: The proto to convert.
+
+    Returns:
+      A FileDescriptor matching the passed in proto.
+    """
+
+    if file_proto.name not in self._file_descriptors:
+      file_descriptor = descriptor.FileDescriptor(
+          name=file_proto.name,
+          package=file_proto.package,
+          options=file_proto.options,
+          serialized_pb=file_proto.SerializeToString())
+      scope = {}
+      dependencies = list(self._GetDeps(file_proto))
+
+      for dependency in dependencies:
+        dep_desc = self.FindFileByName(dependency.name)
+        dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
+            dep_desc.serialized_pb)
+        package = '.' + dep_proto.package
+        package_prefix = package + '.'
+
+        def _strip_package(symbol):
+          if symbol.startswith(package_prefix):
+            return symbol[len(package_prefix):]
+          return symbol
+
+        symbols = list(self._ExtractSymbols(dep_proto.message_type, package))
+        scope.update(symbols)
+        scope.update((_strip_package(k), v) for k, v in symbols)
+
+        symbols = list(self._ExtractEnums(dep_proto.enum_type, package))
+        scope.update(symbols)
+        scope.update((_strip_package(k), v) for k, v in symbols)
+
+      for message_type in file_proto.message_type:
+        message_desc = self._ConvertMessageDescriptor(
+            message_type, file_proto.package, file_descriptor, scope)
+        file_descriptor.message_types_by_name[message_desc.name] = message_desc
+      for enum_type in file_proto.enum_type:
+        self._ConvertEnumDescriptor(enum_type, file_proto.package,
+                                    file_descriptor, None, scope)
+      for desc_proto in self._ExtractMessages(file_proto.message_type):
+        self._SetFieldTypes(desc_proto, scope)
+
+      for desc_proto in file_proto.message_type:
+        desc = scope[desc_proto.name]
+        file_descriptor.message_types_by_name[desc_proto.name] = desc
+      self.Add(file_proto)
+      self._file_descriptors[file_proto.name] = file_descriptor
+
+    return self._file_descriptors[file_proto.name]
+
+  def _ConvertMessageDescriptor(self, desc_proto, package=None, file_desc=None,
+                                scope=None):
+    """Adds the proto to the pool in the specified package.
+
+    Args:
+      desc_proto: The descriptor_pb2.DescriptorProto protobuf message.
+      package: The package the proto should be located in.
+      file_desc: The file containing this message.
+      scope: Dict mapping short and full symbols to message and enum types.
+
+    Returns:
+      The added descriptor.
+    """
+
+    if package:
+      desc_name = '.'.join((package, desc_proto.name))
+    else:
+      desc_name = desc_proto.name
+
+    if file_desc is None:
+      file_name = None
+    else:
+      file_name = file_desc.name
+
+    if scope is None:
+      scope = {}
+
+    nested = [
+        self._ConvertMessageDescriptor(nested, desc_name, file_desc, scope)
+        for nested in desc_proto.nested_type]
+    enums = [
+        self._ConvertEnumDescriptor(enum, desc_name, file_desc, None, scope)
+        for enum in desc_proto.enum_type]
+    fields = [self._MakeFieldDescriptor(field, desc_name, index)
+              for index, field in enumerate(desc_proto.field)]
+    extensions = [self._MakeFieldDescriptor(extension, desc_name, True)
+                  for index, extension in enumerate(desc_proto.extension)]
+    extension_ranges = [(r.start, r.end) for r in desc_proto.extension_range]
+    if extension_ranges:
+      is_extendable = True
+    else:
+      is_extendable = False
+    desc = descriptor.Descriptor(
+        name=desc_proto.name,
+        full_name=desc_name,
+        filename=file_name,
+        containing_type=None,
+        fields=fields,
+        nested_types=nested,
+        enum_types=enums,
+        extensions=extensions,
+        options=desc_proto.options,
+        is_extendable=is_extendable,
+        extension_ranges=extension_ranges,
+        file=file_desc,
+        serialized_start=None,
+        serialized_end=None)
+    for nested in desc.nested_types:
+      nested.containing_type = desc
+    for enum in desc.enum_types:
+      enum.containing_type = desc
+    scope[desc_proto.name] = desc
+    scope['.' + desc_name] = desc
+    self._descriptors[desc_name] = desc
+    return desc
+
+  def _ConvertEnumDescriptor(self, enum_proto, package=None, file_desc=None,
+                             containing_type=None, scope=None):
+    """Make a protobuf EnumDescriptor given an EnumDescriptorProto protobuf.
+
+    Args:
+      enum_proto: The descriptor_pb2.EnumDescriptorProto protobuf message.
+      package: Optional package name for the new message EnumDescriptor.
+      file_desc: The file containing the enum descriptor.
+      containing_type: The type containing this enum.
+      scope: Scope containing available types.
+
+    Returns:
+      The added descriptor
+    """
+
+    if package:
+      enum_name = '.'.join((package, enum_proto.name))
+    else:
+      enum_name = enum_proto.name
+
+    if file_desc is None:
+      file_name = None
+    else:
+      file_name = file_desc.name
+
+    values = [self._MakeEnumValueDescriptor(value, index)
+              for index, value in enumerate(enum_proto.value)]
+    desc = descriptor.EnumDescriptor(name=enum_proto.name,
+                                     full_name=enum_name,
+                                     filename=file_name,
+                                     file=file_desc,
+                                     values=values,
+                                     containing_type=containing_type,
+                                     options=enum_proto.options)
+    scope[enum_proto.name] = desc
+    scope['.%s' % enum_name] = desc
+    self._enum_descriptors[enum_name] = desc
+    return desc
+
+  def _MakeFieldDescriptor(self, field_proto, message_name, index,
+                           is_extension=False):
+    """Creates a field descriptor from a FieldDescriptorProto.
+
+    For message and enum type fields, this method will do a look up
+    in the pool for the appropriate descriptor for that type. If it
+    is unavailable, it will fall back to the _source function to
+    create it. If this type is still unavailable, construction will
+    fail.
+
+    Args:
+      field_proto: The proto describing the field.
+      message_name: The name of the containing message.
+      index: Index of the field
+      is_extension: Indication that this field is for an extension.
+
+    Returns:
+      An initialized FieldDescriptor object
+    """
+
+    if message_name:
+      full_name = '.'.join((message_name, field_proto.name))
+    else:
+      full_name = field_proto.name
+
+    return descriptor.FieldDescriptor(
+        name=field_proto.name,
+        full_name=full_name,
+        index=index,
+        number=field_proto.number,
+        type=field_proto.type,
+        cpp_type=None,
+        message_type=None,
+        enum_type=None,
+        containing_type=None,
+        label=field_proto.label,
+        has_default_value=False,
+        default_value=None,
+        is_extension=is_extension,
+        extension_scope=None,
+        options=field_proto.options)
+
+  def _SetFieldTypes(self, desc_proto, scope):
+    """Sets the field's type, cpp_type, message_type and enum_type.
+
+    Args:
+      desc_proto: The message descriptor to update.
+      scope: Enclosing scope of available types.
+    """
+
+    desc = scope[desc_proto.name]
+    for field_proto, field_desc in zip(desc_proto.field, desc.fields):
+      if field_proto.type_name:
+        type_name = field_proto.type_name
+        if type_name not in scope:
+          type_name = '.' + type_name
+        desc = scope[type_name]
+      else:
+        desc = None
+
+      if not field_proto.HasField('type'):
+        if isinstance(desc, descriptor.Descriptor):
+          field_proto.type = descriptor.FieldDescriptor.TYPE_MESSAGE
+        else:
+          field_proto.type = descriptor.FieldDescriptor.TYPE_ENUM
+
+      field_desc.cpp_type = descriptor.FieldDescriptor.ProtoTypeToCppProtoType(
+          field_proto.type)
+
+      if (field_proto.type == descriptor.FieldDescriptor.TYPE_MESSAGE
+          or field_proto.type == descriptor.FieldDescriptor.TYPE_GROUP):
+        field_desc.message_type = desc
+
+      if field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
+        field_desc.enum_type = desc
+
+      if field_proto.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+        field_desc.has_default = False
+        field_desc.default_value = []
+      elif field_proto.HasField('default_value'):
+        field_desc.has_default = True
+        if (field_proto.type == descriptor.FieldDescriptor.TYPE_DOUBLE or
+            field_proto.type == descriptor.FieldDescriptor.TYPE_FLOAT):
+          field_desc.default_value = float(field_proto.default_value)
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_STRING:
+          field_desc.default_value = field_proto.default_value
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_BOOL:
+          field_desc.default_value = field_proto.default_value.lower() == 'true'
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
+          field_desc.default_value = field_desc.enum_type.values_by_name[
+              field_proto.default_value].index
+        else:
+          field_desc.default_value = int(field_proto.default_value)
+      else:
+        field_desc.has_default = False
+        field_desc.default_value = None
+
+      field_desc.type = field_proto.type
+
+    for nested_type in desc_proto.nested_type:
+      self._SetFieldTypes(nested_type, scope)
+
+  def _MakeEnumValueDescriptor(self, value_proto, index):
+    """Creates a enum value descriptor object from a enum value proto.
+
+    Args:
+      value_proto: The proto describing the enum value.
+      index: The index of the enum value.
+
+    Returns:
+      An initialized EnumValueDescriptor object.
+    """
+
+    return descriptor.EnumValueDescriptor(
+        name=value_proto.name,
+        index=index,
+        number=value_proto.number,
+        options=value_proto.options,
+        type=None)
+
+  def _ExtractSymbols(self, desc_protos, package):
+    """Pulls out all the symbols from descriptor protos.
+
+    Args:
+      desc_protos: The protos to extract symbols from.
+      package: The package containing the descriptor type.
+    Yields:
+      A two element tuple of the type name and descriptor object.
+    """
+
+    for desc_proto in desc_protos:
+      if package:
+        message_name = '.'.join((package, desc_proto.name))
+      else:
+        message_name = desc_proto.name
+      message_desc = self.FindMessageTypeByName(message_name)
+      yield (message_name, message_desc)
+      for symbol in self._ExtractSymbols(desc_proto.nested_type, message_name):
+        yield symbol
+      for symbol in self._ExtractEnums(desc_proto.enum_type, message_name):
+        yield symbol
+
+  def _ExtractEnums(self, enum_protos, package):
+    """Pulls out all the symbols from enum protos.
+
+    Args:
+      enum_protos: The protos to extract symbols from.
+      package: The package containing the enum type.
+
+    Yields:
+      A two element tuple of the type name and enum descriptor object.
+    """
+
+    for enum_proto in enum_protos:
+      if package:
+        enum_name = '.'.join((package, enum_proto.name))
+      else:
+        enum_name = enum_proto.name
+      enum_desc = self.FindEnumTypeByName(enum_name)
+      yield (enum_name, enum_desc)
+
+  def _ExtractMessages(self, desc_protos):
+    """Pulls out all the message protos from descriptos.
+
+    Args:
+      desc_protos: The protos to extract symbols from.
+
+    Yields:
+      Descriptor protos.
+    """
+
+    for desc_proto in desc_protos:
+      yield desc_proto
+      for message in self._ExtractMessages(desc_proto.nested_type):
+        yield message
+
+  def _GetDeps(self, file_proto):
+    """Recursively finds dependencies for file protos.
+
+    Args:
+      file_proto: The proto to get dependencies from.
+
+    Yields:
+      Each direct and indirect dependency.
+    """
+
+    for dependency in file_proto.dependency:
+      dep_desc = self.FindFileByName(dependency)
+      dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
+          dep_desc.serialized_pb)
+      yield dep_proto
+      for parent_dep in self._GetDeps(dep_proto):
+        yield parent_dep
diff --git a/python/google/protobuf/internal/api_implementation.py b/python/google/protobuf/internal/api_implementation.py
index b3e412e2..ce02a329 100755
--- a/python/google/protobuf/internal/api_implementation.py
+++ b/python/google/protobuf/internal/api_implementation.py
@@ -56,9 +56,32 @@ if _implementation_type != 'python':
   #  _implementation_type = 'python'
 
 
+# This environment variable can be used to switch between the two
+# 'cpp' implementations. Right now only 1 and 2 are valid values. Any
+# other value will be ignored.
+_implementation_version_str = os.getenv(
+    'PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION',
+    '1')
+
+
+if _implementation_version_str not in ('1', '2'):
+  raise ValueError(
+      "unsupported PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION: '" +
+      _implementation_version_str + "' (supported versions: 1, 2)"
+      )
+
+
+_implementation_version = int(_implementation_version_str)
+
+
+
 # Usage of this function is discouraged. Clients shouldn't care which
 # implementation of the API is in use. Note that there is no guarantee
 # that differences between APIs will be maintained.
 # Please don't use this function if possible.
 def Type():
   return _implementation_type
+
+# See comment on 'Type' above.
+def Version():
+  return _implementation_version
diff --git a/python/google/protobuf/internal/containers.py b/python/google/protobuf/internal/containers.py
index 097a3c26..34b35f8a 100755
--- a/python/google/protobuf/internal/containers.py
+++ b/python/google/protobuf/internal/containers.py
@@ -78,8 +78,13 @@ class BaseContainer(object):
   def __repr__(self):
     return repr(self._values)
 
-  def sort(self, sort_function=cmp):
-    self._values.sort(sort_function)
+  def sort(self, *args, **kwargs):
+    # Continue to support the old sort_function keyword argument.
+    # This is expected to be a rare occurrence, so use LBYL to avoid
+    # the overhead of actually catching KeyError.
+    if 'sort_function' in kwargs:
+      kwargs['cmp'] = kwargs.pop('sort_function')
+    self._values.sort(*args, **kwargs)
 
 
 class RepeatedScalarFieldContainer(BaseContainer):
@@ -235,6 +240,11 @@ class RepeatedCompositeFieldContainer(BaseContainer):
     """
     self.extend(other._values)
 
+  def remove(self, elem):
+    """Removes an item from the list. Similar to list.remove()."""
+    self._values.remove(elem)
+    self._message_listener.Modified()
+
   def __getslice__(self, start, stop):
     """Retrieves the subset of items from between the specified indices."""
     return self._values[start:stop]
diff --git a/python/google/protobuf/internal/cpp_message.py b/python/google/protobuf/internal/cpp_message.py
index 3f426502..23ab9ba4 100755
--- a/python/google/protobuf/internal/cpp_message.py
+++ b/python/google/protobuf/internal/cpp_message.py
@@ -34,8 +34,10 @@ Descriptor objects at runtime backed by the protocol buffer C++ API.
 
 __author__ = 'petar@google.com (Petar Petrov)'
 
+import copy_reg
 import operator
 from google.protobuf.internal import _net_proto2___python
+from google.protobuf.internal import enum_type_wrapper
 from google.protobuf import message
 
 
@@ -156,10 +158,12 @@ class RepeatedScalarContainer(object):
   def __hash__(self):
     raise TypeError('unhashable object')
 
-  def sort(self, sort_function=cmp):
-    values = self[slice(None, None, None)]
-    values.sort(sort_function)
-    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor, values)
+  def sort(self, *args, **kwargs):
+    # Maintain compatibility with the previous interface.
+    if 'sort_function' in kwargs:
+      kwargs['cmp'] = kwargs.pop('sort_function')
+    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor,
+                                    sorted(self, *args, **kwargs))
 
 
 def RepeatedScalarProperty(cdescriptor):
@@ -202,6 +206,12 @@ class RepeatedCompositeContainer(object):
     for message in elem_seq:
       self.add().MergeFrom(message)
 
+  def remove(self, value):
+    # TODO(protocol-devel): This is inefficient as it needs to generate a
+    # message pointer for each message only to do index().  Move this to a C++
+    # extension function.
+    self.__delitem__(self[slice(None, None, None)].index(value))
+
   def MergeFrom(self, other):
     for message in other[:]:
       self.add().MergeFrom(message)
@@ -236,27 +246,29 @@ class RepeatedCompositeContainer(object):
   def __hash__(self):
     raise TypeError('unhashable object')
 
-  def sort(self, sort_function=cmp):
-    messages = []
-    for index in range(len(self)):
-      # messages[i][0] is where the i-th element of the new array has to come
-      # from.
-      # messages[i][1] is where the i-th element of the old array has to go.
-      messages.append([index, 0, self[index]])
-    messages.sort(lambda x,y: sort_function(x[2], y[2]))
+  def sort(self, cmp=None, key=None, reverse=False, **kwargs):
+    # Maintain compatibility with the old interface.
+    if cmp is None and 'sort_function' in kwargs:
+      cmp = kwargs.pop('sort_function')
 
-    # Remember which position each elements has to move to.
-    for i in range(len(messages)):
-      messages[messages[i][0]][1] = i
+    # The cmp function, if provided, is passed the results of the key function,
+    # so we only need to wrap one of them.
+    if key is None:
+      index_key = self.__getitem__
+    else:
+      index_key = lambda i: key(self[i])
+
+    # Sort the list of current indexes by the underlying object.
+    indexes = range(len(self))
+    indexes.sort(cmp=cmp, key=index_key, reverse=reverse)
 
     # Apply the transposition.
-    for i in range(len(messages)):
-      from_position = messages[i][0]
-      if i == from_position:
+    for dest, src in enumerate(indexes):
+      if dest == src:
         continue
-      self._cmsg.SwapRepeatedFieldElements(
-          self._cfield_descriptor, i, from_position)
-      messages[messages[i][1]][0] = from_position
+      self._cmsg.SwapRepeatedFieldElements(self._cfield_descriptor, dest, src)
+      # Don't swap the same value twice.
+      indexes[src] = src
 
 
 def RepeatedCompositeProperty(cdescriptor, message_type):
@@ -359,11 +371,12 @@ class ExtensionDict(object):
     return None
 
 
-def NewMessage(message_descriptor, dictionary):
+def NewMessage(bases, message_descriptor, dictionary):
   """Creates a new protocol message *class*."""
   _AddClassAttributesForNestedExtensions(message_descriptor, dictionary)
   _AddEnumValues(message_descriptor, dictionary)
   _AddDescriptors(message_descriptor, dictionary)
+  return bases
 
 
 def InitMessage(message_descriptor, cls):
@@ -372,6 +385,7 @@ def InitMessage(message_descriptor, cls):
   _AddInitMethod(message_descriptor, cls)
   _AddMessageMethods(message_descriptor, cls)
   _AddPropertiesForExtensions(message_descriptor, cls)
+  copy_reg.pickle(cls, lambda obj: (cls, (), obj.__getstate__()))
 
 
 def _AddDescriptors(message_descriptor, dictionary):
@@ -387,7 +401,7 @@ def _AddDescriptors(message_descriptor, dictionary):
         field.full_name)
 
   dictionary['__slots__'] = list(dictionary['__descriptors'].iterkeys()) + [
-      '_cmsg', '_owner', '_composite_fields', 'Extensions']
+      '_cmsg', '_owner', '_composite_fields', 'Extensions', '_HACK_REFCOUNTS']
 
 
 def _AddEnumValues(message_descriptor, dictionary):
@@ -398,6 +412,7 @@ def _AddEnumValues(message_descriptor, dictionary):
     dictionary: Class dictionary that should be populated.
   """
   for enum_type in message_descriptor.enum_types:
+    dictionary[enum_type.name] = enum_type_wrapper.EnumTypeWrapper(enum_type)
     for enum_value in enum_type.values:
       dictionary[enum_value.name] = enum_value.number
 
@@ -439,28 +454,35 @@ def _AddInitMethod(message_descriptor, cls):
   def Init(self, **kwargs):
     """Message constructor."""
     cmessage = kwargs.pop('__cmessage', None)
-    if cmessage is None:
-      self._cmsg = NewCMessage(message_descriptor.full_name)
-    else:
+    if cmessage:
       self._cmsg = cmessage
+    else:
+      self._cmsg = NewCMessage(message_descriptor.full_name)
 
     # Keep a reference to the owner, as the owner keeps a reference to the
     # underlying protocol buffer message.
     owner = kwargs.pop('__owner', None)
-    if owner is not None:
+    if owner:
       self._owner = owner
 
-    self.Extensions = ExtensionDict(self)
+    if message_descriptor.is_extendable:
+      self.Extensions = ExtensionDict(self)
+    else:
+      # Reference counting in the C++ code is broken and depends on
+      # the Extensions reference to keep this object alive during unit
+      # tests (see b/4856052).  Remove this once b/4945904 is fixed.
+      self._HACK_REFCOUNTS = self
     self._composite_fields = {}
 
     for field_name, field_value in kwargs.iteritems():
       field_cdescriptor = self.__descriptors.get(field_name, None)
-      if field_cdescriptor is None:
+      if not field_cdescriptor:
         raise ValueError('Protocol message has no "%s" field.' % field_name)
       if field_cdescriptor.label == _LABEL_REPEATED:
         if field_cdescriptor.cpp_type == _CPPTYPE_MESSAGE:
+          field_name = getattr(self, field_name)
           for val in field_value:
-            getattr(self, field_name).add().MergeFrom(val)
+            field_name.add().MergeFrom(val)
         else:
           getattr(self, field_name).extend(field_value)
       elif field_cdescriptor.cpp_type == _CPPTYPE_MESSAGE:
@@ -497,12 +519,34 @@ def _AddMessageMethods(message_descriptor, cls):
     return self._cmsg.HasField(field_name)
 
   def ClearField(self, field_name):
+    child_cmessage = None
     if field_name in self._composite_fields:
+      child_field = self._composite_fields[field_name]
       del self._composite_fields[field_name]
-    self._cmsg.ClearField(field_name)
+
+      child_cdescriptor = self.__descriptors[field_name]
+      # TODO(anuraag): Support clearing repeated message fields as well.
+      if (child_cdescriptor.label != _LABEL_REPEATED and
+          child_cdescriptor.cpp_type == _CPPTYPE_MESSAGE):
+        child_field._owner = None
+        child_cmessage = child_field._cmsg
+
+    if child_cmessage is not None:
+      self._cmsg.ClearField(field_name, child_cmessage)
+    else:
+      self._cmsg.ClearField(field_name)
 
   def Clear(self):
-    return self._cmsg.Clear()
+    cmessages_to_release = []
+    for field_name, child_field in self._composite_fields.iteritems():
+      child_cdescriptor = self.__descriptors[field_name]
+      # TODO(anuraag): Support clearing repeated message fields as well.
+      if (child_cdescriptor.label != _LABEL_REPEATED and
+          child_cdescriptor.cpp_type == _CPPTYPE_MESSAGE):
+        child_field._owner = None
+        cmessages_to_release.append((child_cdescriptor, child_field._cmsg))
+    self._composite_fields.clear()
+    self._cmsg.Clear(cmessages_to_release)
 
   def IsInitialized(self, errors=None):
     if self._cmsg.IsInitialized():
@@ -514,8 +558,8 @@ def _AddMessageMethods(message_descriptor, cls):
   def SerializeToString(self):
     if not self.IsInitialized():
       raise message.EncodeError(
-          'Message is missing required fields: ' +
-          ','.join(self.FindInitializationErrors()))
+          'Message %s is missing required fields: %s' % (
+          self._cmsg.full_name, ','.join(self.FindInitializationErrors())))
     return self._cmsg.SerializeToString()
 
   def SerializePartialToString(self):
@@ -534,7 +578,8 @@ def _AddMessageMethods(message_descriptor, cls):
   def MergeFrom(self, msg):
     if not isinstance(msg, cls):
       raise TypeError(
-          "Parameter to MergeFrom() must be instance of same class.")
+          "Parameter to MergeFrom() must be instance of same class: "
+          "expected %s got %s." % (cls.__name__, type(msg).__name__))
     self._cmsg.MergeFrom(msg._cmsg)
 
   def CopyFrom(self, msg):
@@ -581,6 +626,8 @@ def _AddMessageMethods(message_descriptor, cls):
     raise TypeError('unhashable object')
 
   def __unicode__(self):
+    # Lazy import to prevent circular import when text_format imports this file.
+    from google.protobuf import text_format
     return text_format.MessageToString(self, as_utf8=True).decode('utf-8')
 
   # Attach the local methods to the message class.
diff --git a/python/google/protobuf/internal/decoder.py b/python/google/protobuf/internal/decoder.py
index 55f746f5..cb6f5729 100755
--- a/python/google/protobuf/internal/decoder.py
+++ b/python/google/protobuf/internal/decoder.py
@@ -576,6 +576,7 @@ def MessageSetItemDecoder(extensions_by_number):
   local_SkipField = SkipField
 
   def DecodeItem(buffer, pos, end, message, field_dict):
+    message_set_item_start = pos
     type_id = -1
     message_start = -1
     message_end = -1
@@ -614,6 +615,11 @@ def MessageSetItemDecoder(extensions_by_number):
         # The only reason _InternalParse would return early is if it encountered
         # an end-group tag.
         raise _DecodeError('Unexpected end-group tag.')
+    else:
+      if not message._unknown_fields:
+        message._unknown_fields = []
+      message._unknown_fields.append((MESSAGE_SET_ITEM_TAG,
+                                      buffer[message_set_item_start:pos]))
 
     return pos
 
diff --git a/python/google/protobuf/internal/descriptor_database_test.py b/python/google/protobuf/internal/descriptor_database_test.py
new file mode 100644
index 00000000..d0ca7892
--- /dev/null
+++ b/python/google/protobuf/internal/descriptor_database_test.py
@@ -0,0 +1,63 @@
+#! /usr/bin/python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for google.protobuf.descriptor_database."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+import unittest
+from google.protobuf import descriptor_pb2
+from google.protobuf.internal import factory_test2_pb2
+from google.protobuf import descriptor_database
+
+
+class DescriptorDatabaseTest(unittest.TestCase):
+
+  def testAdd(self):
+    db = descriptor_database.DescriptorDatabase()
+    file_desc_proto = descriptor_pb2.FileDescriptorProto.FromString(
+        factory_test2_pb2.DESCRIPTOR.serialized_pb)
+    db.Add(file_desc_proto)
+
+    self.assertEquals(file_desc_proto, db.FindFileByName(
+        'net/proto2/python/internal/factory_test2.proto'))
+    self.assertEquals(file_desc_proto, db.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory2Message'))
+    self.assertEquals(file_desc_proto, db.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory2Message.NestedFactory2Message'))
+    self.assertEquals(file_desc_proto, db.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory2Enum'))
+    self.assertEquals(file_desc_proto, db.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory2Message.NestedFactory2Enum'))
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/descriptor_pool_test.py b/python/google/protobuf/internal/descriptor_pool_test.py
new file mode 100644
index 00000000..a615d787
--- /dev/null
+++ b/python/google/protobuf/internal/descriptor_pool_test.py
@@ -0,0 +1,220 @@
+#! /usr/bin/python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for google.protobuf.descriptor_pool."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+import unittest
+from google.protobuf import descriptor_pb2
+from google.protobuf.internal import factory_test1_pb2
+from google.protobuf.internal import factory_test2_pb2
+from google.protobuf import descriptor
+from google.protobuf import descriptor_database
+from google.protobuf import descriptor_pool
+
+
+class DescriptorPoolTest(unittest.TestCase):
+
+  def setUp(self):
+    self.pool = descriptor_pool.DescriptorPool()
+    self.factory_test1_fd = descriptor_pb2.FileDescriptorProto.FromString(
+        factory_test1_pb2.DESCRIPTOR.serialized_pb)
+    self.factory_test2_fd = descriptor_pb2.FileDescriptorProto.FromString(
+        factory_test2_pb2.DESCRIPTOR.serialized_pb)
+    self.pool.Add(self.factory_test1_fd)
+    self.pool.Add(self.factory_test2_fd)
+
+  def testFindFileByName(self):
+    name1 = 'net/proto2/python/internal/factory_test1.proto'
+    file_desc1 = self.pool.FindFileByName(name1)
+    self.assertIsInstance(file_desc1, descriptor.FileDescriptor)
+    self.assertEquals(name1, file_desc1.name)
+    self.assertEquals('net.proto2.python.internal', file_desc1.package)
+    self.assertIn('Factory1Message', file_desc1.message_types_by_name)
+
+    name2 = 'net/proto2/python/internal/factory_test2.proto'
+    file_desc2 = self.pool.FindFileByName(name2)
+    self.assertIsInstance(file_desc2, descriptor.FileDescriptor)
+    self.assertEquals(name2, file_desc2.name)
+    self.assertEquals('net.proto2.python.internal', file_desc2.package)
+    self.assertIn('Factory2Message', file_desc2.message_types_by_name)
+
+  def testFindFileByNameFailure(self):
+    try:
+      self.pool.FindFileByName('Does not exist')
+      self.fail('Expected KeyError')
+    except KeyError:
+      pass
+
+  def testFindFileContainingSymbol(self):
+    file_desc1 = self.pool.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory1Message')
+    self.assertIsInstance(file_desc1, descriptor.FileDescriptor)
+    self.assertEquals('net/proto2/python/internal/factory_test1.proto',
+                      file_desc1.name)
+    self.assertEquals('net.proto2.python.internal', file_desc1.package)
+    self.assertIn('Factory1Message', file_desc1.message_types_by_name)
+
+    file_desc2 = self.pool.FindFileContainingSymbol(
+        'net.proto2.python.internal.Factory2Message')
+    self.assertIsInstance(file_desc2, descriptor.FileDescriptor)
+    self.assertEquals('net/proto2/python/internal/factory_test2.proto',
+                      file_desc2.name)
+    self.assertEquals('net.proto2.python.internal', file_desc2.package)
+    self.assertIn('Factory2Message', file_desc2.message_types_by_name)
+
+  def testFindFileContainingSymbolFailure(self):
+    try:
+      self.pool.FindFileContainingSymbol('Does not exist')
+      self.fail('Expected KeyError')
+    except KeyError:
+      pass
+
+  def testFindMessageTypeByName(self):
+    msg1 = self.pool.FindMessageTypeByName(
+        'net.proto2.python.internal.Factory1Message')
+    self.assertIsInstance(msg1, descriptor.Descriptor)
+    self.assertEquals('Factory1Message', msg1.name)
+    self.assertEquals('net.proto2.python.internal.Factory1Message',
+                      msg1.full_name)
+    self.assertEquals(None, msg1.containing_type)
+
+    nested_msg1 = msg1.nested_types[0]
+    self.assertEquals('NestedFactory1Message', nested_msg1.name)
+    self.assertEquals(msg1, nested_msg1.containing_type)
+
+    nested_enum1 = msg1.enum_types[0]
+    self.assertEquals('NestedFactory1Enum', nested_enum1.name)
+    self.assertEquals(msg1, nested_enum1.containing_type)
+
+    self.assertEquals(nested_msg1, msg1.fields_by_name[
+        'nested_factory_1_message'].message_type)
+    self.assertEquals(nested_enum1, msg1.fields_by_name[
+        'nested_factory_1_enum'].enum_type)
+
+    msg2 = self.pool.FindMessageTypeByName(
+        'net.proto2.python.internal.Factory2Message')
+    self.assertIsInstance(msg2, descriptor.Descriptor)
+    self.assertEquals('Factory2Message', msg2.name)
+    self.assertEquals('net.proto2.python.internal.Factory2Message',
+                      msg2.full_name)
+    self.assertIsNone(msg2.containing_type)
+
+    nested_msg2 = msg2.nested_types[0]
+    self.assertEquals('NestedFactory2Message', nested_msg2.name)
+    self.assertEquals(msg2, nested_msg2.containing_type)
+
+    nested_enum2 = msg2.enum_types[0]
+    self.assertEquals('NestedFactory2Enum', nested_enum2.name)
+    self.assertEquals(msg2, nested_enum2.containing_type)
+
+    self.assertEquals(nested_msg2, msg2.fields_by_name[
+        'nested_factory_2_message'].message_type)
+    self.assertEquals(nested_enum2, msg2.fields_by_name[
+        'nested_factory_2_enum'].enum_type)
+
+    self.assertTrue(msg2.fields_by_name['int_with_default'].has_default)
+    self.assertEquals(
+        1776, msg2.fields_by_name['int_with_default'].default_value)
+
+    self.assertTrue(msg2.fields_by_name['double_with_default'].has_default)
+    self.assertEquals(
+        9.99, msg2.fields_by_name['double_with_default'].default_value)
+
+    self.assertTrue(msg2.fields_by_name['string_with_default'].has_default)
+    self.assertEquals(
+        'hello world', msg2.fields_by_name['string_with_default'].default_value)
+
+    self.assertTrue(msg2.fields_by_name['bool_with_default'].has_default)
+    self.assertFalse(msg2.fields_by_name['bool_with_default'].default_value)
+
+    self.assertTrue(msg2.fields_by_name['enum_with_default'].has_default)
+    self.assertEquals(
+        1, msg2.fields_by_name['enum_with_default'].default_value)
+
+    msg3 = self.pool.FindMessageTypeByName(
+        'net.proto2.python.internal.Factory2Message.NestedFactory2Message')
+    self.assertEquals(nested_msg2, msg3)
+
+  def testFindMessageTypeByNameFailure(self):
+    try:
+      self.pool.FindMessageTypeByName('Does not exist')
+      self.fail('Expected KeyError')
+    except KeyError:
+      pass
+
+  def testFindEnumTypeByName(self):
+    enum1 = self.pool.FindEnumTypeByName(
+        'net.proto2.python.internal.Factory1Enum')
+    self.assertIsInstance(enum1, descriptor.EnumDescriptor)
+    self.assertEquals(0, enum1.values_by_name['FACTORY_1_VALUE_0'].number)
+    self.assertEquals(1, enum1.values_by_name['FACTORY_1_VALUE_1'].number)
+
+    nested_enum1 = self.pool.FindEnumTypeByName(
+        'net.proto2.python.internal.Factory1Message.NestedFactory1Enum')
+    self.assertIsInstance(nested_enum1, descriptor.EnumDescriptor)
+    self.assertEquals(
+        0, nested_enum1.values_by_name['NESTED_FACTORY_1_VALUE_0'].number)
+    self.assertEquals(
+        1, nested_enum1.values_by_name['NESTED_FACTORY_1_VALUE_1'].number)
+
+    enum2 = self.pool.FindEnumTypeByName(
+        'net.proto2.python.internal.Factory2Enum')
+    self.assertIsInstance(enum2, descriptor.EnumDescriptor)
+    self.assertEquals(0, enum2.values_by_name['FACTORY_2_VALUE_0'].number)
+    self.assertEquals(1, enum2.values_by_name['FACTORY_2_VALUE_1'].number)
+
+    nested_enum2 = self.pool.FindEnumTypeByName(
+        'net.proto2.python.internal.Factory2Message.NestedFactory2Enum')
+    self.assertIsInstance(nested_enum2, descriptor.EnumDescriptor)
+    self.assertEquals(
+        0, nested_enum2.values_by_name['NESTED_FACTORY_2_VALUE_0'].number)
+    self.assertEquals(
+        1, nested_enum2.values_by_name['NESTED_FACTORY_2_VALUE_1'].number)
+
+  def testFindEnumTypeByNameFailure(self):
+    try:
+      self.pool.FindEnumTypeByName('Does not exist')
+      self.fail('Expected KeyError')
+    except KeyError:
+      pass
+
+  def testUserDefinedDB(self):
+    db = descriptor_database.DescriptorDatabase()
+    self.pool = descriptor_pool.DescriptorPool(db)
+    db.Add(self.factory_test1_fd)
+    db.Add(self.factory_test2_fd)
+    self.testFindMessageTypeByName()
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index 05c27452..c74f882e 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -35,6 +35,7 @@
 __author__ = 'robinson@google.com (Will Robinson)'
 
 import unittest
+from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import descriptor_pb2
@@ -101,6 +102,15 @@ class DescriptorTest(unittest.TestCase):
             self.my_method
         ])
 
+  def testEnumValueName(self):
+    self.assertEqual(self.my_message.EnumValueName('ForeignEnum', 4),
+                     'FOREIGN_FOO')
+
+    self.assertEqual(
+        self.my_message.enum_types_by_name[
+            'ForeignEnum'].values_by_number[4].name,
+        self.my_message.EnumValueName('ForeignEnum', 4))
+
   def testEnumFixups(self):
     self.assertEqual(self.my_enum, self.my_enum.values[0].type)
 
@@ -125,6 +135,257 @@ class DescriptorTest(unittest.TestCase):
     self.assertEqual(self.my_service.GetOptions(),
                      descriptor_pb2.ServiceOptions())
 
+  def testSimpleCustomOptions(self):
+    file_descriptor = unittest_custom_options_pb2.DESCRIPTOR
+    message_descriptor =\
+        unittest_custom_options_pb2.TestMessageWithCustomOptions.DESCRIPTOR
+    field_descriptor = message_descriptor.fields_by_name["field1"]
+    enum_descriptor = message_descriptor.enum_types_by_name["AnEnum"]
+    enum_value_descriptor =\
+        message_descriptor.enum_values_by_name["ANENUM_VAL2"]
+    service_descriptor =\
+        unittest_custom_options_pb2.TestServiceWithCustomOptions.DESCRIPTOR
+    method_descriptor = service_descriptor.FindMethodByName("Foo")
+
+    file_options = file_descriptor.GetOptions()
+    file_opt1 = unittest_custom_options_pb2.file_opt1
+    self.assertEqual(9876543210, file_options.Extensions[file_opt1])
+    message_options = message_descriptor.GetOptions()
+    message_opt1 = unittest_custom_options_pb2.message_opt1
+    self.assertEqual(-56, message_options.Extensions[message_opt1])
+    field_options = field_descriptor.GetOptions()
+    field_opt1 = unittest_custom_options_pb2.field_opt1
+    self.assertEqual(8765432109, field_options.Extensions[field_opt1])
+    field_opt2 = unittest_custom_options_pb2.field_opt2
+    self.assertEqual(42, field_options.Extensions[field_opt2])
+    enum_options = enum_descriptor.GetOptions()
+    enum_opt1 = unittest_custom_options_pb2.enum_opt1
+    self.assertEqual(-789, enum_options.Extensions[enum_opt1])
+    enum_value_options = enum_value_descriptor.GetOptions()
+    enum_value_opt1 = unittest_custom_options_pb2.enum_value_opt1
+    self.assertEqual(123, enum_value_options.Extensions[enum_value_opt1])
+
+    service_options = service_descriptor.GetOptions()
+    service_opt1 = unittest_custom_options_pb2.service_opt1
+    self.assertEqual(-9876543210, service_options.Extensions[service_opt1])
+    method_options = method_descriptor.GetOptions()
+    method_opt1 = unittest_custom_options_pb2.method_opt1
+    self.assertEqual(unittest_custom_options_pb2.METHODOPT1_VAL2,
+                     method_options.Extensions[method_opt1])
+
+  def testDifferentCustomOptionTypes(self):
+    kint32min = -2**31
+    kint64min = -2**63
+    kint32max = 2**31 - 1
+    kint64max = 2**63 - 1
+    kuint32max = 2**32 - 1
+    kuint64max = 2**64 - 1
+
+    message_descriptor =\
+        unittest_custom_options_pb2.CustomOptionMinIntegerValues.DESCRIPTOR
+    message_options = message_descriptor.GetOptions()
+    self.assertEqual(False, message_options.Extensions[
+        unittest_custom_options_pb2.bool_opt])
+    self.assertEqual(kint32min, message_options.Extensions[
+        unittest_custom_options_pb2.int32_opt])
+    self.assertEqual(kint64min, message_options.Extensions[
+        unittest_custom_options_pb2.int64_opt])
+    self.assertEqual(0, message_options.Extensions[
+        unittest_custom_options_pb2.uint32_opt])
+    self.assertEqual(0, message_options.Extensions[
+        unittest_custom_options_pb2.uint64_opt])
+    self.assertEqual(kint32min, message_options.Extensions[
+        unittest_custom_options_pb2.sint32_opt])
+    self.assertEqual(kint64min, message_options.Extensions[
+        unittest_custom_options_pb2.sint64_opt])
+    self.assertEqual(0, message_options.Extensions[
+        unittest_custom_options_pb2.fixed32_opt])
+    self.assertEqual(0, message_options.Extensions[
+        unittest_custom_options_pb2.fixed64_opt])
+    self.assertEqual(kint32min, message_options.Extensions[
+        unittest_custom_options_pb2.sfixed32_opt])
+    self.assertEqual(kint64min, message_options.Extensions[
+        unittest_custom_options_pb2.sfixed64_opt])
+
+    message_descriptor =\
+        unittest_custom_options_pb2.CustomOptionMaxIntegerValues.DESCRIPTOR
+    message_options = message_descriptor.GetOptions()
+    self.assertEqual(True, message_options.Extensions[
+        unittest_custom_options_pb2.bool_opt])
+    self.assertEqual(kint32max, message_options.Extensions[
+        unittest_custom_options_pb2.int32_opt])
+    self.assertEqual(kint64max, message_options.Extensions[
+        unittest_custom_options_pb2.int64_opt])
+    self.assertEqual(kuint32max, message_options.Extensions[
+        unittest_custom_options_pb2.uint32_opt])
+    self.assertEqual(kuint64max, message_options.Extensions[
+        unittest_custom_options_pb2.uint64_opt])
+    self.assertEqual(kint32max, message_options.Extensions[
+        unittest_custom_options_pb2.sint32_opt])
+    self.assertEqual(kint64max, message_options.Extensions[
+        unittest_custom_options_pb2.sint64_opt])
+    self.assertEqual(kuint32max, message_options.Extensions[
+        unittest_custom_options_pb2.fixed32_opt])
+    self.assertEqual(kuint64max, message_options.Extensions[
+        unittest_custom_options_pb2.fixed64_opt])
+    self.assertEqual(kint32max, message_options.Extensions[
+        unittest_custom_options_pb2.sfixed32_opt])
+    self.assertEqual(kint64max, message_options.Extensions[
+        unittest_custom_options_pb2.sfixed64_opt])
+
+    message_descriptor =\
+        unittest_custom_options_pb2.CustomOptionOtherValues.DESCRIPTOR
+    message_options = message_descriptor.GetOptions()
+    self.assertEqual(-100, message_options.Extensions[
+        unittest_custom_options_pb2.int32_opt])
+    self.assertAlmostEqual(12.3456789, message_options.Extensions[
+        unittest_custom_options_pb2.float_opt], 6)
+    self.assertAlmostEqual(1.234567890123456789, message_options.Extensions[
+        unittest_custom_options_pb2.double_opt])
+    self.assertEqual("Hello, \"World\"", message_options.Extensions[
+        unittest_custom_options_pb2.string_opt])
+    self.assertEqual("Hello\0World", message_options.Extensions[
+        unittest_custom_options_pb2.bytes_opt])
+    dummy_enum = unittest_custom_options_pb2.DummyMessageContainingEnum
+    self.assertEqual(
+        dummy_enum.TEST_OPTION_ENUM_TYPE2,
+        message_options.Extensions[unittest_custom_options_pb2.enum_opt])
+
+    message_descriptor =\
+        unittest_custom_options_pb2.SettingRealsFromPositiveInts.DESCRIPTOR
+    message_options = message_descriptor.GetOptions()
+    self.assertAlmostEqual(12, message_options.Extensions[
+        unittest_custom_options_pb2.float_opt], 6)
+    self.assertAlmostEqual(154, message_options.Extensions[
+        unittest_custom_options_pb2.double_opt])
+
+    message_descriptor =\
+        unittest_custom_options_pb2.SettingRealsFromNegativeInts.DESCRIPTOR
+    message_options = message_descriptor.GetOptions()
+    self.assertAlmostEqual(-12, message_options.Extensions[
+        unittest_custom_options_pb2.float_opt], 6)
+    self.assertAlmostEqual(-154, message_options.Extensions[
+        unittest_custom_options_pb2.double_opt])
+
+  def testComplexExtensionOptions(self):
+    descriptor =\
+        unittest_custom_options_pb2.VariousComplexOptions.DESCRIPTOR
+    options = descriptor.GetOptions()
+    self.assertEqual(42, options.Extensions[
+        unittest_custom_options_pb2.complex_opt1].foo)
+    self.assertEqual(324, options.Extensions[
+        unittest_custom_options_pb2.complex_opt1].Extensions[
+            unittest_custom_options_pb2.quux])
+    self.assertEqual(876, options.Extensions[
+        unittest_custom_options_pb2.complex_opt1].Extensions[
+            unittest_custom_options_pb2.corge].qux)
+    self.assertEqual(987, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].baz)
+    self.assertEqual(654, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].Extensions[
+            unittest_custom_options_pb2.grault])
+    self.assertEqual(743, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].bar.foo)
+    self.assertEqual(1999, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].bar.Extensions[
+            unittest_custom_options_pb2.quux])
+    self.assertEqual(2008, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].bar.Extensions[
+            unittest_custom_options_pb2.corge].qux)
+    self.assertEqual(741, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].Extensions[
+            unittest_custom_options_pb2.garply].foo)
+    self.assertEqual(1998, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].Extensions[
+            unittest_custom_options_pb2.garply].Extensions[
+                unittest_custom_options_pb2.quux])
+    self.assertEqual(2121, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].Extensions[
+            unittest_custom_options_pb2.garply].Extensions[
+                unittest_custom_options_pb2.corge].qux)
+    self.assertEqual(1971, options.Extensions[
+        unittest_custom_options_pb2.ComplexOptionType2
+        .ComplexOptionType4.complex_opt4].waldo)
+    self.assertEqual(321, options.Extensions[
+        unittest_custom_options_pb2.complex_opt2].fred.waldo)
+    self.assertEqual(9, options.Extensions[
+        unittest_custom_options_pb2.complex_opt3].qux)
+    self.assertEqual(22, options.Extensions[
+        unittest_custom_options_pb2.complex_opt3].complexoptiontype5.plugh)
+    self.assertEqual(24, options.Extensions[
+        unittest_custom_options_pb2.complexopt6].xyzzy)
+
+  # Check that aggregate options were parsed and saved correctly in
+  # the appropriate descriptors.
+  def testAggregateOptions(self):
+    file_descriptor = unittest_custom_options_pb2.DESCRIPTOR
+    message_descriptor =\
+        unittest_custom_options_pb2.AggregateMessage.DESCRIPTOR
+    field_descriptor = message_descriptor.fields_by_name["fieldname"]
+    enum_descriptor = unittest_custom_options_pb2.AggregateEnum.DESCRIPTOR
+    enum_value_descriptor = enum_descriptor.values_by_name["VALUE"]
+    service_descriptor =\
+        unittest_custom_options_pb2.AggregateService.DESCRIPTOR
+    method_descriptor = service_descriptor.FindMethodByName("Method")
+
+    # Tests for the different types of data embedded in fileopt
+    file_options = file_descriptor.GetOptions().Extensions[
+        unittest_custom_options_pb2.fileopt]
+    self.assertEqual(100, file_options.i)
+    self.assertEqual("FileAnnotation", file_options.s)
+    self.assertEqual("NestedFileAnnotation", file_options.sub.s)
+    self.assertEqual("FileExtensionAnnotation", file_options.file.Extensions[
+        unittest_custom_options_pb2.fileopt].s)
+    self.assertEqual("EmbeddedMessageSetElement", file_options.mset.Extensions[
+        unittest_custom_options_pb2.AggregateMessageSetElement
+        .message_set_extension].s)
+
+    # Simple tests for all the other types of annotations
+    self.assertEqual(
+        "MessageAnnotation",
+        message_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.msgopt].s)
+    self.assertEqual(
+        "FieldAnnotation",
+        field_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.fieldopt].s)
+    self.assertEqual(
+        "EnumAnnotation",
+        enum_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.enumopt].s)
+    self.assertEqual(
+        "EnumValueAnnotation",
+        enum_value_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.enumvalopt].s)
+    self.assertEqual(
+        "ServiceAnnotation",
+        service_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.serviceopt].s)
+    self.assertEqual(
+        "MethodAnnotation",
+        method_descriptor.GetOptions().Extensions[
+            unittest_custom_options_pb2.methodopt].s)
+
+  def testNestedOptions(self):
+    nested_message =\
+        unittest_custom_options_pb2.NestedOptionType.NestedMessage.DESCRIPTOR
+    self.assertEqual(1001, nested_message.GetOptions().Extensions[
+        unittest_custom_options_pb2.message_opt1])
+    nested_field = nested_message.fields_by_name["nested_field"]
+    self.assertEqual(1002, nested_field.GetOptions().Extensions[
+        unittest_custom_options_pb2.field_opt1])
+    outer_message =\
+        unittest_custom_options_pb2.NestedOptionType.DESCRIPTOR
+    nested_enum = outer_message.enum_types_by_name["NestedEnum"]
+    self.assertEqual(1003, nested_enum.GetOptions().Extensions[
+        unittest_custom_options_pb2.enum_opt1])
+    nested_enum_value = outer_message.enum_values_by_name["NESTED_ENUM_VALUE"]
+    self.assertEqual(1004, nested_enum_value.GetOptions().Extensions[
+        unittest_custom_options_pb2.enum_value_opt1])
+    nested_extension = outer_message.extensions_by_name["nested_extension"]
+    self.assertEqual(1005, nested_extension.GetOptions().Extensions[
+        unittest_custom_options_pb2.field_opt2])
+
   def testFileDescriptorReferences(self):
     self.assertEqual(self.my_enum.file, self.my_file)
     self.assertEqual(self.my_message.file, self.my_file)
@@ -273,6 +534,7 @@ class DescriptorCopyToProtoTest(unittest.TestCase):
     UNITTEST_IMPORT_FILE_DESCRIPTOR_ASCII = ("""
       name: 'google/protobuf/unittest_import.proto'
       package: 'protobuf_unittest_import'
+      dependency: 'google/protobuf/unittest_import_public.proto'
       message_type: <
         name: 'ImportMessage'
         field: <
@@ -302,6 +564,7 @@ class DescriptorCopyToProtoTest(unittest.TestCase):
         java_package: 'com.google.protobuf.test'
         optimize_for: 1  # SPEED
       >
+      public_dependency: 0
       """)
 
     self._InternalTestCopyToProto(
@@ -330,5 +593,21 @@ class DescriptorCopyToProtoTest(unittest.TestCase):
         TEST_SERVICE_ASCII)
 
 
+class MakeDescriptorTest(unittest.TestCase):
+  def testMakeDescriptorWithUnsignedIntField(self):
+    file_descriptor_proto = descriptor_pb2.FileDescriptorProto()
+    file_descriptor_proto.name = 'Foo'
+    message_type = file_descriptor_proto.message_type.add()
+    message_type.name = file_descriptor_proto.name
+    field = message_type.field.add()
+    field.number = 1
+    field.name = 'uint64_field'
+    field.label = descriptor.FieldDescriptor.LABEL_REQUIRED
+    field.type = descriptor.FieldDescriptor.TYPE_UINT64
+    result = descriptor.MakeDescriptor(message_type)
+    self.assertEqual(result.fields[0].cpp_type,
+                     descriptor.FieldDescriptor.CPPTYPE_UINT64)
+
+
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/enum_type_wrapper.py b/python/google/protobuf/internal/enum_type_wrapper.py
new file mode 100644
index 00000000..7b28645a
--- /dev/null
+++ b/python/google/protobuf/internal/enum_type_wrapper.py
@@ -0,0 +1,89 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A simple wrapper around enum types to expose utility functions.
+
+Instances are created as properties with the same name as the enum they wrap
+on proto classes.  For usage, see:
+  reflection_test.py
+"""
+
+__author__ = 'rabsatt@google.com (Kevin Rabsatt)'
+
+
+class EnumTypeWrapper(object):
+  """A utility for finding the names of enum values."""
+
+  DESCRIPTOR = None
+
+  def __init__(self, enum_type):
+    """Inits EnumTypeWrapper with an EnumDescriptor."""
+    self._enum_type = enum_type
+    self.DESCRIPTOR = enum_type;
+
+  def Name(self, number):
+    """Returns a string containing the name of an enum value."""
+    if number in self._enum_type.values_by_number:
+      return self._enum_type.values_by_number[number].name
+    raise ValueError('Enum %s has no name defined for value %d' % (
+        self._enum_type.name, number))
+
+  def Value(self, name):
+    """Returns the value coresponding to the given enum name."""
+    if name in self._enum_type.values_by_name:
+      return self._enum_type.values_by_name[name].number
+    raise ValueError('Enum %s has no value defined for name %s' % (
+        self._enum_type.name, name))
+
+  def keys(self):
+    """Return a list of the string names in the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+
+    return [value_descriptor.name
+            for value_descriptor in self._enum_type.values]
+
+  def values(self):
+    """Return a list of the integer values in the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+
+    return [value_descriptor.number
+            for value_descriptor in self._enum_type.values]
+
+  def items(self):
+    """Return a list of the (name, value) pairs of the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+    return [(value_descriptor.name, value_descriptor.number)
+            for value_descriptor in self._enum_type.values]
diff --git a/python/google/protobuf/internal/factory_test1.proto b/python/google/protobuf/internal/factory_test1.proto
new file mode 100644
index 00000000..9f55e037
--- /dev/null
+++ b/python/google/protobuf/internal/factory_test1.proto
@@ -0,0 +1,55 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: matthewtoia@google.com (Matt Toia)
+
+
+package google.protobuf.python.internal;
+
+
+enum Factory1Enum {
+  FACTORY_1_VALUE_0 = 0;
+  FACTORY_1_VALUE_1 = 1;
+}
+
+message Factory1Message {
+  optional Factory1Enum factory_1_enum = 1;
+  enum NestedFactory1Enum {
+    NESTED_FACTORY_1_VALUE_0 = 0;
+    NESTED_FACTORY_1_VALUE_1 = 1;
+  }
+  optional NestedFactory1Enum nested_factory_1_enum = 2;
+  message NestedFactory1Message {
+    optional string value = 1;
+  }
+  optional NestedFactory1Message nested_factory_1_message = 3;
+  optional int32 scalar_value = 4;
+  repeated string list_value = 5;
+}
diff --git a/python/google/protobuf/internal/factory_test2.proto b/python/google/protobuf/internal/factory_test2.proto
new file mode 100644
index 00000000..d3ce4d7f
--- /dev/null
+++ b/python/google/protobuf/internal/factory_test2.proto
@@ -0,0 +1,77 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: matthewtoia@google.com (Matt Toia)
+
+
+package google.protobuf.python.internal;
+
+import "google/protobuf/internal/factory_test1.proto";
+
+
+enum Factory2Enum {
+  FACTORY_2_VALUE_0 = 0;
+  FACTORY_2_VALUE_1 = 1;
+}
+
+message Factory2Message {
+  required int32 mandatory = 1;
+  optional Factory2Enum factory_2_enum = 2;
+  enum NestedFactory2Enum {
+    NESTED_FACTORY_2_VALUE_0 = 0;
+    NESTED_FACTORY_2_VALUE_1 = 1;
+  }
+  optional NestedFactory2Enum nested_factory_2_enum = 3;
+  message NestedFactory2Message {
+    optional string value = 1;
+  }
+  optional NestedFactory2Message nested_factory_2_message = 4;
+  optional Factory1Message factory_1_message = 5;
+  optional Factory1Enum factory_1_enum = 6;
+  optional Factory1Message.NestedFactory1Enum nested_factory_1_enum = 7;
+  optional Factory1Message.NestedFactory1Message nested_factory_1_message = 8;
+  optional Factory2Message circular_message = 9;
+  optional string scalar_value = 10;
+  repeated string list_value = 11;
+  repeated group Grouped = 12 {
+    optional string part_1 = 13;
+    optional string part_2 = 14;
+  }
+  optional LoopMessage loop = 15;
+  optional int32 int_with_default = 16 [default = 1776];
+  optional double double_with_default = 17 [default = 9.99];
+  optional string string_with_default = 18 [default = "hello world"];
+  optional bool bool_with_default = 19 [default = false];
+  optional Factory2Enum enum_with_default = 20 [default = FACTORY_2_VALUE_1];
+}
+
+message LoopMessage {
+  optional Factory2Message loop = 1;
+}
diff --git a/python/google/protobuf/internal/generator_test.py b/python/google/protobuf/internal/generator_test.py
index b3f7d9b1..8343aba1 100755
--- a/python/google/protobuf/internal/generator_test.py
+++ b/python/google/protobuf/internal/generator_test.py
@@ -42,8 +42,10 @@ further ensures that we can use Python protocol message objects as we expect.
 __author__ = 'robinson@google.com (Will Robinson)'
 
 import unittest
+from google.protobuf.internal import test_bad_identifiers_pb2
 from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_import_pb2
+from google.protobuf import unittest_import_public_pb2
 from google.protobuf import unittest_mset_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import unittest_no_generic_services_pb2
@@ -239,6 +241,29 @@ class GeneratorTest(unittest.TestCase):
         unittest_pb2._TESTALLTYPES_NESTEDMESSAGE.name in
         file_type.message_types_by_name)
 
+  def testPublicImports(self):
+    # Test public imports as embedded message.
+    all_type_proto = unittest_pb2.TestAllTypes()
+    self.assertEqual(0, all_type_proto.optional_public_import_message.e)
+
+    # PublicImportMessage is actually defined in unittest_import_public_pb2
+    # module, and is public imported by unittest_import_pb2 module.
+    public_import_proto = unittest_import_pb2.PublicImportMessage()
+    self.assertEqual(0, public_import_proto.e)
+    self.assertTrue(unittest_import_public_pb2.PublicImportMessage is
+                    unittest_import_pb2.PublicImportMessage)
+
+  def testBadIdentifiers(self):
+    # We're just testing that the code was imported without problems.
+    message = test_bad_identifiers_pb2.TestBadIdentifiers()
+    self.assertEqual(message.Extensions[test_bad_identifiers_pb2.message],
+                     "foo")
+    self.assertEqual(message.Extensions[test_bad_identifiers_pb2.descriptor],
+                     "bar")
+    self.assertEqual(message.Extensions[test_bad_identifiers_pb2.reflection],
+                     "baz")
+    self.assertEqual(message.Extensions[test_bad_identifiers_pb2.service],
+                     "qux")
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/message_cpp_test.py b/python/google/protobuf/internal/message_cpp_test.py
new file mode 100644
index 00000000..0d84b320
--- /dev/null
+++ b/python/google/protobuf/internal/message_cpp_test.py
@@ -0,0 +1,45 @@
+#! /usr/bin/python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for google.protobuf.internal.message_cpp."""
+
+__author__ = 'shahms@google.com (Shahms King)'
+
+import os
+os.environ['PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'] = 'cpp'
+
+import unittest
+from google.protobuf.internal.message_test import *
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/message_factory_test.py b/python/google/protobuf/internal/message_factory_test.py
new file mode 100644
index 00000000..0bc9be99
--- /dev/null
+++ b/python/google/protobuf/internal/message_factory_test.py
@@ -0,0 +1,113 @@
+#! /usr/bin/python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for google.protobuf.message_factory."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+import unittest
+from google.protobuf import descriptor_pb2
+from google.protobuf.internal import factory_test1_pb2
+from google.protobuf.internal import factory_test2_pb2
+from google.protobuf import descriptor_database
+from google.protobuf import descriptor_pool
+from google.protobuf import message_factory
+
+
+class MessageFactoryTest(unittest.TestCase):
+
+  def setUp(self):
+    self.factory_test1_fd = descriptor_pb2.FileDescriptorProto.FromString(
+        factory_test1_pb2.DESCRIPTOR.serialized_pb)
+    self.factory_test2_fd = descriptor_pb2.FileDescriptorProto.FromString(
+        factory_test2_pb2.DESCRIPTOR.serialized_pb)
+
+  def _ExerciseDynamicClass(self, cls):
+    msg = cls()
+    msg.mandatory = 42
+    msg.nested_factory_2_enum = 0
+    msg.nested_factory_2_message.value = 'nested message value'
+    msg.factory_1_message.factory_1_enum = 1
+    msg.factory_1_message.nested_factory_1_enum = 0
+    msg.factory_1_message.nested_factory_1_message.value = (
+        'nested message value')
+    msg.factory_1_message.scalar_value = 22
+    msg.factory_1_message.list_value.extend(['one', 'two', 'three'])
+    msg.factory_1_message.list_value.append('four')
+    msg.factory_1_enum = 1
+    msg.nested_factory_1_enum = 0
+    msg.nested_factory_1_message.value = 'nested message value'
+    msg.circular_message.mandatory = 1
+    msg.circular_message.circular_message.mandatory = 2
+    msg.circular_message.scalar_value = 'one deep'
+    msg.scalar_value = 'zero deep'
+    msg.list_value.extend(['four', 'three', 'two'])
+    msg.list_value.append('one')
+    msg.grouped.add()
+    msg.grouped[0].part_1 = 'hello'
+    msg.grouped[0].part_2 = 'world'
+    msg.grouped.add(part_1='testing', part_2='123')
+    msg.loop.loop.mandatory = 2
+    msg.loop.loop.loop.loop.mandatory = 4
+    serialized = msg.SerializeToString()
+    converted = factory_test2_pb2.Factory2Message.FromString(serialized)
+    reserialized = converted.SerializeToString()
+    self.assertEquals(serialized, reserialized)
+    result = cls.FromString(reserialized)
+    self.assertEquals(msg, result)
+
+  def testGetPrototype(self):
+    db = descriptor_database.DescriptorDatabase()
+    pool = descriptor_pool.DescriptorPool(db)
+    db.Add(self.factory_test1_fd)
+    db.Add(self.factory_test2_fd)
+    factory = message_factory.MessageFactory()
+    cls = factory.GetPrototype(pool.FindMessageTypeByName(
+        'net.proto2.python.internal.Factory2Message'))
+    self.assertIsNot(cls, factory_test2_pb2.Factory2Message)
+    self._ExerciseDynamicClass(cls)
+    cls2 = factory.GetPrototype(pool.FindMessageTypeByName(
+        'net.proto2.python.internal.Factory2Message'))
+    self.assertIs(cls, cls2)
+
+  def testGetMessages(self):
+    messages = message_factory.GetMessages([self.factory_test2_fd,
+                                            self.factory_test1_fd])
+    self.assertContainsSubset(
+        ['net.proto2.python.internal.Factory2Message',
+         'net.proto2.python.internal.Factory1Message'],
+        messages.keys())
+    self._ExerciseDynamicClass(
+        messages['net.proto2.python.internal.Factory2Message'])
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/message_test.py b/python/google/protobuf/internal/message_test.py
index 65174373..53e9d507 100755
--- a/python/google/protobuf/internal/message_test.py
+++ b/python/google/protobuf/internal/message_test.py
@@ -45,10 +45,15 @@ __author__ = 'gps@google.com (Gregory P. Smith)'
 
 import copy
 import math
+import operator
+import pickle
+
 import unittest
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
+from google.protobuf.internal import api_implementation
 from google.protobuf.internal import test_util
+from google.protobuf import message
 
 # Python pre-2.6 does not have isinf() or isnan() functions, so we have
 # to provide our own.
@@ -70,9 +75,9 @@ class MessageTest(unittest.TestCase):
     golden_message = unittest_pb2.TestAllTypes()
     golden_message.ParseFromString(golden_data)
     test_util.ExpectAllFieldsSet(self, golden_message)
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
     golden_copy = copy.deepcopy(golden_message)
-    self.assertTrue(golden_copy.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_copy.SerializeToString())
 
   def testGoldenExtensions(self):
     golden_data = test_util.GoldenFile('golden_message').read()
@@ -81,9 +86,9 @@ class MessageTest(unittest.TestCase):
     all_set = unittest_pb2.TestAllExtensions()
     test_util.SetAllExtensions(all_set)
     self.assertEquals(all_set, golden_message)
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
     golden_copy = copy.deepcopy(golden_message)
-    self.assertTrue(golden_copy.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_copy.SerializeToString())
 
   def testGoldenPackedMessage(self):
     golden_data = test_util.GoldenFile('golden_packed_fields_message').read()
@@ -92,9 +97,9 @@ class MessageTest(unittest.TestCase):
     all_set = unittest_pb2.TestPackedTypes()
     test_util.SetAllPackedFields(all_set)
     self.assertEquals(all_set, golden_message)
-    self.assertTrue(all_set.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, all_set.SerializeToString())
     golden_copy = copy.deepcopy(golden_message)
-    self.assertTrue(golden_copy.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_copy.SerializeToString())
 
   def testGoldenPackedExtensions(self):
     golden_data = test_util.GoldenFile('golden_packed_fields_message').read()
@@ -103,9 +108,28 @@ class MessageTest(unittest.TestCase):
     all_set = unittest_pb2.TestPackedExtensions()
     test_util.SetAllPackedExtensions(all_set)
     self.assertEquals(all_set, golden_message)
-    self.assertTrue(all_set.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, all_set.SerializeToString())
     golden_copy = copy.deepcopy(golden_message)
-    self.assertTrue(golden_copy.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_copy.SerializeToString())
+
+  def testPickleSupport(self):
+    golden_data = test_util.GoldenFile('golden_message').read()
+    golden_message = unittest_pb2.TestAllTypes()
+    golden_message.ParseFromString(golden_data)
+    pickled_message = pickle.dumps(golden_message)
+
+    unpickled_message = pickle.loads(pickled_message)
+    self.assertEquals(unpickled_message, golden_message)
+
+  def testPickleIncompleteProto(self):
+    golden_message = unittest_pb2.TestRequired(a=1)
+    pickled_message = pickle.dumps(golden_message)
+
+    unpickled_message = pickle.loads(pickled_message)
+    self.assertEquals(unpickled_message, golden_message)
+    self.assertEquals(unpickled_message.a, 1)
+    # This is still an incomplete proto - so serializing should fail
+    self.assertRaises(message.EncodeError, unpickled_message.SerializeToString)
 
   def testPositiveInfinity(self):
     golden_data = ('\x5D\x00\x00\x80\x7F'
@@ -118,7 +142,7 @@ class MessageTest(unittest.TestCase):
     self.assertTrue(IsPosInf(golden_message.optional_double))
     self.assertTrue(IsPosInf(golden_message.repeated_float[0]))
     self.assertTrue(IsPosInf(golden_message.repeated_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
 
   def testNegativeInfinity(self):
     golden_data = ('\x5D\x00\x00\x80\xFF'
@@ -131,7 +155,7 @@ class MessageTest(unittest.TestCase):
     self.assertTrue(IsNegInf(golden_message.optional_double))
     self.assertTrue(IsNegInf(golden_message.repeated_float[0]))
     self.assertTrue(IsNegInf(golden_message.repeated_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
 
   def testNotANumber(self):
     golden_data = ('\x5D\x00\x00\xC0\x7F'
@@ -144,7 +168,18 @@ class MessageTest(unittest.TestCase):
     self.assertTrue(isnan(golden_message.optional_double))
     self.assertTrue(isnan(golden_message.repeated_float[0]))
     self.assertTrue(isnan(golden_message.repeated_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+    # The protocol buffer may serialize to any one of multiple different
+    # representations of a NaN.  Rather than verify a specific representation,
+    # verify the serialized string can be converted into a correctly
+    # behaving protocol buffer.
+    serialized = golden_message.SerializeToString()
+    message = unittest_pb2.TestAllTypes()
+    message.ParseFromString(serialized)
+    self.assertTrue(isnan(message.optional_float))
+    self.assertTrue(isnan(message.optional_double))
+    self.assertTrue(isnan(message.repeated_float[0]))
+    self.assertTrue(isnan(message.repeated_double[0]))
 
   def testPositiveInfinityPacked(self):
     golden_data = ('\xA2\x06\x04\x00\x00\x80\x7F'
@@ -153,7 +188,7 @@ class MessageTest(unittest.TestCase):
     golden_message.ParseFromString(golden_data)
     self.assertTrue(IsPosInf(golden_message.packed_float[0]))
     self.assertTrue(IsPosInf(golden_message.packed_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
 
   def testNegativeInfinityPacked(self):
     golden_data = ('\xA2\x06\x04\x00\x00\x80\xFF'
@@ -162,7 +197,7 @@ class MessageTest(unittest.TestCase):
     golden_message.ParseFromString(golden_data)
     self.assertTrue(IsNegInf(golden_message.packed_float[0]))
     self.assertTrue(IsNegInf(golden_message.packed_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+    self.assertEqual(golden_data, golden_message.SerializeToString())
 
   def testNotANumberPacked(self):
     golden_data = ('\xA2\x06\x04\x00\x00\xC0\x7F'
@@ -171,7 +206,12 @@ class MessageTest(unittest.TestCase):
     golden_message.ParseFromString(golden_data)
     self.assertTrue(isnan(golden_message.packed_float[0]))
     self.assertTrue(isnan(golden_message.packed_double[0]))
-    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+    serialized = golden_message.SerializeToString()
+    message = unittest_pb2.TestPackedTypes()
+    message.ParseFromString(serialized)
+    self.assertTrue(isnan(message.packed_float[0]))
+    self.assertTrue(isnan(message.packed_double[0]))
 
   def testExtremeFloatValues(self):
     message = unittest_pb2.TestAllTypes()
@@ -218,7 +258,7 @@ class MessageTest(unittest.TestCase):
     message.ParseFromString(message.SerializeToString())
     self.assertTrue(message.optional_float == -kMostNegExponentOneSigBit)
 
-  def testExtremeFloatValues(self):
+  def testExtremeDoubleValues(self):
     message = unittest_pb2.TestAllTypes()
 
     # Most positive exponent, no significand bits set.
@@ -338,6 +378,117 @@ class MessageTest(unittest.TestCase):
     self.assertEqual(message.repeated_nested_message[4].bb, 5)
     self.assertEqual(message.repeated_nested_message[5].bb, 6)
 
+  def testRepeatedCompositeFieldSortArguments(self):
+    """Check sorting a repeated composite field using list.sort() arguments."""
+    message = unittest_pb2.TestAllTypes()
+
+    get_bb = operator.attrgetter('bb')
+    cmp_bb = lambda a, b: cmp(a.bb, b.bb)
+    message.repeated_nested_message.add().bb = 1
+    message.repeated_nested_message.add().bb = 3
+    message.repeated_nested_message.add().bb = 2
+    message.repeated_nested_message.add().bb = 6
+    message.repeated_nested_message.add().bb = 5
+    message.repeated_nested_message.add().bb = 4
+    message.repeated_nested_message.sort(key=get_bb)
+    self.assertEqual([k.bb for k in message.repeated_nested_message],
+                     [1, 2, 3, 4, 5, 6])
+    message.repeated_nested_message.sort(key=get_bb, reverse=True)
+    self.assertEqual([k.bb for k in message.repeated_nested_message],
+                     [6, 5, 4, 3, 2, 1])
+    message.repeated_nested_message.sort(sort_function=cmp_bb)
+    self.assertEqual([k.bb for k in message.repeated_nested_message],
+                     [1, 2, 3, 4, 5, 6])
+    message.repeated_nested_message.sort(cmp=cmp_bb, reverse=True)
+    self.assertEqual([k.bb for k in message.repeated_nested_message],
+                     [6, 5, 4, 3, 2, 1])
+
+  def testRepeatedScalarFieldSortArguments(self):
+    """Check sorting a scalar field using list.sort() arguments."""
+    message = unittest_pb2.TestAllTypes()
+
+    abs_cmp = lambda a, b: cmp(abs(a), abs(b))
+    message.repeated_int32.append(-3)
+    message.repeated_int32.append(-2)
+    message.repeated_int32.append(-1)
+    message.repeated_int32.sort(key=abs)
+    self.assertEqual(list(message.repeated_int32), [-1, -2, -3])
+    message.repeated_int32.sort(key=abs, reverse=True)
+    self.assertEqual(list(message.repeated_int32), [-3, -2, -1])
+    message.repeated_int32.sort(sort_function=abs_cmp)
+    self.assertEqual(list(message.repeated_int32), [-1, -2, -3])
+    message.repeated_int32.sort(cmp=abs_cmp, reverse=True)
+    self.assertEqual(list(message.repeated_int32), [-3, -2, -1])
+
+    len_cmp = lambda a, b: cmp(len(a), len(b))
+    message.repeated_string.append('aaa')
+    message.repeated_string.append('bb')
+    message.repeated_string.append('c')
+    message.repeated_string.sort(key=len)
+    self.assertEqual(list(message.repeated_string), ['c', 'bb', 'aaa'])
+    message.repeated_string.sort(key=len, reverse=True)
+    self.assertEqual(list(message.repeated_string), ['aaa', 'bb', 'c'])
+    message.repeated_string.sort(sort_function=len_cmp)
+    self.assertEqual(list(message.repeated_string), ['c', 'bb', 'aaa'])
+    message.repeated_string.sort(cmp=len_cmp, reverse=True)
+    self.assertEqual(list(message.repeated_string), ['aaa', 'bb', 'c'])
+
+  def testParsingMerge(self):
+    """Check the merge behavior when a required or optional field appears
+    multiple times in the input."""
+    messages = [
+        unittest_pb2.TestAllTypes(),
+        unittest_pb2.TestAllTypes(),
+        unittest_pb2.TestAllTypes() ]
+    messages[0].optional_int32 = 1
+    messages[1].optional_int64 = 2
+    messages[2].optional_int32 = 3
+    messages[2].optional_string = 'hello'
+
+    merged_message = unittest_pb2.TestAllTypes()
+    merged_message.optional_int32 = 3
+    merged_message.optional_int64 = 2
+    merged_message.optional_string = 'hello'
+
+    generator = unittest_pb2.TestParsingMerge.RepeatedFieldsGenerator()
+    generator.field1.extend(messages)
+    generator.field2.extend(messages)
+    generator.field3.extend(messages)
+    generator.ext1.extend(messages)
+    generator.ext2.extend(messages)
+    generator.group1.add().field1.MergeFrom(messages[0])
+    generator.group1.add().field1.MergeFrom(messages[1])
+    generator.group1.add().field1.MergeFrom(messages[2])
+    generator.group2.add().field1.MergeFrom(messages[0])
+    generator.group2.add().field1.MergeFrom(messages[1])
+    generator.group2.add().field1.MergeFrom(messages[2])
+
+    data = generator.SerializeToString()
+    parsing_merge = unittest_pb2.TestParsingMerge()
+    parsing_merge.ParseFromString(data)
+
+    # Required and optional fields should be merged.
+    self.assertEqual(parsing_merge.required_all_types, merged_message)
+    self.assertEqual(parsing_merge.optional_all_types, merged_message)
+    self.assertEqual(parsing_merge.optionalgroup.optional_group_all_types,
+                     merged_message)
+    self.assertEqual(parsing_merge.Extensions[
+                     unittest_pb2.TestParsingMerge.optional_ext],
+                     merged_message)
+
+    # Repeated fields should not be merged.
+    self.assertEqual(len(parsing_merge.repeated_all_types), 3)
+    self.assertEqual(len(parsing_merge.repeatedgroup), 3)
+    self.assertEqual(len(parsing_merge.Extensions[
+        unittest_pb2.TestParsingMerge.repeated_ext]), 3)
+
+
+  def testSortEmptyRepeatedCompositeContainer(self):
+    """Exercise a scenario that has led to segfaults in the past.
+    """
+    m = unittest_pb2.TestAllTypes()
+    m.repeated_nested_message.sort()
+
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/more_extensions_dynamic.proto b/python/google/protobuf/internal/more_extensions_dynamic.proto
new file mode 100644
index 00000000..df98ac4b
--- /dev/null
+++ b/python/google/protobuf/internal/more_extensions_dynamic.proto
@@ -0,0 +1,49 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: jasonh@google.com (Jason Hsueh)
+//
+// This file is used to test a corner case in the CPP implementation where the
+// generated C++ type is available for the extendee, but the extension is
+// defined in a file whose C++ type is not in the binary.
+
+
+import "google/protobuf/internal/more_extensions.proto";
+
+package google.protobuf.internal;
+
+message DynamicMessageType {
+  optional int32 a = 1;
+}
+
+extend ExtendedMessage {
+  optional int32 dynamic_int32_extension = 100;
+  optional DynamicMessageType dynamic_message_extension = 101;
+}
diff --git a/python/google/protobuf/internal/python_message.py b/python/google/protobuf/internal/python_message.py
index 66fca918..4bea57ac 100755
--- a/python/google/protobuf/internal/python_message.py
+++ b/python/google/protobuf/internal/python_message.py
@@ -54,6 +54,7 @@ try:
   from cStringIO import StringIO
 except ImportError:
   from StringIO import StringIO
+import copy_reg
 import struct
 import weakref
 
@@ -61,6 +62,7 @@ import weakref
 from google.protobuf.internal import containers
 from google.protobuf.internal import decoder
 from google.protobuf.internal import encoder
+from google.protobuf.internal import enum_type_wrapper
 from google.protobuf.internal import message_listener as message_listener_mod
 from google.protobuf.internal import type_checkers
 from google.protobuf.internal import wire_format
@@ -71,9 +73,10 @@ from google.protobuf import text_format
 _FieldDescriptor = descriptor_mod.FieldDescriptor
 
 
-def NewMessage(descriptor, dictionary):
+def NewMessage(bases, descriptor, dictionary):
   _AddClassAttributesForNestedExtensions(descriptor, dictionary)
   _AddSlots(descriptor, dictionary)
+  return bases
 
 
 def InitMessage(descriptor, cls):
@@ -96,6 +99,7 @@ def InitMessage(descriptor, cls):
   _AddStaticMethods(cls)
   _AddMessageMethods(descriptor, cls)
   _AddPrivateHelperMethods(cls)
+  copy_reg.pickle(cls, lambda obj: (cls, (), obj.__getstate__()))
 
 
 # Stateless helpers for GeneratedProtocolMessageType below.
@@ -145,6 +149,10 @@ def _VerifyExtensionHandle(message, extension_handle):
   if not extension_handle.is_extension:
     raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
 
+  if not extension_handle.containing_type:
+    raise KeyError('"%s" is missing a containing_type.'
+                   % extension_handle.full_name)
+
   if extension_handle.containing_type is not message.DESCRIPTOR:
     raise KeyError('Extension "%s" extends message type "%s", but this '
                    'message is of type "%s".' %
@@ -164,6 +172,7 @@ def _AddSlots(message_descriptor, dictionary):
   dictionary['__slots__'] = ['_cached_byte_size',
                              '_cached_byte_size_dirty',
                              '_fields',
+                             '_unknown_fields',
                              '_is_present_in_parent',
                              '_listener',
                              '_listener_for_children',
@@ -224,11 +233,14 @@ def _AddClassAttributesForNestedExtensions(descriptor, dictionary):
 def _AddEnumValues(descriptor, cls):
   """Sets class-level attributes for all enum fields defined in this message.
 
+  Also exporting a class-level object that can name enum values.
+
   Args:
     descriptor: Descriptor object for this message type.
     cls: Class we're constructing for this message type.
   """
   for enum_type in descriptor.enum_types:
+    setattr(cls, enum_type.name, enum_type_wrapper.EnumTypeWrapper(enum_type))
     for enum_value in enum_type.values:
       setattr(cls, enum_value.name, enum_value.number)
 
@@ -248,7 +260,7 @@ def _DefaultValueConstructorForField(field):
   """
 
   if field.label == _FieldDescriptor.LABEL_REPEATED:
-    if field.default_value != []:
+    if field.has_default_value and field.default_value != []:
       raise ValueError('Repeated field default value not empty list: %s' % (
           field.default_value))
     if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
@@ -276,6 +288,8 @@ def _DefaultValueConstructorForField(field):
     return MakeSubMessageDefault
 
   def MakeScalarDefault(message):
+    # TODO(protobuf-team): This may be broken since there may not be
+    # default_value.  Combine with has_default_value somehow.
     return field.default_value
   return MakeScalarDefault
 
@@ -287,6 +301,9 @@ def _AddInitMethod(message_descriptor, cls):
     self._cached_byte_size = 0
     self._cached_byte_size_dirty = len(kwargs) > 0
     self._fields = {}
+    # _unknown_fields is () when empty for efficiency, and will be turned into
+    # a list if fields are added.
+    self._unknown_fields = ()
     self._is_present_in_parent = False
     self._listener = message_listener_mod.NullMessageListener()
     self._listener_for_children = _Listener(self)
@@ -428,6 +445,8 @@ def _AddPropertiesForNonRepeatedScalarField(field, cls):
   valid_values = set()
 
   def getter(self):
+    # TODO(protobuf-team): This may be broken since there may not be
+    # default_value.  Combine with has_default_value somehow.
     return self._fields.get(field, default_value)
   getter.__module__ = None
   getter.__doc__ = 'Getter for %s.' % proto_field_name
@@ -462,13 +481,18 @@ def _AddPropertiesForNonRepeatedCompositeField(field, cls):
   # for non-repeated scalars.
   proto_field_name = field.name
   property_name = _PropertyName(proto_field_name)
+
+  # TODO(komarek): Can anyone explain to me why we cache the message_type this
+  # way, instead of referring to field.message_type inside of getter(self)?
+  # What if someone sets message_type later on (which makes for simpler
+  # dyanmic proto descriptor and class creation code).
   message_type = field.message_type
 
   def getter(self):
     field_value = self._fields.get(field)
     if field_value is None:
       # Construct a new object to represent this field.
-      field_value = message_type._concrete_class()
+      field_value = message_type._concrete_class()  # use field.message_type?
       field_value._SetListener(self._listener_for_children)
 
       # Atomically check if another thread has preempted us and, if not, swap
@@ -620,6 +644,7 @@ def _AddClearMethod(message_descriptor, cls):
   def Clear(self):
     # Clear fields.
     self._fields = {}
+    self._unknown_fields = ()
     self._Modified()
   cls.Clear = Clear
 
@@ -649,7 +674,16 @@ def _AddEqualsMethod(message_descriptor, cls):
     if self is other:
       return True
 
-    return self.ListFields() == other.ListFields()
+    if not self.ListFields() == other.ListFields():
+      return False
+
+    # Sort unknown fields because their order shouldn't affect equality test.
+    unknown_fields = list(self._unknown_fields)
+    unknown_fields.sort()
+    other_unknown_fields = list(other._unknown_fields)
+    other_unknown_fields.sort()
+
+    return unknown_fields == other_unknown_fields
 
   cls.__eq__ = __eq__
 
@@ -710,6 +744,9 @@ def _AddByteSizeMethod(message_descriptor, cls):
     for field_descriptor, field_value in self.ListFields():
       size += field_descriptor._sizer(field_value)
 
+    for tag_bytes, value_bytes in self._unknown_fields:
+      size += len(tag_bytes) + len(value_bytes)
+
     self._cached_byte_size = size
     self._cached_byte_size_dirty = False
     self._listener_for_children.dirty = False
@@ -726,8 +763,8 @@ def _AddSerializeToStringMethod(message_descriptor, cls):
     errors = []
     if not self.IsInitialized():
       raise message_mod.EncodeError(
-          'Message is missing required fields: ' +
-          ','.join(self.FindInitializationErrors()))
+          'Message %s is missing required fields: %s' % (
+          self.DESCRIPTOR.full_name, ','.join(self.FindInitializationErrors())))
     return self.SerializePartialToString()
   cls.SerializeToString = SerializeToString
 
@@ -744,6 +781,9 @@ def _AddSerializePartialToStringMethod(message_descriptor, cls):
   def InternalSerialize(self, write_bytes):
     for field_descriptor, field_value in self.ListFields():
       field_descriptor._encoder(write_bytes, field_value)
+    for tag_bytes, value_bytes in self._unknown_fields:
+      write_bytes(tag_bytes)
+      write_bytes(value_bytes)
   cls._InternalSerialize = InternalSerialize
 
 
@@ -770,13 +810,18 @@ def _AddMergeFromStringMethod(message_descriptor, cls):
   def InternalParse(self, buffer, pos, end):
     self._Modified()
     field_dict = self._fields
+    unknown_field_list = self._unknown_fields
     while pos != end:
       (tag_bytes, new_pos) = local_ReadTag(buffer, pos)
       field_decoder = decoders_by_tag.get(tag_bytes)
       if field_decoder is None:
+        value_start_pos = new_pos
         new_pos = local_SkipField(buffer, new_pos, end, tag_bytes)
         if new_pos == -1:
           return pos
+        if not unknown_field_list:
+          unknown_field_list = self._unknown_fields = []
+        unknown_field_list.append((tag_bytes, buffer[value_start_pos:new_pos]))
         pos = new_pos
       else:
         pos = field_decoder(buffer, new_pos, end, self, field_dict)
@@ -873,7 +918,8 @@ def _AddMergeFromMethod(cls):
   def MergeFrom(self, msg):
     if not isinstance(msg, cls):
       raise TypeError(
-          "Parameter to MergeFrom() must be instance of same class.")
+          "Parameter to MergeFrom() must be instance of same class: "
+          "expected %s got %s." % (cls.__name__, type(msg).__name__))
 
     assert msg is not self
     self._Modified()
@@ -898,6 +944,12 @@ def _AddMergeFromMethod(cls):
           field_value.MergeFrom(value)
       else:
         self._fields[field] = value
+
+    if msg._unknown_fields:
+      if not self._unknown_fields:
+        self._unknown_fields = []
+      self._unknown_fields.extend(msg._unknown_fields)
+
   cls.MergeFrom = MergeFrom
 
 
diff --git a/python/google/protobuf/internal/reflection_cpp_generated_test.py b/python/google/protobuf/internal/reflection_cpp_generated_test.py
new file mode 100755
index 00000000..2a0a5124
--- /dev/null
+++ b/python/google/protobuf/internal/reflection_cpp_generated_test.py
@@ -0,0 +1,91 @@
+#! /usr/bin/python
+# -*- coding: utf-8 -*-
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Unittest for reflection.py, which tests the generated C++ implementation."""
+
+__author__ = 'jasonh@google.com (Jason Hsueh)'
+
+import os
+os.environ['PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'] = 'cpp'
+
+import unittest
+from google.protobuf.internal import api_implementation
+from google.protobuf.internal import more_extensions_dynamic_pb2
+from google.protobuf.internal import more_extensions_pb2
+from google.protobuf.internal.reflection_test import *
+
+
+class ReflectionCppTest(unittest.TestCase):
+  def testImplementationSetting(self):
+    self.assertEqual('cpp', api_implementation.Type())
+
+  def testExtensionOfGeneratedTypeInDynamicFile(self):
+    """Tests that a file built dynamically can extend a generated C++ type.
+
+    The C++ implementation uses a DescriptorPool that has the generated
+    DescriptorPool as an underlay. Typically, a type can only find
+    extensions in its own pool. With the python C-extension, the generated C++
+    extendee may be available, but not the extension. This tests that the
+    C-extension implements the correct special handling to make such extensions
+    available.
+    """
+    pb1 = more_extensions_pb2.ExtendedMessage()
+    # Test that basic accessors work.
+    self.assertFalse(
+        pb1.HasExtension(more_extensions_dynamic_pb2.dynamic_int32_extension))
+    self.assertFalse(
+        pb1.HasExtension(more_extensions_dynamic_pb2.dynamic_message_extension))
+    pb1.Extensions[more_extensions_dynamic_pb2.dynamic_int32_extension] = 17
+    pb1.Extensions[more_extensions_dynamic_pb2.dynamic_message_extension].a = 24
+    self.assertTrue(
+        pb1.HasExtension(more_extensions_dynamic_pb2.dynamic_int32_extension))
+    self.assertTrue(
+        pb1.HasExtension(more_extensions_dynamic_pb2.dynamic_message_extension))
+
+    # Now serialize the data and parse to a new message.
+    pb2 = more_extensions_pb2.ExtendedMessage()
+    pb2.MergeFromString(pb1.SerializeToString())
+
+    self.assertTrue(
+        pb2.HasExtension(more_extensions_dynamic_pb2.dynamic_int32_extension))
+    self.assertTrue(
+        pb2.HasExtension(more_extensions_dynamic_pb2.dynamic_message_extension))
+    self.assertEqual(
+        17, pb2.Extensions[more_extensions_dynamic_pb2.dynamic_int32_extension])
+    self.assertEqual(
+        24,
+        pb2.Extensions[more_extensions_dynamic_pb2.dynamic_message_extension].a)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/reflection_test.py b/python/google/protobuf/internal/reflection_test.py
index 7b9d3398..ed286461 100755
--- a/python/google/protobuf/internal/reflection_test.py
+++ b/python/google/protobuf/internal/reflection_test.py
@@ -37,6 +37,7 @@ pure-Python protocol compiler.
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
+import gc
 import operator
 import struct
 
@@ -318,15 +319,6 @@ class ReflectionTest(unittest.TestCase):
       # ...and ensure that the scalar field has returned to its default.
       self.assertEqual(0, getattr(composite_field, scalar_field_name))
 
-      # Finally, ensure that modifications to the old composite field object
-      # don't have any effect on the parent. Possible only with the pure-python
-      # implementation of the API.
-      #
-      # (NOTE that when we clear the composite field in the parent, we actually
-      # don't recursively clear down the tree.  Instead, we just disconnect the
-      # cleared composite from the tree.)
-      if api_implementation.Type() != 'python':
-        return
       self.assertTrue(old_composite_field is not composite_field)
       setattr(old_composite_field, scalar_field_name, new_val)
       self.assertTrue(not composite_field.HasField(scalar_field_name))
@@ -348,8 +340,6 @@ class ReflectionTest(unittest.TestCase):
     nested.bb = 23
 
   def testDisconnectingNestedMessageBeforeSettingField(self):
-    if api_implementation.Type() != 'python':
-      return
     proto = unittest_pb2.TestAllTypes()
     nested = proto.optional_nested_message
     proto.ClearField('optional_nested_message')  # Should disconnect from parent
@@ -358,6 +348,64 @@ class ReflectionTest(unittest.TestCase):
     self.assertTrue(not proto.HasField('optional_nested_message'))
     self.assertEqual(0, proto.optional_nested_message.bb)
 
+  def testGetDefaultMessageAfterDisconnectingDefaultMessage(self):
+    proto = unittest_pb2.TestAllTypes()
+    nested = proto.optional_nested_message
+    proto.ClearField('optional_nested_message')
+    del proto
+    del nested
+    # Force a garbage collect so that the underlying CMessages are freed along
+    # with the Messages they point to. This is to make sure we're not deleting
+    # default message instances.
+    gc.collect()
+    proto = unittest_pb2.TestAllTypes()
+    nested = proto.optional_nested_message
+
+  def testDisconnectingNestedMessageAfterSettingField(self):
+    proto = unittest_pb2.TestAllTypes()
+    nested = proto.optional_nested_message
+    nested.bb = 5
+    self.assertTrue(proto.HasField('optional_nested_message'))
+    proto.ClearField('optional_nested_message')  # Should disconnect from parent
+    self.assertEqual(5, nested.bb)
+    self.assertEqual(0, proto.optional_nested_message.bb)
+    self.assertTrue(nested is not proto.optional_nested_message)
+    nested.bb = 23
+    self.assertTrue(not proto.HasField('optional_nested_message'))
+    self.assertEqual(0, proto.optional_nested_message.bb)
+
+  def testDisconnectingNestedMessageBeforeGettingField(self):
+    proto = unittest_pb2.TestAllTypes()
+    self.assertTrue(not proto.HasField('optional_nested_message'))
+    proto.ClearField('optional_nested_message')
+    self.assertTrue(not proto.HasField('optional_nested_message'))
+
+  def testDisconnectingNestedMessageAfterMerge(self):
+    # This test exercises the code path that does not use ReleaseMessage().
+    # The underlying fear is that if we use ReleaseMessage() incorrectly,
+    # we will have memory leaks.  It's hard to check that that doesn't happen,
+    # but at least we can exercise that code path to make sure it works.
+    proto1 = unittest_pb2.TestAllTypes()
+    proto2 = unittest_pb2.TestAllTypes()
+    proto2.optional_nested_message.bb = 5
+    proto1.MergeFrom(proto2)
+    self.assertTrue(proto1.HasField('optional_nested_message'))
+    proto1.ClearField('optional_nested_message')
+    self.assertTrue(not proto1.HasField('optional_nested_message'))
+
+  def testDisconnectingLazyNestedMessage(self):
+    # This test exercises releasing a nested message that is lazy. This test
+    # only exercises real code in the C++ implementation as Python does not
+    # support lazy parsing, but the current C++ implementation results in
+    # memory corruption and a crash.
+    if api_implementation.Type() != 'python':
+      return
+    proto = unittest_pb2.TestAllTypes()
+    proto.optional_lazy_message.bb = 5
+    proto.ClearField('optional_lazy_message')
+    del proto
+    gc.collect()
+
   def testHasBitsWhenModifyingRepeatedFields(self):
     # Test nesting when we add an element to a repeated field in a submessage.
     proto = unittest_pb2.TestNestedMessageHasBits()
@@ -635,6 +683,77 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(3, proto.BAZ)
     self.assertEqual(3, unittest_pb2.TestAllTypes.BAZ)
 
+  def testEnum_Name(self):
+    self.assertEqual('FOREIGN_FOO',
+                     unittest_pb2.ForeignEnum.Name(unittest_pb2.FOREIGN_FOO))
+    self.assertEqual('FOREIGN_BAR',
+                     unittest_pb2.ForeignEnum.Name(unittest_pb2.FOREIGN_BAR))
+    self.assertEqual('FOREIGN_BAZ',
+                     unittest_pb2.ForeignEnum.Name(unittest_pb2.FOREIGN_BAZ))
+    self.assertRaises(ValueError,
+                      unittest_pb2.ForeignEnum.Name, 11312)
+
+    proto = unittest_pb2.TestAllTypes()
+    self.assertEqual('FOO',
+                     proto.NestedEnum.Name(proto.FOO))
+    self.assertEqual('FOO',
+                     unittest_pb2.TestAllTypes.NestedEnum.Name(proto.FOO))
+    self.assertEqual('BAR',
+                     proto.NestedEnum.Name(proto.BAR))
+    self.assertEqual('BAR',
+                     unittest_pb2.TestAllTypes.NestedEnum.Name(proto.BAR))
+    self.assertEqual('BAZ',
+                     proto.NestedEnum.Name(proto.BAZ))
+    self.assertEqual('BAZ',
+                     unittest_pb2.TestAllTypes.NestedEnum.Name(proto.BAZ))
+    self.assertRaises(ValueError,
+                      proto.NestedEnum.Name, 11312)
+    self.assertRaises(ValueError,
+                      unittest_pb2.TestAllTypes.NestedEnum.Name, 11312)
+
+  def testEnum_Value(self):
+    self.assertEqual(unittest_pb2.FOREIGN_FOO,
+                     unittest_pb2.ForeignEnum.Value('FOREIGN_FOO'))
+    self.assertEqual(unittest_pb2.FOREIGN_BAR,
+                     unittest_pb2.ForeignEnum.Value('FOREIGN_BAR'))
+    self.assertEqual(unittest_pb2.FOREIGN_BAZ,
+                     unittest_pb2.ForeignEnum.Value('FOREIGN_BAZ'))
+    self.assertRaises(ValueError,
+                      unittest_pb2.ForeignEnum.Value, 'FO')
+
+    proto = unittest_pb2.TestAllTypes()
+    self.assertEqual(proto.FOO,
+                     proto.NestedEnum.Value('FOO'))
+    self.assertEqual(proto.FOO,
+                     unittest_pb2.TestAllTypes.NestedEnum.Value('FOO'))
+    self.assertEqual(proto.BAR,
+                     proto.NestedEnum.Value('BAR'))
+    self.assertEqual(proto.BAR,
+                     unittest_pb2.TestAllTypes.NestedEnum.Value('BAR'))
+    self.assertEqual(proto.BAZ,
+                     proto.NestedEnum.Value('BAZ'))
+    self.assertEqual(proto.BAZ,
+                     unittest_pb2.TestAllTypes.NestedEnum.Value('BAZ'))
+    self.assertRaises(ValueError,
+                      proto.NestedEnum.Value, 'Foo')
+    self.assertRaises(ValueError,
+                      unittest_pb2.TestAllTypes.NestedEnum.Value, 'Foo')
+
+  def testEnum_KeysAndValues(self):
+    self.assertEqual(['FOREIGN_FOO', 'FOREIGN_BAR', 'FOREIGN_BAZ'],
+                     unittest_pb2.ForeignEnum.keys())
+    self.assertEqual([4, 5, 6],
+                     unittest_pb2.ForeignEnum.values())
+    self.assertEqual([('FOREIGN_FOO', 4), ('FOREIGN_BAR', 5),
+                      ('FOREIGN_BAZ', 6)],
+                     unittest_pb2.ForeignEnum.items())
+
+    proto = unittest_pb2.TestAllTypes()
+    self.assertEqual(['FOO', 'BAR', 'BAZ'], proto.NestedEnum.keys())
+    self.assertEqual([1, 2, 3], proto.NestedEnum.values())
+    self.assertEqual([('FOO', 1), ('BAR', 2), ('BAZ', 3)],
+                     proto.NestedEnum.items())
+
   def testRepeatedScalars(self):
     proto = unittest_pb2.TestAllTypes()
 
@@ -826,6 +945,35 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(1, len(proto.repeated_nested_message))
     self.assertEqual(23, proto.repeated_nested_message[0].bb)
 
+  def testRepeatedCompositeRemove(self):
+    proto = unittest_pb2.TestAllTypes()
+
+    self.assertEqual(0, len(proto.repeated_nested_message))
+    m0 = proto.repeated_nested_message.add()
+    # Need to set some differentiating variable so m0 != m1 != m2:
+    m0.bb = len(proto.repeated_nested_message)
+    m1 = proto.repeated_nested_message.add()
+    m1.bb = len(proto.repeated_nested_message)
+    self.assertTrue(m0 != m1)
+    m2 = proto.repeated_nested_message.add()
+    m2.bb = len(proto.repeated_nested_message)
+    self.assertListsEqual([m0, m1, m2], proto.repeated_nested_message)
+
+    self.assertEqual(3, len(proto.repeated_nested_message))
+    proto.repeated_nested_message.remove(m0)
+    self.assertEqual(2, len(proto.repeated_nested_message))
+    self.assertEqual(m1, proto.repeated_nested_message[0])
+    self.assertEqual(m2, proto.repeated_nested_message[1])
+
+    # Removing m0 again or removing None should raise error
+    self.assertRaises(ValueError, proto.repeated_nested_message.remove, m0)
+    self.assertRaises(ValueError, proto.repeated_nested_message.remove, None)
+    self.assertEqual(2, len(proto.repeated_nested_message))
+
+    proto.repeated_nested_message.remove(m2)
+    self.assertEqual(1, len(proto.repeated_nested_message))
+    self.assertEqual(m1, proto.repeated_nested_message[0])
+
   def testHandWrittenReflection(self):
     # Hand written extensions are only supported by the pure-Python
     # implementation of the API.
@@ -856,6 +1004,68 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(23, myproto_instance.foo_field)
     self.assertTrue(myproto_instance.HasField('foo_field'))
 
+  def testDescriptorProtoSupport(self):
+    # Hand written descriptors/reflection are only supported by the pure-Python
+    # implementation of the API.
+    if api_implementation.Type() != 'python':
+      return
+
+    def AddDescriptorField(proto, field_name, field_type):
+      AddDescriptorField.field_index += 1
+      new_field = proto.field.add()
+      new_field.name = field_name
+      new_field.type = field_type
+      new_field.number = AddDescriptorField.field_index
+      new_field.label = descriptor_pb2.FieldDescriptorProto.LABEL_OPTIONAL
+
+    AddDescriptorField.field_index = 0
+
+    desc_proto = descriptor_pb2.DescriptorProto()
+    desc_proto.name = 'Car'
+    fdp = descriptor_pb2.FieldDescriptorProto
+    AddDescriptorField(desc_proto, 'name', fdp.TYPE_STRING)
+    AddDescriptorField(desc_proto, 'year', fdp.TYPE_INT64)
+    AddDescriptorField(desc_proto, 'automatic', fdp.TYPE_BOOL)
+    AddDescriptorField(desc_proto, 'price', fdp.TYPE_DOUBLE)
+    # Add a repeated field
+    AddDescriptorField.field_index += 1
+    new_field = desc_proto.field.add()
+    new_field.name = 'owners'
+    new_field.type = fdp.TYPE_STRING
+    new_field.number = AddDescriptorField.field_index
+    new_field.label = descriptor_pb2.FieldDescriptorProto.LABEL_REPEATED
+
+    desc = descriptor.MakeDescriptor(desc_proto)
+    self.assertTrue(desc.fields_by_name.has_key('name'))
+    self.assertTrue(desc.fields_by_name.has_key('year'))
+    self.assertTrue(desc.fields_by_name.has_key('automatic'))
+    self.assertTrue(desc.fields_by_name.has_key('price'))
+    self.assertTrue(desc.fields_by_name.has_key('owners'))
+
+    class CarMessage(message.Message):
+      __metaclass__ = reflection.GeneratedProtocolMessageType
+      DESCRIPTOR = desc
+
+    prius = CarMessage()
+    prius.name = 'prius'
+    prius.year = 2010
+    prius.automatic = True
+    prius.price = 25134.75
+    prius.owners.extend(['bob', 'susan'])
+
+    serialized_prius = prius.SerializeToString()
+    new_prius = reflection.ParseMessage(desc, serialized_prius)
+    self.assertTrue(new_prius is not prius)
+    self.assertEqual(prius, new_prius)
+
+    # these are unnecessary assuming message equality works as advertised but
+    # explicitly check to be safe since we're mucking about in metaclass foo
+    self.assertEqual(prius.name, new_prius.name)
+    self.assertEqual(prius.year, new_prius.year)
+    self.assertEqual(prius.automatic, new_prius.automatic)
+    self.assertEqual(prius.price, new_prius.price)
+    self.assertEqual(prius.owners, new_prius.owners)
+
   def testTopLevelExtensionsForOptionalScalar(self):
     extendee_proto = unittest_pb2.TestAllExtensions()
     extension = unittest_pb2.optional_int32_extension
@@ -1243,7 +1453,12 @@ class ReflectionTest(unittest.TestCase):
 
   def testClear(self):
     proto = unittest_pb2.TestAllTypes()
-    test_util.SetAllFields(proto)
+    # C++ implementation does not support lazy fields right now so leave it
+    # out for now.
+    if api_implementation.Type() == 'python':
+      test_util.SetAllFields(proto)
+    else:
+      test_util.SetAllNonLazyFields(proto)
     # Clear the message.
     proto.Clear()
     self.assertEquals(proto.ByteSize(), 0)
@@ -1259,6 +1474,33 @@ class ReflectionTest(unittest.TestCase):
     empty_proto = unittest_pb2.TestAllExtensions()
     self.assertEquals(proto, empty_proto)
 
+  def testDisconnectingBeforeClear(self):
+    proto = unittest_pb2.TestAllTypes()
+    nested = proto.optional_nested_message
+    proto.Clear()
+    self.assertTrue(nested is not proto.optional_nested_message)
+    nested.bb = 23
+    self.assertTrue(not proto.HasField('optional_nested_message'))
+    self.assertEqual(0, proto.optional_nested_message.bb)
+
+    proto = unittest_pb2.TestAllTypes()
+    nested = proto.optional_nested_message
+    nested.bb = 5
+    foreign = proto.optional_foreign_message
+    foreign.c = 6
+
+    proto.Clear()
+    self.assertTrue(nested is not proto.optional_nested_message)
+    self.assertTrue(foreign is not proto.optional_foreign_message)
+    self.assertEqual(5, nested.bb)
+    self.assertEqual(6, foreign.c)
+    nested.bb = 15
+    foreign.c = 16
+    self.assertTrue(not proto.HasField('optional_nested_message'))
+    self.assertEqual(0, proto.optional_nested_message.bb)
+    self.assertTrue(not proto.HasField('optional_foreign_message'))
+    self.assertEqual(0, proto.optional_foreign_message.c)
+
   def assertInitialized(self, proto):
     self.assertTrue(proto.IsInitialized())
     # Neither method should raise an exception.
@@ -1408,7 +1650,7 @@ class ReflectionTest(unittest.TestCase):
     unicode_decode_failed = False
     try:
       message2.MergeFromString(bytes)
-    except UnicodeDecodeError, e:
+    except UnicodeDecodeError as e:
       unicode_decode_failed = True
     string_field = message2.str
     self.assertTrue(unicode_decode_failed or type(string_field) == str)
@@ -2119,7 +2361,7 @@ class SerializationTest(unittest.TestCase):
     """This method checks if the excpetion type and message are as expected."""
     try:
       callable_obj()
-    except exc_class, ex:
+    except exc_class as ex:
       # Check if the exception message is the right one.
       self.assertEqual(exception, str(ex))
       return
@@ -2131,15 +2373,22 @@ class SerializationTest(unittest.TestCase):
     self._CheckRaises(
         message.EncodeError,
         proto.SerializeToString,
-        'Message is missing required fields: a,b,c')
+        'Message protobuf_unittest.TestRequired is missing required fields: '
+        'a,b,c')
     # Shouldn't raise exceptions.
     partial = proto.SerializePartialToString()
 
+    proto2 = unittest_pb2.TestRequired()
+    self.assertFalse(proto2.HasField('a'))
+    # proto2 ParseFromString does not check that required fields are set.
+    proto2.ParseFromString(partial)
+    self.assertFalse(proto2.HasField('a'))
+
     proto.a = 1
     self._CheckRaises(
         message.EncodeError,
         proto.SerializeToString,
-        'Message is missing required fields: b,c')
+        'Message protobuf_unittest.TestRequired is missing required fields: b,c')
     # Shouldn't raise exceptions.
     partial = proto.SerializePartialToString()
 
@@ -2147,7 +2396,7 @@ class SerializationTest(unittest.TestCase):
     self._CheckRaises(
         message.EncodeError,
         proto.SerializeToString,
-        'Message is missing required fields: c')
+        'Message protobuf_unittest.TestRequired is missing required fields: c')
     # Shouldn't raise exceptions.
     partial = proto.SerializePartialToString()
 
@@ -2176,7 +2425,8 @@ class SerializationTest(unittest.TestCase):
     self._CheckRaises(
         message.EncodeError,
         proto.SerializeToString,
-        'Message is missing required fields: '
+        'Message protobuf_unittest.TestRequiredForeign '
+        'is missing required fields: '
         'optional_message.b,optional_message.c')
 
     proto.optional_message.b = 2
@@ -2188,7 +2438,7 @@ class SerializationTest(unittest.TestCase):
     self._CheckRaises(
         message.EncodeError,
         proto.SerializeToString,
-        'Message is missing required fields: '
+        'Message protobuf_unittest.TestRequiredForeign is missing required fields: '
         'repeated_message[0].b,repeated_message[0].c,'
         'repeated_message[1].a,repeated_message[1].c')
 
diff --git a/python/google/protobuf/internal/test_bad_identifiers.proto b/python/google/protobuf/internal/test_bad_identifiers.proto
new file mode 100644
index 00000000..6a82299a
--- /dev/null
+++ b/python/google/protobuf/internal/test_bad_identifiers.proto
@@ -0,0 +1,52 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+
+
+package protobuf_unittest;
+
+option py_generic_services = true;
+
+message TestBadIdentifiers {
+  extensions 100 to max;
+}
+
+// Make sure these reasonable extension names don't conflict with internal
+// variables.
+extend TestBadIdentifiers {
+  optional string message = 100 [default="foo"];
+  optional string descriptor = 101 [default="bar"];
+  optional string reflection = 102 [default="baz"];
+  optional string service = 103 [default="qux"];
+}
+
+message AnotherMessage {}
+service AnotherService {}
diff --git a/python/google/protobuf/internal/test_util.py b/python/google/protobuf/internal/test_util.py
index 1df16194..be8ae7be 100755
--- a/python/google/protobuf/internal/test_util.py
+++ b/python/google/protobuf/internal/test_util.py
@@ -42,8 +42,8 @@ from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
 
 
-def SetAllFields(message):
-  """Sets every field in the message to a unique value.
+def SetAllNonLazyFields(message):
+  """Sets every non-lazy field in the message to a unique value.
 
   Args:
     message: A unittest_pb2.TestAllTypes instance.
@@ -79,6 +79,7 @@ def SetAllFields(message):
   message.optional_nested_message.bb = 118
   message.optional_foreign_message.c = 119
   message.optional_import_message.d = 120
+  message.optional_public_import_message.e = 126
 
   message.optional_nested_enum = unittest_pb2.TestAllTypes.BAZ
   message.optional_foreign_enum = unittest_pb2.FOREIGN_BAZ
@@ -111,6 +112,7 @@ def SetAllFields(message):
   message.repeated_nested_message.add().bb = 218
   message.repeated_foreign_message.add().c = 219
   message.repeated_import_message.add().d = 220
+  message.repeated_lazy_message.add().bb = 227
 
   message.repeated_nested_enum.append(unittest_pb2.TestAllTypes.BAR)
   message.repeated_foreign_enum.append(unittest_pb2.FOREIGN_BAR)
@@ -140,6 +142,7 @@ def SetAllFields(message):
   message.repeated_nested_message.add().bb = 318
   message.repeated_foreign_message.add().c = 319
   message.repeated_import_message.add().d = 320
+  message.repeated_lazy_message.add().bb = 327
 
   message.repeated_nested_enum.append(unittest_pb2.TestAllTypes.BAZ)
   message.repeated_foreign_enum.append(unittest_pb2.FOREIGN_BAZ)
@@ -176,6 +179,11 @@ def SetAllFields(message):
   message.default_cord = '425'
 
 
+def SetAllFields(message):
+  SetAllNonLazyFields(message)
+  message.optional_lazy_message.bb = 127
+
+
 def SetAllExtensions(message):
   """Sets every extension in the message to a unique value.
 
@@ -211,6 +219,8 @@ def SetAllExtensions(message):
   extensions[pb2.optional_nested_message_extension].bb = 118
   extensions[pb2.optional_foreign_message_extension].c = 119
   extensions[pb2.optional_import_message_extension].d = 120
+  extensions[pb2.optional_public_import_message_extension].e = 126
+  extensions[pb2.optional_lazy_message_extension].bb = 127
 
   extensions[pb2.optional_nested_enum_extension] = pb2.TestAllTypes.BAZ
   extensions[pb2.optional_nested_enum_extension] = pb2.TestAllTypes.BAZ
@@ -244,6 +254,7 @@ def SetAllExtensions(message):
   extensions[pb2.repeated_nested_message_extension].add().bb = 218
   extensions[pb2.repeated_foreign_message_extension].add().c = 219
   extensions[pb2.repeated_import_message_extension].add().d = 220
+  extensions[pb2.repeated_lazy_message_extension].add().bb = 227
 
   extensions[pb2.repeated_nested_enum_extension].append(pb2.TestAllTypes.BAR)
   extensions[pb2.repeated_foreign_enum_extension].append(pb2.FOREIGN_BAR)
@@ -273,6 +284,7 @@ def SetAllExtensions(message):
   extensions[pb2.repeated_nested_message_extension].add().bb = 318
   extensions[pb2.repeated_foreign_message_extension].add().c = 319
   extensions[pb2.repeated_import_message_extension].add().d = 320
+  extensions[pb2.repeated_lazy_message_extension].add().bb = 327
 
   extensions[pb2.repeated_nested_enum_extension].append(pb2.TestAllTypes.BAZ)
   extensions[pb2.repeated_foreign_enum_extension].append(pb2.FOREIGN_BAZ)
@@ -407,6 +419,8 @@ def ExpectAllFieldsSet(test_case, message):
   test_case.assertEqual(118, message.optional_nested_message.bb)
   test_case.assertEqual(119, message.optional_foreign_message.c)
   test_case.assertEqual(120, message.optional_import_message.d)
+  test_case.assertEqual(126, message.optional_public_import_message.e)
+  test_case.assertEqual(127, message.optional_lazy_message.bb)
 
   test_case.assertEqual(unittest_pb2.TestAllTypes.BAZ,
                         message.optional_nested_enum)
@@ -464,6 +478,7 @@ def ExpectAllFieldsSet(test_case, message):
   test_case.assertEqual(218, message.repeated_nested_message[0].bb)
   test_case.assertEqual(219, message.repeated_foreign_message[0].c)
   test_case.assertEqual(220, message.repeated_import_message[0].d)
+  test_case.assertEqual(227, message.repeated_lazy_message[0].bb)
 
   test_case.assertEqual(unittest_pb2.TestAllTypes.BAR,
                         message.repeated_nested_enum[0])
@@ -492,6 +507,7 @@ def ExpectAllFieldsSet(test_case, message):
   test_case.assertEqual(318, message.repeated_nested_message[1].bb)
   test_case.assertEqual(319, message.repeated_foreign_message[1].c)
   test_case.assertEqual(320, message.repeated_import_message[1].d)
+  test_case.assertEqual(327, message.repeated_lazy_message[1].bb)
 
   test_case.assertEqual(unittest_pb2.TestAllTypes.BAZ,
                         message.repeated_nested_enum[1])
diff --git a/python/google/protobuf/internal/text_format_test.py b/python/google/protobuf/internal/text_format_test.py
index 73d97d18..23b50eb5 100755
--- a/python/google/protobuf/internal/text_format_test.py
+++ b/python/google/protobuf/internal/text_format_test.py
@@ -94,6 +94,28 @@ class TextFormatTest(unittest.TestCase):
       '  }\n'
       '}\n')
 
+  def testPrintBadEnumValue(self):
+    message = unittest_pb2.TestAllTypes()
+    message.optional_nested_enum = 100
+    message.optional_foreign_enum = 101
+    message.optional_import_enum = 102
+    self.CompareToGoldenText(
+        text_format.MessageToString(message),
+        'optional_nested_enum: 100\n'
+        'optional_foreign_enum: 101\n'
+        'optional_import_enum: 102\n')
+
+  def testPrintBadEnumValueExtensions(self):
+    message = unittest_pb2.TestAllExtensions()
+    message.Extensions[unittest_pb2.optional_nested_enum_extension] = 100
+    message.Extensions[unittest_pb2.optional_foreign_enum_extension] = 101
+    message.Extensions[unittest_pb2.optional_import_enum_extension] = 102
+    self.CompareToGoldenText(
+        text_format.MessageToString(message),
+        '[protobuf_unittest.optional_nested_enum_extension]: 100\n'
+        '[protobuf_unittest.optional_foreign_enum_extension]: 101\n'
+        '[protobuf_unittest.optional_import_enum_extension]: 102\n')
+
   def testPrintExotic(self):
     message = unittest_pb2.TestAllTypes()
     message.repeated_int64.append(-9223372036854775808)
@@ -399,6 +421,14 @@ class TextFormatTest(unittest.TestCase):
          'has no value with number 100.'),
         text_format.Merge, text, message)
 
+  def testMergeBadIntValue(self):
+    message = unittest_pb2.TestAllTypes()
+    text = 'optional_int32: bork'
+    self.assertRaisesWithMessage(
+        text_format.ParseError,
+        ('1:17 : Couldn\'t parse integer: bork'),
+        text_format.Merge, text, message)
+
   def assertRaisesWithMessage(self, e_class, e, func, *args, **kwargs):
     """Same as assertRaises, but also compares the exception message."""
     if hasattr(e_class, '__name__'):
@@ -408,7 +438,7 @@ class TextFormatTest(unittest.TestCase):
 
     try:
       func(*args, **kwargs)
-    except e_class, expr:
+    except e_class as expr:
       if str(expr) != e:
         msg = '%s raised, but with wrong message: "%s" instead of "%s"'
         raise self.failureException(msg % (exc_name,
@@ -427,7 +457,7 @@ class TokenizerTest(unittest.TestCase):
             'identifiER_4 : 1.1e+2 ID5:-0.23 ID6:\'aaaa\\\'bbbb\'\n'
             'ID7 : "aa\\"bb"\n\n\n\n ID8: {A:inf B:-inf C:true D:false}\n'
             'ID9: 22 ID10: -111111111111111111 ID11: -22\n'
-            'ID12: 2222222222222222222 '
+            'ID12: 2222222222222222222 ID13: 1.23456f ID14: 1.2e+2f '
             'false_bool:  0 true_BOOL:t \n true_bool1:  1 false_BOOL1:f ' )
     tokenizer = text_format._Tokenizer(text)
     methods = [(tokenizer.ConsumeIdentifier, 'identifier1'),
@@ -456,10 +486,10 @@ class TokenizerTest(unittest.TestCase):
                '{',
                (tokenizer.ConsumeIdentifier, 'A'),
                ':',
-               (tokenizer.ConsumeFloat, text_format._INFINITY),
+               (tokenizer.ConsumeFloat, float('inf')),
                (tokenizer.ConsumeIdentifier, 'B'),
                ':',
-               (tokenizer.ConsumeFloat, -text_format._INFINITY),
+               (tokenizer.ConsumeFloat, -float('inf')),
                (tokenizer.ConsumeIdentifier, 'C'),
                ':',
                (tokenizer.ConsumeBool, True),
@@ -479,6 +509,12 @@ class TokenizerTest(unittest.TestCase):
                (tokenizer.ConsumeIdentifier, 'ID12'),
                ':',
                (tokenizer.ConsumeUint64, 2222222222222222222),
+               (tokenizer.ConsumeIdentifier, 'ID13'),
+               ':',
+               (tokenizer.ConsumeFloat, 1.23456),
+               (tokenizer.ConsumeIdentifier, 'ID14'),
+               ':',
+               (tokenizer.ConsumeFloat, 1.2e+2),
                (tokenizer.ConsumeIdentifier, 'false_bool'),
                ':',
                (tokenizer.ConsumeBool, False),
@@ -556,16 +592,6 @@ class TokenizerTest(unittest.TestCase):
     tokenizer = text_format._Tokenizer(text)
     self.assertRaises(text_format.ParseError, tokenizer.ConsumeBool)
 
-  def testInfNan(self):
-    # Make sure our infinity and NaN definitions are sound.
-    self.assertEquals(float, type(text_format._INFINITY))
-    self.assertEquals(float, type(text_format._NAN))
-    self.assertTrue(text_format._NAN != text_format._NAN)
-
-    inf_times_zero = text_format._INFINITY * 0
-    self.assertTrue(inf_times_zero != inf_times_zero)
-    self.assertTrue(text_format._INFINITY > 0)
-
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/unknown_fields_test.py b/python/google/protobuf/internal/unknown_fields_test.py
new file mode 100755
index 00000000..84984b40
--- /dev/null
+++ b/python/google/protobuf/internal/unknown_fields_test.py
@@ -0,0 +1,170 @@
+#! /usr/bin/python
+# -*- coding: utf-8 -*-
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Test for preservation of unknown fields in the pure Python implementation."""
+
+__author__ = 'bohdank@google.com (Bohdan Koval)'
+
+import unittest
+from google.protobuf import unittest_mset_pb2
+from google.protobuf import unittest_pb2
+from google.protobuf.internal import encoder
+from google.protobuf.internal import test_util
+from google.protobuf.internal import type_checkers
+
+
+class UnknownFieldsTest(unittest.TestCase):
+
+  def setUp(self):
+    self.descriptor = unittest_pb2.TestAllTypes.DESCRIPTOR
+    self.all_fields = unittest_pb2.TestAllTypes()
+    test_util.SetAllFields(self.all_fields)
+    self.all_fields_data = self.all_fields.SerializeToString()
+    self.empty_message = unittest_pb2.TestEmptyMessage()
+    self.empty_message.ParseFromString(self.all_fields_data)
+    self.unknown_fields = self.empty_message._unknown_fields
+
+  def GetField(self, name):
+    field_descriptor = self.descriptor.fields_by_name[name]
+    wire_type = type_checkers.FIELD_TYPE_TO_WIRE_TYPE[field_descriptor.type]
+    field_tag = encoder.TagBytes(field_descriptor.number, wire_type)
+    for tag_bytes, value in self.unknown_fields:
+      if tag_bytes == field_tag:
+        decoder = unittest_pb2.TestAllTypes._decoders_by_tag[tag_bytes]
+        result_dict = {}
+        decoder(value, 0, len(value), self.all_fields, result_dict)
+        return result_dict[field_descriptor]
+
+  def testVarint(self):
+    value = self.GetField('optional_int32')
+    self.assertEqual(self.all_fields.optional_int32, value)
+
+  def testFixed32(self):
+    value = self.GetField('optional_fixed32')
+    self.assertEqual(self.all_fields.optional_fixed32, value)
+
+  def testFixed64(self):
+    value = self.GetField('optional_fixed64')
+    self.assertEqual(self.all_fields.optional_fixed64, value)
+
+  def testLengthDelimited(self):
+    value = self.GetField('optional_string')
+    self.assertEqual(self.all_fields.optional_string, value)
+
+  def testGroup(self):
+    value = self.GetField('optionalgroup')
+    self.assertEqual(self.all_fields.optionalgroup, value)
+
+  def testSerialize(self):
+    data = self.empty_message.SerializeToString()
+
+    # Don't use assertEqual because we don't want to dump raw binary data to
+    # stdout.
+    self.assertTrue(data == self.all_fields_data)
+
+  def testCopyFrom(self):
+    message = unittest_pb2.TestEmptyMessage()
+    message.CopyFrom(self.empty_message)
+    self.assertEqual(self.unknown_fields, message._unknown_fields)
+
+  def testMergeFrom(self):
+    message = unittest_pb2.TestAllTypes()
+    message.optional_int32 = 1
+    message.optional_uint32 = 2
+    source = unittest_pb2.TestEmptyMessage()
+    source.ParseFromString(message.SerializeToString())
+
+    message.ClearField('optional_int32')
+    message.optional_int64 = 3
+    message.optional_uint32 = 4
+    destination = unittest_pb2.TestEmptyMessage()
+    destination.ParseFromString(message.SerializeToString())
+    unknown_fields = destination._unknown_fields[:]
+
+    destination.MergeFrom(source)
+    self.assertEqual(unknown_fields + source._unknown_fields,
+                     destination._unknown_fields)
+
+  def testClear(self):
+    self.empty_message.Clear()
+    self.assertEqual(0, len(self.empty_message._unknown_fields))
+
+  def testByteSize(self):
+    self.assertEqual(self.all_fields.ByteSize(), self.empty_message.ByteSize())
+
+  def testUnknownExtensions(self):
+    message = unittest_pb2.TestEmptyMessageWithExtensions()
+    message.ParseFromString(self.all_fields_data)
+    self.assertEqual(self.empty_message._unknown_fields,
+                     message._unknown_fields)
+
+  def testListFields(self):
+    # Make sure ListFields doesn't return unknown fields.
+    self.assertEqual(0, len(self.empty_message.ListFields()))
+
+  def testSerializeMessageSetWireFormatUnknownExtension(self):
+    # Create a message using the message set wire format with an unknown
+    # message.
+    raw = unittest_mset_pb2.RawMessageSet()
+
+    # Add an unknown extension.
+    item = raw.item.add()
+    item.type_id = 1545009
+    message1 = unittest_mset_pb2.TestMessageSetExtension1()
+    message1.i = 12345
+    item.message = message1.SerializeToString()
+
+    serialized = raw.SerializeToString()
+
+    # Parse message using the message set wire format.
+    proto = unittest_mset_pb2.TestMessageSet()
+    proto.MergeFromString(serialized)
+
+    # Verify that the unknown extension is serialized unchanged
+    reserialized = proto.SerializeToString()
+    new_raw = unittest_mset_pb2.RawMessageSet()
+    new_raw.MergeFromString(reserialized)
+    self.assertEqual(raw, new_raw)
+
+  def testEquals(self):
+    message = unittest_pb2.TestEmptyMessage()
+    message.ParseFromString(self.all_fields_data)
+    self.assertEqual(self.empty_message, message)
+
+    self.all_fields.ClearField('optional_string')
+    message.ParseFromString(self.all_fields.SerializeToString())
+    self.assertNotEqual(self.empty_message, message)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
index 6f19f85f..6ec2f8be 100755
--- a/python/google/protobuf/message.py
+++ b/python/google/protobuf/message.py
@@ -73,6 +73,7 @@ class Message(object):
     return clone
 
   def __eq__(self, other_msg):
+    """Recursively compares two messages by value and structure."""
     raise NotImplementedError
 
   def __ne__(self, other_msg):
@@ -83,9 +84,11 @@ class Message(object):
     raise TypeError('unhashable object')
 
   def __str__(self):
+    """Outputs a human-readable representation of the message."""
     raise NotImplementedError
 
   def __unicode__(self):
+    """Outputs a human-readable representation of the message."""
     raise NotImplementedError
 
   def MergeFrom(self, other_msg):
@@ -266,3 +269,12 @@ class Message(object):
     via a previous _SetListener() call.
     """
     raise NotImplementedError
+
+  def __getstate__(self):
+    """Support the pickle protocol."""
+    return dict(serialized=self.SerializePartialToString())
+
+  def __setstate__(self, state):
+    """Support the pickle protocol."""
+    self.__init__()
+    self.ParseFromString(state['serialized'])
diff --git a/python/google/protobuf/message_factory.py b/python/google/protobuf/message_factory.py
new file mode 100644
index 00000000..36e2fef0
--- /dev/null
+++ b/python/google/protobuf/message_factory.py
@@ -0,0 +1,113 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides a factory class for generating dynamic messages."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+from google.protobuf import descriptor_database
+from google.protobuf import descriptor_pool
+from google.protobuf import message
+from google.protobuf import reflection
+
+
+class MessageFactory(object):
+  """Factory for creating Proto2 messages from descriptors in a pool."""
+
+  def __init__(self):
+    """Initializes a new factory."""
+    self._classes = {}
+
+  def GetPrototype(self, descriptor):
+    """Builds a proto2 message class based on the passed in descriptor.
+
+    Passing a descriptor with a fully qualified name matching a previous
+    invocation will cause the same class to be returned.
+
+    Args:
+      descriptor: The descriptor to build from.
+
+    Returns:
+      A class describing the passed in descriptor.
+    """
+
+    if descriptor.full_name not in self._classes:
+      result_class = reflection.GeneratedProtocolMessageType(
+          descriptor.name.encode('ascii', 'ignore'),
+          (message.Message,),
+          {'DESCRIPTOR': descriptor})
+      self._classes[descriptor.full_name] = result_class
+      for field in descriptor.fields:
+        if field.message_type:
+          self.GetPrototype(field.message_type)
+    return self._classes[descriptor.full_name]
+
+
+_DB = descriptor_database.DescriptorDatabase()
+_POOL = descriptor_pool.DescriptorPool(_DB)
+_FACTORY = MessageFactory()
+
+
+def GetMessages(file_protos):
+  """Builds a dictionary of all the messages available in a set of files.
+
+  Args:
+    file_protos: A sequence of file protos to build messages out of.
+
+  Returns:
+    A dictionary containing all the message types in the files mapping the
+    fully qualified name to a Message subclass for the descriptor.
+  """
+
+  result = {}
+  for file_proto in file_protos:
+    _DB.Add(file_proto)
+  for file_proto in file_protos:
+    for desc in _GetAllDescriptors(file_proto.message_type, file_proto.package):
+      result[desc.full_name] = _FACTORY.GetPrototype(desc)
+  return result
+
+
+def _GetAllDescriptors(desc_protos, package):
+  """Gets all levels of nested message types as a flattened list of descriptors.
+
+  Args:
+    desc_protos: The descriptor protos to process.
+    package: The package where the protos are defined.
+
+  Yields:
+    Each message descriptor for each nested type.
+  """
+
+  for desc_proto in desc_protos:
+    name = '.'.join((package, desc_proto.name))
+    yield _POOL.FindMessageTypeByName(name)
+    for nested_desc in _GetAllDescriptors(desc_proto.nested_type, name):
+      yield nested_desc
diff --git a/python/google/protobuf/pyext/python-proto2.cc b/python/google/protobuf/pyext/python-proto2.cc
index 181d7e97..62753413 100644
--- a/python/google/protobuf/pyext/python-proto2.cc
+++ b/python/google/protobuf/pyext/python-proto2.cc
@@ -207,9 +207,9 @@ static PyMethodDef CMessageMethods[] = {
           "Clears and sets the values of a repeated scalar field."),
   CMETHOD(ByteSize, METH_NOARGS,
           "Returns the size of the message in bytes."),
-  CMETHOD(Clear, METH_NOARGS,
+  CMETHOD(Clear, METH_O,
           "Clears a protocol message."),
-  CMETHOD(ClearField, METH_O,
+  CMETHOD(ClearField, METH_VARARGS,
           "Clears a protocol message field by name."),
   CMETHOD(ClearFieldByDescriptor, METH_O,
           "Clears a protocol message field by descriptor."),
@@ -274,7 +274,7 @@ static PyMemberDef CMessageMembers[] = {
 PyTypeObject CMessage_Type = {
   PyObject_HEAD_INIT(&PyType_Type)
   0,
-  C("google3.net.google.protobuf.python.internal."
+  C("google.protobuf.internal."
     "_net_proto2___python."
     "CMessage"),                       // tp_name
   sizeof(CMessage),                    //  tp_basicsize
@@ -319,14 +319,12 @@ PyTypeObject CMessage_Type = {
 // ------ Helper Functions:
 
 static void FormatTypeError(PyObject* arg, char* expected_types) {
-  PyObject* s = PyObject_Str(PyObject_Type(arg));
-  PyObject* repr = PyObject_Repr(PyObject_Type(arg));
+  PyObject* repr = PyObject_Repr(arg);
   PyErr_Format(PyExc_TypeError,
                "%.100s has type %.100s, but expected one of: %s",
                PyString_AS_STRING(repr),
-               PyString_AS_STRING(s),
+               arg->ob_type->tp_name,
                expected_types);
-  Py_DECREF(s);
   Py_DECREF(repr);
 }
 
@@ -398,6 +396,28 @@ static const google::protobuf::Message* CreateMessage(const char* message_type)
   return global_message_factory->GetPrototype(descriptor);
 }
 
+static void ReleaseSubMessage(google::protobuf::Message* message,
+                           const google::protobuf::FieldDescriptor* field_descriptor,
+                           CMessage* child_cmessage) {
+  Message* released_message = message->GetReflection()->ReleaseMessage(
+      message, field_descriptor, global_message_factory);
+  GOOGLE_DCHECK(child_cmessage->message != NULL);
+  // ReleaseMessage will return NULL which differs from
+  // child_cmessage->message, if the field does not exist.  In this case,
+  // the latter points to the default instance via a const_cast<>, so we
+  // have to reset it to a new mutable object since we are taking ownership.
+  if (released_message == NULL) {
+    const Message* prototype = global_message_factory->GetPrototype(
+        child_cmessage->message->GetDescriptor());
+    GOOGLE_DCHECK(prototype != NULL);
+    child_cmessage->message = prototype->New();
+  }
+  child_cmessage->parent = NULL;
+  child_cmessage->parent_field = NULL;
+  child_cmessage->free_message = true;
+  child_cmessage->read_only = false;
+}
+
 static bool CheckAndSetString(
     PyObject* arg, google::protobuf::Message* message,
     const google::protobuf::FieldDescriptor* descriptor,
@@ -407,6 +427,9 @@ static bool CheckAndSetString(
   GOOGLE_DCHECK(descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING ||
          descriptor->type() == google::protobuf::FieldDescriptor::TYPE_BYTES);
   if (descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
+#else
+  if (descriptor->file()->options().cc_api_version() == 2 &&
+      descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
     if (!PyString_Check(arg) && !PyUnicode_Check(arg)) {
       FormatTypeError(arg, "str, unicode");
       return false;
@@ -434,6 +457,9 @@ static bool CheckAndSetString(
 
   PyObject* encoded_string = NULL;
   if (descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
+#else
+  if (descriptor->file()->options().cc_api_version() == 2 &&
+      descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
     if (PyString_Check(arg)) {
       encoded_string = PyString_AsEncodedObject(arg, "utf-8", NULL);
     } else {
@@ -504,8 +530,6 @@ static void AssureWritable(CMessage* self) {
   self->message = reflection->MutableMessage(
       message, self->parent_field->descriptor, global_message_factory);
   self->read_only = false;
-  self->parent = NULL;
-  self->parent_field = NULL;
 }
 
 static PyObject* InternalGetScalar(
@@ -955,9 +979,41 @@ static void CMessageDealloc(CMessage* self) {
 
 // ------ Methods:
 
-static PyObject* CMessage_Clear(CMessage* self, PyObject* args) {
+static PyObject* CMessage_Clear(CMessage* self, PyObject* arg) {
   AssureWritable(self);
-  self->message->Clear();
+  google::protobuf::Message* message = self->message;
+
+  // This block of code is equivalent to the following:
+  // for cfield_descriptor, child_cmessage in arg:
+  //   ReleaseSubMessage(cfield_descriptor, child_cmessage)
+  if (!PyList_Check(arg)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a list");
+    return NULL;
+  }
+  PyObject* messages_to_clear = arg;
+  Py_ssize_t num_messages_to_clear = PyList_GET_SIZE(messages_to_clear);
+  for(int i = 0; i < num_messages_to_clear; ++i) {
+    PyObject* message_tuple = PyList_GET_ITEM(messages_to_clear, i);
+    if (!PyTuple_Check(message_tuple) || PyTuple_GET_SIZE(message_tuple) != 2) {
+      PyErr_SetString(PyExc_TypeError, "Must be a tuple of size 2");
+      return NULL;
+    }
+
+    PyObject* py_cfield_descriptor = PyTuple_GET_ITEM(message_tuple, 0);
+    PyObject* py_child_cmessage = PyTuple_GET_ITEM(message_tuple, 1);
+    if (!PyObject_TypeCheck(py_cfield_descriptor, &CFieldDescriptor_Type) ||
+        !PyObject_TypeCheck(py_child_cmessage, &CMessage_Type)) {
+      PyErr_SetString(PyExc_ValueError, "Invalid Tuple");
+      return NULL;
+    }
+
+    CFieldDescriptor* cfield_descriptor = reinterpret_cast<CFieldDescriptor *>(
+        py_cfield_descriptor);
+    CMessage* child_cmessage = reinterpret_cast<CMessage *>(py_child_cmessage);
+    ReleaseSubMessage(message, cfield_descriptor->descriptor, child_cmessage);
+  }
+
+  message->Clear();
   Py_RETURN_NONE;
 }
 
@@ -1039,9 +1095,11 @@ static PyObject* CMessage_ClearFieldByDescriptor(
   Py_RETURN_NONE;
 }
 
-static PyObject* CMessage_ClearField(CMessage* self, PyObject* arg) {
+static PyObject* CMessage_ClearField(CMessage* self, PyObject* args) {
   char* field_name;
-  if (PyString_AsStringAndSize(arg, &field_name, NULL) < 0) {
+  CMessage* child_cmessage = NULL;
+  if (!PyArg_ParseTuple(args, C("s|O!:ClearField"), &field_name,
+                        &CMessage_Type, &child_cmessage)) {
     return NULL;
   }
 
@@ -1054,7 +1112,11 @@ static PyObject* CMessage_ClearField(CMessage* self, PyObject* arg) {
     return NULL;
   }
 
-  message->GetReflection()->ClearField(message, field_descriptor);
+  if (child_cmessage != NULL && !FIELD_IS_REPEATED(field_descriptor)) {
+    ReleaseSubMessage(message, field_descriptor, child_cmessage);
+  } else {
+    message->GetReflection()->ClearField(message, field_descriptor);
+  }
   Py_RETURN_NONE;
 }
 
@@ -1313,6 +1375,7 @@ static PyObject* CMessage_MergeFromString(CMessage* self, PyObject* arg) {
   AssureWritable(self);
   google::protobuf::io::CodedInputStream input(
       reinterpret_cast<const uint8*>(data), data_length);
+  input.SetExtensionRegistry(GetDescriptorPool(), global_message_factory);
   bool success = self->message->MergePartialFromCodedStream(&input);
   if (success) {
     return PyInt_FromLong(self->message->ByteSize());
diff --git a/python/google/protobuf/pyext/python_descriptor.cc b/python/google/protobuf/pyext/python_descriptor.cc
index fb87bad1..5e3e9ea4 100644
--- a/python/google/protobuf/pyext/python_descriptor.cc
+++ b/python/google/protobuf/pyext/python_descriptor.cc
@@ -31,6 +31,7 @@
 // Author: petar@google.com (Petar Petrov)
 
 #include <Python.h>
+#include <string>
 
 #include <google/protobuf/pyext/python_descriptor.h>
 #include <google/protobuf/descriptor.pb.h>
@@ -41,6 +42,7 @@ namespace google {
 namespace protobuf {
 namespace python {
 
+
 static void CFieldDescriptorDealloc(CFieldDescriptor* self);
 
 static google::protobuf::DescriptorPool* g_descriptor_pool = NULL;
@@ -93,7 +95,7 @@ static PyGetSetDef CFieldDescriptorGetters[] = {
 PyTypeObject CFieldDescriptor_Type = {
   PyObject_HEAD_INIT(&PyType_Type)
   0,
-  C("google3.net.google.protobuf.python.internal."
+  C("google.protobuf.internal."
     "_net_proto2___python."
     "CFieldDescriptor"),                // tp_name
   sizeof(CFieldDescriptor),             // tp_basicsize
@@ -181,6 +183,8 @@ static PyObject* CDescriptorPool_FindFieldByName(
   const google::protobuf::FieldDescriptor* field_descriptor = NULL;
 
   field_descriptor = self->pool->FindFieldByName(full_field_name);
+
+
   if (field_descriptor == NULL) {
     PyErr_Format(PyExc_TypeError, "Couldn't find field %.200s",
                  full_field_name);
@@ -223,7 +227,7 @@ static PyMethodDef CDescriptorPoolMethods[] = {
 PyTypeObject CDescriptorPool_Type = {
   PyObject_HEAD_INIT(&PyType_Type)
   0,
-  C("google3.net.google.protobuf.python.internal."
+  C("google.protobuf.internal."
     "_net_proto2___python."
     "CFieldDescriptor"),               // tp_name
   sizeof(CDescriptorPool),             // tp_basicsize
@@ -301,7 +305,6 @@ PyObject* Python_BuildFile(PyObject* ignored, PyObject* arg) {
     return NULL;
   }
 
-  // If this file is already in the generated pool, don't add it again.
   if (google::protobuf::DescriptorPool::generated_pool()->FindFileByName(
       file_proto.name()) != NULL) {
     Py_RETURN_NONE;
diff --git a/python/google/protobuf/reflection.py b/python/google/protobuf/reflection.py
index 1373c882..9570fd50 100755
--- a/python/google/protobuf/reflection.py
+++ b/python/google/protobuf/reflection.py
@@ -50,13 +50,20 @@ __author__ = 'robinson@google.com (Will Robinson)'
 
 from google.protobuf.internal import api_implementation
 from google.protobuf import descriptor as descriptor_mod
+from google.protobuf import message
+
 _FieldDescriptor = descriptor_mod.FieldDescriptor
 
 
 if api_implementation.Type() == 'cpp':
-  from google.protobuf.internal import cpp_message
-  _NewMessage = cpp_message.NewMessage
-  _InitMessage = cpp_message.InitMessage
+  if api_implementation.Version() == 2:
+    from google.protobuf.internal.cpp import cpp_message
+    _NewMessage = cpp_message.NewMessage
+    _InitMessage = cpp_message.InitMessage
+  else:
+    from google.protobuf.internal import cpp_message
+    _NewMessage = cpp_message.NewMessage
+    _InitMessage = cpp_message.InitMessage
 else:
   from google.protobuf.internal import python_message
   _NewMessage = python_message.NewMessage
@@ -112,7 +119,7 @@ class GeneratedProtocolMessageType(type):
       Newly-allocated class.
     """
     descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
-    _NewMessage(descriptor, dictionary)
+    bases = _NewMessage(bases, descriptor, dictionary)
     superclass = super(GeneratedProtocolMessageType, cls)
 
     new_class = superclass.__new__(cls, name, bases, dictionary)
@@ -140,3 +147,23 @@ class GeneratedProtocolMessageType(type):
     _InitMessage(descriptor, cls)
     superclass = super(GeneratedProtocolMessageType, cls)
     superclass.__init__(name, bases, dictionary)
+
+
+def ParseMessage(descriptor, byte_str):
+  """Generate a new Message instance from this Descriptor and a byte string.
+
+  Args:
+    descriptor: Protobuf Descriptor object
+    byte_str: Serialized protocol buffer byte string
+
+  Returns:
+    Newly created protobuf Message object.
+  """
+
+  class _ResultClass(message.Message):
+    __metaclass__ = GeneratedProtocolMessageType
+    DESCRIPTOR = descriptor
+
+  new_msg = _ResultClass()
+  new_msg.ParseFromString(byte_str)
+  return new_msg
diff --git a/python/google/protobuf/text_format.py b/python/google/protobuf/text_format.py
index c3a1cf60..0714c39d 100755
--- a/python/google/protobuf/text_format.py
+++ b/python/google/protobuf/text_format.py
@@ -43,10 +43,12 @@ __all__ = [ 'MessageToString', 'PrintMessage', 'PrintField',
             'PrintFieldValue', 'Merge' ]
 
 
-# Infinity and NaN are not explicitly supported by Python pre-2.6, and
-# float('inf') does not work on Windows (pre-2.6).
-_INFINITY = 1e10000    # overflows, thus will actually be infinity.
-_NAN = _INFINITY * 0
+_INTEGER_CHECKERS = (type_checkers.Uint32ValueChecker(),
+                     type_checkers.Int32ValueChecker(),
+                     type_checkers.Uint64ValueChecker(),
+                     type_checkers.Int64ValueChecker())
+_FLOAT_INFINITY = re.compile('-?inf(?:inity)?f?', re.IGNORECASE)
+_FLOAT_NAN = re.compile('nanf?', re.IGNORECASE)
 
 
 class ParseError(Exception):
@@ -120,7 +122,11 @@ def PrintFieldValue(field, value, out, indent=0,
       PrintMessage(value, out, indent + 2, as_utf8, as_one_line)
       out.write(' ' * indent + '}')
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
-    out.write(field.enum_type.values_by_number[value].name)
+    enum_value = field.enum_type.values_by_number.get(value, None)
+    if enum_value is not None:
+      out.write(enum_value.name)
+    else:
+      out.write(str(value))
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
     out.write('\"')
     if type(value) is unicode:
@@ -271,24 +277,7 @@ def _MergeScalarField(tokenizer, message, field):
   elif field.type == descriptor.FieldDescriptor.TYPE_BYTES:
     value = tokenizer.ConsumeByteString()
   elif field.type == descriptor.FieldDescriptor.TYPE_ENUM:
-    # Enum can be specified by a number (the enum value), or by
-    # a string literal (the enum name).
-    enum_descriptor = field.enum_type
-    if tokenizer.LookingAtInteger():
-      number = tokenizer.ConsumeInt32()
-      enum_value = enum_descriptor.values_by_number.get(number, None)
-      if enum_value is None:
-        raise tokenizer.ParseErrorPreviousToken(
-            'Enum type "%s" has no value with number %d.' % (
-                enum_descriptor.full_name, number))
-    else:
-      identifier = tokenizer.ConsumeIdentifier()
-      enum_value = enum_descriptor.values_by_name.get(identifier, None)
-      if enum_value is None:
-        raise tokenizer.ParseErrorPreviousToken(
-            'Enum type "%s" has no value named %s.' % (
-                enum_descriptor.full_name, identifier))
-    value = enum_value.number
+    value = tokenizer.ConsumeEnum(field)
   else:
     raise RuntimeError('Unknown field type %d' % field.type)
 
@@ -320,12 +309,6 @@ class _Tokenizer(object):
       '\"([^\"\n\\\\]|\\\\.)*(\"|\\\\?$)|'  # a double-quoted string
       '\'([^\'\n\\\\]|\\\\.)*(\'|\\\\?$)')  # a single-quoted string
   _IDENTIFIER = re.compile('\w+')
-  _INTEGER_CHECKERS = [type_checkers.Uint32ValueChecker(),
-                       type_checkers.Int32ValueChecker(),
-                       type_checkers.Uint64ValueChecker(),
-                       type_checkers.Int64ValueChecker()]
-  _FLOAT_INFINITY = re.compile('-?inf(inity)?f?', re.IGNORECASE)
-  _FLOAT_NAN = re.compile("nanf?", re.IGNORECASE)
 
   def __init__(self, text_message):
     self._text_message = text_message
@@ -394,17 +377,6 @@ class _Tokenizer(object):
     if not self.TryConsume(token):
       raise self._ParseError('Expected "%s".' % token)
 
-  def LookingAtInteger(self):
-    """Checks if the current token is an integer.
-
-    Returns:
-      True iff the current token is an integer.
-    """
-    if not self.token:
-      return False
-    c = self.token[0]
-    return (c >= '0' and c <= '9') or c == '-' or c == '+'
-
   def ConsumeIdentifier(self):
     """Consumes protocol message field identifier.
 
@@ -430,9 +402,9 @@ class _Tokenizer(object):
       ParseError: If a signed 32bit integer couldn't be consumed.
     """
     try:
-      result = self._ParseInteger(self.token, is_signed=True, is_long=False)
+      result = ParseInteger(self.token, is_signed=True, is_long=False)
     except ValueError, e:
-      raise self._IntegerParseError(e)
+      raise self._ParseError(str(e))
     self.NextToken()
     return result
 
@@ -446,9 +418,9 @@ class _Tokenizer(object):
       ParseError: If an unsigned 32bit integer couldn't be consumed.
     """
     try:
-      result = self._ParseInteger(self.token, is_signed=False, is_long=False)
+      result = ParseInteger(self.token, is_signed=False, is_long=False)
     except ValueError, e:
-      raise self._IntegerParseError(e)
+      raise self._ParseError(str(e))
     self.NextToken()
     return result
 
@@ -462,9 +434,9 @@ class _Tokenizer(object):
       ParseError: If a signed 64bit integer couldn't be consumed.
     """
     try:
-      result = self._ParseInteger(self.token, is_signed=True, is_long=True)
+      result = ParseInteger(self.token, is_signed=True, is_long=True)
     except ValueError, e:
-      raise self._IntegerParseError(e)
+      raise self._ParseError(str(e))
     self.NextToken()
     return result
 
@@ -478,9 +450,9 @@ class _Tokenizer(object):
       ParseError: If an unsigned 64bit integer couldn't be consumed.
     """
     try:
-      result = self._ParseInteger(self.token, is_signed=False, is_long=True)
+      result = ParseInteger(self.token, is_signed=False, is_long=True)
     except ValueError, e:
-      raise self._IntegerParseError(e)
+      raise self._ParseError(str(e))
     self.NextToken()
     return result
 
@@ -493,21 +465,10 @@ class _Tokenizer(object):
     Raises:
       ParseError: If a floating point number couldn't be consumed.
     """
-    text = self.token
-    if self._FLOAT_INFINITY.match(text):
-      self.NextToken()
-      if text.startswith('-'):
-        return -_INFINITY
-      return _INFINITY
-
-    if self._FLOAT_NAN.match(text):
-      self.NextToken()
-      return _NAN
-
     try:
-      result = float(text)
+      result = ParseFloat(self.token)
     except ValueError, e:
-      raise self._FloatParseError(e)
+      raise self._ParseError(str(e))
     self.NextToken()
     return result
 
@@ -520,14 +481,12 @@ class _Tokenizer(object):
     Raises:
       ParseError: If a boolean value couldn't be consumed.
     """
-    if self.token in ('true', 't', '1'):
-      self.NextToken()
-      return True
-    elif self.token in ('false', 'f', '0'):
-      self.NextToken()
-      return False
-    else:
-      raise self._ParseError('Expected "true" or "false".')
+    try:
+      result = ParseBool(self.token)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
 
   def ConsumeString(self):
     """Consumes a string value.
@@ -567,7 +526,7 @@ class _Tokenizer(object):
     """
     text = self.token
     if len(text) < 1 or text[0] not in ('\'', '"'):
-      raise self._ParseError('Exptected string.')
+      raise self._ParseError('Expected string.')
 
     if len(text) < 2 or text[-1] != text[0]:
       raise self._ParseError('String missing ending quote.')
@@ -579,36 +538,12 @@ class _Tokenizer(object):
     self.NextToken()
     return result
 
-  def _ParseInteger(self, text, is_signed=False, is_long=False):
-    """Parses an integer.
-
-    Args:
-      text: The text to parse.
-      is_signed: True if a signed integer must be parsed.
-      is_long: True if a long integer must be parsed.
-
-    Returns:
-      The integer value.
-
-    Raises:
-      ValueError: Thrown Iff the text is not a valid integer.
-    """
-    pos = 0
-    if text.startswith('-'):
-      pos += 1
-
-    base = 10
-    if text.startswith('0x', pos) or text.startswith('0X', pos):
-      base = 16
-    elif text.startswith('0', pos):
-      base = 8
-
-    # Do the actual parsing. Exception handling is propagated to caller.
-    result = int(text, base)
-
-    # Check if the integer is sane. Exceptions handled by callers.
-    checker = self._INTEGER_CHECKERS[2 * int(is_long) + int(is_signed)]
-    checker.CheckValue(result)
+  def ConsumeEnum(self, field):
+    try:
+      result = ParseEnum(field, self.token)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
     return result
 
   def ParseErrorPreviousToken(self, message):
@@ -626,13 +561,7 @@ class _Tokenizer(object):
   def _ParseError(self, message):
     """Creates and *returns* a ParseError for the current token."""
     return ParseError('%d:%d : %s' % (
-        self._line + 1, self._column - len(self.token) + 1, message))
-
-  def _IntegerParseError(self, e):
-    return self._ParseError('Couldn\'t parse integer: ' + str(e))
-
-  def _FloatParseError(self, e):
-    return self._ParseError('Couldn\'t parse number: ' + str(e))
+        self._line + 1, self._column + 1, message))
 
   def _StringParseError(self, e):
     return self._ParseError('Couldn\'t parse string: ' + str(e))
@@ -689,3 +618,117 @@ def _CUnescape(text):
   # allow single-digit hex escapes (like '\xf').
   result = _CUNESCAPE_HEX.sub(ReplaceHex, text)
   return result.decode('string_escape')
+
+
+def ParseInteger(text, is_signed=False, is_long=False):
+  """Parses an integer.
+
+  Args:
+    text: The text to parse.
+    is_signed: True if a signed integer must be parsed.
+    is_long: True if a long integer must be parsed.
+
+  Returns:
+    The integer value.
+
+  Raises:
+    ValueError: Thrown Iff the text is not a valid integer.
+  """
+  # Do the actual parsing. Exception handling is propagated to caller.
+  try:
+    result = int(text, 0)
+  except ValueError:
+    raise ValueError('Couldn\'t parse integer: %s' % text)
+
+  # Check if the integer is sane. Exceptions handled by callers.
+  checker = _INTEGER_CHECKERS[2 * int(is_long) + int(is_signed)]
+  checker.CheckValue(result)
+  return result
+
+
+def ParseFloat(text):
+  """Parse a floating point number.
+
+  Args:
+    text: Text to parse.
+
+  Returns:
+    The number parsed.
+
+  Raises:
+    ValueError: If a floating point number couldn't be parsed.
+  """
+  try:
+    # Assume Python compatible syntax.
+    return float(text)
+  except ValueError:
+    # Check alternative spellings.
+    if _FLOAT_INFINITY.match(text):
+      if text[0] == '-':
+        return float('-inf')
+      else:
+        return float('inf')
+    elif _FLOAT_NAN.match(text):
+      return float('nan')
+    else:
+      # assume '1.0f' format
+      try:
+        return float(text.rstrip('f'))
+      except ValueError:
+        raise ValueError('Couldn\'t parse float: %s' % text)
+
+
+def ParseBool(text):
+  """Parse a boolean value.
+
+  Args:
+    text: Text to parse.
+
+  Returns:
+    Boolean values parsed
+
+  Raises:
+    ValueError: If text is not a valid boolean.
+  """
+  if text in ('true', 't', '1'):
+    return True
+  elif text in ('false', 'f', '0'):
+    return False
+  else:
+    raise ValueError('Expected "true" or "false".')
+
+
+def ParseEnum(field, value):
+  """Parse an enum value.
+
+  The value can be specified by a number (the enum value), or by
+  a string literal (the enum name).
+
+  Args:
+    field: Enum field descriptor.
+    value: String value.
+
+  Returns:
+    Enum value number.
+
+  Raises:
+    ValueError: If the enum value could not be parsed.
+  """
+  enum_descriptor = field.enum_type
+  try:
+    number = int(value, 0)
+  except ValueError:
+    # Identifier.
+    enum_value = enum_descriptor.values_by_name.get(value, None)
+    if enum_value is None:
+      raise ValueError(
+          'Enum type "%s" has no value named %s.' % (
+              enum_descriptor.full_name, value))
+  else:
+    # Numeric value.
+    enum_value = enum_descriptor.values_by_number.get(number, None)
+    if enum_value is None:
+      raise ValueError(
+          'Enum type "%s" has no value with number %d.' % (
+              enum_descriptor.full_name, number))
+  return enum_value.number
diff --git a/python/setup.py b/python/setup.py
index 5f0acbac..fbe27660 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -63,19 +63,26 @@ def generate_proto(source):
     if subprocess.call(protoc_command) != 0:
       sys.exit(-1)
 
-def MakeTestSuite():
-  # This is apparently needed on some systems to make sure that the tests
-  # work even if a previous version is already installed.
-  if 'google' in sys.modules:
-    del sys.modules['google']
-
+def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/unittest.proto")
   generate_proto("../src/google/protobuf/unittest_custom_options.proto")
   generate_proto("../src/google/protobuf/unittest_import.proto")
+  generate_proto("../src/google/protobuf/unittest_import_public.proto")
   generate_proto("../src/google/protobuf/unittest_mset.proto")
   generate_proto("../src/google/protobuf/unittest_no_generic_services.proto")
+  generate_proto("google/protobuf/internal/test_bad_identifiers.proto")
   generate_proto("google/protobuf/internal/more_extensions.proto")
+  generate_proto("google/protobuf/internal/more_extensions_dynamic.proto")
   generate_proto("google/protobuf/internal/more_messages.proto")
+  generate_proto("google/protobuf/internal/factory_test1.proto")
+  generate_proto("google/protobuf/internal/factory_test2.proto")
+
+def MakeTestSuite():
+  # This is apparently needed on some systems to make sure that the tests
+  # work even if a previous version is already installed.
+  if 'google' in sys.modules:
+    del sys.modules['google']
+  GenerateUnittestProtos()
 
   import unittest
   import google.protobuf.internal.generator_test     as generator_test
@@ -85,6 +92,14 @@ def MakeTestSuite():
     as service_reflection_test
   import google.protobuf.internal.text_format_test   as text_format_test
   import google.protobuf.internal.wire_format_test   as wire_format_test
+  import google.protobuf.internal.unknown_fields_test as unknown_fields_test
+  import google.protobuf.internal.descriptor_database_test \
+      as descriptor_database_test
+  import google.protobuf.internal.descriptor_pool_test as descriptor_pool_test
+  import google.protobuf.internal.message_factory_test as message_factory_test
+  import google.protobuf.internal.message_cpp_test as message_cpp_test
+  import google.protobuf.internal.reflection_cpp_generated_test \
+      as reflection_cpp_generated_test
 
   loader = unittest.defaultTestLoader
   suite = unittest.TestSuite()
@@ -117,6 +132,8 @@ class build_py(_build_py):
     # Generate necessary .proto file if it doesn't exist.
     generate_proto("../src/google/protobuf/descriptor.proto")
     generate_proto("../src/google/protobuf/compiler/plugin.proto")
+
+    GenerateUnittestProtos()
     # Make sure google.protobuf.compiler is a valid package.
     open('google/protobuf/compiler/__init__.py', 'a').close()
     # _build_py is an old-style class, so super() doesn't work.
@@ -156,6 +173,9 @@ if __name__ == '__main__':
           'google.protobuf.descriptor_pb2',
           'google.protobuf.compiler.plugin_pb2',
           'google.protobuf.message',
+          'google.protobuf.descriptor_database',
+          'google.protobuf.descriptor_pool',
+          'google.protobuf.message_factory',
           'google.protobuf.reflection',
           'google.protobuf.service',
           'google.protobuf.service_reflection',
diff --git a/src/Makefile.am b/src/Makefile.am
index db9e7af9..172d0cdd 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -52,6 +52,7 @@ nobase_include_HEADERS =                                       \
   google/protobuf/descriptor_database.h                        \
   google/protobuf/dynamic_message.h                            \
   google/protobuf/extension_set.h                              \
+  google/protobuf/generated_enum_reflection.h                  \
   google/protobuf/generated_message_util.h                     \
   google/protobuf/generated_message_reflection.h               \
   google/protobuf/message.h                                    \
@@ -91,7 +92,11 @@ libprotobuf_lite_la_SOURCES =                                  \
   google/protobuf/stubs/once.cc                                \
   google/protobuf/stubs/hash.h                                 \
   google/protobuf/stubs/map-util.h                             \
-  google/protobuf/stubs/stl_util-inl.h                         \
+  google/protobuf/stubs/stl_util.h                             \
+  google/protobuf/stubs/stringprintf.cc                        \
+  google/protobuf/stubs/stringprintf.h                         \
+  google/protobuf/stubs/template_util.h                        \
+  google/protobuf/stubs/type_traits.h                          \
   google/protobuf/extension_set.cc                             \
   google/protobuf/generated_message_util.cc                    \
   google/protobuf/message_lite.cc                              \
@@ -158,6 +163,7 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/cpp/cpp_message.h                   \
   google/protobuf/compiler/cpp/cpp_message_field.cc            \
   google/protobuf/compiler/cpp/cpp_message_field.h             \
+  google/protobuf/compiler/cpp/cpp_options.h                   \
   google/protobuf/compiler/cpp/cpp_primitive_field.cc          \
   google/protobuf/compiler/cpp/cpp_primitive_field.h           \
   google/protobuf/compiler/cpp/cpp_service.cc                  \
@@ -187,6 +193,8 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/java/java_service.h                 \
   google/protobuf/compiler/java/java_string_field.cc           \
   google/protobuf/compiler/java/java_string_field.h            \
+  google/protobuf/compiler/java/java_doc_comment.cc            \
+  google/protobuf/compiler/java/java_doc_comment.h             \
   google/protobuf/compiler/python/python_generator.cc
 
 bin_PROGRAMS = protoc
@@ -199,12 +207,14 @@ protoc_inputs =                                                \
   google/protobuf/unittest.proto                               \
   google/protobuf/unittest_empty.proto                         \
   google/protobuf/unittest_import.proto                        \
+  google/protobuf/unittest_import_public.proto                 \
   google/protobuf/unittest_mset.proto                          \
   google/protobuf/unittest_optimize_for.proto                  \
   google/protobuf/unittest_embed_optimize_for.proto            \
   google/protobuf/unittest_custom_options.proto                \
   google/protobuf/unittest_lite.proto                          \
   google/protobuf/unittest_import_lite.proto                   \
+  google/protobuf/unittest_import_public_lite.proto            \
   google/protobuf/unittest_lite_imports_nonlite.proto          \
   google/protobuf/unittest_no_generic_services.proto           \
   google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
@@ -228,7 +238,9 @@ protoc_lite_outputs =                                          \
   google/protobuf/unittest_lite.pb.cc                          \
   google/protobuf/unittest_lite.pb.h                           \
   google/protobuf/unittest_import_lite.pb.cc                   \
-  google/protobuf/unittest_import_lite.pb.h
+  google/protobuf/unittest_import_lite.pb.h                    \
+  google/protobuf/unittest_import_public_lite.pb.cc            \
+  google/protobuf/unittest_import_public_lite.pb.h
 
 protoc_outputs =                                               \
   $(protoc_lite_outputs)                                       \
@@ -238,6 +250,8 @@ protoc_outputs =                                               \
   google/protobuf/unittest_empty.pb.h                          \
   google/protobuf/unittest_import.pb.cc                        \
   google/protobuf/unittest_import.pb.h                         \
+  google/protobuf/unittest_import_public.pb.cc                 \
+  google/protobuf/unittest_import_public.pb.h                  \
   google/protobuf/unittest_mset.pb.cc                          \
   google/protobuf/unittest_mset.pb.h                           \
   google/protobuf/unittest_optimize_for.pb.cc                  \
@@ -298,6 +312,9 @@ protobuf_test_SOURCES =                                        \
   google/protobuf/stubs/once_unittest.cc                       \
   google/protobuf/stubs/strutil_unittest.cc                    \
   google/protobuf/stubs/structurally_valid_unittest.cc         \
+  google/protobuf/stubs/stringprintf_unittest.cc               \
+  google/protobuf/stubs/template_util_unittest.cc              \
+  google/protobuf/stubs/type_traits_unittest.cc                \
   google/protobuf/descriptor_database_unittest.cc              \
   google/protobuf/descriptor_unittest.cc                       \
   google/protobuf/dynamic_message_unittest.cc                  \
@@ -306,6 +323,7 @@ protobuf_test_SOURCES =                                        \
   google/protobuf/message_unittest.cc                          \
   google/protobuf/reflection_ops_unittest.cc                   \
   google/protobuf/repeated_field_unittest.cc                   \
+  google/protobuf/repeated_field_reflection_unittest.cc        \
   google/protobuf/text_format_unittest.cc                      \
   google/protobuf/unknown_field_set_unittest.cc                \
   google/protobuf/wire_format_unittest.cc                      \
@@ -319,9 +337,11 @@ protobuf_test_SOURCES =                                        \
   google/protobuf/compiler/mock_code_generator.h               \
   google/protobuf/compiler/parser_unittest.cc                  \
   google/protobuf/compiler/cpp/cpp_bootstrap_unittest.cc       \
+  google/protobuf/compiler/cpp/cpp_unittest.h                  \
   google/protobuf/compiler/cpp/cpp_unittest.cc                 \
   google/protobuf/compiler/cpp/cpp_plugin_unittest.cc          \
   google/protobuf/compiler/java/java_plugin_unittest.cc        \
+  google/protobuf/compiler/java/java_doc_comment_unittest.cc   \
   google/protobuf/compiler/python/python_plugin_unittest.cc    \
   $(COMMON_TEST_SOURCES)
 nodist_protobuf_test_SOURCES = $(protoc_outputs)
diff --git a/src/google/protobuf/compiler/command_line_interface.cc b/src/google/protobuf/compiler/command_line_interface.cc
index 1c76994b..8dac5f42 100644
--- a/src/google/protobuf/compiler/command_line_interface.cc
+++ b/src/google/protobuf/compiler/command_line_interface.cc
@@ -59,12 +59,13 @@
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/text_format.h>
 #include <google/protobuf/dynamic_message.h>
+#include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/stubs/map-util.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 
 namespace google {
@@ -145,7 +146,7 @@ void AddTrailingSlash(string* path) {
 bool VerifyDirectoryExists(const string& path) {
   if (path.empty()) return true;
 
-  if (access(path.c_str(), W_OK) == -1) {
+  if (access(path.c_str(), F_OK) == -1) {
     cerr << path << ": " << strerror(errno) << endl;
     return false;
   } else {
@@ -566,6 +567,7 @@ CommandLineInterface::CommandLineInterface()
   : mode_(MODE_COMPILE),
     error_format_(ERROR_FORMAT_GCC),
     imports_in_descriptor_set_(false),
+    source_info_in_descriptor_set_(false),
     disallow_services_(false),
     inputs_are_proto_path_relative_(false) {}
 CommandLineInterface::~CommandLineInterface() {}
@@ -574,9 +576,23 @@ void CommandLineInterface::RegisterGenerator(const string& flag_name,
                                              CodeGenerator* generator,
                                              const string& help_text) {
   GeneratorInfo info;
+  info.flag_name = flag_name;
   info.generator = generator;
   info.help_text = help_text;
-  generators_[flag_name] = info;
+  generators_by_flag_name_[flag_name] = info;
+}
+
+void CommandLineInterface::RegisterGenerator(const string& flag_name,
+                                             const string& option_flag_name,
+                                             CodeGenerator* generator,
+                                             const string& help_text) {
+  GeneratorInfo info;
+  info.flag_name = flag_name;
+  info.option_flag_name = option_flag_name;
+  info.generator = generator;
+  info.help_text = help_text;
+  generators_by_flag_name_[flag_name] = info;
+  generators_by_option_name_[option_flag_name] = info;
 }
 
 void CommandLineInterface::AllowPlugins(const string& exe_name_prefix) {
@@ -585,7 +601,14 @@ void CommandLineInterface::AllowPlugins(const string& exe_name_prefix) {
 
 int CommandLineInterface::Run(int argc, const char* const argv[]) {
   Clear();
-  if (!ParseArguments(argc, argv)) return 1;
+  switch (ParseArguments(argc, argv)) {
+    case PARSE_ARGUMENT_DONE_AND_EXIT:
+      return 0;
+    case PARSE_ARGUMENT_FAIL:
+      return 1;
+    case PARSE_ARGUMENT_DONE_AND_CONTINUE:
+      break;
+  }
 
   // Set up the source tree.
   DiskSourceTree source_tree;
@@ -713,6 +736,7 @@ void CommandLineInterface::Clear() {
 
   mode_ = MODE_COMPILE;
   imports_in_descriptor_set_ = false;
+  source_info_in_descriptor_set_ = false;
   disallow_services_ = false;
 }
 
@@ -755,7 +779,8 @@ bool CommandLineInterface::MakeInputsBeProtoPathRelative(
   return true;
 }
 
-bool CommandLineInterface::ParseArguments(int argc, const char* const argv[]) {
+CommandLineInterface::ParseArgumentStatus
+CommandLineInterface::ParseArguments(int argc, const char* const argv[]) {
   executable_name_ = argv[0];
 
   // Iterate through all arguments and parse them.
@@ -769,41 +794,50 @@ bool CommandLineInterface::ParseArguments(int argc, const char* const argv[]) {
         if (name == "--decode") {
           cerr << "To decode an unknown message, use --decode_raw." << endl;
         }
-        return false;
+        return PARSE_ARGUMENT_FAIL;
       } else {
         ++i;
         value = argv[i];
       }
     }
 
-    if (!InterpretArgument(name, value)) return false;
+    ParseArgumentStatus status = InterpretArgument(name, value);
+    if (status != PARSE_ARGUMENT_DONE_AND_CONTINUE)
+      return status;
   }
 
   // If no --proto_path was given, use the current working directory.
   if (proto_path_.empty()) {
-    proto_path_.push_back(make_pair<string, string>("", "."));
+    // Don't use make_pair as the old/default standard library on Solaris
+    // doesn't support it without explicit template parameters, which are
+    // incompatible with C++0x's make_pair.
+    proto_path_.push_back(pair<string, string>("", "."));
   }
 
   // Check some errror cases.
   bool decoding_raw = (mode_ == MODE_DECODE) && codec_type_.empty();
   if (decoding_raw && !input_files_.empty()) {
     cerr << "When using --decode_raw, no input files should be given." << endl;
-    return false;
+    return PARSE_ARGUMENT_FAIL;
   } else if (!decoding_raw && input_files_.empty()) {
     cerr << "Missing input file." << endl;
-    return false;
+    return PARSE_ARGUMENT_FAIL;
   }
   if (mode_ == MODE_COMPILE && output_directives_.empty() &&
       descriptor_set_name_.empty()) {
     cerr << "Missing output directives." << endl;
-    return false;
+    return PARSE_ARGUMENT_FAIL;
   }
   if (imports_in_descriptor_set_ && descriptor_set_name_.empty()) {
     cerr << "--include_imports only makes sense when combined with "
             "--descriptor_set_out." << endl;
   }
+  if (source_info_in_descriptor_set_ && descriptor_set_name_.empty()) {
+    cerr << "--include_source_info only makes sense when combined with "
+            "--descriptor_set_out." << endl;
+  }
 
-  return true;
+  return PARSE_ARGUMENT_DONE_AND_CONTINUE;
 }
 
 bool CommandLineInterface::ParseArgument(const char* arg,
@@ -853,6 +887,7 @@ bool CommandLineInterface::ParseArgument(const char* arg,
   if (*name == "-h" || *name == "--help" ||
       *name == "--disallow_services" ||
       *name == "--include_imports" ||
+      *name == "--include_source_info" ||
       *name == "--version" ||
       *name == "--decode_raw") {
     // HACK:  These are the only flags that don't take a value.
@@ -865,8 +900,9 @@ bool CommandLineInterface::ParseArgument(const char* arg,
   return true;
 }
 
-bool CommandLineInterface::InterpretArgument(const string& name,
-                                             const string& value) {
+CommandLineInterface::ParseArgumentStatus
+CommandLineInterface::InterpretArgument(const string& name,
+                                        const string& value) {
   if (name.empty()) {
     // Not a flag.  Just a filename.
     if (value.empty()) {
@@ -874,7 +910,7 @@ bool CommandLineInterface::InterpretArgument(const string& name,
               "arguments to " << executable_name_ << ".  This is actually "
               "sort of hard to do.  Congrats.  Unfortunately it is not valid "
               "input so the program is going to die now." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
 
     input_files_.push_back(value);
@@ -902,7 +938,7 @@ bool CommandLineInterface::InterpretArgument(const string& name,
       if (disk_path.empty()) {
         cerr << "--proto_path passed empty directory name.  (Use \".\" for "
                 "current directory.)" << endl;
-        return false;
+        return PARSE_ARGUMENT_FAIL;
       }
 
       // Make sure disk path exists, warn otherwise.
@@ -910,35 +946,45 @@ bool CommandLineInterface::InterpretArgument(const string& name,
         cerr << disk_path << ": warning: directory does not exist." << endl;
       }
 
-      proto_path_.push_back(make_pair<string, string>(virtual_path, disk_path));
+      // Don't use make_pair as the old/default standard library on Solaris
+      // doesn't support it without explicit template parameters, which are
+      // incompatible with C++0x's make_pair.
+      proto_path_.push_back(pair<string, string>(virtual_path, disk_path));
     }
 
   } else if (name == "-o" || name == "--descriptor_set_out") {
     if (!descriptor_set_name_.empty()) {
       cerr << name << " may only be passed once." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
     if (value.empty()) {
       cerr << name << " requires a non-empty value." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
     if (mode_ != MODE_COMPILE) {
       cerr << "Cannot use --encode or --decode and generate descriptors at the "
               "same time." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
     descriptor_set_name_ = value;
 
   } else if (name == "--include_imports") {
     if (imports_in_descriptor_set_) {
       cerr << name << " may only be passed once." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
     imports_in_descriptor_set_ = true;
 
+  } else if (name == "--include_source_info") {
+    if (source_info_in_descriptor_set_) {
+      cerr << name << " may only be passed once." << endl;
+      return PARSE_ARGUMENT_FAIL;
+    }
+    source_info_in_descriptor_set_ = true;
+
   } else if (name == "-h" || name == "--help") {
     PrintHelpText();
-    return false;  // Exit without running compiler.
+    return PARSE_ARGUMENT_DONE_AND_EXIT;  // Exit without running compiler.
 
   } else if (name == "--version") {
     if (!version_info_.empty()) {
@@ -947,7 +993,7 @@ bool CommandLineInterface::InterpretArgument(const string& name,
     cout << "libprotoc "
          << protobuf::internal::VersionString(GOOGLE_PROTOBUF_VERSION)
          << endl;
-    return false;  // Exit without running compiler.
+    return PARSE_ARGUMENT_DONE_AND_EXIT;  // Exit without running compiler.
 
   } else if (name == "--disallow_services") {
     disallow_services_ = true;
@@ -956,12 +1002,12 @@ bool CommandLineInterface::InterpretArgument(const string& name,
              name == "--decode_raw") {
     if (mode_ != MODE_COMPILE) {
       cerr << "Only one of --encode and --decode can be specified." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
     if (!output_directives_.empty() || !descriptor_set_name_.empty()) {
       cerr << "Cannot use " << name
            << " and generate code or descriptors at the same time." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
 
     mode_ = (name == "--encode") ? MODE_ENCODE : MODE_DECODE;
@@ -971,10 +1017,10 @@ bool CommandLineInterface::InterpretArgument(const string& name,
       if (name == "--decode") {
         cerr << "To decode an unknown message, use --decode_raw." << endl;
       }
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     } else if (!value.empty() && name == "--decode_raw") {
       cerr << "--decode_raw does not take a parameter." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
 
     codec_type_ = value;
@@ -986,16 +1032,16 @@ bool CommandLineInterface::InterpretArgument(const string& name,
       error_format_ = ERROR_FORMAT_MSVS;
     } else {
       cerr << "Unknown error format: " << value << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
 
   } else if (name == "--plugin") {
     if (plugin_prefix_.empty()) {
       cerr << "This compiler does not support plugins." << endl;
-      return false;
+      return PARSE_ARGUMENT_FAIL;
     }
 
-    string name;
+    string plugin_name;
     string path;
 
     string::size_type equals_pos = value.find_first_of('=');
@@ -1003,57 +1049,68 @@ bool CommandLineInterface::InterpretArgument(const string& name,
       // Use the basename of the file.
       string::size_type slash_pos = value.find_last_of('/');
       if (slash_pos == string::npos) {
-        name = value;
+        plugin_name = value;
       } else {
-        name = value.substr(slash_pos + 1);
+        plugin_name = value.substr(slash_pos + 1);
       }
       path = value;
     } else {
-      name = value.substr(0, equals_pos);
+      plugin_name = value.substr(0, equals_pos);
       path = value.substr(equals_pos + 1);
     }
 
-    plugins_[name] = path;
+    plugins_[plugin_name] = path;
 
   } else {
     // Some other flag.  Look it up in the generators list.
-    const GeneratorInfo* generator_info = FindOrNull(generators_, name);
+    const GeneratorInfo* generator_info =
+        FindOrNull(generators_by_flag_name_, name);
     if (generator_info == NULL &&
         (plugin_prefix_.empty() || !HasSuffixString(name, "_out"))) {
-      cerr << "Unknown flag: " << name << endl;
-      return false;
-    }
+      // Check if it's a generator option flag.
+      generator_info = FindOrNull(generators_by_option_name_, name);
+      if (generator_info == NULL) {
+        cerr << "Unknown flag: " << name << endl;
+        return PARSE_ARGUMENT_FAIL;
+      } else {
+        string* parameters = &generator_parameters_[generator_info->flag_name];
+        if (!parameters->empty()) {
+          parameters->append(",");
+        }
+        parameters->append(value);
+      }
+    } else {
+      // It's an output flag.  Add it to the output directives.
+      if (mode_ != MODE_COMPILE) {
+        cerr << "Cannot use --encode or --decode and generate code at the "
+                "same time." << endl;
+        return PARSE_ARGUMENT_FAIL;
+      }
 
-    // It's an output flag.  Add it to the output directives.
-    if (mode_ != MODE_COMPILE) {
-      cerr << "Cannot use --encode or --decode and generate code at the "
-              "same time." << endl;
-      return false;
-    }
+      OutputDirective directive;
+      directive.name = name;
+      if (generator_info == NULL) {
+        directive.generator = NULL;
+      } else {
+        directive.generator = generator_info->generator;
+      }
 
-    OutputDirective directive;
-    directive.name = name;
-    if (generator_info == NULL) {
-      directive.generator = NULL;
-    } else {
-      directive.generator = generator_info->generator;
-    }
+      // Split value at ':' to separate the generator parameter from the
+      // filename.  However, avoid doing this if the colon is part of a valid
+      // Windows-style absolute path.
+      string::size_type colon_pos = value.find_first_of(':');
+      if (colon_pos == string::npos || IsWindowsAbsolutePath(value)) {
+        directive.output_location = value;
+      } else {
+        directive.parameter = value.substr(0, colon_pos);
+        directive.output_location = value.substr(colon_pos + 1);
+      }
 
-    // Split value at ':' to separate the generator parameter from the
-    // filename.  However, avoid doing this if the colon is part of a valid
-    // Windows-style absolute path.
-    string::size_type colon_pos = value.find_first_of(':');
-    if (colon_pos == string::npos || IsWindowsAbsolutePath(value)) {
-      directive.output_location = value;
-    } else {
-      directive.parameter = value.substr(0, colon_pos);
-      directive.output_location = value.substr(colon_pos + 1);
+      output_directives_.push_back(directive);
     }
-
-    output_directives_.push_back(directive);
   }
 
-  return true;
+  return PARSE_ARGUMENT_DONE_AND_CONTINUE;
 }
 
 void CommandLineInterface::PrintHelpText() {
@@ -1086,6 +1143,12 @@ void CommandLineInterface::PrintHelpText() {
 "  --include_imports           When using --descriptor_set_out, also include\n"
 "                              all dependencies of the input files in the\n"
 "                              set, so that the set is self-contained.\n"
+"  --include_source_info       When using --descriptor_set_out, do not strip\n"
+"                              SourceCodeInfo from the FileDescriptorProto.\n"
+"                              This results in vastly larger descriptors that\n"
+"                              include information about the original\n"
+"                              location of each decl in the source file as\n"
+"                              well as surrounding comments.\n"
 "  --error_format=FORMAT       Set the format in which to print errors.\n"
 "                              FORMAT may be 'gcc' (the default) or 'msvs'\n"
 "                              (Microsoft Visual Studio format)." << endl;
@@ -1101,8 +1164,8 @@ void CommandLineInterface::PrintHelpText() {
 "                              the executable's own name differs." << endl;
   }
 
-  for (GeneratorMap::iterator iter = generators_.begin();
-       iter != generators_.end(); ++iter) {
+  for (GeneratorMap::iterator iter = generators_by_flag_name_.begin();
+       iter != generators_by_flag_name_.end(); ++iter) {
     // FIXME(kenton):  If the text is long enough it will wrap, which is ugly,
     //   but fixing this nicely (e.g. splitting on spaces) is probably more
     //   trouble than it's worth.
@@ -1136,10 +1199,16 @@ bool CommandLineInterface::GenerateOutput(
     }
   } else {
     // Regular generator.
+    string parameters = output_directive.parameter;
+    if (!generator_parameters_[output_directive.name].empty()) {
+      if (!parameters.empty()) {
+        parameters.append(",");
+      }
+      parameters.append(generator_parameters_[output_directive.name]);
+    }
     for (int i = 0; i < parsed_files.size(); i++) {
-      if (!output_directive.generator->Generate(
-          parsed_files[i], output_directive.parameter,
-          generator_context, &error)) {
+      if (!output_directive.generator->Generate(parsed_files[i], parameters,
+                                                generator_context, &error)) {
         // Generator returned an error.
         cerr << output_directive.name << ": " << parsed_files[i]->name() << ": "
              << error << endl;
@@ -1168,8 +1237,9 @@ bool CommandLineInterface::GeneratePluginOutput(
   set<const FileDescriptor*> already_seen;
   for (int i = 0; i < parsed_files.size(); i++) {
     request.add_file_to_generate(parsed_files[i]->name());
-    GetTransitiveDependencies(parsed_files[i], &already_seen,
-                              request.mutable_proto_file());
+    GetTransitiveDependencies(parsed_files[i],
+                              true,  // Include source code info.
+                              &already_seen, request.mutable_proto_file());
   }
 
   // Invoke the plugin.
@@ -1299,12 +1369,17 @@ bool CommandLineInterface::WriteDescriptorSet(
   if (imports_in_descriptor_set_) {
     set<const FileDescriptor*> already_seen;
     for (int i = 0; i < parsed_files.size(); i++) {
-      GetTransitiveDependencies(
-          parsed_files[i], &already_seen, file_set.mutable_file());
+      GetTransitiveDependencies(parsed_files[i],
+                                source_info_in_descriptor_set_,
+                                &already_seen, file_set.mutable_file());
     }
   } else {
     for (int i = 0; i < parsed_files.size(); i++) {
-      parsed_files[i]->CopyTo(file_set.add_file());
+      FileDescriptorProto* file_proto = file_set.add_file();
+      parsed_files[i]->CopyTo(file_proto);
+      if (source_info_in_descriptor_set_) {
+        parsed_files[i]->CopySourceCodeInfoTo(file_proto);
+      }
     }
   }
 
@@ -1334,7 +1409,7 @@ bool CommandLineInterface::WriteDescriptorSet(
 }
 
 void CommandLineInterface::GetTransitiveDependencies(
-    const FileDescriptor* file,
+    const FileDescriptor* file, bool include_source_code_info,
     set<const FileDescriptor*>* already_seen,
     RepeatedPtrField<FileDescriptorProto>* output) {
   if (!already_seen->insert(file).second) {
@@ -1344,11 +1419,16 @@ void CommandLineInterface::GetTransitiveDependencies(
 
   // Add all dependencies.
   for (int i = 0; i < file->dependency_count(); i++) {
-    GetTransitiveDependencies(file->dependency(i), already_seen, output);
+    GetTransitiveDependencies(file->dependency(i), include_source_code_info,
+                              already_seen, output);
   }
 
   // Add this file.
-  file->CopyTo(output->Add());
+  FileDescriptorProto* new_descriptor = output->Add();
+  file->CopyTo(new_descriptor);
+  if (include_source_code_info) {
+    file->CopySourceCodeInfoTo(new_descriptor);
+  }
 }
 
 
diff --git a/src/google/protobuf/compiler/command_line_interface.h b/src/google/protobuf/compiler/command_line_interface.h
index 0b507d80..86ea9bde 100644
--- a/src/google/protobuf/compiler/command_line_interface.h
+++ b/src/google/protobuf/compiler/command_line_interface.h
@@ -112,6 +112,19 @@ class LIBPROTOC_EXPORT CommandLineInterface {
                          CodeGenerator* generator,
                          const string& help_text);
 
+  // Register a code generator for a language.
+  // Besides flag_name you can specify another option_flag_name that could be
+  // used to pass extra parameters to the registered code generator.
+  // Suppose you have registered a generator by calling:
+  //   command_line_interface.RegisterGenerator("--foo_out", "--foo_opt", ...)
+  // Then you could invoke the compiler with a command like:
+  //   protoc --foo_out=enable_bar:outdir --foo_opt=enable_baz
+  // This will pass "enable_bar,enable_baz" as the parameter to the generator.
+  void RegisterGenerator(const string& flag_name,
+                         const string& option_flag_name,
+                         CodeGenerator* generator,
+                         const string& help_text);
+
   // Enables "plugins".  In this mode, if a command-line flag ends with "_out"
   // but does not match any registered generator, the compiler will attempt to
   // find a "plugin" to implement the generator.  Plugins are just executables.
@@ -186,8 +199,15 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   bool MakeInputsBeProtoPathRelative(
     DiskSourceTree* source_tree);
 
+  // Return status for ParseArguments() and InterpretArgument().
+  enum ParseArgumentStatus {
+    PARSE_ARGUMENT_DONE_AND_CONTINUE,
+    PARSE_ARGUMENT_DONE_AND_EXIT,
+    PARSE_ARGUMENT_FAIL
+  };
+
   // Parse all command-line arguments.
-  bool ParseArguments(int argc, const char* const argv[]);
+  ParseArgumentStatus ParseArguments(int argc, const char* const argv[]);
 
   // Parses a command-line argument into a name/value pair.  Returns
   // true if the next argument in the argv should be used as the value,
@@ -203,7 +223,8 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   bool ParseArgument(const char* arg, string* name, string* value);
 
   // Interprets arguments parsed with ParseArgument.
-  bool InterpretArgument(const string& name, const string& value);
+  ParseArgumentStatus InterpretArgument(const string& name,
+                                        const string& value);
 
   // Print the --help text to stderr.
   void PrintHelpText();
@@ -230,9 +251,11 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // protos will be ordered such that every file is listed before any file that
   // depends on it, so that you can call DescriptorPool::BuildFile() on them
   // in order.  Any files in *already_seen will not be added, and each file
-  // added will be inserted into *already_seen.
+  // added will be inserted into *already_seen.  If include_source_code_info is
+  // true then include the source code information in the FileDescriptorProtos.
   static void GetTransitiveDependencies(
       const FileDescriptor* file,
+      bool include_source_code_info,
       set<const FileDescriptor*>* already_seen,
       RepeatedPtrField<FileDescriptorProto>* output);
 
@@ -244,13 +267,21 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // Version info set with SetVersionInfo().
   string version_info_;
 
-  // Map from flag names to registered generators.
+  // Registered generators.
   struct GeneratorInfo {
+    string flag_name;
+    string option_flag_name;
     CodeGenerator* generator;
     string help_text;
   };
   typedef map<string, GeneratorInfo> GeneratorMap;
-  GeneratorMap generators_;
+  GeneratorMap generators_by_flag_name_;
+  GeneratorMap generators_by_option_name_;
+  // A map from generator names to the parameters specified using the option
+  // flag. For example, if the user invokes the compiler with:
+  //   protoc --foo_out=outputdir --foo_opt=enable_bar ...
+  // Then there will be an entry ("--foo_out", "enable_bar") in this map.
+  map<string, string> generator_parameters_;
 
   // See AllowPlugins().  If this is empty, plugins aren't allowed.
   string plugin_prefix_;
@@ -302,6 +333,10 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // the .proto files listed on the command-line are added.
   bool imports_in_descriptor_set_;
 
+  // True if --include_source_info was given, meaning that we should not strip
+  // SourceCodeInfo from the DescriptorSet.
+  bool source_info_in_descriptor_set_;
+
   // Was the --disallow_services flag used?
   bool disallow_services_;
 
diff --git a/src/google/protobuf/compiler/command_line_interface_unittest.cc b/src/google/protobuf/compiler/command_line_interface_unittest.cc
index d5b3a1dc..16559923 100644
--- a/src/google/protobuf/compiler/command_line_interface_unittest.cc
+++ b/src/google/protobuf/compiler/command_line_interface_unittest.cc
@@ -122,6 +122,10 @@ class CommandLineInterfaceTest : public testing::Test {
   // substring.
   void ExpectErrorSubstring(const string& expected_substring);
 
+  // Like ExpectErrorSubstring, but checks that Run() returned zero.
+  void ExpectErrorSubstringWithZeroReturnCode(
+      const string& expected_substring);
+
   // Returns true if ExpectErrorSubstring(expected_substring) would pass, but
   // does not fail otherwise.
   bool HasAlternateErrorSubstring(const string& expected_substring);
@@ -225,7 +229,7 @@ void CommandLineInterfaceTest::SetUp() {
   // Register generators.
   CodeGenerator* generator = new MockCodeGenerator("test_generator");
   mock_generators_to_delete_.push_back(generator);
-  cli_.RegisterGenerator("--test_out", generator, "Test output.");
+  cli_.RegisterGenerator("--test_out", "--test_opt", generator, "Test output.");
   cli_.RegisterGenerator("-t", generator, "Test output.");
 
   generator = new MockCodeGenerator("alt_generator");
@@ -345,6 +349,12 @@ void CommandLineInterfaceTest::ExpectErrorSubstring(
   EXPECT_PRED_FORMAT2(testing::IsSubstring, expected_substring, error_text_);
 }
 
+void CommandLineInterfaceTest::ExpectErrorSubstringWithZeroReturnCode(
+    const string& expected_substring) {
+  EXPECT_EQ(0, return_code_);
+  EXPECT_PRED_FORMAT2(testing::IsSubstring, expected_substring, error_text_);
+}
+
 bool CommandLineInterfaceTest::HasAlternateErrorSubstring(
     const string& expected_substring) {
   EXPECT_NE(0, return_code_);
@@ -544,6 +554,32 @@ TEST_F(CommandLineInterfaceTest, GeneratorParameters) {
   ExpectGenerated("test_plugin", "TestPluginParameter", "foo.proto", "Foo");
 }
 
+TEST_F(CommandLineInterfaceTest, ExtraGeneratorParameters) {
+  // Test that generator parameters specified with the option flag are
+  // correctly passed to the code generator.
+
+  CreateTempFile("foo.proto",
+    "syntax = \"proto2\";\n"
+    "message Foo {}\n");
+  // Create the "a" and "b" sub-directories.
+  CreateTempDir("a");
+  CreateTempDir("b");
+
+  Run("protocol_compiler "
+      "--test_opt=foo1 "
+      "--test_out=bar:$tmpdir/a "
+      "--test_opt=foo2 "
+      "--test_out=baz:$tmpdir/b "
+      "--test_opt=foo3 "
+      "--proto_path=$tmpdir foo.proto");
+
+  ExpectNoErrors();
+  ExpectGenerated(
+      "test_generator", "bar,foo1,foo2,foo3", "foo.proto", "Foo", "a");
+  ExpectGenerated(
+      "test_generator", "baz,foo1,foo2,foo3", "foo.proto", "Foo", "b");
+}
+
 TEST_F(CommandLineInterfaceTest, Insert) {
   // Test running a generator that inserts code into another's output.
 
@@ -779,6 +815,33 @@ TEST_F(CommandLineInterfaceTest, WriteDescriptorSet) {
   if (HasFatalFailure()) return;
   ASSERT_EQ(1, descriptor_set.file_size());
   EXPECT_EQ("bar.proto", descriptor_set.file(0).name());
+  // Descriptor set should not have source code info.
+  EXPECT_FALSE(descriptor_set.file(0).has_source_code_info());
+}
+
+TEST_F(CommandLineInterfaceTest, WriteDescriptorSetWithSourceInfo) {
+  CreateTempFile("foo.proto",
+    "syntax = \"proto2\";\n"
+    "message Foo {}\n");
+  CreateTempFile("bar.proto",
+    "syntax = \"proto2\";\n"
+    "import \"foo.proto\";\n"
+    "message Bar {\n"
+    "  optional Foo foo = 1;\n"
+    "}\n");
+
+  Run("protocol_compiler --descriptor_set_out=$tmpdir/descriptor_set "
+      "--include_source_info --proto_path=$tmpdir bar.proto");
+
+  ExpectNoErrors();
+
+  FileDescriptorSet descriptor_set;
+  ReadDescriptorSet("descriptor_set", &descriptor_set);
+  if (HasFatalFailure()) return;
+  ASSERT_EQ(1, descriptor_set.file_size());
+  EXPECT_EQ("bar.proto", descriptor_set.file(0).name());
+  // Source code info included.
+  EXPECT_TRUE(descriptor_set.file(0).has_source_code_info());
 }
 
 TEST_F(CommandLineInterfaceTest, WriteTransitiveDescriptorSet) {
@@ -807,6 +870,40 @@ TEST_F(CommandLineInterfaceTest, WriteTransitiveDescriptorSet) {
   }
   EXPECT_EQ("foo.proto", descriptor_set.file(0).name());
   EXPECT_EQ("bar.proto", descriptor_set.file(1).name());
+  // Descriptor set should not have source code info.
+  EXPECT_FALSE(descriptor_set.file(0).has_source_code_info());
+  EXPECT_FALSE(descriptor_set.file(1).has_source_code_info());
+}
+
+TEST_F(CommandLineInterfaceTest, WriteTransitiveDescriptorSetWithSourceInfo) {
+  CreateTempFile("foo.proto",
+    "syntax = \"proto2\";\n"
+    "message Foo {}\n");
+  CreateTempFile("bar.proto",
+    "syntax = \"proto2\";\n"
+    "import \"foo.proto\";\n"
+    "message Bar {\n"
+    "  optional Foo foo = 1;\n"
+    "}\n");
+
+  Run("protocol_compiler --descriptor_set_out=$tmpdir/descriptor_set "
+      "--include_imports --include_source_info --proto_path=$tmpdir bar.proto");
+
+  ExpectNoErrors();
+
+  FileDescriptorSet descriptor_set;
+  ReadDescriptorSet("descriptor_set", &descriptor_set);
+  if (HasFatalFailure()) return;
+  ASSERT_EQ(2, descriptor_set.file_size());
+  if (descriptor_set.file(0).name() == "bar.proto") {
+    std::swap(descriptor_set.mutable_file()->mutable_data()[0],
+              descriptor_set.mutable_file()->mutable_data()[1]);
+  }
+  EXPECT_EQ("foo.proto", descriptor_set.file(0).name());
+  EXPECT_EQ("bar.proto", descriptor_set.file(1).name());
+  // Source code info included.
+  EXPECT_TRUE(descriptor_set.file(0).has_source_code_info());
+  EXPECT_TRUE(descriptor_set.file(1).has_source_code_info());
 }
 
 // -------------------------------------------------------------------
@@ -1129,6 +1226,17 @@ TEST_F(CommandLineInterfaceTest, GeneratorPluginCrash) {
 #endif
 }
 
+TEST_F(CommandLineInterfaceTest, PluginReceivesSourceCodeInfo) {
+  CreateTempFile("foo.proto",
+    "syntax = \"proto2\";\n"
+    "message MockCodeGenerator_HasSourceCodeInfo {}\n");
+
+  Run("protocol_compiler --plug_out=$tmpdir --proto_path=$tmpdir foo.proto");
+
+  ExpectErrorSubstring(
+      "Saw message type MockCodeGenerator_HasSourceCodeInfo: 1.");
+}
+
 TEST_F(CommandLineInterfaceTest, GeneratorPluginNotFound) {
   // Test what happens if the plugin isn't found.
 
@@ -1171,11 +1279,11 @@ TEST_F(CommandLineInterfaceTest, GeneratorPluginNotAllowed) {
 TEST_F(CommandLineInterfaceTest, HelpText) {
   Run("test_exec_name --help");
 
-  ExpectErrorSubstring("Usage: test_exec_name ");
-  ExpectErrorSubstring("--test_out=OUT_DIR");
-  ExpectErrorSubstring("Test output.");
-  ExpectErrorSubstring("--alt_out=OUT_DIR");
-  ExpectErrorSubstring("Alt output.");
+  ExpectErrorSubstringWithZeroReturnCode("Usage: test_exec_name ");
+  ExpectErrorSubstringWithZeroReturnCode("--test_out=OUT_DIR");
+  ExpectErrorSubstringWithZeroReturnCode("Test output.");
+  ExpectErrorSubstringWithZeroReturnCode("--alt_out=OUT_DIR");
+  ExpectErrorSubstringWithZeroReturnCode("Alt output.");
 }
 
 TEST_F(CommandLineInterfaceTest, GccFormatErrors) {
diff --git a/src/google/protobuf/compiler/cpp/cpp_bootstrap_unittest.cc b/src/google/protobuf/compiler/cpp/cpp_bootstrap_unittest.cc
index bcfa5020..b7c1766b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_bootstrap_unittest.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_bootstrap_unittest.cc
@@ -48,8 +48,8 @@
 #include <google/protobuf/compiler/importer.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
 #include <google/protobuf/stubs/map-util.h>
+#include <google/protobuf/stubs/stl_util.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum.cc b/src/google/protobuf/compiler/cpp/cpp_enum.cc
index 76d2b798..67c12d7a 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_enum.cc
@@ -46,10 +46,10 @@ namespace compiler {
 namespace cpp {
 
 EnumGenerator::EnumGenerator(const EnumDescriptor* descriptor,
-                             const string& dllexport_decl)
+                             const Options& options)
   : descriptor_(descriptor),
     classname_(ClassName(descriptor, false)),
-    dllexport_decl_(dllexport_decl) {
+    options_(options) {
 }
 
 EnumGenerator::~EnumGenerator() {}
@@ -88,10 +88,10 @@ void EnumGenerator::GenerateDefinition(io::Printer* printer) {
   vars["min_name"] = min_value->name();
   vars["max_name"] = max_value->name();
 
-  if (dllexport_decl_.empty()) {
+  if (options_.dllexport_decl.empty()) {
     vars["dllexport"] = "";
   } else {
-    vars["dllexport"] = dllexport_decl_ + " ";
+    vars["dllexport"] = options_.dllexport_decl + " ";
   }
 
   printer->Print(vars,
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum.h b/src/google/protobuf/compiler/cpp/cpp_enum.h
index 58f7721e..2e85a0bd 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum.h
+++ b/src/google/protobuf/compiler/cpp/cpp_enum.h
@@ -36,8 +36,10 @@
 #define GOOGLE_PROTOBUF_COMPILER_CPP_ENUM_H__
 
 #include <string>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 #include <google/protobuf/descriptor.h>
 
+
 namespace google {
 namespace protobuf {
   namespace io {
@@ -53,7 +55,7 @@ class EnumGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
   explicit EnumGenerator(const EnumDescriptor* descriptor,
-                         const string& dllexport_decl);
+                         const Options& options);
   ~EnumGenerator();
 
   // Header stuff.
@@ -86,7 +88,7 @@ class EnumGenerator {
  private:
   const EnumDescriptor* descriptor_;
   string classname_;
-  string dllexport_decl_;
+  Options options_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(EnumGenerator);
 };
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum_field.cc b/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
index a369f417..6e1620d4 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
@@ -46,8 +46,9 @@ namespace cpp {
 namespace {
 
 void SetEnumVariables(const FieldDescriptor* descriptor,
-                      map<string, string>* variables) {
-  SetCommonFieldVariables(descriptor, variables);
+                      map<string, string>* variables,
+                      const Options& options) {
+  SetCommonFieldVariables(descriptor, variables, options);
   const EnumValueDescriptor* default_value = descriptor->default_value_enum();
   (*variables)["type"] = ClassName(descriptor->enum_type(), true);
   (*variables)["default"] = SimpleItoa(default_value->number());
@@ -58,9 +59,10 @@ void SetEnumVariables(const FieldDescriptor* descriptor,
 // ===================================================================
 
 EnumFieldGenerator::
-EnumFieldGenerator(const FieldDescriptor* descriptor)
+EnumFieldGenerator(const FieldDescriptor* descriptor,
+                   const Options& options)
   : descriptor_(descriptor) {
-  SetEnumVariables(descriptor, &variables_);
+  SetEnumVariables(descriptor, &variables_, options);
 }
 
 EnumFieldGenerator::~EnumFieldGenerator() {}
@@ -84,7 +86,7 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "  return static_cast< $type$ >($name$_);\n"
     "}\n"
     "inline void $classname$::set_$name$($type$ value) {\n"
-    "  GOOGLE_DCHECK($type$_IsValid(value));\n"
+    "  assert($type$_IsValid(value));\n"
     "  set_has_$name$();\n"
     "  $name$_ = value;\n"
     "}\n");
@@ -152,9 +154,10 @@ GenerateByteSize(io::Printer* printer) const {
 // ===================================================================
 
 RepeatedEnumFieldGenerator::
-RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor)
+RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor,
+                           const Options& options)
   : descriptor_(descriptor) {
-  SetEnumVariables(descriptor, &variables_);
+  SetEnumVariables(descriptor, &variables_, options);
 }
 
 RepeatedEnumFieldGenerator::~RepeatedEnumFieldGenerator() {}
@@ -187,11 +190,11 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "  return static_cast< $type$ >($name$_.Get(index));\n"
     "}\n"
     "inline void $classname$::set_$name$(int index, $type$ value) {\n"
-    "  GOOGLE_DCHECK($type$_IsValid(value));\n"
+    "  assert($type$_IsValid(value));\n"
     "  $name$_.Set(index, value);\n"
     "}\n"
     "inline void $classname$::add_$name$($type$ value) {\n"
-    "  GOOGLE_DCHECK($type$_IsValid(value));\n"
+    "  assert($type$_IsValid(value));\n"
     "  $name$_.Add(value);\n"
     "}\n");
   printer->Print(variables_,
@@ -345,7 +348,9 @@ GenerateByteSize(io::Printer* printer) const {
       "  total_size += $tag_size$ +\n"
       "    ::google::protobuf::internal::WireFormatLite::Int32Size(data_size);\n"
       "}\n"
+      "GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();\n"
       "_$name$_cached_byte_size_ = data_size;\n"
+      "GOOGLE_SAFE_CONCURRENT_WRITES_END();\n"
       "total_size += data_size;\n");
   } else {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum_field.h b/src/google/protobuf/compiler/cpp/cpp_enum_field.h
index 0793430c..65770083 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_enum_field.h
@@ -46,7 +46,8 @@ namespace cpp {
 
 class EnumFieldGenerator : public FieldGenerator {
  public:
-  explicit EnumFieldGenerator(const FieldDescriptor* descriptor);
+  explicit EnumFieldGenerator(const FieldDescriptor* descriptor,
+                              const Options& options);
   ~EnumFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
@@ -71,7 +72,8 @@ class EnumFieldGenerator : public FieldGenerator {
 
 class RepeatedEnumFieldGenerator : public FieldGenerator {
  public:
-  explicit RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor);
+  explicit RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor,
+                                      const Options& options);
   ~RepeatedEnumFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
diff --git a/src/google/protobuf/compiler/cpp/cpp_extension.cc b/src/google/protobuf/compiler/cpp/cpp_extension.cc
index 658a7077..ef56b5e5 100644
--- a/src/google/protobuf/compiler/cpp/cpp_extension.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_extension.cc
@@ -57,9 +57,9 @@ string ExtendeeClassName(const FieldDescriptor* descriptor) {
 }  // anonymous namespace
 
 ExtensionGenerator::ExtensionGenerator(const FieldDescriptor* descriptor,
-                                       const string& dllexport_decl)
+                                       const Options& options)
   : descriptor_(descriptor),
-    dllexport_decl_(dllexport_decl) {
+    options_(options) {
   // Construct type_traits_.
   if (descriptor_->is_repeated()) {
     type_traits_ = "Repeated";
@@ -106,8 +106,8 @@ void ExtensionGenerator::GenerateDeclaration(io::Printer* printer) {
   // export/import specifier.
   if (descriptor_->extension_scope() == NULL) {
     vars["qualifier"] = "extern";
-    if (!dllexport_decl_.empty()) {
-      vars["qualifier"] = dllexport_decl_ + " " + vars["qualifier"];
+    if (!options_.dllexport_decl.empty()) {
+      vars["qualifier"] = options_.dllexport_decl + " " + vars["qualifier"];
     }
   } else {
     vars["qualifier"] = "static";
diff --git a/src/google/protobuf/compiler/cpp/cpp_extension.h b/src/google/protobuf/compiler/cpp/cpp_extension.h
index 3068b091..50ad035b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_extension.h
+++ b/src/google/protobuf/compiler/cpp/cpp_extension.h
@@ -37,6 +37,7 @@
 
 #include <string>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 
 namespace google {
 namespace protobuf {
@@ -56,8 +57,8 @@ namespace cpp {
 class ExtensionGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
-  explicit ExtensionGenerator(const FieldDescriptor* descriptor,
-                              const string& dllexport_decl);
+  explicit ExtensionGenerator(const FieldDescriptor* desycriptor,
+                              const Options& options);
   ~ExtensionGenerator();
 
   // Header stuff.
@@ -72,7 +73,7 @@ class ExtensionGenerator {
  private:
   const FieldDescriptor* descriptor_;
   string type_traits_;
-  string dllexport_decl_;
+  Options options_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ExtensionGenerator);
 };
diff --git a/src/google/protobuf/compiler/cpp/cpp_field.cc b/src/google/protobuf/compiler/cpp/cpp_field.cc
index 103cac4a..0786176b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_field.cc
@@ -52,7 +52,8 @@ namespace cpp {
 using internal::WireFormat;
 
 void SetCommonFieldVariables(const FieldDescriptor* descriptor,
-                             map<string, string>* variables) {
+                             map<string, string>* variables,
+                             const Options& options) {
   (*variables)["name"] = FieldName(descriptor);
   (*variables)["index"] = SimpleItoa(descriptor->index());
   (*variables)["number"] = SimpleItoa(descriptor->number());
@@ -64,6 +65,7 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
   (*variables)["deprecation"] = descriptor->options().deprecated()
       ? " PROTOBUF_DEPRECATED" : "";
 
+  (*variables)["cppget"] = "Get";
 }
 
 FieldGenerator::~FieldGenerator() {}
@@ -80,46 +82,47 @@ GenerateMergeFromCodedStreamWithPacking(io::Printer* printer) const {
 
 }
 
-FieldGeneratorMap::FieldGeneratorMap(const Descriptor* descriptor)
+FieldGeneratorMap::FieldGeneratorMap(const Descriptor* descriptor,
+                                     const Options& options)
   : descriptor_(descriptor),
-    field_generators_(
-      new scoped_ptr<FieldGenerator>[descriptor->field_count()]) {
+    field_generators_(new scoped_ptr<FieldGenerator>[descriptor->field_count()]) {
   // Construct all the FieldGenerators.
   for (int i = 0; i < descriptor->field_count(); i++) {
-    field_generators_[i].reset(MakeGenerator(descriptor->field(i)));
+    field_generators_[i].reset(MakeGenerator(descriptor->field(i), options));
   }
 }
 
-FieldGenerator* FieldGeneratorMap::MakeGenerator(const FieldDescriptor* field) {
+FieldGenerator* FieldGeneratorMap::MakeGenerator(const FieldDescriptor* field,
+                                                 const Options& options) {
   if (field->is_repeated()) {
     switch (field->cpp_type()) {
       case FieldDescriptor::CPPTYPE_MESSAGE:
-        return new RepeatedMessageFieldGenerator(field);
+        return new RepeatedMessageFieldGenerator(field, options);
       case FieldDescriptor::CPPTYPE_STRING:
         switch (field->options().ctype()) {
           default:  // RepeatedStringFieldGenerator handles unknown ctypes.
           case FieldOptions::STRING:
-            return new RepeatedStringFieldGenerator(field);
+            return new RepeatedStringFieldGenerator(field, options);
         }
       case FieldDescriptor::CPPTYPE_ENUM:
-        return new RepeatedEnumFieldGenerator(field);
+        return new RepeatedEnumFieldGenerator(field, options);
       default:
-        return new RepeatedPrimitiveFieldGenerator(field);
+        return new RepeatedPrimitiveFieldGenerator(field, options);
     }
   } else {
     switch (field->cpp_type()) {
       case FieldDescriptor::CPPTYPE_MESSAGE:
-        return new MessageFieldGenerator(field);
+        return new MessageFieldGenerator(field, options);
       case FieldDescriptor::CPPTYPE_STRING:
         switch (field->options().ctype()) {
           default:  // StringFieldGenerator handles unknown ctypes.
           case FieldOptions::STRING:
-            return new StringFieldGenerator(field);
+            return new StringFieldGenerator(field, options);
         }
       case FieldDescriptor::CPPTYPE_ENUM:
-        return new EnumFieldGenerator(field);
+        return new EnumFieldGenerator(field, options);
       default:
-        return new PrimitiveFieldGenerator(field);
+        return new PrimitiveFieldGenerator(field, options);
     }
   }
 }
diff --git a/src/google/protobuf/compiler/cpp/cpp_field.h b/src/google/protobuf/compiler/cpp/cpp_field.h
index c303a337..f7d99b15 100644
--- a/src/google/protobuf/compiler/cpp/cpp_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_field.h
@@ -40,6 +40,7 @@
 
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 
 namespace google {
 namespace protobuf {
@@ -57,7 +58,8 @@ namespace cpp {
 // ['name', 'index', 'number', 'classname', 'declared_type', 'tag_size',
 // 'deprecation'].
 void SetCommonFieldVariables(const FieldDescriptor* descriptor,
-                             map<string, string>* variables);
+                             map<string, string>* variables,
+                             const Options& options);
 
 class FieldGenerator {
  public:
@@ -114,6 +116,13 @@ class FieldGenerator {
   // Most field types don't need this, so the default implementation is empty.
   virtual void GenerateDestructorCode(io::Printer* printer) const {}
 
+  // Generate code that allocates the fields's default instance.
+  virtual void GenerateDefaultInstanceAllocator(io::Printer* printer) const {}
+
+  // Generate code that should be run when ShutdownProtobufLibrary() is called,
+  // to delete all dynamically-allocated objects.
+  virtual void GenerateShutdownCode(io::Printer* printer) const {}
+
   // Generate lines to decode this field, which will be placed inside the
   // message's MergeFromCodedStream() method.
   virtual void GenerateMergeFromCodedStream(io::Printer* printer) const = 0;
@@ -144,7 +153,7 @@ class FieldGenerator {
 // Convenience class which constructs FieldGenerators for a Descriptor.
 class FieldGeneratorMap {
  public:
-  explicit FieldGeneratorMap(const Descriptor* descriptor);
+  explicit FieldGeneratorMap(const Descriptor* descriptor, const Options& options);
   ~FieldGeneratorMap();
 
   const FieldGenerator& get(const FieldDescriptor* field) const;
@@ -153,7 +162,8 @@ class FieldGeneratorMap {
   const Descriptor* descriptor_;
   scoped_array<scoped_ptr<FieldGenerator> > field_generators_;
 
-  static FieldGenerator* MakeGenerator(const FieldDescriptor* field);
+  static FieldGenerator* MakeGenerator(const FieldDescriptor* field,
+                                       const Options& options);
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FieldGeneratorMap);
 };
diff --git a/src/google/protobuf/compiler/cpp/cpp_file.cc b/src/google/protobuf/compiler/cpp/cpp_file.cc
index b8e7708f..1bbc89c4 100644
--- a/src/google/protobuf/compiler/cpp/cpp_file.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_file.cc
@@ -51,7 +51,7 @@ namespace cpp {
 // ===================================================================
 
 FileGenerator::FileGenerator(const FileDescriptor* file,
-                             const string& dllexport_decl)
+                             const Options& options)
   : file_(file),
     message_generators_(
       new scoped_ptr<MessageGenerator>[file->message_type_count()]),
@@ -61,26 +61,26 @@ FileGenerator::FileGenerator(const FileDescriptor* file,
       new scoped_ptr<ServiceGenerator>[file->service_count()]),
     extension_generators_(
       new scoped_ptr<ExtensionGenerator>[file->extension_count()]),
-    dllexport_decl_(dllexport_decl) {
+    options_(options) {
 
   for (int i = 0; i < file->message_type_count(); i++) {
     message_generators_[i].reset(
-      new MessageGenerator(file->message_type(i), dllexport_decl));
+      new MessageGenerator(file->message_type(i), options));
   }
 
   for (int i = 0; i < file->enum_type_count(); i++) {
     enum_generators_[i].reset(
-      new EnumGenerator(file->enum_type(i), dllexport_decl));
+      new EnumGenerator(file->enum_type(i), options));
   }
 
   for (int i = 0; i < file->service_count(); i++) {
     service_generators_[i].reset(
-      new ServiceGenerator(file->service(i), dllexport_decl));
+      new ServiceGenerator(file->service(i), options));
   }
 
   for (int i = 0; i < file->extension_count(); i++) {
     extension_generators_[i].reset(
-      new ExtensionGenerator(file->extension(i), dllexport_decl));
+      new ExtensionGenerator(file->extension(i), options));
   }
 
   SplitStringUsing(file_->package(), ".", &package_parts_);
@@ -104,6 +104,7 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
     "filename", file_->name(),
     "filename_identifier", filename_identifier);
 
+
   printer->Print(
     "#include <google/protobuf/stubs/common.h>\n"
     "\n");
@@ -128,13 +129,23 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
 
   // OK, it's now safe to #include other files.
   printer->Print(
-    "#include <google/protobuf/generated_message_util.h>\n"
+    "#include <google/protobuf/generated_message_util.h>\n");
+  if (file_->message_type_count() > 0) {
+    if (HasDescriptorMethods(file_)) {
+      printer->Print(
+        "#include <google/protobuf/message.h>\n");
+    } else {
+      printer->Print(
+        "#include <google/protobuf/message_lite.h>\n");
+    }
+  }
+  printer->Print(
     "#include <google/protobuf/repeated_field.h>\n"
     "#include <google/protobuf/extension_set.h>\n");
 
-  if (HasDescriptorMethods(file_)) {
+  if (HasDescriptorMethods(file_) && HasEnumDefinitions(file_)) {
     printer->Print(
-      "#include <google/protobuf/generated_message_reflection.h>\n");
+      "#include <google/protobuf/generated_enum_reflection.h>\n");
   }
 
   if (HasGenericServices(file_)) {
@@ -142,6 +153,11 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
       "#include <google/protobuf/service.h>\n");
   }
 
+  if (HasUnknownFields(file_) && file_->message_type_count() > 0) {
+    printer->Print(
+      "#include <google/protobuf/unknown_field_set.h>\n");
+  }
+
 
   for (int i = 0; i < file_->dependency_count(); i++) {
     printer->Print(
@@ -149,9 +165,11 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
       "dependency", StripProto(file_->dependency(i)->name()));
   }
 
+
   printer->Print(
     "// @@protoc_insertion_point(includes)\n");
 
+
   // Open namespace.
   GenerateNamespaceOpeners(printer);
 
@@ -162,7 +180,7 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
     "// Internal implementation detail -- do not call these.\n"
     "void $dllexport_decl$ $adddescriptorsname$();\n",
     "adddescriptorsname", GlobalAddDescriptorsName(file_->name()),
-    "dllexport_decl", dllexport_decl_);
+    "dllexport_decl", options_.dllexport_decl);
 
   printer->Print(
     // Note that we don't put dllexport_decl on these because they are only
@@ -282,6 +300,7 @@ void FileGenerator::GenerateHeader(io::Printer* printer) {
 void FileGenerator::GenerateSource(io::Printer* printer) {
   printer->Print(
     "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
+    "// source: $filename$\n"
     "\n"
 
     // The generated code calls accessors that might be deprecated. We don't
@@ -294,11 +313,13 @@ void FileGenerator::GenerateSource(io::Printer* printer) {
     "#include <google/protobuf/stubs/once.h>\n"
     "#include <google/protobuf/io/coded_stream.h>\n"
     "#include <google/protobuf/wire_format_lite_inl.h>\n",
+    "filename", file_->name(),
     "basename", StripProto(file_->name()));
 
   if (HasDescriptorMethods(file_)) {
     printer->Print(
       "#include <google/protobuf/descriptor.h>\n"
+      "#include <google/protobuf/generated_message_reflection.h>\n"
       "#include <google/protobuf/reflection_ops.h>\n"
       "#include <google/protobuf/wire_format.h>\n");
   }
@@ -504,10 +525,12 @@ void FileGenerator::GenerateBuildDescriptors(io::Printer* printer) {
     "  static bool already_here = false;\n"
     "  if (already_here) return;\n"
     "  already_here = true;\n"
-    "  GOOGLE_PROTOBUF_VERIFY_VERSION;\n",
+    "  GOOGLE_PROTOBUF_VERIFY_VERSION;\n"
+    "\n",
     // Without.
     "void $adddescriptorsname$_impl() {\n"
-    "  GOOGLE_PROTOBUF_VERIFY_VERSION;\n",
+    "  GOOGLE_PROTOBUF_VERIFY_VERSION;\n"
+    "\n",
     // Vars.
     "adddescriptorsname", GlobalAddDescriptorsName(file_->name()));
 
@@ -521,9 +544,9 @@ void FileGenerator::GenerateBuildDescriptors(io::Printer* printer) {
     vector<string> dependency_package_parts;
     SplitStringUsing(dependency->package(), ".", &dependency_package_parts);
     printer->Print("::");
-    for (int i = 0; i < dependency_package_parts.size(); i++) {
+    for (int j = 0; j < dependency_package_parts.size(); j++) {
       printer->Print("$name$::",
-                     "name", dependency_package_parts[i]);
+                     "name", dependency_package_parts[j]);
     }
     // Call its AddDescriptors function.
     printer->Print(
@@ -547,10 +570,12 @@ void FileGenerator::GenerateBuildDescriptors(io::Printer* printer) {
     static const int kBytesPerLine = 40;
     for (int i = 0; i < file_data.size(); i += kBytesPerLine) {
       printer->Print("\n  \"$data$\"",
-        "data", EscapeTrigraphs(CEscape(file_data.substr(i, kBytesPerLine))));
+                     "data",
+                     EscapeTrigraphs(
+                         CEscape(file_data.substr(i, kBytesPerLine))));
     }
     printer->Print(
-      ", $size$);\n",
+        ", $size$);\n",
       "size", SimpleItoa(file_data.size()));
 
     // Call MessageFactory::InternalRegisterGeneratedFile().
@@ -594,7 +619,7 @@ void FileGenerator::GenerateBuildDescriptors(io::Printer* printer) {
     // Without.
     "GOOGLE_PROTOBUF_DECLARE_ONCE($adddescriptorsname$_once_);\n"
     "void $adddescriptorsname$() {\n"
-    "  ::google::protobuf::GoogleOnceInit(&$adddescriptorsname$_once_,\n"
+    "  ::google::protobuf::::google::protobuf::GoogleOnceInit(&$adddescriptorsname$_once_,\n"
     "                 &$adddescriptorsname$_impl);\n"
     "}\n",
     // Vars.
diff --git a/src/google/protobuf/compiler/cpp/cpp_file.h b/src/google/protobuf/compiler/cpp/cpp_file.h
index b4e01285..2deefaa8 100644
--- a/src/google/protobuf/compiler/cpp/cpp_file.h
+++ b/src/google/protobuf/compiler/cpp/cpp_file.h
@@ -39,6 +39,7 @@
 #include <vector>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/compiler/cpp/cpp_field.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 
 namespace google {
 namespace protobuf {
@@ -61,7 +62,7 @@ class FileGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
   explicit FileGenerator(const FileDescriptor* file,
-                         const string& dllexport_decl);
+                         const Options& options);
   ~FileGenerator();
 
   void GenerateHeader(io::Printer* printer);
@@ -85,7 +86,7 @@ class FileGenerator {
   // E.g. if the package is foo.bar, package_parts_ is {"foo", "bar"}.
   vector<string> package_parts_;
 
-  string dllexport_decl_;
+  const Options options_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileGenerator);
 };
diff --git a/src/google/protobuf/compiler/cpp/cpp_generator.cc b/src/google/protobuf/compiler/cpp/cpp_generator.cc
index bb84e2ab..1813510b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_generator.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_generator.cc
@@ -78,11 +78,13 @@ bool CppGenerator::Generate(const FileDescriptor* file,
   //   }
   // FOO_EXPORT is a macro which should expand to __declspec(dllexport) or
   // __declspec(dllimport) depending on what is being compiled.
-  string dllexport_decl;
+  Options file_options;
 
   for (int i = 0; i < options.size(); i++) {
     if (options[i].first == "dllexport_decl") {
-      dllexport_decl = options[i].second;
+      file_options.dllexport_decl = options[i].second;
+    } else if (options[i].first == "safe_boundary_check") {
+      file_options.safe_boundary_check = true;
     } else {
       *error = "Unknown generator option: " + options[i].first;
       return false;
@@ -95,7 +97,7 @@ bool CppGenerator::Generate(const FileDescriptor* file,
   string basename = StripProto(file->name());
   basename.append(".pb");
 
-  FileGenerator file_generator(file, dllexport_decl);
+  FileGenerator file_generator(file, file_options);
 
   // Generate header.
   {
diff --git a/src/google/protobuf/compiler/cpp/cpp_helpers.cc b/src/google/protobuf/compiler/cpp/cpp_helpers.cc
index c4b868c2..28911ab0 100644
--- a/src/google/protobuf/compiler/cpp/cpp_helpers.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_helpers.cc
@@ -148,7 +148,7 @@ string ClassName(const Descriptor* descriptor, bool qualified) {
 string ClassName(const EnumDescriptor* enum_descriptor, bool qualified) {
   if (enum_descriptor->containing_type() == NULL) {
     if (qualified) {
-      return DotsToColons(enum_descriptor->full_name());
+      return "::" + DotsToColons(enum_descriptor->full_name());
     } else {
       return enum_descriptor->name();
     }
@@ -259,10 +259,23 @@ const char* DeclaredTypeMethodName(FieldDescriptor::Type type) {
 string DefaultValue(const FieldDescriptor* field) {
   switch (field->cpp_type()) {
     case FieldDescriptor::CPPTYPE_INT32:
+      // gcc rejects the decimal form of kint32min and kint64min.
+      if (field->default_value_int32() == kint32min) {
+        // Make sure we are in a 2's complement system.
+        GOOGLE_COMPILE_ASSERT(kint32min == -0x80000000, kint32min_value_error);
+        return "-0x80000000";
+      }
       return SimpleItoa(field->default_value_int32());
     case FieldDescriptor::CPPTYPE_UINT32:
       return SimpleItoa(field->default_value_uint32()) + "u";
     case FieldDescriptor::CPPTYPE_INT64:
+      // See the comments for CPPTYPE_INT32.
+      if (field->default_value_int64() == kint64min) {
+        // Make sure we are in a 2's complement system.
+        GOOGLE_COMPILE_ASSERT(kint64min == GOOGLE_LONGLONG(-0x8000000000000000),
+                       kint64min_value_error);
+        return "GOOGLE_LONGLONG(-0x8000000000000000)";
+      }
       return "GOOGLE_LONGLONG(" + SimpleItoa(field->default_value_int64()) + ")";
     case FieldDescriptor::CPPTYPE_UINT64:
       return "GOOGLE_ULONGLONG(" + SimpleItoa(field->default_value_uint64())+ ")";
@@ -308,8 +321,9 @@ string DefaultValue(const FieldDescriptor* field) {
           ClassName(field->enum_type(), true),
           field->default_value_enum()->number());
     case FieldDescriptor::CPPTYPE_STRING:
-      return "\"" + EscapeTrigraphs(CEscape(field->default_value_string())) +
-             "\"";
+      return "\"" + EscapeTrigraphs(
+        CEscape(field->default_value_string())) +
+        "\"";
     case FieldDescriptor::CPPTYPE_MESSAGE:
       return FieldMessageTypeName(field) + "::default_instance()";
   }
@@ -401,6 +415,23 @@ void PrintHandlingOptionalStaticInitializers(
   }
 }
 
+
+static bool HasEnumDefinitions(const Descriptor* message_type) {
+  if (message_type->enum_type_count() > 0) return true;
+  for (int i = 0; i < message_type->nested_type_count(); ++i) {
+    if (HasEnumDefinitions(message_type->nested_type(i))) return true;
+  }
+  return false;
+}
+
+bool HasEnumDefinitions(const FileDescriptor* file) {
+  if (file->enum_type_count() > 0) return true;
+  for (int i = 0; i < file->message_type_count(); ++i) {
+    if (HasEnumDefinitions(file->message_type(i))) return true;
+  }
+  return false;
+}
+
 }  // namespace cpp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/cpp/cpp_helpers.h b/src/google/protobuf/compiler/cpp/cpp_helpers.h
index 662a7c31..526e19cc 100644
--- a/src/google/protobuf/compiler/cpp/cpp_helpers.h
+++ b/src/google/protobuf/compiler/cpp/cpp_helpers.h
@@ -122,23 +122,27 @@ string GlobalShutdownFileName(const string& filename);
 string EscapeTrigraphs(const string& to_escape);
 
 // Do message classes in this file keep track of unknown fields?
-inline bool HasUnknownFields(const FileDescriptor *file) {
+inline bool HasUnknownFields(const FileDescriptor* file) {
   return file->options().optimize_for() != FileOptions::LITE_RUNTIME;
 }
 
+
+// Does this file have any enum type definitions?
+bool HasEnumDefinitions(const FileDescriptor* file);
+
 // Does this file have generated parsing, serialization, and other
 // standard methods for which reflection-based fallback implementations exist?
-inline bool HasGeneratedMethods(const FileDescriptor *file) {
+inline bool HasGeneratedMethods(const FileDescriptor* file) {
   return file->options().optimize_for() != FileOptions::CODE_SIZE;
 }
 
-// Do message classes in this file have descriptor and refelction methods?
-inline bool HasDescriptorMethods(const FileDescriptor *file) {
+// Do message classes in this file have descriptor and reflection methods?
+inline bool HasDescriptorMethods(const FileDescriptor* file) {
   return file->options().optimize_for() != FileOptions::LITE_RUNTIME;
 }
 
 // Should we generate generic services for this file?
-inline bool HasGenericServices(const FileDescriptor *file) {
+inline bool HasGenericServices(const FileDescriptor* file) {
   return file->service_count() > 0 &&
          file->options().optimize_for() != FileOptions::LITE_RUNTIME &&
          file->options().cc_generic_services();
@@ -173,6 +177,7 @@ void PrintHandlingOptionalStaticInitializers(
     io::Printer* printer, const char* with_static_init,
     const char* without_static_init);
 
+
 }  // namespace cpp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.cc b/src/google/protobuf/compiler/cpp/cpp_message.cc
index 1c158be0..1ea4f13d 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message.cc
@@ -48,6 +48,7 @@
 #include <google/protobuf/wire_format.h>
 #include <google/protobuf/descriptor.pb.h>
 
+
 namespace google {
 namespace protobuf {
 namespace compiler {
@@ -103,6 +104,13 @@ struct ExtensionRangeSorter {
   }
 };
 
+// Returns true if the "required" restriction check should be ignored for the
+// given field.
+inline static bool ShouldIgnoreRequiredFieldCheck(
+    const FieldDescriptor* field) {
+  return false;
+}
+
 // Returns true if the message type has any required fields.  If it doesn't,
 // we can optimize out calls to its IsInitialized() method.
 //
@@ -129,7 +137,8 @@ static bool HasRequiredFields(
     if (field->is_required()) {
       return true;
     }
-    if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE &&
+        !ShouldIgnoreRequiredFieldCheck(field)) {
       if (HasRequiredFields(field->message_type(), already_seen)) {
         return true;
       }
@@ -280,11 +289,11 @@ void OptimizePadding(vector<const FieldDescriptor*>* fields) {
 // ===================================================================
 
 MessageGenerator::MessageGenerator(const Descriptor* descriptor,
-                                   const string& dllexport_decl)
+                                   const Options& options)
   : descriptor_(descriptor),
     classname_(ClassName(descriptor, false)),
-    dllexport_decl_(dllexport_decl),
-    field_generators_(descriptor),
+    options_(options),
+    field_generators_(descriptor, options),
     nested_generators_(new scoped_ptr<MessageGenerator>[
       descriptor->nested_type_count()]),
     enum_generators_(new scoped_ptr<EnumGenerator>[
@@ -294,17 +303,17 @@ MessageGenerator::MessageGenerator(const Descriptor* descriptor,
 
   for (int i = 0; i < descriptor->nested_type_count(); i++) {
     nested_generators_[i].reset(
-      new MessageGenerator(descriptor->nested_type(i), dllexport_decl));
+      new MessageGenerator(descriptor->nested_type(i), options));
   }
 
   for (int i = 0; i < descriptor->enum_type_count(); i++) {
     enum_generators_[i].reset(
-      new EnumGenerator(descriptor->enum_type(i), dllexport_decl));
+      new EnumGenerator(descriptor->enum_type(i), options));
   }
 
   for (int i = 0; i < descriptor->extension_count(); i++) {
     extension_generators_[i].reset(
-      new ExtensionGenerator(descriptor->extension(i), dllexport_decl));
+      new ExtensionGenerator(descriptor->extension(i), options));
   }
 }
 
@@ -349,7 +358,7 @@ GenerateFieldAccessorDeclarations(io::Printer* printer) {
     PrintFieldComment(printer, field);
 
     map<string, string> vars;
-    SetCommonFieldVariables(field, &vars);
+    SetCommonFieldVariables(field, &vars, options_);
     vars["constant_name"] = FieldConstantName(field);
 
     if (field->is_repeated()) {
@@ -386,7 +395,7 @@ GenerateFieldAccessorDefinitions(io::Printer* printer) {
     PrintFieldComment(printer, field);
 
     map<string, string> vars;
-    SetCommonFieldVariables(field, &vars);
+    SetCommonFieldVariables(field, &vars, options_);
 
     // Generate has_$name$() or $name$_size().
     if (field->is_repeated()) {
@@ -446,10 +455,10 @@ GenerateClassDefinition(io::Printer* printer) {
   map<string, string> vars;
   vars["classname"] = classname_;
   vars["field_count"] = SimpleItoa(descriptor_->field_count());
-  if (dllexport_decl_.empty()) {
+  if (options_.dllexport_decl.empty()) {
     vars["dllexport"] = "";
   } else {
-    vars["dllexport"] = dllexport_decl_ + " ";
+    vars["dllexport"] = options_.dllexport_decl + " ";
   }
   vars["superclass"] = SuperClassName(descriptor_);
 
@@ -507,6 +516,7 @@ GenerateClassDefinition(io::Printer* printer) {
       "\n");
   }
 
+
   printer->Print(vars,
     "void Swap($classname$* other);\n"
     "\n"
@@ -605,6 +615,7 @@ GenerateClassDefinition(io::Printer* printer) {
   printer->Print(" private:\n");
   printer->Indent();
 
+
   for (int i = 0; i < descriptor_->field_count(); i++) {
     if (!descriptor_->field(i)->is_repeated()) {
       printer->Print(
@@ -680,7 +691,7 @@ GenerateClassDefinition(io::Printer* printer) {
     // Without.
     "friend void $dllexport_decl$ $adddescriptorsname$_impl();\n",
     // Vars.
-    "dllexport_decl", dllexport_decl_,
+    "dllexport_decl", options_.dllexport_decl,
     "adddescriptorsname",
     GlobalAddDescriptorsName(descriptor_->file()->name()));
 
@@ -772,9 +783,11 @@ GenerateDescriptorInitializer(io::Printer* printer, int index) {
     printer->Print(vars,
       "    -1,\n");
   }
+  printer->Print(
+    "    ::google::protobuf::DescriptorPool::generated_pool(),\n");
+  printer->Print(vars,
+    "    ::google::protobuf::MessageFactory::generated_factory(),\n");
   printer->Print(vars,
-    "    ::google::protobuf::DescriptorPool::generated_pool(),\n"
-    "    ::google::protobuf::MessageFactory::generated_factory(),\n"
     "    sizeof($classname$));\n");
 
   // Handle nested types.
@@ -803,6 +816,13 @@ GenerateTypeRegistrations(io::Printer* printer) {
 
 void MessageGenerator::
 GenerateDefaultInstanceAllocator(io::Printer* printer) {
+  // Construct the default instances of all fields, as they will be used
+  // when creating the default instance of the entire message.
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    field_generators_.get(descriptor_->field(i))
+                     .GenerateDefaultInstanceAllocator(printer);
+  }
+
   // Construct the default instance.  We can't call InitAsDefaultInstance() yet
   // because we need to make sure all default instances that this one might
   // depend on are constructed first.
@@ -846,6 +866,12 @@ GenerateShutdownCode(io::Printer* printer) {
       "classname", classname_);
   }
 
+  // Handle default instances of fields.
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    field_generators_.get(descriptor_->field(i))
+                     .GenerateShutdownCode(printer);
+  }
+
   // Handle nested types.
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
     nested_generators_[i]->GenerateShutdownCode(printer);
@@ -1957,6 +1983,7 @@ GenerateIsInitialized(io::Printer* printer) {
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
     if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE &&
+        !ShouldIgnoreRequiredFieldCheck(field) &&
         HasRequiredFields(field->message_type())) {
       if (field->is_repeated()) {
         printer->Print(
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.h b/src/google/protobuf/compiler/cpp/cpp_message.h
index 04778f6d..a7e43d9c 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.h
+++ b/src/google/protobuf/compiler/cpp/cpp_message.h
@@ -38,6 +38,7 @@
 #include <string>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/compiler/cpp/cpp_field.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 
 namespace google {
 namespace protobuf {
@@ -57,7 +58,7 @@ class MessageGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
   explicit MessageGenerator(const Descriptor* descriptor,
-                            const string& dllexport_decl);
+                            const Options& options);
   ~MessageGenerator();
 
   // Header stuff.
@@ -153,7 +154,7 @@ class MessageGenerator {
 
   const Descriptor* descriptor_;
   string classname_;
-  string dllexport_decl_;
+  Options options_;
   FieldGeneratorMap field_generators_;
   scoped_array<scoped_ptr<MessageGenerator> > nested_generators_;
   scoped_array<scoped_ptr<EnumGenerator> > enum_generators_;
diff --git a/src/google/protobuf/compiler/cpp/cpp_message_field.cc b/src/google/protobuf/compiler/cpp/cpp_message_field.cc
index 7c785e7e..447f975f 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message_field.cc
@@ -45,8 +45,9 @@ namespace cpp {
 namespace {
 
 void SetMessageVariables(const FieldDescriptor* descriptor,
-                         map<string, string>* variables) {
-  SetCommonFieldVariables(descriptor, variables);
+                         map<string, string>* variables,
+                         const Options& options) {
+  SetCommonFieldVariables(descriptor, variables, options);
   (*variables)["type"] = FieldMessageTypeName(descriptor);
   (*variables)["stream_writer"] = (*variables)["declared_type"] +
       (HasFastArraySerialization(descriptor->message_type()->file()) ?
@@ -59,9 +60,10 @@ void SetMessageVariables(const FieldDescriptor* descriptor,
 // ===================================================================
 
 MessageFieldGenerator::
-MessageFieldGenerator(const FieldDescriptor* descriptor)
+MessageFieldGenerator(const FieldDescriptor* descriptor,
+                      const Options& options)
   : descriptor_(descriptor) {
-  SetMessageVariables(descriptor, &variables_);
+  SetMessageVariables(descriptor, &variables_, options);
 }
 
 MessageFieldGenerator::~MessageFieldGenerator() {}
@@ -76,7 +78,8 @@ GenerateAccessorDeclarations(io::Printer* printer) const {
   printer->Print(variables_,
     "inline const $type$& $name$() const$deprecation$;\n"
     "inline $type$* mutable_$name$()$deprecation$;\n"
-    "inline $type$* release_$name$()$deprecation$;\n");
+    "inline $type$* release_$name$()$deprecation$;\n"
+    "inline void set_allocated_$name$($type$* $name$)$deprecation$;\n");
 }
 
 void MessageFieldGenerator::
@@ -103,6 +106,15 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "  $type$* temp = $name$_;\n"
     "  $name$_ = NULL;\n"
     "  return temp;\n"
+    "}\n"
+    "inline void $classname$::set_allocated_$name$($type$* $name$) {\n"
+    "  delete $name$_;\n"
+    "  $name$_ = $name$;\n"
+    "  if ($name$) {\n"
+    "    set_has_$name$();\n"
+    "  } else {\n"
+    "    clear_has_$name$();\n"
+    "  }\n"
     "}\n");
 }
 
@@ -167,9 +179,10 @@ GenerateByteSize(io::Printer* printer) const {
 // ===================================================================
 
 RepeatedMessageFieldGenerator::
-RepeatedMessageFieldGenerator(const FieldDescriptor* descriptor)
+RepeatedMessageFieldGenerator(const FieldDescriptor* descriptor,
+                              const Options& options)
   : descriptor_(descriptor) {
-  SetMessageVariables(descriptor, &variables_);
+  SetMessageVariables(descriptor, &variables_, options);
 }
 
 RepeatedMessageFieldGenerator::~RepeatedMessageFieldGenerator() {}
@@ -197,7 +210,7 @@ void RepeatedMessageFieldGenerator::
 GenerateInlineAccessorDefinitions(io::Printer* printer) const {
   printer->Print(variables_,
     "inline const $type$& $classname$::$name$(int index) const {\n"
-    "  return $name$_.Get(index);\n"
+    "  return $name$_.$cppget$(index);\n"
     "}\n"
     "inline $type$* $classname$::mutable_$name$(int index) {\n"
     "  return $name$_.Mutable(index);\n"
diff --git a/src/google/protobuf/compiler/cpp/cpp_message_field.h b/src/google/protobuf/compiler/cpp/cpp_message_field.h
index f5147278..a5ed68a5 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_message_field.h
@@ -46,7 +46,8 @@ namespace cpp {
 
 class MessageFieldGenerator : public FieldGenerator {
  public:
-  explicit MessageFieldGenerator(const FieldDescriptor* descriptor);
+  explicit MessageFieldGenerator(const FieldDescriptor* descriptor,
+                                 const Options& options);
   ~MessageFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
@@ -71,7 +72,8 @@ class MessageFieldGenerator : public FieldGenerator {
 
 class RepeatedMessageFieldGenerator : public FieldGenerator {
  public:
-  explicit RepeatedMessageFieldGenerator(const FieldDescriptor* descriptor);
+  explicit RepeatedMessageFieldGenerator(const FieldDescriptor* descriptor,
+                                         const Options& options);
   ~RepeatedMessageFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
diff --git a/src/google/protobuf/compiler/cpp/cpp_options.h b/src/google/protobuf/compiler/cpp/cpp_options.h
new file mode 100644
index 00000000..78770662
--- /dev/null
+++ b/src/google/protobuf/compiler/cpp/cpp_options.h
@@ -0,0 +1,58 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: rennie@google.com (Jeffrey Rennie)
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_CPP_OPTIONS_H__
+#define GOOGLE_PROTOBUF_COMPILER_CPP_OPTIONS_H__
+
+#include <string>
+
+#include <google/protobuf/stubs/common.h>
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace cpp {
+
+// Generator options:
+struct Options {
+  Options() : safe_boundary_check(false) {
+  }
+  string dllexport_decl;
+  bool safe_boundary_check;
+};
+
+}  // namespace cpp
+}  // namespace compiler
+}  // namespace protobuf
+
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_COMPILER_CPP_OPTIONS_H__
diff --git a/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc b/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
index 5e8df0f4..1c35fefa 100644
--- a/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
@@ -80,8 +80,9 @@ int FixedSize(FieldDescriptor::Type type) {
 }
 
 void SetPrimitiveVariables(const FieldDescriptor* descriptor,
-                           map<string, string>* variables) {
-  SetCommonFieldVariables(descriptor, variables);
+                           map<string, string>* variables,
+                           const Options& options) {
+  SetCommonFieldVariables(descriptor, variables, options);
   (*variables)["type"] = PrimitiveTypeName(descriptor->cpp_type());
   (*variables)["default"] = DefaultValue(descriptor);
   (*variables)["tag"] = SimpleItoa(internal::WireFormat::MakeTag(descriptor));
@@ -99,9 +100,10 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
 // ===================================================================
 
 PrimitiveFieldGenerator::
-PrimitiveFieldGenerator(const FieldDescriptor* descriptor)
+PrimitiveFieldGenerator(const FieldDescriptor* descriptor,
+                        const Options& options)
   : descriptor_(descriptor) {
-  SetPrimitiveVariables(descriptor, &variables_);
+  SetPrimitiveVariables(descriptor, &variables_, options);
 }
 
 PrimitiveFieldGenerator::~PrimitiveFieldGenerator() {}
@@ -190,9 +192,10 @@ GenerateByteSize(io::Printer* printer) const {
 // ===================================================================
 
 RepeatedPrimitiveFieldGenerator::
-RepeatedPrimitiveFieldGenerator(const FieldDescriptor* descriptor)
+RepeatedPrimitiveFieldGenerator(const FieldDescriptor* descriptor,
+                                const Options& options)
   : descriptor_(descriptor) {
-  SetPrimitiveVariables(descriptor, &variables_);
+  SetPrimitiveVariables(descriptor, &variables_, options);
 
   if (descriptor->options().packed()) {
     variables_["packed_reader"] = "ReadPackedPrimitive";
@@ -366,7 +369,9 @@ GenerateByteSize(io::Printer* printer) const {
       "  total_size += $tag_size$ +\n"
       "    ::google::protobuf::internal::WireFormatLite::Int32Size(data_size);\n"
       "}\n"
+      "GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();\n"
       "_$name$_cached_byte_size_ = data_size;\n"
+      "GOOGLE_SAFE_CONCURRENT_WRITES_END();\n"
       "total_size += data_size;\n");
   } else {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/cpp/cpp_primitive_field.h b/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
index 8fcd74ae..48249c40 100644
--- a/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
@@ -46,7 +46,8 @@ namespace cpp {
 
 class PrimitiveFieldGenerator : public FieldGenerator {
  public:
-  explicit PrimitiveFieldGenerator(const FieldDescriptor* descriptor);
+  explicit PrimitiveFieldGenerator(const FieldDescriptor* descriptor,
+                                   const Options& options);
   ~PrimitiveFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
@@ -71,7 +72,8 @@ class PrimitiveFieldGenerator : public FieldGenerator {
 
 class RepeatedPrimitiveFieldGenerator : public FieldGenerator {
  public:
-  explicit RepeatedPrimitiveFieldGenerator(const FieldDescriptor* descriptor);
+  explicit RepeatedPrimitiveFieldGenerator(const FieldDescriptor* descriptor,
+                                           const Options& options);
   ~RepeatedPrimitiveFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
diff --git a/src/google/protobuf/compiler/cpp/cpp_service.cc b/src/google/protobuf/compiler/cpp/cpp_service.cc
index c2825683..d20018ea 100644
--- a/src/google/protobuf/compiler/cpp/cpp_service.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_service.cc
@@ -43,14 +43,14 @@ namespace compiler {
 namespace cpp {
 
 ServiceGenerator::ServiceGenerator(const ServiceDescriptor* descriptor,
-                                   const string& dllexport_decl)
+                                   const Options& options)
   : descriptor_(descriptor) {
   vars_["classname"] = descriptor_->name();
   vars_["full_name"] = descriptor_->full_name();
-  if (dllexport_decl.empty()) {
+  if (options.dllexport_decl.empty()) {
     vars_["dllexport"] = "";
   } else {
-    vars_["dllexport"] = dllexport_decl + " ";
+    vars_["dllexport"] = options.dllexport_decl + " ";
   }
 }
 
diff --git a/src/google/protobuf/compiler/cpp/cpp_service.h b/src/google/protobuf/compiler/cpp/cpp_service.h
index 10e9dd3c..820f9f5f 100644
--- a/src/google/protobuf/compiler/cpp/cpp_service.h
+++ b/src/google/protobuf/compiler/cpp/cpp_service.h
@@ -38,6 +38,7 @@
 #include <map>
 #include <string>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 #include <google/protobuf/descriptor.h>
 
 namespace google {
@@ -55,7 +56,7 @@ class ServiceGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
   explicit ServiceGenerator(const ServiceDescriptor* descriptor,
-                            const string& dllexport_decl);
+                            const Options& options);
   ~ServiceGenerator();
 
   // Header stuff.
diff --git a/src/google/protobuf/compiler/cpp/cpp_string_field.cc b/src/google/protobuf/compiler/cpp/cpp_string_field.cc
index 3cec2b6b..9c0911ac 100644
--- a/src/google/protobuf/compiler/cpp/cpp_string_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_string_field.cc
@@ -46,11 +46,14 @@ namespace cpp {
 namespace {
 
 void SetStringVariables(const FieldDescriptor* descriptor,
-                        map<string, string>* variables) {
-  SetCommonFieldVariables(descriptor, variables);
+                        map<string, string>* variables,
+                        const Options& options) {
+  SetCommonFieldVariables(descriptor, variables, options);
   (*variables)["default"] = DefaultValue(descriptor);
+  (*variables)["default_length"] =
+      SimpleItoa(descriptor->default_value_string().length());
   (*variables)["default_variable"] = descriptor->default_value_string().empty()
-      ? "::google::protobuf::internal::kEmptyString"
+      ? "&::google::protobuf::internal::kEmptyString"
       : "_default_" + FieldName(descriptor) + "_";
   (*variables)["pointer_type"] =
       descriptor->type() == FieldDescriptor::TYPE_BYTES ? "void" : "char";
@@ -61,9 +64,10 @@ void SetStringVariables(const FieldDescriptor* descriptor,
 // ===================================================================
 
 StringFieldGenerator::
-StringFieldGenerator(const FieldDescriptor* descriptor)
+StringFieldGenerator(const FieldDescriptor* descriptor,
+                     const Options& options)
   : descriptor_(descriptor) {
-  SetStringVariables(descriptor, &variables_);
+  SetStringVariables(descriptor, &variables_, options);
 }
 
 StringFieldGenerator::~StringFieldGenerator() {}
@@ -72,7 +76,7 @@ void StringFieldGenerator::
 GeneratePrivateMembers(io::Printer* printer) const {
   printer->Print(variables_, "::std::string* $name$_;\n");
   if (!descriptor_->default_value_string().empty()) {
-    printer->Print(variables_, "static const ::std::string $default_variable$;\n");
+    printer->Print(variables_, "static ::std::string* $default_variable$;\n");
   }
 }
 
@@ -109,7 +113,9 @@ GenerateAccessorDeclarations(io::Printer* printer) const {
     "inline void set_$name$(const $pointer_type$* value, size_t size)"
                  "$deprecation$;\n"
     "inline ::std::string* mutable_$name$()$deprecation$;\n"
-    "inline ::std::string* release_$name$()$deprecation$;\n");
+    "inline ::std::string* release_$name$()$deprecation$;\n"
+    "inline void set_allocated_$name$(::std::string* $name$)$deprecation$;\n");
+
 
   if (descriptor_->options().ctype() != FieldOptions::STRING) {
     printer->Outdent();
@@ -126,14 +132,14 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "}\n"
     "inline void $classname$::set_$name$(const ::std::string& value) {\n"
     "  set_has_$name$();\n"
-    "  if ($name$_ == &$default_variable$) {\n"
+    "  if ($name$_ == $default_variable$) {\n"
     "    $name$_ = new ::std::string;\n"
     "  }\n"
     "  $name$_->assign(value);\n"
     "}\n"
     "inline void $classname$::set_$name$(const char* value) {\n"
     "  set_has_$name$();\n"
-    "  if ($name$_ == &$default_variable$) {\n"
+    "  if ($name$_ == $default_variable$) {\n"
     "    $name$_ = new ::std::string;\n"
     "  }\n"
     "  $name$_->assign(value);\n"
@@ -141,20 +147,20 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "inline "
     "void $classname$::set_$name$(const $pointer_type$* value, size_t size) {\n"
     "  set_has_$name$();\n"
-    "  if ($name$_ == &$default_variable$) {\n"
+    "  if ($name$_ == $default_variable$) {\n"
     "    $name$_ = new ::std::string;\n"
     "  }\n"
     "  $name$_->assign(reinterpret_cast<const char*>(value), size);\n"
     "}\n"
     "inline ::std::string* $classname$::mutable_$name$() {\n"
     "  set_has_$name$();\n"
-    "  if ($name$_ == &$default_variable$) {\n");
+    "  if ($name$_ == $default_variable$) {\n");
   if (descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
       "    $name$_ = new ::std::string;\n");
   } else {
     printer->Print(variables_,
-      "    $name$_ = new ::std::string($default_variable$);\n");
+      "    $name$_ = new ::std::string(*$default_variable$);\n");
   }
   printer->Print(variables_,
     "  }\n"
@@ -162,21 +168,34 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "}\n"
     "inline ::std::string* $classname$::release_$name$() {\n"
     "  clear_has_$name$();\n"
-    "  if ($name$_ == &$default_variable$) {\n"
+    "  if ($name$_ == $default_variable$) {\n"
     "    return NULL;\n"
     "  } else {\n"
     "    ::std::string* temp = $name$_;\n"
-    "    $name$_ = const_cast< ::std::string*>(&$default_variable$);\n"
+    "    $name$_ = const_cast< ::std::string*>($default_variable$);\n"
     "    return temp;\n"
     "  }\n"
+    "}\n"
+    "inline void $classname$::set_allocated_$name$(::std::string* $name$) {\n"
+    "  if ($name$_ != $default_variable$) {\n"
+    "    delete $name$_;\n"
+    "  }\n"
+    "  if ($name$) {\n"
+    "    set_has_$name$();\n"
+    "    $name$_ = $name$;\n"
+    "  } else {\n"
+    "    clear_has_$name$();\n"
+    "    $name$_ = const_cast< ::std::string*>($default_variable$);\n"
+    "  }\n"
     "}\n");
 }
 
 void StringFieldGenerator::
 GenerateNonInlineAccessorDefinitions(io::Printer* printer) const {
   if (!descriptor_->default_value_string().empty()) {
+    // Initialized in GenerateDefaultInstanceAllocator.
     printer->Print(variables_,
-      "const ::std::string $classname$::$default_variable$($default$);\n");
+      "::std::string* $classname$::$default_variable$ = NULL;\n");
   }
 }
 
@@ -184,13 +203,13 @@ void StringFieldGenerator::
 GenerateClearingCode(io::Printer* printer) const {
   if (descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
-      "if ($name$_ != &$default_variable$) {\n"
+      "if ($name$_ != $default_variable$) {\n"
       "  $name$_->clear();\n"
       "}\n");
   } else {
     printer->Print(variables_,
-      "if ($name$_ != &$default_variable$) {\n"
-      "  $name$_->assign($default_variable$);\n"
+      "if ($name$_ != $default_variable$) {\n"
+      "  $name$_->assign(*$default_variable$);\n"
       "}\n");
   }
 }
@@ -208,18 +227,35 @@ GenerateSwappingCode(io::Printer* printer) const {
 void StringFieldGenerator::
 GenerateConstructorCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "$name$_ = const_cast< ::std::string*>(&$default_variable$);\n");
+    "$name$_ = const_cast< ::std::string*>($default_variable$);\n");
 }
 
 void StringFieldGenerator::
 GenerateDestructorCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if ($name$_ != &$default_variable$) {\n"
+    "if ($name$_ != $default_variable$) {\n"
     "  delete $name$_;\n"
     "}\n");
 }
 
 void StringFieldGenerator::
+GenerateDefaultInstanceAllocator(io::Printer* printer) const {
+  if (!descriptor_->default_value_string().empty()) {
+    printer->Print(variables_,
+      "$classname$::$default_variable$ =\n"
+      "    new ::std::string($default$, $default_length$);\n");
+  }
+}
+
+void StringFieldGenerator::
+GenerateShutdownCode(io::Printer* printer) const {
+  if (!descriptor_->default_value_string().empty()) {
+    printer->Print(variables_,
+      "delete $classname$::$default_variable$;\n");
+  }
+}
+
+void StringFieldGenerator::
 GenerateMergeFromCodedStream(io::Printer* printer) const {
   printer->Print(variables_,
     "DO_(::google::protobuf::internal::WireFormatLite::Read$declared_type$(\n"
@@ -273,9 +309,10 @@ GenerateByteSize(io::Printer* printer) const {
 // ===================================================================
 
 RepeatedStringFieldGenerator::
-RepeatedStringFieldGenerator(const FieldDescriptor* descriptor)
+RepeatedStringFieldGenerator(const FieldDescriptor* descriptor,
+                             const Options& options)
   : descriptor_(descriptor) {
-  SetStringVariables(descriptor, &variables_);
+  SetStringVariables(descriptor, &variables_, options);
 }
 
 RepeatedStringFieldGenerator::~RepeatedStringFieldGenerator() {}
@@ -328,7 +365,7 @@ void RepeatedStringFieldGenerator::
 GenerateInlineAccessorDefinitions(io::Printer* printer) const {
   printer->Print(variables_,
     "inline const ::std::string& $classname$::$name$(int index) const {\n"
-    "  return $name$_.Get(index);\n"
+    "  return $name$_.$cppget$(index);\n"
     "}\n"
     "inline ::std::string* $classname$::mutable_$name$(int index) {\n"
     "  return $name$_.Mutable(index);\n"
diff --git a/src/google/protobuf/compiler/cpp/cpp_string_field.h b/src/google/protobuf/compiler/cpp/cpp_string_field.h
index 7f45107d..3264134a 100644
--- a/src/google/protobuf/compiler/cpp/cpp_string_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_string_field.h
@@ -46,7 +46,8 @@ namespace cpp {
 
 class StringFieldGenerator : public FieldGenerator {
  public:
-  explicit StringFieldGenerator(const FieldDescriptor* descriptor);
+  explicit StringFieldGenerator(const FieldDescriptor* descriptor,
+                                const Options& options);
   ~StringFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
@@ -59,6 +60,8 @@ class StringFieldGenerator : public FieldGenerator {
   void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateConstructorCode(io::Printer* printer) const;
   void GenerateDestructorCode(io::Printer* printer) const;
+  void GenerateDefaultInstanceAllocator(io::Printer* printer) const;
+  void GenerateShutdownCode(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizesToArray(io::Printer* printer) const;
@@ -73,7 +76,8 @@ class StringFieldGenerator : public FieldGenerator {
 
 class RepeatedStringFieldGenerator : public FieldGenerator {
  public:
-  explicit RepeatedStringFieldGenerator(const FieldDescriptor* descriptor);
+  explicit RepeatedStringFieldGenerator(const FieldDescriptor* descriptor,
+                                        const Options& options);
   ~RepeatedStringFieldGenerator();
 
   // implements FieldGenerator ---------------------------------------
diff --git a/src/google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto b/src/google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
index 54d830fc..e14a818c 100644
--- a/src/google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
+++ b/src/google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
@@ -103,9 +103,19 @@ message TestConflictingSymbolNames {
   message DO {}
   optional DO do = 32;
 
+  // Some template parameter names for extensions.
+  optional int32 field_type = 33;
+  optional bool is_packed = 34;
+
   extensions 1000 to max;
 }
 
+message TestConflictingSymbolNamesExtension {
+  extend TestConflictingSymbolNames {
+    repeated int32 repeated_int32_ext = 20423638 [packed=true];
+  }
+}
+
 message DummyMessage {}
 
 service TestConflictingMethodNames {
diff --git a/src/google/protobuf/compiler/cpp/cpp_unittest.cc b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
index 301a7ce6..b5f9ab58 100644
--- a/src/google/protobuf/compiler/cpp/cpp_unittest.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
@@ -44,6 +44,8 @@
 // correctly and produces the interfaces we expect, which is why this test
 // is written this way.
 
+#include <google/protobuf/compiler/cpp/cpp_unittest.h>
+
 #include <vector>
 
 #include <google/protobuf/unittest.pb.h>
@@ -64,7 +66,7 @@
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -74,6 +76,8 @@ namespace cpp {
 // Can't use an anonymous namespace here due to brokenness of Tru64 compiler.
 namespace cpp_unittest {
 
+namespace protobuf_unittest = ::protobuf_unittest;
+
 
 class MockErrorCollector : public MultiFileErrorCollector {
  public:
@@ -174,6 +178,15 @@ TEST(GeneratedMessageTest, Trigraph) {
   EXPECT_EQ("? ? ?? ?? ??? ?\?/ ?\?-", extreme_default.cpp_trigraph());
 }
 
+TEST(GeneratedMessageTest, ExtremeSmallIntegerDefault) {
+  const unittest::TestExtremeDefaultValues& extreme_default =
+      unittest::TestExtremeDefaultValues::default_instance();
+  EXPECT_EQ(-0x80000000, kint32min);
+  EXPECT_EQ(GOOGLE_LONGLONG(-0x8000000000000000), kint64min);
+  EXPECT_EQ(kint32min, extreme_default.really_small_int32());
+  EXPECT_EQ(kint64min, extreme_default.really_small_int64());
+}
+
 TEST(GeneratedMessageTest, Accessors) {
   // Set every field to a unique value then go back and check all those
   // values.
@@ -202,6 +215,13 @@ TEST(GeneratedMessageTest, MutableStringDefault) {
   EXPECT_EQ("hello", *message.mutable_default_string());
 }
 
+TEST(GeneratedMessageTest, StringDefaults) {
+  unittest::TestExtremeDefaultValues message;
+  // Check if '\000' can be used in default string value.
+  EXPECT_EQ(string("hel\000lo", 6), message.string_with_zero());
+  EXPECT_EQ(string("wor\000ld", 6), message.bytes_with_zero());
+}
+
 TEST(GeneratedMessageTest, ReleaseString) {
   // Check that release_foo() starts out NULL, and gives us a value
   // that we can delete after it's been set.
@@ -244,6 +264,49 @@ TEST(GeneratedMessageTest, ReleaseMessage) {
   EXPECT_FALSE(message.has_optional_nested_message());
 }
 
+TEST(GeneratedMessageTest, SetAllocatedString) {
+  // Check that set_allocated_foo() works for strings.
+  unittest::TestAllTypes message;
+
+  EXPECT_FALSE(message.has_optional_string());
+  const string kHello("hello");
+  message.set_optional_string(kHello);
+  EXPECT_TRUE(message.has_optional_string());
+
+  message.set_allocated_optional_string(NULL);
+  EXPECT_FALSE(message.has_optional_string());
+  EXPECT_EQ("", message.optional_string());
+
+  message.set_allocated_optional_string(new string(kHello));
+  EXPECT_TRUE(message.has_optional_string());
+  EXPECT_EQ(kHello, message.optional_string());
+}
+
+TEST(GeneratedMessageTest, SetAllocatedMessage) {
+  // Check that set_allocated_foo() can be called in all cases.
+  unittest::TestAllTypes message;
+
+  EXPECT_FALSE(message.has_optional_nested_message());
+
+  message.mutable_optional_nested_message()->set_bb(1);
+  EXPECT_TRUE(message.has_optional_nested_message());
+
+  message.set_allocated_optional_nested_message(NULL);
+  EXPECT_FALSE(message.has_optional_nested_message());
+  EXPECT_EQ(&unittest::TestAllTypes::NestedMessage::default_instance(),
+            &message.optional_nested_message());
+
+  message.mutable_optional_nested_message()->set_bb(1);
+  unittest::TestAllTypes::NestedMessage* nest =
+      message.release_optional_nested_message();
+  ASSERT_TRUE(nest != NULL);
+  EXPECT_FALSE(message.has_optional_nested_message());
+
+  message.set_allocated_optional_nested_message(nest);
+  EXPECT_TRUE(message.has_optional_nested_message());
+  EXPECT_EQ(1, message.optional_nested_message().bb());
+}
+
 TEST(GeneratedMessageTest, Clear) {
   // Set every field to a unique value, clear the message, then check that
   // it is cleared.
@@ -695,6 +758,13 @@ TEST(GeneratedMessageTest, TestConflictingSymbolNames) {
 
   message.set_friend_(5);
   EXPECT_EQ(5, message.friend_());
+
+  // Instantiate extension template functions to test conflicting template
+  // parameter names.
+  typedef protobuf_unittest::TestConflictingSymbolNamesExtension ExtensionMessage;
+  message.AddExtension(ExtensionMessage::repeated_int32_ext, 123);
+  EXPECT_EQ(123,
+            message.GetExtension(ExtensionMessage::repeated_int32_ext, 0));
 }
 
 #ifndef PROTOBUF_TEST_NO_DESCRIPTORS
@@ -869,11 +939,10 @@ TEST(GeneratedEnumTest, MinAndMax) {
   EXPECT_NE(null_pointer, &unittest::ForeignEnum_MAX);
   EXPECT_NE(null_pointer, &unittest::ForeignEnum_ARRAYSIZE);
 
-  // Make sure we can use _MIN, _MAX and _ARRAYSIZE as switch cases.
+  // Make sure we can use _MIN and _MAX as switch cases.
   switch (unittest::SPARSE_A) {
     case unittest::TestSparseEnum_MIN:
     case unittest::TestSparseEnum_MAX:
-    case unittest::TestSparseEnum_ARRAYSIZE:
       break;
     default:
       break;
diff --git a/src/google/protobuf/compiler/cpp/cpp_unittest.h b/src/google/protobuf/compiler/cpp/cpp_unittest.h
new file mode 100644
index 00000000..a3a1d1ba
--- /dev/null
+++ b/src/google/protobuf/compiler/cpp/cpp_unittest.h
@@ -0,0 +1,51 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This header declares the namespace google::protobuf::protobuf_unittest in order to expose
+// any problems with the generated class names. We use this header to ensure
+// unittest.cc will declare the namespace prior to other includes, while obeying
+// normal include ordering.
+//
+// When generating a class name of "foo.Bar" we must ensure we prefix the class
+// name with "::", in case the namespace google::protobuf::foo exists. We intentionally
+// trigger that case here by declaring google::protobuf::protobuf_unittest.
+//
+// See ClassName in helpers.h for more details.
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_CPP_UNITTEST_H__
+#define GOOGLE_PROTOBUF_COMPILER_CPP_UNITTEST_H__
+
+namespace google {
+namespace protobuf {
+namespace protobuf_unittest {}
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_COMPILER_CPP_UNITTEST_H__
diff --git a/src/google/protobuf/compiler/importer.h b/src/google/protobuf/compiler/importer.h
index 7a2efc29..7a62fa0e 100644
--- a/src/google/protobuf/compiler/importer.h
+++ b/src/google/protobuf/compiler/importer.h
@@ -280,8 +280,9 @@ class LIBPROTOBUF_EXPORT DiskSourceTree : public SourceTree {
     string virtual_path;
     string disk_path;
 
-    inline Mapping(const string& virtual_path, const string& disk_path)
-      : virtual_path(virtual_path), disk_path(disk_path) {}
+    inline Mapping(const string& virtual_path_param,
+                   const string& disk_path_param)
+      : virtual_path(virtual_path_param), disk_path(disk_path_param) {}
   };
   vector<Mapping> mappings_;
 
diff --git a/src/google/protobuf/compiler/java/java_doc_comment.cc b/src/google/protobuf/compiler/java/java_doc_comment.cc
new file mode 100644
index 00000000..60b4f2ac
--- /dev/null
+++ b/src/google/protobuf/compiler/java/java_doc_comment.cc
@@ -0,0 +1,236 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+
+#include <google/protobuf/compiler/java/java_doc_comment.h>
+
+#include <vector>
+
+#include <google/protobuf/io/printer.h>
+#include <google/protobuf/stubs/strutil.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace java {
+
+string EscapeJavadoc(const string& input) {
+  string result;
+  result.reserve(input.size() * 2);
+
+  char prev = '*';
+
+  for (string::size_type i = 0; i < input.size(); i++) {
+    char c = input[i];
+    switch (c) {
+      case '*':
+        // Avoid "/*".
+        if (prev == '/') {
+          result.append("&#42;");
+        } else {
+          result.push_back(c);
+        }
+        break;
+      case '/':
+        // Avoid "*/".
+        if (prev == '*') {
+          result.append("&#47;");
+        } else {
+          result.push_back(c);
+        }
+        break;
+      case '@':
+        // "{@" starts Javadoc markup.
+        if (prev == '{') {
+          result.append("&#64;");
+        } else {
+          result.push_back(c);
+        }
+        break;
+      case '<':
+        // Avoid interpretation as HTML.
+        result.append("&lt;");
+        break;
+      case '>':
+        // Avoid interpretation as HTML.
+        result.append("&gt;");
+        break;
+      case '&':
+        // Avoid interpretation as HTML.
+        result.append("&amp;");
+        break;
+      case '\\':
+        // Java interprets Unicode escape sequences anywhere!
+        result.append("&#92;");
+        break;
+      default:
+        result.push_back(c);
+        break;
+    }
+
+    prev = c;
+  }
+
+  return result;
+}
+
+static void WriteDocCommentBodyForLocation(
+    io::Printer* printer, const SourceLocation& location) {
+  string comments = location.leading_comments.empty() ?
+      location.trailing_comments : location.leading_comments;
+  if (!comments.empty()) {
+    // TODO(kenton):  Ideally we should parse the comment text as Markdown and
+    //   write it back as HTML, but this requires a Markdown parser.  For now
+    //   we just use <pre> to get fixed-width text formatting.
+
+    // If the comment itself contains block comment start or end markers,
+    // HTML-escape them so that they don't accidentally close the doc comment.
+    comments = EscapeJavadoc(comments);
+
+    vector<string> lines;
+    SplitStringAllowEmpty(comments, "\n", &lines);
+    while (!lines.empty() && lines.back().empty()) {
+      lines.pop_back();
+    }
+
+    printer->Print(
+        " *\n"
+        " * <pre>\n");
+    for (int i = 0; i < lines.size(); i++) {
+      // Most lines should start with a space.  Watch out for lines that start
+      // with a /, since putting that right after the leading asterisk will
+      // close the comment.
+      if (!lines[i].empty() && lines[i][0] == '/') {
+        printer->Print(" * $line$\n", "line", lines[i]);
+      } else {
+        printer->Print(" *$line$\n", "line", lines[i]);
+      }
+    }
+    printer->Print(" * </pre>\n");
+  }
+}
+
+template <typename DescriptorType>
+static void WriteDocCommentBody(
+    io::Printer* printer, const DescriptorType* descriptor) {
+  SourceLocation location;
+  if (descriptor->GetSourceLocation(&location)) {
+    WriteDocCommentBodyForLocation(printer, location);
+  }
+}
+
+static string FirstLineOf(const string& value) {
+  string result = value;
+
+  string::size_type pos = result.find_first_of('\n');
+  if (pos != string::npos) {
+    result.erase(pos);
+  }
+
+  // If line ends in an opening brace, make it "{ ... }" so it looks nice.
+  if (!result.empty() && result[result.size() - 1] == '{') {
+    result.append(" ... }");
+  }
+
+  return result;
+}
+
+void WriteMessageDocComment(io::Printer* printer, const Descriptor* message) {
+  printer->Print(
+    "/**\n"
+    " * Protobuf type {@code $fullname$}\n",
+    "fullname", EscapeJavadoc(message->full_name()));
+  WriteDocCommentBody(printer, message);
+  printer->Print(" */\n");
+}
+
+void WriteFieldDocComment(io::Printer* printer, const FieldDescriptor* field) {
+  // In theory we should have slightly different comments for setters, getters,
+  // etc., but in practice everyone already knows the difference between these
+  // so it's redundant information.
+
+  // We use the field declaration as the first line of the comment, e.g.:
+  //   optional string foo = 5;
+  // This communicates a lot of information about the field in a small space.
+  // If the field is a group, the debug string might end with {.
+  printer->Print(
+    "/**\n"
+    " * <code>$def$</code>\n",
+    "def", EscapeJavadoc(FirstLineOf(field->DebugString())));
+  WriteDocCommentBody(printer, field);
+  printer->Print(" */\n");
+}
+
+void WriteEnumDocComment(io::Printer* printer, const EnumDescriptor* enum_) {
+  printer->Print(
+    "/**\n"
+    " * Protobuf enum {@code $fullname$}\n",
+    "fullname", EscapeJavadoc(enum_->full_name()));
+  WriteDocCommentBody(printer, enum_);
+  printer->Print(" */\n");
+}
+
+void WriteEnumValueDocComment(io::Printer* printer,
+                              const EnumValueDescriptor* value) {
+  printer->Print(
+    "/**\n"
+    " * <code>$def$</code>\n",
+    "def", EscapeJavadoc(FirstLineOf(value->DebugString())));
+  WriteDocCommentBody(printer, value);
+  printer->Print(" */\n");
+}
+
+void WriteServiceDocComment(io::Printer* printer,
+                            const ServiceDescriptor* service) {
+  printer->Print(
+    "/**\n"
+    " * Protobuf service {@code $fullname$}\n",
+    "fullname", EscapeJavadoc(service->full_name()));
+  WriteDocCommentBody(printer, service);
+  printer->Print(" */\n");
+}
+
+void WriteMethodDocComment(io::Printer* printer,
+                           const MethodDescriptor* method) {
+  printer->Print(
+    "/**\n"
+    " * <code>$def$</code>\n",
+    "def", EscapeJavadoc(FirstLineOf(method->DebugString())));
+  WriteDocCommentBody(printer, method);
+  printer->Print(" */\n");
+}
+
+}  // namespace java
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/compiler/java/java_doc_comment.h b/src/google/protobuf/compiler/java/java_doc_comment.h
new file mode 100644
index 00000000..f77720b6
--- /dev/null
+++ b/src/google/protobuf/compiler/java/java_doc_comment.h
@@ -0,0 +1,69 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_DOC_COMMENT_H__
+#define GOOGLE_PROTOBUF_COMPILER_JAVA_DOC_COMMENT_H__
+
+#include <google/protobuf/descriptor.h>
+
+namespace google {
+namespace protobuf {
+  namespace io {
+    class Printer;             // printer.h
+  }
+}
+
+namespace protobuf {
+namespace compiler {
+namespace java {
+
+void WriteMessageDocComment(io::Printer* printer, const Descriptor* message);
+void WriteFieldDocComment(io::Printer* printer, const FieldDescriptor* field);
+void WriteEnumDocComment(io::Printer* printer, const EnumDescriptor* enum_);
+void WriteEnumValueDocComment(io::Printer* printer,
+                              const EnumValueDescriptor* value);
+void WriteServiceDocComment(io::Printer* printer,
+                            const ServiceDescriptor* service);
+void WriteMethodDocComment(io::Printer* printer,
+                           const MethodDescriptor* method);
+
+// Exposed for testing only.
+string EscapeJavadoc(const string& input);
+
+}  // namespace java
+}  // namespace compiler
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_DOC_COMMENT_H__
diff --git a/src/google/protobuf/compiler/java/java_doc_comment_unittest.cc b/src/google/protobuf/compiler/java/java_doc_comment_unittest.cc
new file mode 100644
index 00000000..28b6d8b4
--- /dev/null
+++ b/src/google/protobuf/compiler/java/java_doc_comment_unittest.cc
@@ -0,0 +1,66 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+
+#include <google/protobuf/compiler/java/java_doc_comment.h>
+
+#include <gtest/gtest.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace java {
+namespace {
+
+TEST(JavaDocCommentTest, Escaping) {
+  EXPECT_EQ("foo /&#42; bar *&#47; baz", EscapeJavadoc("foo /* bar */ baz"));
+  EXPECT_EQ("foo /&#42;&#47; baz", EscapeJavadoc("foo /*/ baz"));
+  EXPECT_EQ("{&#64;foo}", EscapeJavadoc("{@foo}"));
+  EXPECT_EQ("&lt;i&gt;&amp;&lt;/i&gt;", EscapeJavadoc("<i>&</i>"));
+  EXPECT_EQ("foo&#92;u1234bar", EscapeJavadoc("foo\\u1234bar"));
+}
+
+// TODO(kenton):  It's hard to write a robust test of the doc comments -- we
+//   can only really compare the output against a golden value, which is a
+//   fairly tedious and fragile testing strategy.  If we want to go that route,
+//   it probably makes sense to bite the bullet and write a test that compares
+//   the whole generated output for unittest.proto against a golden value, with
+//   a very simple script that can be run to regenerate it with the latest code.
+//   This would mean that updates to the golden file would have to be included
+//   in any change to the code generator, which would actually be fairly useful
+//   as it allows the reviewer to see clearly how the generated code is
+//   changing.
+
+}  // namespace
+}  // namespace java
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/compiler/java/java_enum.cc b/src/google/protobuf/compiler/java/java_enum.cc
index 9d7bcab6..cfed815f 100644
--- a/src/google/protobuf/compiler/java/java_enum.cc
+++ b/src/google/protobuf/compiler/java/java_enum.cc
@@ -36,6 +36,7 @@
 #include <string>
 
 #include <google/protobuf/compiler/java/java_enum.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/descriptor.pb.h>
@@ -67,6 +68,7 @@ EnumGenerator::EnumGenerator(const EnumDescriptor* descriptor)
 EnumGenerator::~EnumGenerator() {}
 
 void EnumGenerator::Generate(io::Printer* printer) {
+  WriteEnumDocComment(printer, descriptor_);
   if (HasDescriptorMethods(descriptor_)) {
     printer->Print(
       "public enum $classname$\n"
@@ -85,6 +87,7 @@ void EnumGenerator::Generate(io::Printer* printer) {
     vars["name"] = canonical_values_[i]->name();
     vars["index"] = SimpleItoa(canonical_values_[i]->index());
     vars["number"] = SimpleItoa(canonical_values_[i]->number());
+    WriteEnumValueDocComment(printer, canonical_values_[i]);
     printer->Print(vars,
       "$name$($index$, $number$),\n");
   }
@@ -100,6 +103,7 @@ void EnumGenerator::Generate(io::Printer* printer) {
     vars["classname"] = descriptor_->name();
     vars["name"] = aliases_[i].value->name();
     vars["canonical_name"] = aliases_[i].canonical_value->name();
+    WriteEnumValueDocComment(printer, aliases_[i].value);
     printer->Print(vars,
       "public static final $classname$ $name$ = $canonical_name$;\n");
   }
@@ -108,6 +112,7 @@ void EnumGenerator::Generate(io::Printer* printer) {
     map<string, string> vars;
     vars["name"] = descriptor_->value(i)->name();
     vars["number"] = SimpleItoa(descriptor_->value(i)->number());
+    WriteEnumValueDocComment(printer, descriptor_->value(i));
     printer->Print(vars,
       "public static final int $name$_VALUE = $number$;\n");
   }
@@ -187,19 +192,30 @@ void EnumGenerator::Generate(io::Printer* printer) {
     printer->Print(
       "}\n"
       "\n"
-      "private static final $classname$[] VALUES = {\n"
-      "  ",
+      "private static final $classname$[] VALUES = ",
       "classname", descriptor_->name());
 
-    for (int i = 0; i < descriptor_->value_count(); i++) {
-      printer->Print("$name$, ",
-        "name", descriptor_->value(i)->name());
+    if (CanUseEnumValues()) {
+      // If the constants we are going to output are exactly the ones we
+      // have declared in the Java enum in the same order, then we can use
+      // the values() method that the Java compiler automatically generates
+      // for every enum.
+      printer->Print("values();\n");
+    } else {
+      printer->Print(
+        "{\n"
+        "  ");
+      for (int i = 0; i < descriptor_->value_count(); i++) {
+        printer->Print("$name$, ",
+          "name", descriptor_->value(i)->name());
+      }
+      printer->Print(
+          "\n"
+          "};\n");
     }
 
     printer->Print(
       "\n"
-      "};\n"
-      "\n"
       "public static $classname$ valueOf(\n"
       "    com.google.protobuf.Descriptors.EnumValueDescriptor desc) {\n"
       "  if (desc.getType() != getDescriptor()) {\n"
@@ -237,6 +253,18 @@ void EnumGenerator::Generate(io::Printer* printer) {
   printer->Print("}\n\n");
 }
 
+bool EnumGenerator::CanUseEnumValues() {
+  if (canonical_values_.size() != descriptor_->value_count()) {
+    return false;
+  }
+  for (int i = 0; i < descriptor_->value_count(); i++) {
+    if (descriptor_->value(i)->name() != canonical_values_[i]->name()) {
+      return false;
+    }
+  }
+  return true;
+}
+
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/java/java_enum.h b/src/google/protobuf/compiler/java/java_enum.h
index 05ece1f1..9a9e5742 100644
--- a/src/google/protobuf/compiler/java/java_enum.h
+++ b/src/google/protobuf/compiler/java/java_enum.h
@@ -73,6 +73,8 @@ class EnumGenerator {
   };
   vector<Alias> aliases_;
 
+  bool CanUseEnumValues();
+
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(EnumGenerator);
 };
 
diff --git a/src/google/protobuf/compiler/java/java_enum_field.cc b/src/google/protobuf/compiler/java/java_enum_field.cc
index 72caa10b..ec0b067e 100644
--- a/src/google/protobuf/compiler/java/java_enum_field.cc
+++ b/src/google/protobuf/compiler/java/java_enum_field.cc
@@ -36,6 +36,7 @@
 #include <string>
 
 #include <google/protobuf/compiler/java/java_enum_field.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
@@ -75,6 +76,7 @@ void SetEnumVariables(const FieldDescriptor* descriptor,
 
   // For singular messages and builders, one bit is used for the hasField bit.
   (*variables)["get_has_field_bit_message"] = GenerateGetBit(messageBitIndex);
+  (*variables)["set_has_field_bit_message"] = GenerateSetBit(messageBitIndex);
 
   (*variables)["get_has_field_bit_builder"] = GenerateGetBit(builderBitIndex);
   (*variables)["set_has_field_bit_builder"] = GenerateSetBit(builderBitIndex);
@@ -86,6 +88,13 @@ void SetEnumVariables(const FieldDescriptor* descriptor,
   (*variables)["set_mutable_bit_builder"] = GenerateSetBit(builderBitIndex);
   (*variables)["clear_mutable_bit_builder"] = GenerateClearBit(builderBitIndex);
 
+  // For repeated fields, one bit is used for whether the array is immutable
+  // in the parsing constructor.
+  (*variables)["get_mutable_bit_parser"] =
+      GenerateGetBitMutableLocal(builderBitIndex);
+  (*variables)["set_mutable_bit_parser"] =
+      GenerateSetBitMutableLocal(builderBitIndex);
+
   (*variables)["get_has_field_bit_from_local"] =
       GenerateGetBitFromLocal(builderBitIndex);
   (*variables)["set_has_field_bit_to_local"] =
@@ -117,18 +126,25 @@ int EnumFieldGenerator::GetNumBitsForBuilder() const {
 
 void EnumFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$boolean has$capitalized_name$();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$boolean has$capitalized_name$();\n"
     "$deprecation$$type$ get$capitalized_name$();\n");
 }
 
 void EnumFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $type$ $name$_;\n"
+    "private $type$ $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_message$;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n");
@@ -137,13 +153,19 @@ GenerateMembers(io::Printer* printer) const {
 void EnumFieldGenerator::
 GenerateBuilderMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $type$ $name$_ = $default$;\n"
+    "private $type$ $name$_ = $default$;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_builder$;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$($type$ value) {\n"
     "  if (value == null) {\n"
     "    throw new NullPointerException();\n"
@@ -152,7 +174,9 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_ = value;\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $clear_has_field_bit_builder$;\n"
     "  $name$_ = $default$;\n"
@@ -210,12 +234,17 @@ GenerateParsingCode(io::Printer* printer) const {
       "if (value != null) {\n");
   }
   printer->Print(variables_,
-    "  $set_has_field_bit_builder$;\n"
+    "  $set_has_field_bit_message$;\n"
     "  $name$_ = value;\n"
     "}\n");
 }
 
 void EnumFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  // noop for enums
+}
+
+void EnumFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
     "if ($get_has_field_bit_message$) {\n"
@@ -273,22 +302,33 @@ int RepeatedEnumFieldGenerator::GetNumBitsForBuilder() const {
 
 void RepeatedEnumFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$java.util.List<$type$> get$capitalized_name$List();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$int get$capitalized_name$Count();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$java.util.List<$type$> get$capitalized_name$List();\n"
-    "$deprecation$int get$capitalized_name$Count();\n"
     "$deprecation$$type$ get$capitalized_name$(int index);\n");
 }
 
 void RepeatedEnumFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private java.util.List<$type$> $name$_;\n"
+    "private java.util.List<$type$> $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.util.List<$type$> get$capitalized_name$List() {\n"
     "  return $name$_;\n"   // note:  unmodifiable list
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
     "}\n");
@@ -320,21 +360,29 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "    $name$_ = new java.util.ArrayList<$type$>($name$_);\n"
     "    $set_mutable_bit_builder$;\n"
     "  }\n"
-    "}\n"
+    "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     // Note:  We return an unmodifiable list because otherwise the caller
     //   could hold on to the returned list and modify it after the message
     //   has been built, thus mutating the message which is supposed to be
     //   immutable.
     "$deprecation$public java.util.List<$type$> get$capitalized_name$List() {\n"
     "  return java.util.Collections.unmodifiableList($name$_);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    int index, $type$ value) {\n"
     "  if (value == null) {\n"
@@ -344,7 +392,9 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_.set(index, value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder add$capitalized_name$($type$ value) {\n"
     "  if (value == null) {\n"
     "    throw new NullPointerException();\n"
@@ -353,14 +403,18 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_.add(value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder addAll$capitalized_name$(\n"
     "    java.lang.Iterable<? extends $type$> values) {\n"
     "  ensure$capitalized_name$IsMutable();\n"
     "  super.addAll(values, $name$_);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $name$_ = java.util.Collections.emptyList();\n"
     "  $clear_mutable_bit_builder$;\n"
@@ -434,7 +488,11 @@ GenerateParsingCode(io::Printer* printer) const {
       "if (value != null) {\n");
   }
   printer->Print(variables_,
-    "  add$capitalized_name$(value);\n"
+    "  if (!$get_mutable_bit_parser$) {\n"
+    "    $name$_ = new java.util.ArrayList<$type$>();\n"
+    "    $set_mutable_bit_parser$;\n"
+    "  }\n"
+    "  $name$_.add(value);\n"
     "}\n");
 }
 
@@ -457,6 +515,14 @@ GenerateParsingCodeFromPacked(io::Printer* printer) const {
 }
 
 void RepeatedEnumFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  printer->Print(variables_,
+    "if ($get_mutable_bit_parser$) {\n"
+    "  $name$_ = java.util.Collections.unmodifiableList($name$_);\n"
+    "}\n");
+}
+
+void RepeatedEnumFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   if (descriptor_->options().packed()) {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/java/java_enum_field.h b/src/google/protobuf/compiler/java/java_enum_field.h
index 0cad6be0..90fae639 100644
--- a/src/google/protobuf/compiler/java/java_enum_field.h
+++ b/src/google/protobuf/compiler/java/java_enum_field.h
@@ -61,6 +61,7 @@ class EnumFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
@@ -96,6 +97,7 @@ class RepeatedEnumFieldGenerator : public FieldGenerator {
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
   void GenerateParsingCodeFromPacked(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/java/java_extension.cc b/src/google/protobuf/compiler/java/java_extension.cc
index 9b147c77..921fe658 100644
--- a/src/google/protobuf/compiler/java/java_extension.cc
+++ b/src/google/protobuf/compiler/java/java_extension.cc
@@ -33,6 +33,7 @@
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
 #include <google/protobuf/compiler/java/java_extension.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/io/printer.h>
@@ -130,6 +131,7 @@ void ExtensionGenerator::Generate(io::Printer* printer) {
   printer->Print(vars,
       "public static final int $constant_name$ = $number$;\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   if (HasDescriptorMethods(descriptor_->file())) {
     // Non-lite extensions
     if (descriptor_->extension_scope() == NULL) {
diff --git a/src/google/protobuf/compiler/java/java_field.h b/src/google/protobuf/compiler/java/java_field.h
index 6097f357..4dd0efd6 100644
--- a/src/google/protobuf/compiler/java/java_field.h
+++ b/src/google/protobuf/compiler/java/java_field.h
@@ -66,6 +66,7 @@ class FieldGenerator {
   virtual void GenerateBuildingCode(io::Printer* printer) const = 0;
   virtual void GenerateParsingCode(io::Printer* printer) const = 0;
   virtual void GenerateParsingCodeFromPacked(io::Printer* printer) const;
+  virtual void GenerateParsingDoneCode(io::Printer* printer) const = 0;
   virtual void GenerateSerializationCode(io::Printer* printer) const = 0;
   virtual void GenerateSerializedSizeCode(io::Printer* printer) const = 0;
   virtual void GenerateFieldBuilderInitializationCode(io::Printer* printer)
diff --git a/src/google/protobuf/compiler/java/java_file.cc b/src/google/protobuf/compiler/java/java_file.cc
index 8968069f..f43e5500 100644
--- a/src/google/protobuf/compiler/java/java_file.cc
+++ b/src/google/protobuf/compiler/java/java_file.cc
@@ -42,6 +42,7 @@
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/dynamic_message.h>
 #include <google/protobuf/stubs/strutil.h>
 
 namespace google {
@@ -51,18 +52,24 @@ namespace java {
 
 namespace {
 
-// Recursively searches the given message to see if it contains any extensions.
-bool UsesExtensions(const Message& message) {
+
+// Recursively searches the given message to collect extensions.
+// Returns true if all the extensions can be recognized. The extensions will be
+// appended in to the extensions parameter.
+// Returns false when there are unknown fields, in which case the data in the
+// extensions output parameter is not reliable and should be discarded.
+bool CollectExtensions(const Message& message,
+                       vector<const FieldDescriptor*>* extensions) {
   const Reflection* reflection = message.GetReflection();
 
-  // We conservatively assume that unknown fields are extensions.
-  if (reflection->GetUnknownFields(message).field_count() > 0) return true;
+  // There are unknown fields that could be extensions, thus this call fails.
+  if (reflection->GetUnknownFields(message).field_count() > 0) return false;
 
   vector<const FieldDescriptor*> fields;
   reflection->ListFields(message, &fields);
 
   for (int i = 0; i < fields.size(); i++) {
-    if (fields[i]->is_extension()) return true;
+    if (fields[i]->is_extension()) extensions->push_back(fields[i]);
 
     if (GetJavaType(fields[i]) == JAVATYPE_MESSAGE) {
       if (fields[i]->is_repeated()) {
@@ -70,16 +77,56 @@ bool UsesExtensions(const Message& message) {
         for (int j = 0; j < size; j++) {
           const Message& sub_message =
             reflection->GetRepeatedMessage(message, fields[i], j);
-          if (UsesExtensions(sub_message)) return true;
+          if (!CollectExtensions(sub_message, extensions)) return false;
         }
       } else {
         const Message& sub_message = reflection->GetMessage(message, fields[i]);
-        if (UsesExtensions(sub_message)) return true;
+        if (!CollectExtensions(sub_message, extensions)) return false;
       }
     }
   }
 
-  return false;
+  return true;
+}
+
+// Finds all extensions in the given message and its sub-messages.  If the
+// message contains unknown fields (which could be extensions), then those
+// extensions are defined in alternate_pool.
+// The message will be converted to a DynamicMessage backed by alternate_pool
+// in order to handle this case.
+void CollectExtensions(const FileDescriptorProto& file_proto,
+                       const DescriptorPool& alternate_pool,
+                       vector<const FieldDescriptor*>* extensions,
+                       const string& file_data) {
+  if (!CollectExtensions(file_proto, extensions)) {
+    // There are unknown fields in the file_proto, which are probably
+    // extensions. We need to parse the data into a dynamic message based on the
+    // builder-pool to find out all extensions.
+    const Descriptor* file_proto_desc = alternate_pool.FindMessageTypeByName(
+        file_proto.GetDescriptor()->full_name());
+    GOOGLE_CHECK(file_proto_desc)
+        << "Find unknown fields in FileDescriptorProto when building "
+        << file_proto.name()
+        << ". It's likely that those fields are custom options, however, "
+           "descriptor.proto is not in the transitive dependencies. "
+           "This normally should not happen. Please report a bug.";
+    DynamicMessageFactory factory;
+    scoped_ptr<Message> dynamic_file_proto(
+        factory.GetPrototype(file_proto_desc)->New());
+    GOOGLE_CHECK(dynamic_file_proto.get() != NULL);
+    GOOGLE_CHECK(dynamic_file_proto->ParseFromString(file_data));
+
+    // Collect the extensions again from the dynamic message. There should be no
+    // more unknown fields this time, i.e. all the custom options should be
+    // parsed as extensions now.
+    extensions->clear();
+    GOOGLE_CHECK(CollectExtensions(*dynamic_file_proto, extensions))
+        << "Find unknown fields in FileDescriptorProto when building "
+        << file_proto.name()
+        << ". It's likely that those fields are custom options, however, "
+           "those options cannot be recognized in the builder pool. "
+           "This normally should not happen. Please report a bug.";
+  }
 }
 
 
@@ -306,19 +353,32 @@ void FileGenerator::GenerateEmbeddedDescriptor(io::Printer* printer) {
         .GenerateNonNestedInitializationCode(printer);
   }
 
-  if (UsesExtensions(file_proto)) {
-    // Must construct an ExtensionRegistry containing all possible extensions
+  // Proto compiler builds a DescriptorPool, which holds all the descriptors to
+  // generate, when processing the ".proto" files. We call this DescriptorPool
+  // the parsed pool (a.k.a. file_->pool()).
+  //
+  // Note that when users try to extend the (.*)DescriptorProto in their
+  // ".proto" files, it does not affect the pre-built FileDescriptorProto class
+  // in proto compiler. When we put the descriptor data in the file_proto, those
+  // extensions become unknown fields.
+  //
+  // Now we need to find out all the extension value to the (.*)DescriptorProto
+  // in the file_proto message, and prepare an ExtensionRegistry to return.
+  //
+  // To find those extensions, we need to parse the data into a dynamic message
+  // of the FileDescriptor based on the builder-pool, then we can use
+  // reflections to find all extension fields
+  vector<const FieldDescriptor*> extensions;
+  CollectExtensions(file_proto, *file_->pool(), &extensions, file_data);
+
+  if (extensions.size() > 0) {
+    // Must construct an ExtensionRegistry containing all existing extensions
     // and return it.
     printer->Print(
       "com.google.protobuf.ExtensionRegistry registry =\n"
-      "  com.google.protobuf.ExtensionRegistry.newInstance();\n"
-      "registerAllExtensions(registry);\n");
-    for (int i = 0; i < file_->dependency_count(); i++) {
-      if (ShouldIncludeDependency(file_->dependency(i))) {
-        printer->Print(
-            "$dependency$.registerAllExtensions(registry);\n",
-            "dependency", ClassName(file_->dependency(i)));
-      }
+      "  com.google.protobuf.ExtensionRegistry.newInstance();\n");
+    for (int i = 0; i < extensions.size(); i++) {
+      ExtensionGenerator(extensions[i]).GenerateRegistrationCode(printer);
     }
     printer->Print(
       "return registry;\n");
@@ -375,7 +435,9 @@ static void GenerateSibling(const string& package_dir,
 
   printer.Print(
     "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
-    "\n");
+    "// source: $filename$\n"
+    "\n",
+    "filename", descriptor->file()->name());
   if (!java_package.empty()) {
     printer.Print(
       "package $package$;\n"
diff --git a/src/google/protobuf/compiler/java/java_helpers.cc b/src/google/protobuf/compiler/java/java_helpers.cc
index 1b6f1653..cf241b8a 100644
--- a/src/google/protobuf/compiler/java/java_helpers.cc
+++ b/src/google/protobuf/compiler/java/java_helpers.cc
@@ -177,6 +177,18 @@ string ToJavaName(const string& full_name, const FileDescriptor* file) {
   return result;
 }
 
+string ClassName(const Descriptor* descriptor) {
+  return ToJavaName(descriptor->full_name(), descriptor->file());
+}
+
+string ClassName(const EnumDescriptor* descriptor) {
+  return ToJavaName(descriptor->full_name(), descriptor->file());
+}
+
+string ClassName(const ServiceDescriptor* descriptor) {
+  return ToJavaName(descriptor->full_name(), descriptor->file());
+}
+
 string ClassName(const FileDescriptor* descriptor) {
   string result = FileJavaPackage(descriptor);
   if (!result.empty()) result += '.';
@@ -326,14 +338,14 @@ string DefaultValue(const FieldDescriptor* field) {
         } else {
           // See comments in Internal.java for gory details.
           return strings::Substitute(
-            "com.google.protobuf.Internal.stringDefaultValue(\"$0\")",
-            CEscape(field->default_value_string()));
+              "com.google.protobuf.Internal.stringDefaultValue(\"$0\")",
+              CEscape(field->default_value_string()));
         }
       }
 
     case FieldDescriptor::CPPTYPE_ENUM:
       return ClassName(field->enum_type()) + "." +
-             field->default_value_enum()->name();
+          field->default_value_enum()->name();
 
     case FieldDescriptor::CPPTYPE_MESSAGE:
       return ClassName(field->message_type()) + ".getDefaultInstance()";
@@ -427,8 +439,10 @@ string GetBitFieldNameForBit(int bitIndex) {
   return GetBitFieldName(bitIndex / 32);
 }
 
-string GenerateGetBit(int bitIndex) {
-  string varName = GetBitFieldNameForBit(bitIndex);
+namespace {
+
+string GenerateGetBitInternal(const string& prefix, int bitIndex) {
+  string varName = prefix + GetBitFieldNameForBit(bitIndex);
   int bitInVarIndex = bitIndex % 32;
 
   string mask = bit_masks[bitInVarIndex];
@@ -436,8 +450,8 @@ string GenerateGetBit(int bitIndex) {
   return result;
 }
 
-string GenerateSetBit(int bitIndex) {
-  string varName = GetBitFieldNameForBit(bitIndex);
+string GenerateSetBitInternal(const string& prefix, int bitIndex) {
+  string varName = prefix + GetBitFieldNameForBit(bitIndex);
   int bitInVarIndex = bitIndex % 32;
 
   string mask = bit_masks[bitInVarIndex];
@@ -445,6 +459,16 @@ string GenerateSetBit(int bitIndex) {
   return result;
 }
 
+}  // namespace
+
+string GenerateGetBit(int bitIndex) {
+  return GenerateGetBitInternal("", bitIndex);
+}
+
+string GenerateSetBit(int bitIndex) {
+  return GenerateSetBitInternal("", bitIndex);
+}
+
 string GenerateClearBit(int bitIndex) {
   string varName = GetBitFieldNameForBit(bitIndex);
   int bitInVarIndex = bitIndex % 32;
@@ -455,21 +479,19 @@ string GenerateClearBit(int bitIndex) {
 }
 
 string GenerateGetBitFromLocal(int bitIndex) {
-  string varName = "from_" + GetBitFieldNameForBit(bitIndex);
-  int bitInVarIndex = bitIndex % 32;
-
-  string mask = bit_masks[bitInVarIndex];
-  string result = "((" + varName + " & " + mask + ") == " + mask + ")";
-  return result;
+  return GenerateGetBitInternal("from_", bitIndex);
 }
 
 string GenerateSetBitToLocal(int bitIndex) {
-  string varName = "to_" + GetBitFieldNameForBit(bitIndex);
-  int bitInVarIndex = bitIndex % 32;
+  return GenerateSetBitInternal("to_", bitIndex);
+}
 
-  string mask = bit_masks[bitInVarIndex];
-  string result = varName + " |= " + mask;
-  return result;
+string GenerateGetBitMutableLocal(int bitIndex) {
+  return GenerateGetBitInternal("mutable_", bitIndex);
+}
+
+string GenerateSetBitMutableLocal(int bitIndex) {
+  return GenerateSetBitInternal("mutable_", bitIndex);
 }
 
 }  // namespace java
diff --git a/src/google/protobuf/compiler/java/java_helpers.h b/src/google/protobuf/compiler/java/java_helpers.h
index 4ae07f15..3937f069 100644
--- a/src/google/protobuf/compiler/java/java_helpers.h
+++ b/src/google/protobuf/compiler/java/java_helpers.h
@@ -78,19 +78,14 @@ string ToJavaName(const string& full_name, const FileDescriptor* file);
 
 // These return the fully-qualified class name corresponding to the given
 // descriptor.
-inline string ClassName(const Descriptor* descriptor) {
-  return ToJavaName(descriptor->full_name(), descriptor->file());
-}
-inline string ClassName(const EnumDescriptor* descriptor) {
-  return ToJavaName(descriptor->full_name(), descriptor->file());
-}
-inline string ClassName(const ServiceDescriptor* descriptor) {
-  return ToJavaName(descriptor->full_name(), descriptor->file());
-}
+string ClassName(const Descriptor* descriptor);
+string ClassName(const EnumDescriptor* descriptor);
+string ClassName(const ServiceDescriptor* descriptor);
+string ClassName(const FileDescriptor* descriptor);
+
 inline string ExtensionIdentifierName(const FieldDescriptor* descriptor) {
   return ToJavaName(descriptor->full_name(), descriptor->file());
 }
-string ClassName(const FileDescriptor* descriptor);
 
 // Get the unqualified name that should be used for a field's field
 // number constant.
@@ -205,6 +200,18 @@ string GenerateGetBitFromLocal(int bitIndex);
 // Example: "to_bitField1_ = (to_bitField1_ | 0x04)"
 string GenerateSetBitToLocal(int bitIndex);
 
+// Does the same as GenerateGetBit but operates on the bit field on a local
+// variable. This is used by the parsing constructor to record if a repeated
+// field is mutable.
+// Example: "((mutable_bitField1_ & 0x04) == 0x04)"
+string GenerateGetBitMutableLocal(int bitIndex);
+
+// Does the same as GenerateSetBit but operates on the bit field on a local
+// variable. This is used by the parsing constructor to record if a repeated
+// field is mutable.
+// Example: "mutable_bitField1_ = (mutable_bitField1_ | 0x04)"
+string GenerateSetBitMutableLocal(int bitIndex);
+
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/java/java_message.cc b/src/google/protobuf/compiler/java/java_message.cc
index 4c087db5..9322e242 100644
--- a/src/google/protobuf/compiler/java/java_message.cc
+++ b/src/google/protobuf/compiler/java/java_message.cc
@@ -32,17 +32,23 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
+#include <google/protobuf/compiler/java/java_message.h>
+
 #include <algorithm>
 #include <google/protobuf/stubs/hash.h>
-#include <google/protobuf/compiler/java/java_message.h>
+#include <map>
+#include <vector>
+
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_enum.h>
 #include <google/protobuf/compiler/java/java_extension.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
-#include <google/protobuf/stubs/strutil.h>
-#include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/coded_stream.h>
-#include <google/protobuf/wire_format.h>
+#include <google/protobuf/io/printer.h>
 #include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/wire_format.h>
+#include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/substitute.h>
 
 namespace google {
 namespace protobuf {
@@ -233,10 +239,8 @@ void MessageGenerator::GenerateStaticVariableInitializers(
         "field_name",
           UnderscoresToCapitalizedCamelCase(descriptor_->field(i)));
     }
-    printer->Print("},\n"
-      "    $classname$.class,\n"
-      "    $classname$.Builder.class);\n",
-      "classname", ClassName(descriptor_));
+    printer->Print(
+        "});\n");
   }
 
   // Generate static member initializers for all nested types.
@@ -250,7 +254,6 @@ void MessageGenerator::GenerateStaticVariableInitializers(
 // ===================================================================
 
 void MessageGenerator::GenerateInterface(io::Printer* printer) {
-
   if (descriptor_->extension_range_count() > 0) {
     if (HasDescriptorMethods(descriptor_)) {
       printer->Print(
@@ -298,6 +301,10 @@ void MessageGenerator::Generate(io::Printer* printer) {
     descriptor_->containing_type() == NULL &&
     descriptor_->file()->options().java_multiple_files();
 
+  WriteMessageDocComment(printer, descriptor_);
+
+  // The builder_type stores the super type name of the nested Builder class.
+  string builder_type;
   if (descriptor_->extension_range_count() > 0) {
     if (HasDescriptorMethods(descriptor_)) {
       printer->Print(
@@ -306,6 +313,9 @@ void MessageGenerator::Generate(io::Printer* printer) {
         "      $classname$> implements $classname$OrBuilder {\n",
         "static", is_own_file ? "" : "static",
         "classname", descriptor_->name());
+      builder_type = strings::Substitute(
+          "com.google.protobuf.GeneratedMessage.ExtendableBuilder<$0, ?>",
+          ClassName(descriptor_));
     } else {
       printer->Print(
         "public $static$ final class $classname$ extends\n"
@@ -313,6 +323,9 @@ void MessageGenerator::Generate(io::Printer* printer) {
         "      $classname$> implements $classname$OrBuilder {\n",
         "static", is_own_file ? "" : "static",
         "classname", descriptor_->name());
+      builder_type = strings::Substitute(
+          "com.google.protobuf.GeneratedMessageLite.ExtendableBuilder<$0, ?>",
+          ClassName(descriptor_));
     }
   } else {
     if (HasDescriptorMethods(descriptor_)) {
@@ -322,6 +335,7 @@ void MessageGenerator::Generate(io::Printer* printer) {
         "    implements $classname$OrBuilder {\n",
         "static", is_own_file ? "" : "static",
         "classname", descriptor_->name());
+      builder_type = "com.google.protobuf.GeneratedMessage.Builder<?>";
     } else {
       printer->Print(
         "public $static$ final class $classname$ extends\n"
@@ -329,17 +343,28 @@ void MessageGenerator::Generate(io::Printer* printer) {
         "    implements $classname$OrBuilder {\n",
         "static", is_own_file ? "" : "static",
         "classname", descriptor_->name());
+      builder_type = "com.google.protobuf.GeneratedMessageLite.Builder";
     }
   }
   printer->Indent();
+  // Using builder_type, instead of Builder, prevents the Builder class from
+  // being loaded into PermGen space when the default instance is created.
+  // This optimizes the PermGen space usage for clients that do not modify
+  // messages.
   printer->Print(
     "// Use $classname$.newBuilder() to construct.\n"
-    "private $classname$(Builder builder) {\n"
+    "private $classname$($buildertype$ builder) {\n"
     "  super(builder);\n"
-    "}\n"
+    "$set_unknown_fields$\n"
+    "}\n",
+    "classname", descriptor_->name(),
+    "buildertype", builder_type,
+    "set_unknown_fields", HasUnknownFields(descriptor_)
+        ? "  this.unknownFields = builder.getUnknownFields();" : "");
+  printer->Print(
     // Used when constructing the default instance, which cannot be initialized
     // immediately because it may cyclically refer to other default instances.
-    "private $classname$(boolean noInit) {}\n"
+    "private $classname$(boolean noInit) {$set_default_unknown_fields$}\n"
     "\n"
     "private static final $classname$ defaultInstance;\n"
     "public static $classname$ getDefaultInstance() {\n"
@@ -350,9 +375,28 @@ void MessageGenerator::Generate(io::Printer* printer) {
     "  return defaultInstance;\n"
     "}\n"
     "\n",
-    "classname", descriptor_->name());
+    "classname", descriptor_->name(),
+    "set_default_unknown_fields", HasUnknownFields(descriptor_)
+        ? " this.unknownFields ="
+          " com.google.protobuf.UnknownFieldSet.getDefaultInstance(); " : "");
+
+  if (HasUnknownFields(descriptor_)) {
+    printer->Print(
+        "private final com.google.protobuf.UnknownFieldSet unknownFields;\n"
+        ""
+        "@java.lang.Override\n"
+        "public final com.google.protobuf.UnknownFieldSet\n"
+        "    getUnknownFields() {\n"
+        "  return this.unknownFields;\n"
+        "}\n");
+  }
+
+  if (HasGeneratedMethods(descriptor_)) {
+    GenerateParsingConstructor(printer);
+  }
 
   GenerateDescriptorMethods(printer);
+  GenerateParser(printer);
 
   // Nested types
   for (int i = 0; i < descriptor_->enum_type_count(); i++) {
@@ -567,68 +611,54 @@ GenerateParseFromMethods(io::Printer* printer) {
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.ByteString data)\n"
     "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
-    "  return newBuilder().mergeFrom(data).buildParsed();\n"
+    "  return PARSER.parseFrom(data);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.ByteString data,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
-    "  return newBuilder().mergeFrom(data, extensionRegistry)\n"
-    "           .buildParsed();\n"
+    "  return PARSER.parseFrom(data, extensionRegistry);\n"
     "}\n"
     "public static $classname$ parseFrom(byte[] data)\n"
     "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
-    "  return newBuilder().mergeFrom(data).buildParsed();\n"
+    "  return PARSER.parseFrom(data);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    byte[] data,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
-    "  return newBuilder().mergeFrom(data, extensionRegistry)\n"
-    "           .buildParsed();\n"
+    "  return PARSER.parseFrom(data, extensionRegistry);\n"
     "}\n"
     "public static $classname$ parseFrom(java.io.InputStream input)\n"
     "    throws java.io.IOException {\n"
-    "  return newBuilder().mergeFrom(input).buildParsed();\n"
+    "  return PARSER.parseFrom(input);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    java.io.InputStream input,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws java.io.IOException {\n"
-    "  return newBuilder().mergeFrom(input, extensionRegistry)\n"
-    "           .buildParsed();\n"
+    "  return PARSER.parseFrom(input, extensionRegistry);\n"
     "}\n"
     "public static $classname$ parseDelimitedFrom(java.io.InputStream input)\n"
     "    throws java.io.IOException {\n"
-    "  Builder builder = newBuilder();\n"
-    "  if (builder.mergeDelimitedFrom(input)) {\n"
-    "    return builder.buildParsed();\n"
-    "  } else {\n"
-    "    return null;\n"
-    "  }\n"
+    "  return PARSER.parseDelimitedFrom(input);\n"
     "}\n"
     "public static $classname$ parseDelimitedFrom(\n"
     "    java.io.InputStream input,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws java.io.IOException {\n"
-    "  Builder builder = newBuilder();\n"
-    "  if (builder.mergeDelimitedFrom(input, extensionRegistry)) {\n"
-    "    return builder.buildParsed();\n"
-    "  } else {\n"
-    "    return null;\n"
-    "  }\n"
+    "  return PARSER.parseDelimitedFrom(input, extensionRegistry);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.CodedInputStream input)\n"
     "    throws java.io.IOException {\n"
-    "  return newBuilder().mergeFrom(input).buildParsed();\n"
+    "  return PARSER.parseFrom(input);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.CodedInputStream input,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws java.io.IOException {\n"
-    "  return newBuilder().mergeFrom(input, extensionRegistry)\n"
-    "           .buildParsed();\n"
+    "  return PARSER.parseFrom(input, extensionRegistry);\n"
     "}\n"
     "\n",
     "classname", ClassName(descriptor_));
@@ -669,6 +699,8 @@ void MessageGenerator::GenerateBuilder(io::Printer* printer) {
       "}\n");
   }
 
+  WriteMessageDocComment(printer, descriptor_);
+
   if (descriptor_->extension_range_count() > 0) {
     if (HasDescriptorMethods(descriptor_)) {
       printer->Print(
@@ -739,17 +771,25 @@ void MessageGenerator::GenerateBuilder(io::Printer* printer) {
 
 void MessageGenerator::GenerateDescriptorMethods(io::Printer* printer) {
   if (HasDescriptorMethods(descriptor_)) {
+    if (!descriptor_->options().no_standard_descriptor_accessor()) {
+      printer->Print(
+        "public static final com.google.protobuf.Descriptors.Descriptor\n"
+        "    getDescriptor() {\n"
+        "  return $fileclass$.internal_$identifier$_descriptor;\n"
+        "}\n"
+        "\n",
+        "fileclass", ClassName(descriptor_->file()),
+        "identifier", UniqueFileScopeIdentifier(descriptor_));
+    }
     printer->Print(
-      "public static final com.google.protobuf.Descriptors.Descriptor\n"
-      "    getDescriptor() {\n"
-      "  return $fileclass$.internal_$identifier$_descriptor;\n"
-      "}\n"
-      "\n"
       "protected com.google.protobuf.GeneratedMessage.FieldAccessorTable\n"
       "    internalGetFieldAccessorTable() {\n"
-      "  return $fileclass$.internal_$identifier$_fieldAccessorTable;\n"
+      "  return $fileclass$.internal_$identifier$_fieldAccessorTable\n"
+      "      .ensureFieldAccessorsInitialized(\n"
+      "          $classname$.class, $classname$.Builder.class);\n"
       "}\n"
       "\n",
+      "classname", ClassName(descriptor_),
       "fileclass", ClassName(descriptor_->file()),
       "identifier", UniqueFileScopeIdentifier(descriptor_));
   }
@@ -768,7 +808,8 @@ void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
 
   if (HasDescriptorMethods(descriptor_)) {
     printer->Print(
-      "private Builder(BuilderParent parent) {\n"
+      "private Builder(\n"
+      "    com.google.protobuf.GeneratedMessage.BuilderParent parent) {\n"
       "  super(parent);\n"
       "  maybeForceBuilderInitialization();\n"
       "}\n",
@@ -830,10 +871,11 @@ void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
     printer->Print(
       "public com.google.protobuf.Descriptors.Descriptor\n"
       "    getDescriptorForType() {\n"
-      "  return $classname$.getDescriptor();\n"
+      "  return $fileclass$.internal_$identifier$_descriptor;\n"
       "}\n"
       "\n",
-      "classname", ClassName(descriptor_));
+      "fileclass", ClassName(descriptor_->file()),
+      "identifier", UniqueFileScopeIdentifier(descriptor_));
   }
   printer->Print(
     "public $classname$ getDefaultInstanceForType() {\n"
@@ -853,16 +895,6 @@ void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
     "  return result;\n"
     "}\n"
     "\n"
-    "private $classname$ buildParsed()\n"
-    "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
-    "  $classname$ result = buildPartial();\n"
-    "  if (!result.isInitialized()) {\n"
-    "    throw newUninitializedMessageException(\n"
-    "      result).asInvalidProtocolBufferException();\n"
-    "  }\n"
-    "  return result;\n"
-    "}\n"
-    "\n"
     "public $classname$ buildPartial() {\n"
     "  $classname$ result = new $classname$(this);\n",
     "classname", ClassName(descriptor_));
@@ -969,108 +1001,25 @@ void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
 // ===================================================================
 
 void MessageGenerator::GenerateBuilderParsingMethods(io::Printer* printer) {
-  scoped_array<const FieldDescriptor*> sorted_fields(
-    SortFieldsByNumber(descriptor_));
-
   printer->Print(
     "public Builder mergeFrom(\n"
     "    com.google.protobuf.CodedInputStream input,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
-    "    throws java.io.IOException {\n");
-  printer->Indent();
-
-  if (HasUnknownFields(descriptor_)) {
-    printer->Print(
-      "com.google.protobuf.UnknownFieldSet.Builder unknownFields =\n"
-      "  com.google.protobuf.UnknownFieldSet.newBuilder(\n"
-      "    this.getUnknownFields());\n");
-  }
-
-  printer->Print(
-    "while (true) {\n");
-  printer->Indent();
-
-  printer->Print(
-    "int tag = input.readTag();\n"
-    "switch (tag) {\n");
-  printer->Indent();
-
-  if (HasUnknownFields(descriptor_)) {
-    printer->Print(
-      "case 0:\n"          // zero signals EOF / limit reached
-      "  this.setUnknownFields(unknownFields.build());\n"
-      "  $on_changed$\n"
-      "  return this;\n"
-      "default: {\n"
-      "  if (!parseUnknownField(input, unknownFields,\n"
-      "                         extensionRegistry, tag)) {\n"
-      "    this.setUnknownFields(unknownFields.build());\n"
-      "    $on_changed$\n"
-      "    return this;\n"   // it's an endgroup tag
-      "  }\n"
-      "  break;\n"
-      "}\n",
-      "on_changed", HasDescriptorMethods(descriptor_) ? "onChanged();" : "");
-  } else {
-    printer->Print(
-      "case 0:\n"          // zero signals EOF / limit reached
-      "  $on_changed$\n"
-      "  return this;\n"
-      "default: {\n"
-      "  if (!parseUnknownField(input, extensionRegistry, tag)) {\n"
-      "    $on_changed$\n"
-      "    return this;\n"   // it's an endgroup tag
-      "  }\n"
-      "  break;\n"
-      "}\n",
-      "on_changed", HasDescriptorMethods(descriptor_) ? "onChanged();" : "");
-  }
-
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* field = sorted_fields[i];
-    uint32 tag = WireFormatLite::MakeTag(field->number(),
-      WireFormat::WireTypeForFieldType(field->type()));
-
-    printer->Print(
-      "case $tag$: {\n",
-      "tag", SimpleItoa(tag));
-    printer->Indent();
-
-    field_generators_.get(field).GenerateParsingCode(printer);
-
-    printer->Outdent();
-    printer->Print(
-      "  break;\n"
-      "}\n");
-
-    if (field->is_packable()) {
-      // To make packed = true wire compatible, we generate parsing code from a
-      // packed version of this field regardless of field->options().packed().
-      uint32 packed_tag = WireFormatLite::MakeTag(field->number(),
-        WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
-      printer->Print(
-        "case $tag$: {\n",
-        "tag", SimpleItoa(packed_tag));
-      printer->Indent();
-
-      field_generators_.get(field).GenerateParsingCodeFromPacked(printer);
-
-      printer->Outdent();
-      printer->Print(
-        "  break;\n"
-        "}\n");
-    }
-  }
-
-  printer->Outdent();
-  printer->Outdent();
-  printer->Outdent();
-  printer->Print(
-    "    }\n"     // switch (tag)
-    "  }\n"       // while (true)
-    "}\n"
-
-    "\n");
+    "    throws java.io.IOException {\n"
+    "  $classname$ parsedMessage = null;\n"
+    "  try {\n"
+    "    parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);\n"
+    "  } catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
+    "    parsedMessage = ($classname$) e.getUnfinishedMessage();\n"
+    "    throw e;\n"
+    "  } finally {\n"
+    "    if (parsedMessage != null) {\n"
+    "      mergeFrom(parsedMessage);\n"
+    "    }\n"
+    "  }\n"
+    "  return this;\n"
+    "}\n",
+    "classname", ClassName(descriptor_));
 }
 
 // ===================================================================
@@ -1232,10 +1181,19 @@ void MessageGenerator::GenerateEqualsAndHashCode(io::Printer* printer) {
     "\n");
 
   printer->Print(
+    "private int memoizedHashCode = 0;\n");
+  printer->Print(
     "@java.lang.Override\n"
     "public int hashCode() {\n");
   printer->Indent();
   printer->Print(
+    "if (memoizedHashCode != 0) {\n");
+  printer->Indent();
+  printer->Print(
+    "return memoizedHashCode;\n");
+  printer->Outdent();
+  printer->Print(
+    "}\n"
     "int hash = 41;\n"
     "hash = (19 * hash) + getDescriptorForType().hashCode();\n");
   for (int i = 0; i < descriptor_->field_count(); i++) {
@@ -1260,6 +1218,7 @@ void MessageGenerator::GenerateEqualsAndHashCode(io::Printer* printer) {
   }
   printer->Print(
     "hash = (29 * hash) + getUnknownFields().hashCode();\n"
+    "memoizedHashCode = hash;\n"
     "return hash;\n");
   printer->Outdent();
   printer->Print(
@@ -1281,6 +1240,195 @@ void MessageGenerator::GenerateExtensionRegistrationCode(io::Printer* printer) {
   }
 }
 
+// ===================================================================
+void MessageGenerator::GenerateParsingConstructor(io::Printer* printer) {
+  scoped_array<const FieldDescriptor*> sorted_fields(
+      SortFieldsByNumber(descriptor_));
+
+  printer->Print(
+      "private $classname$(\n"
+      "    com.google.protobuf.CodedInputStream input,\n"
+      "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
+      "    throws com.google.protobuf.InvalidProtocolBufferException {\n",
+      "classname", descriptor_->name());
+  printer->Indent();
+
+  // Initialize all fields to default.
+  printer->Print(
+      "initFields();\n");
+
+  // Use builder bits to track mutable repeated fields.
+  int totalBuilderBits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldGenerator& field = field_generators_.get(descriptor_->field(i));
+    totalBuilderBits += field.GetNumBitsForBuilder();
+  }
+  int totalBuilderInts = (totalBuilderBits + 31) / 32;
+  for (int i = 0; i < totalBuilderInts; i++) {
+    printer->Print("int mutable_$bit_field_name$ = 0;\n",
+      "bit_field_name", GetBitFieldName(i));
+  }
+
+  if (HasUnknownFields(descriptor_)) {
+    printer->Print(
+      "com.google.protobuf.UnknownFieldSet.Builder unknownFields =\n"
+      "    com.google.protobuf.UnknownFieldSet.newBuilder();\n");
+  }
+
+  printer->Print(
+      "try {\n");
+  printer->Indent();
+
+  printer->Print(
+    "boolean done = false;\n"
+    "while (!done) {\n");
+  printer->Indent();
+
+  printer->Print(
+    "int tag = input.readTag();\n"
+    "switch (tag) {\n");
+  printer->Indent();
+
+  printer->Print(
+    "case 0:\n"          // zero signals EOF / limit reached
+    "  done = true;\n"
+    "  break;\n"
+    "default: {\n"
+    "  if (!parseUnknownField(input,$unknown_fields$\n"
+    "                         extensionRegistry, tag)) {\n"
+    "    done = true;\n"  // it's an endgroup tag
+    "  }\n"
+    "  break;\n"
+    "}\n",
+    "unknown_fields", HasUnknownFields(descriptor_)
+        ? " unknownFields," : "");
+
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldDescriptor* field = sorted_fields[i];
+    uint32 tag = WireFormatLite::MakeTag(field->number(),
+      WireFormat::WireTypeForFieldType(field->type()));
+
+    printer->Print(
+      "case $tag$: {\n",
+      "tag", SimpleItoa(tag));
+    printer->Indent();
+
+    field_generators_.get(field).GenerateParsingCode(printer);
+
+    printer->Outdent();
+    printer->Print(
+      "  break;\n"
+      "}\n");
+
+    if (field->is_packable()) {
+      // To make packed = true wire compatible, we generate parsing code from a
+      // packed version of this field regardless of field->options().packed().
+      uint32 packed_tag = WireFormatLite::MakeTag(field->number(),
+        WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+      printer->Print(
+        "case $tag$: {\n",
+        "tag", SimpleItoa(packed_tag));
+      printer->Indent();
+
+      field_generators_.get(field).GenerateParsingCodeFromPacked(printer);
+
+      printer->Outdent();
+      printer->Print(
+        "  break;\n"
+        "}\n");
+    }
+  }
+
+  printer->Outdent();
+  printer->Outdent();
+  printer->Print(
+      "  }\n"     // switch (tag)
+      "}\n");     // while (!done)
+
+  printer->Outdent();
+  printer->Print(
+      "} catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
+      "  throw e.setUnfinishedMessage(this);\n"
+      "} catch (java.io.IOException e) {\n"
+      "  throw new com.google.protobuf.InvalidProtocolBufferException(\n"
+      "      e.getMessage()).setUnfinishedMessage(this);\n"
+      "} finally {\n");
+  printer->Indent();
+
+  // Make repeated field list immutable.
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldDescriptor* field = sorted_fields[i];
+    field_generators_.get(field).GenerateParsingDoneCode(printer);
+  }
+
+  // Make unknown fields immutable.
+  if (HasUnknownFields(descriptor_)) {
+    printer->Print(
+        "this.unknownFields = unknownFields.build();\n");
+  }
+
+  // Make extensions immutable.
+  printer->Print(
+      "makeExtensionsImmutable();\n");
+
+  printer->Outdent();
+  printer->Outdent();
+  printer->Print(
+      "  }\n"     // finally
+      "}\n");
+}
+
+// ===================================================================
+void MessageGenerator::GenerateParser(io::Printer* printer) {
+  printer->Print(
+      "public static com.google.protobuf.Parser<$classname$> PARSER =\n"
+      "    new com.google.protobuf.AbstractParser<$classname$>() {\n",
+      "classname", descriptor_->name());
+  printer->Indent();
+  printer->Print(
+      "public $classname$ parsePartialFrom(\n"
+      "    com.google.protobuf.CodedInputStream input,\n"
+      "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
+      "    throws com.google.protobuf.InvalidProtocolBufferException {\n",
+      "classname", descriptor_->name());
+  if (HasGeneratedMethods(descriptor_)) {
+    printer->Print(
+        "  return new $classname$(input, extensionRegistry);\n",
+        "classname", descriptor_->name());
+  } else {
+    // When parsing constructor isn't generated, use builder to parse messages.
+    // Note, will fallback to use reflection based mergeFieldFrom() in
+    // AbstractMessage.Builder.
+    printer->Indent();
+    printer->Print(
+        "Builder builder = newBuilder();\n"
+        "try {\n"
+        "  builder.mergeFrom(input, extensionRegistry);\n"
+        "} catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
+        "  throw e.setUnfinishedMessage(builder.buildPartial());\n"
+        "} catch (java.io.IOException e) {\n"
+        "  throw new com.google.protobuf.InvalidProtocolBufferException(\n"
+        "      e.getMessage()).setUnfinishedMessage(builder.buildPartial());\n"
+        "}\n"
+        "return builder.buildPartial();\n");
+    printer->Outdent();
+  }
+  printer->Print(
+        "}\n");
+  printer->Outdent();
+  printer->Print(
+      "};\n"
+      "\n");
+
+  printer->Print(
+      "@java.lang.Override\n"
+      "public com.google.protobuf.Parser<$classname$> getParserForType() {\n"
+      "  return PARSER;\n"
+      "}\n"
+      "\n",
+      "classname", descriptor_->name());
+}
+
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/java/java_message.h b/src/google/protobuf/compiler/java/java_message.h
index 4c6fbbe5..a30f0202 100644
--- a/src/google/protobuf/compiler/java/java_message.h
+++ b/src/google/protobuf/compiler/java/java_message.h
@@ -95,6 +95,9 @@ class MessageGenerator {
       UseMemoization useMemoization);
   void GenerateEqualsAndHashCode(io::Printer* printer);
 
+  void GenerateParser(io::Printer* printer);
+  void GenerateParsingConstructor(io::Printer* printer);
+
   const Descriptor* descriptor_;
   FieldGeneratorMap field_generators_;
 
diff --git a/src/google/protobuf/compiler/java/java_message_field.cc b/src/google/protobuf/compiler/java/java_message_field.cc
index 251945af..b0b284f7 100644
--- a/src/google/protobuf/compiler/java/java_message_field.cc
+++ b/src/google/protobuf/compiler/java/java_message_field.cc
@@ -36,6 +36,7 @@
 #include <string>
 
 #include <google/protobuf/compiler/java/java_message_field.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/wire_format.h>
@@ -73,6 +74,7 @@ void SetMessageVariables(const FieldDescriptor* descriptor,
 
   // For singular messages and builders, one bit is used for the hasField bit.
   (*variables)["get_has_field_bit_message"] = GenerateGetBit(messageBitIndex);
+  (*variables)["set_has_field_bit_message"] = GenerateSetBit(messageBitIndex);
 
   (*variables)["get_has_field_bit_builder"] = GenerateGetBit(builderBitIndex);
   (*variables)["set_has_field_bit_builder"] = GenerateSetBit(builderBitIndex);
@@ -84,6 +86,13 @@ void SetMessageVariables(const FieldDescriptor* descriptor,
   (*variables)["set_mutable_bit_builder"] = GenerateSetBit(builderBitIndex);
   (*variables)["clear_mutable_bit_builder"] = GenerateClearBit(builderBitIndex);
 
+  // For repeated fields, one bit is used for whether the array is immutable
+  // in the parsing constructor.
+  (*variables)["get_mutable_bit_parser"] =
+      GenerateGetBitMutableLocal(builderBitIndex);
+  (*variables)["set_mutable_bit_parser"] =
+      GenerateSetBitMutableLocal(builderBitIndex);
+
   (*variables)["get_has_field_bit_from_local"] =
       GenerateGetBitFromLocal(builderBitIndex);
   (*variables)["set_has_field_bit_to_local"] =
@@ -120,11 +129,15 @@ GenerateInterfaceMembers(io::Printer* printer) const {
   // interface so that builders can choose dynamically to either return a
   // message or a nested builder, so that asking for the interface doesn't
   // cause a message to ever be built.
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$boolean has$capitalized_name$();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$boolean has$capitalized_name$();\n"
     "$deprecation$$type$ get$capitalized_name$();\n");
 
   if (HasNestedBuilders(descriptor_->containing_type())) {
+    WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$$type$OrBuilder get$capitalized_name$OrBuilder();\n");
   }
@@ -133,15 +146,20 @@ GenerateInterfaceMembers(io::Printer* printer) const {
 void MessageFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $type$ $name$_;\n"
+    "private $type$ $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_message$;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n");
 
   if (HasNestedBuilders(descriptor_->containing_type())) {
+    WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$public $type$OrBuilder get$capitalized_name$OrBuilder() {\n"
       "  return $name$_;\n"
@@ -208,12 +226,14 @@ GenerateBuilderMembers(io::Printer* printer) const {
   // field of type "Field" called "Field".
 
   // boolean hasField()
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_builder$;\n"
     "}\n");
 
   // Field getField()
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public $type$ get$capitalized_name$()",
 
@@ -224,6 +244,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     NULL);
 
   // Field.Builder setField(Field value)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder set$capitalized_name$($type$ value)",
 
@@ -239,6 +260,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Field.Builder setField(Field.Builder builderForValue)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    $type$.Builder builderForValue)",
@@ -252,6 +274,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Field.Builder mergeField(Field value)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder merge$capitalized_name$($type$ value)",
 
@@ -270,6 +293,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Field.Builder clearField()
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder clear$capitalized_name$()",
 
@@ -282,19 +306,24 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   if (HasNestedBuilders(descriptor_->containing_type())) {
+    WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$public $type$.Builder get$capitalized_name$Builder() {\n"
       "  $set_has_field_bit_builder$;\n"
       "  $on_changed$\n"
       "  return get$capitalized_name$FieldBuilder().getBuilder();\n"
-      "}\n"
+      "}\n");
+    WriteFieldDocComment(printer, descriptor_);
+    printer->Print(variables_,
       "$deprecation$public $type$OrBuilder get$capitalized_name$OrBuilder() {\n"
       "  if ($name$Builder_ != null) {\n"
       "    return $name$Builder_.getMessageOrBuilder();\n"
       "  } else {\n"
       "    return $name$_;\n"
       "  }\n"
-      "}\n"
+      "}\n");
+    WriteFieldDocComment(printer, descriptor_);
+    printer->Print(variables_,
       "private com.google.protobuf.SingleFieldBuilder<\n"
       "    $type$, $type$.Builder, $type$OrBuilder> \n"
       "    get$capitalized_name$FieldBuilder() {\n"
@@ -357,21 +386,32 @@ GenerateBuildingCode(io::Printer* printer) const {
 void MessageFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "$type$.Builder subBuilder = $type$.newBuilder();\n"
-    "if (has$capitalized_name$()) {\n"
-    "  subBuilder.mergeFrom(get$capitalized_name$());\n"
+    "$type$.Builder subBuilder = null;\n"
+    "if ($get_has_field_bit_message$) {\n"
+    "  subBuilder = $name$_.toBuilder();\n"
     "}\n");
 
   if (GetType(descriptor_) == FieldDescriptor::TYPE_GROUP) {
     printer->Print(variables_,
-      "input.readGroup($number$, subBuilder, extensionRegistry);\n");
+      "$name$_ = input.readGroup($number$, $type$.PARSER,\n"
+      "    extensionRegistry);\n");
   } else {
     printer->Print(variables_,
-      "input.readMessage(subBuilder, extensionRegistry);\n");
+      "$name$_ = input.readMessage($type$.PARSER, extensionRegistry);\n");
   }
 
   printer->Print(variables_,
-    "set$capitalized_name$(subBuilder.buildPartial());\n");
+    "if (subBuilder != null) {\n"
+    "  subBuilder.mergeFrom($name$_);\n"
+    "  $name$_ = subBuilder.buildPartial();\n"
+    "}\n");
+  printer->Print(variables_,
+    "$set_has_field_bit_message$;\n");
+}
+
+void MessageFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  // noop for messages.
 }
 
 void MessageFieldGenerator::
@@ -437,15 +477,23 @@ GenerateInterfaceMembers(io::Printer* printer) const {
   // interface so that builders can choose dynamically to either return a
   // message or a nested builder, so that asking for the interface doesn't
   // cause a message to ever be built.
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$java.util.List<$type$> \n"
-    "    get$capitalized_name$List();\n"
-    "$deprecation$$type$ get$capitalized_name$(int index);\n"
+    "    get$capitalized_name$List();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$$type$ get$capitalized_name$(int index);\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$int get$capitalized_name$Count();\n");
   if (HasNestedBuilders(descriptor_->containing_type())) {
+    WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$java.util.List<? extends $type$OrBuilder> \n"
-      "    get$capitalized_name$OrBuilderList();\n"
+      "    get$capitalized_name$OrBuilderList();\n");
+    WriteFieldDocComment(printer, descriptor_);
+    printer->Print(variables_,
       "$deprecation$$type$OrBuilder get$capitalized_name$OrBuilder(\n"
       "    int index);\n");
   }
@@ -454,20 +502,30 @@ GenerateInterfaceMembers(io::Printer* printer) const {
 void RepeatedMessageFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private java.util.List<$type$> $name$_;\n"
+    "private java.util.List<$type$> $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.util.List<$type$> get$capitalized_name$List() {\n"
     "  return $name$_;\n"   // note:  unmodifiable list
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.util.List<? extends $type$OrBuilder> \n"
     "    get$capitalized_name$OrBuilderList() {\n"
     "  return $name$_;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$OrBuilder get$capitalized_name$OrBuilder(\n"
     "    int index) {\n"
     "  return $name$_.get(index);\n"
@@ -552,6 +610,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
   // repeated field of type "Field" called "RepeatedField".
 
   // List<Field> getRepeatedFieldList()
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public java.util.List<$type$> get$capitalized_name$List()",
 
@@ -561,6 +620,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     NULL);
 
   // int getRepeatedFieldCount()
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public int get$capitalized_name$Count()",
 
@@ -570,6 +630,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     NULL);
 
   // Field getRepeatedField(int index)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public $type$ get$capitalized_name$(int index)",
 
@@ -580,6 +641,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     NULL);
 
   // Builder setRepeatedField(int index, Field value)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    int index, $type$ value)",
@@ -593,6 +655,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder setRepeatedField(int index, Field.Builder builderForValue)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    int index, $type$.Builder builderForValue)",
@@ -606,6 +669,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder addRepeatedField(Field value)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder add$capitalized_name$($type$ value)",
 
@@ -622,6 +686,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder addRepeatedField(int index, Field value)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder add$capitalized_name$(\n"
     "    int index, $type$ value)",
@@ -638,6 +703,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder addRepeatedField(Field.Builder builderForValue)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder add$capitalized_name$(\n"
     "    $type$.Builder builderForValue)",
@@ -651,6 +717,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder addRepeatedField(int index, Field.Builder builderForValue)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder add$capitalized_name$(\n"
     "    int index, $type$.Builder builderForValue)",
@@ -664,6 +731,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder addAllRepeatedField(Iterable<Field> values)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder addAll$capitalized_name$(\n"
     "    java.lang.Iterable<? extends $type$> values)",
@@ -677,6 +745,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder clearAllRepeatedField()
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder clear$capitalized_name$()",
 
@@ -689,6 +758,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   // Builder removeRepeatedField(int index)
+  WriteFieldDocComment(printer, descriptor_);
   PrintNestedBuilderFunction(printer,
     "$deprecation$public Builder remove$capitalized_name$(int index)",
 
@@ -701,12 +771,15 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "return this;\n");
 
   if (HasNestedBuilders(descriptor_->containing_type())) {
+    WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$public $type$.Builder get$capitalized_name$Builder(\n"
       "    int index) {\n"
       "  return get$capitalized_name$FieldBuilder().getBuilder(index);\n"
-      "}\n"
+      "}\n");
 
+    WriteFieldDocComment(printer, descriptor_);
+        printer->Print(variables_,
       "$deprecation$public $type$OrBuilder get$capitalized_name$OrBuilder(\n"
       "    int index) {\n"
       "  if ($name$Builder_ == null) {\n"
@@ -714,8 +787,10 @@ GenerateBuilderMembers(io::Printer* printer) const {
       "  } else {\n"
       "    return $name$Builder_.getMessageOrBuilder(index);\n"
       "  }\n"
-      "}\n"
+      "}\n");
 
+    WriteFieldDocComment(printer, descriptor_);
+        printer->Print(variables_,
       "$deprecation$public java.util.List<? extends $type$OrBuilder> \n"
       "     get$capitalized_name$OrBuilderList() {\n"
       "  if ($name$Builder_ != null) {\n"
@@ -723,17 +798,23 @@ GenerateBuilderMembers(io::Printer* printer) const {
       "  } else {\n"
       "    return java.util.Collections.unmodifiableList($name$_);\n"
       "  }\n"
-      "}\n"
+      "}\n");
 
+    WriteFieldDocComment(printer, descriptor_);
+        printer->Print(variables_,
       "$deprecation$public $type$.Builder add$capitalized_name$Builder() {\n"
       "  return get$capitalized_name$FieldBuilder().addBuilder(\n"
       "      $type$.getDefaultInstance());\n"
-      "}\n"
+      "}\n");
+    WriteFieldDocComment(printer, descriptor_);
+        printer->Print(variables_,
       "$deprecation$public $type$.Builder add$capitalized_name$Builder(\n"
       "    int index) {\n"
       "  return get$capitalized_name$FieldBuilder().addBuilder(\n"
       "      index, $type$.getDefaultInstance());\n"
-      "}\n"
+      "}\n");
+    WriteFieldDocComment(printer, descriptor_);
+        printer->Print(variables_,
       "$deprecation$public java.util.List<$type$.Builder> \n"
       "     get$capitalized_name$BuilderList() {\n"
       "  return get$capitalized_name$FieldBuilder().getBuilderList();\n"
@@ -827,18 +908,27 @@ GenerateBuildingCode(io::Printer* printer) const {
 void RepeatedMessageFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "$type$.Builder subBuilder = $type$.newBuilder();\n");
+    "if (!$get_mutable_bit_parser$) {\n"
+    "  $name$_ = new java.util.ArrayList<$type$>();\n"
+    "  $set_mutable_bit_parser$;\n"
+    "}\n");
 
   if (GetType(descriptor_) == FieldDescriptor::TYPE_GROUP) {
     printer->Print(variables_,
-      "input.readGroup($number$, subBuilder, extensionRegistry);\n");
+      "$name$_.add(input.readGroup($number$, $type$.PARSER,\n"
+      "    extensionRegistry));\n");
   } else {
     printer->Print(variables_,
-      "input.readMessage(subBuilder, extensionRegistry);\n");
+      "$name$_.add(input.readMessage($type$.PARSER, extensionRegistry));\n");
   }
+}
 
+void RepeatedMessageFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "add$capitalized_name$(subBuilder.buildPartial());\n");
+    "if ($get_mutable_bit_parser$) {\n"
+    "  $name$_ = java.util.Collections.unmodifiableList($name$_);\n"
+    "}\n");
 }
 
 void RepeatedMessageFieldGenerator::
diff --git a/src/google/protobuf/compiler/java/java_message_field.h b/src/google/protobuf/compiler/java/java_message_field.h
index 2efbcd97..5c8078a1 100644
--- a/src/google/protobuf/compiler/java/java_message_field.h
+++ b/src/google/protobuf/compiler/java/java_message_field.h
@@ -61,6 +61,7 @@ class MessageFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
@@ -102,6 +103,7 @@ class RepeatedMessageFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/java/java_primitive_field.cc b/src/google/protobuf/compiler/java/java_primitive_field.cc
index 712e047a..0140e23f 100644
--- a/src/google/protobuf/compiler/java/java_primitive_field.cc
+++ b/src/google/protobuf/compiler/java/java_primitive_field.cc
@@ -36,6 +36,7 @@
 #include <string>
 
 #include <google/protobuf/compiler/java/java_primitive_field.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
@@ -197,6 +198,7 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
 
   // For singular messages and builders, one bit is used for the hasField bit.
   (*variables)["get_has_field_bit_message"] = GenerateGetBit(messageBitIndex);
+  (*variables)["set_has_field_bit_message"] = GenerateSetBit(messageBitIndex);
 
   (*variables)["get_has_field_bit_builder"] = GenerateGetBit(builderBitIndex);
   (*variables)["set_has_field_bit_builder"] = GenerateSetBit(builderBitIndex);
@@ -208,6 +210,13 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
   (*variables)["set_mutable_bit_builder"] = GenerateSetBit(builderBitIndex);
   (*variables)["clear_mutable_bit_builder"] = GenerateClearBit(builderBitIndex);
 
+  // For repeated fields, one bit is used for whether the array is immutable
+  // in the parsing constructor.
+  (*variables)["get_mutable_bit_parser"] =
+      GenerateGetBitMutableLocal(builderBitIndex);
+  (*variables)["set_mutable_bit_parser"] =
+      GenerateSetBitMutableLocal(builderBitIndex);
+
   (*variables)["get_has_field_bit_from_local"] =
       GenerateGetBitFromLocal(builderBitIndex);
   (*variables)["set_has_field_bit_to_local"] =
@@ -240,19 +249,26 @@ int PrimitiveFieldGenerator::GetNumBitsForBuilder() const {
 
 void PrimitiveFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$boolean has$capitalized_name$();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$boolean has$capitalized_name$();\n"
     "$deprecation$$type$ get$capitalized_name$();\n");
 }
 
 void PrimitiveFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $field_type$ $name$_;\n"
+    "private $field_type$ $name$_;\n");
+
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_message$;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
@@ -262,16 +278,21 @@ GenerateMembers(io::Printer* printer) const {
 void PrimitiveFieldGenerator::
 GenerateBuilderMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $field_type$ $name$_ $default_init$;\n"
+    "private $field_type$ $name$_ $default_init$;\n");
+
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_builder$;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$($type$ value) {\n"
     "$null_check$"
@@ -279,7 +300,10 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_ = value;\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $clear_has_field_bit_builder$;\n");
   JavaType type = GetJavaType(descriptor_);
@@ -335,11 +359,16 @@ GenerateBuildingCode(io::Printer* printer) const {
 void PrimitiveFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "$set_has_field_bit_builder$;\n"
+    "$set_has_field_bit_message$;\n"
     "$name$_ = input.read$capitalized_type$();\n");
 }
 
 void PrimitiveFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  // noop for primitives.
+}
+
+void PrimitiveFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
     "if ($get_has_field_bit_message$) {\n"
@@ -468,9 +497,14 @@ int RepeatedPrimitiveFieldGenerator::GetNumBitsForBuilder() const {
 
 void RepeatedPrimitiveFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$java.util.List<$boxed_type$> get$capitalized_name$List();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$int get$capitalized_name$Count();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$java.util.List<$boxed_type$> get$capitalized_name$List();\n"
-    "$deprecation$int get$capitalized_name$Count();\n"
     "$deprecation$$type$ get$capitalized_name$(int index);\n");
 }
 
@@ -478,14 +512,20 @@ GenerateInterfaceMembers(io::Printer* printer) const {
 void RepeatedPrimitiveFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private $field_list_type$ $name$_;\n"
+    "private $field_list_type$ $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.util.List<$boxed_type$>\n"
     "    get$capitalized_name$List() {\n"
     "  return $name$_;\n"   // note:  unmodifiable list
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
     "}\n");
@@ -523,17 +563,24 @@ GenerateBuilderMembers(io::Printer* printer) const {
     //   could hold on to the returned list and modify it after the message
     //   has been built, thus mutating the message which is supposed to be
     //   immutable.
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public java.util.List<$boxed_type$>\n"
     "    get$capitalized_name$List() {\n"
     "  return java.util.Collections.unmodifiableList($name$_);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    int index, $type$ value) {\n"
     "$null_check$"
@@ -541,21 +588,27 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_.set(index, value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder add$capitalized_name$($type$ value) {\n"
     "$null_check$"
     "  ensure$capitalized_name$IsMutable();\n"
     "  $name$_.add(value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder addAll$capitalized_name$(\n"
     "    java.lang.Iterable<? extends $boxed_type$> values) {\n"
     "  ensure$capitalized_name$IsMutable();\n"
     "  super.addAll(values, $name$_);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $name$_ = $empty_list$;\n"
     "  $clear_mutable_bit_builder$;\n"
@@ -616,7 +669,10 @@ GenerateBuildingCode(io::Printer* printer) const {
 void RepeatedPrimitiveFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "ensure$capitalized_name$IsMutable();\n"
+    "if (!$get_mutable_bit_parser$) {\n"
+    "  $name$_ = new java.util.ArrayList<$boxed_type$>();\n"
+    "  $set_mutable_bit_parser$;\n"
+    "}\n"
     "$name$_.add(input.read$capitalized_type$());\n");
 }
 
@@ -625,13 +681,25 @@ GenerateParsingCodeFromPacked(io::Printer* printer) const {
   printer->Print(variables_,
     "int length = input.readRawVarint32();\n"
     "int limit = input.pushLimit(length);\n"
+    "if (!$get_mutable_bit_parser$ && input.getBytesUntilLimit() > 0) {\n"
+    "  $name$_ = new java.util.ArrayList<$boxed_type$>();\n"
+    "  $set_mutable_bit_parser$;\n"
+    "}\n"
     "while (input.getBytesUntilLimit() > 0) {\n"
-    "  add$capitalized_name$(input.read$capitalized_type$());\n"
+    "  $name$_.add(input.read$capitalized_type$());\n"
     "}\n"
     "input.popLimit(limit);\n");
 }
 
 void RepeatedPrimitiveFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  printer->Print(variables_,
+    "if ($get_mutable_bit_parser$) {\n"
+    "  $name$_ = java.util.Collections.unmodifiableList($name$_);\n"
+    "}\n");
+}
+
+void RepeatedPrimitiveFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   if (descriptor_->options().packed()) {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/java/java_primitive_field.h b/src/google/protobuf/compiler/java/java_primitive_field.h
index 7900fac5..1b5b6d95 100644
--- a/src/google/protobuf/compiler/java/java_primitive_field.h
+++ b/src/google/protobuf/compiler/java/java_primitive_field.h
@@ -61,6 +61,7 @@ class PrimitiveFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
@@ -96,6 +97,7 @@ class RepeatedPrimitiveFieldGenerator : public FieldGenerator {
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
   void GenerateParsingCodeFromPacked(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/java/java_service.cc b/src/google/protobuf/compiler/java/java_service.cc
index 1ae4f461..bbd24806 100644
--- a/src/google/protobuf/compiler/java/java_service.cc
+++ b/src/google/protobuf/compiler/java/java_service.cc
@@ -33,6 +33,7 @@
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
 #include <google/protobuf/compiler/java/java_service.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/descriptor.pb.h>
@@ -50,6 +51,7 @@ ServiceGenerator::~ServiceGenerator() {}
 
 void ServiceGenerator::Generate(io::Printer* printer) {
   bool is_own_file = descriptor_->file()->options().java_multiple_files();
+  WriteServiceDocComment(printer, descriptor_);
   printer->Print(
     "public $static$ abstract class $classname$\n"
     "    implements com.google.protobuf.Service {\n",
@@ -157,6 +159,7 @@ void ServiceGenerator::GenerateNewReflectiveBlockingServiceMethod(
 void ServiceGenerator::GenerateAbstractMethods(io::Printer* printer) {
   for (int i = 0; i < descriptor_->method_count(); i++) {
     const MethodDescriptor* method = descriptor_->method(i);
+    WriteMethodDocComment(printer, method);
     GenerateMethodSignature(printer, method, IS_ABSTRACT);
     printer->Print(";\n\n");
   }
diff --git a/src/google/protobuf/compiler/java/java_string_field.cc b/src/google/protobuf/compiler/java/java_string_field.cc
index 222285bd..4815663b 100644
--- a/src/google/protobuf/compiler/java/java_string_field.cc
+++ b/src/google/protobuf/compiler/java/java_string_field.cc
@@ -37,6 +37,7 @@
 #include <string>
 
 #include <google/protobuf/compiler/java/java_string_field.h>
+#include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
 #include <google/protobuf/io/printer.h>
@@ -85,6 +86,7 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
 
   // For singular messages and builders, one bit is used for the hasField bit.
   (*variables)["get_has_field_bit_message"] = GenerateGetBit(messageBitIndex);
+  (*variables)["set_has_field_bit_message"] = GenerateSetBit(messageBitIndex);
 
   (*variables)["get_has_field_bit_builder"] = GenerateGetBit(builderBitIndex);
   (*variables)["set_has_field_bit_builder"] = GenerateSetBit(builderBitIndex);
@@ -96,6 +98,13 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
   (*variables)["set_mutable_bit_builder"] = GenerateSetBit(builderBitIndex);
   (*variables)["clear_mutable_bit_builder"] = GenerateClearBit(builderBitIndex);
 
+  // For repeated fields, one bit is used for whether the array is immutable
+  // in the parsing constructor.
+  (*variables)["get_mutable_bit_parser"] =
+      GenerateGetBitMutableLocal(builderBitIndex);
+  (*variables)["set_mutable_bit_parser"] =
+      GenerateSetBitMutableLocal(builderBitIndex);
+
   (*variables)["get_has_field_bit_from_local"] =
       GenerateGetBitFromLocal(builderBitIndex);
   (*variables)["set_has_field_bit_to_local"] =
@@ -160,19 +169,29 @@ int StringFieldGenerator::GetNumBitsForBuilder() const {
 // UnmodifiableLazyStringList.
 void StringFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$boolean has$capitalized_name$();\n");
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "$deprecation$boolean has$capitalized_name$();\n"
     "$deprecation$java.lang.String get$capitalized_name$();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes();\n");
 }
 
 void StringFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private java.lang.Object $name$_;\n"
+    "private java.lang.Object $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_message$;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public java.lang.String get$capitalized_name$() {\n"
     "  java.lang.Object ref = $name$_;\n"
@@ -182,13 +201,16 @@ GenerateMembers(io::Printer* printer) const {
     "    com.google.protobuf.ByteString bs = \n"
     "        (com.google.protobuf.ByteString) ref;\n"
     "    java.lang.String s = bs.toStringUtf8();\n"
-    "    if (com.google.protobuf.Internal.isValidUtf8(bs)) {\n"
+    "    if (bs.isValidUtf8()) {\n"
     "      $name$_ = s;\n"
     "    }\n"
     "    return s;\n"
     "  }\n"
-    "}\n"
-    "private com.google.protobuf.ByteString get$capitalized_name$Bytes() {\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$public com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes() {\n"
     "  java.lang.Object ref = $name$_;\n"
     "  if (ref instanceof java.lang.String) {\n"
     "    com.google.protobuf.ByteString b = \n"
@@ -205,11 +227,14 @@ GenerateMembers(io::Printer* printer) const {
 void StringFieldGenerator::
 GenerateBuilderMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private java.lang.Object $name$_ $default_init$;\n"
+    "private java.lang.Object $name$_ $default_init$;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public boolean has$capitalized_name$() {\n"
     "  return $get_has_field_bit_builder$;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public java.lang.String get$capitalized_name$() {\n"
     "  java.lang.Object ref = $name$_;\n"
@@ -223,6 +248,23 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  }\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$public com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes() {\n"
+    "  java.lang.Object ref = $name$_;\n"
+    "  if (ref instanceof String) {\n"
+    "    com.google.protobuf.ByteString b = \n"
+    "        com.google.protobuf.ByteString.copyFromUtf8(\n"
+    "            (java.lang.String) ref);\n"
+    "    $name$_ = b;\n"
+    "    return b;\n"
+    "  } else {\n"
+    "    return (com.google.protobuf.ByteString) ref;\n"
+    "  }\n"
+    "}\n");
+
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    java.lang.String value) {\n"
@@ -231,7 +273,9 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_ = value;\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $clear_has_field_bit_builder$;\n");
   // The default value is not a simple literal so we want to avoid executing
@@ -243,11 +287,15 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  return this;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "void set$capitalized_name$(com.google.protobuf.ByteString value) {\n"
+    "$deprecation$public Builder set$capitalized_name$Bytes(\n"
+    "    com.google.protobuf.ByteString value) {\n"
+    "$null_check$"
     "  $set_has_field_bit_builder$;\n"
     "  $name$_ = value;\n"
     "  $on_changed$\n"
+    "  return this;\n"
     "}\n");
 }
 
@@ -270,9 +318,13 @@ GenerateBuilderClearCode(io::Printer* printer) const {
 
 void StringFieldGenerator::
 GenerateMergingCode(io::Printer* printer) const {
+  // Allow a slight breach of abstraction here in order to avoid forcing
+  // all string fields to Strings when copying fields from a Message.
   printer->Print(variables_,
     "if (other.has$capitalized_name$()) {\n"
-    "  set$capitalized_name$(other.get$capitalized_name$());\n"
+    "  $set_has_field_bit_builder$;\n"
+    "  $name$_ = other.$name$_;\n"
+    "  $on_changed$\n"
     "}\n");
 }
 
@@ -288,11 +340,16 @@ GenerateBuildingCode(io::Printer* printer) const {
 void StringFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "$set_has_field_bit_builder$;\n"
+    "$set_has_field_bit_message$;\n"
     "$name$_ = input.readBytes();\n");
 }
 
 void StringFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  // noop for strings.
+}
+
+void StringFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
     "if ($get_has_field_bit_message$) {\n"
@@ -353,28 +410,49 @@ int RepeatedStringFieldGenerator::GetNumBitsForBuilder() const {
 
 void RepeatedStringFieldGenerator::
 GenerateInterfaceMembers(io::Printer* printer) const {
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$java.util.List<java.lang.String>\n"
-    "    get$capitalized_name$List();\n"
-    "$deprecation$int get$capitalized_name$Count();\n"
+    "get$capitalized_name$List();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$int get$capitalized_name$Count();\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$java.lang.String get$capitalized_name$(int index);\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes(int index);\n");
 }
 
 
 void RepeatedStringFieldGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    "private com.google.protobuf.LazyStringList $name$_;\n"
+    "private com.google.protobuf.LazyStringList $name$_;\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.util.List<java.lang.String>\n"
     "    get$capitalized_name$List() {\n"
     "  return $name$_;\n"   // note:  unmodifiable list
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.lang.String get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
     "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$public com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes(int index) {\n"
+    "  return $name$_.getByteString(index);\n"
+    "}\n");
 
   if (descriptor_->options().packed() &&
       HasGeneratedMethods(descriptor_->containing_type())) {
@@ -409,17 +487,30 @@ GenerateBuilderMembers(io::Printer* printer) const {
     //   could hold on to the returned list and modify it after the message
     //   has been built, thus mutating the message which is supposed to be
     //   immutable.
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public java.util.List<java.lang.String>\n"
     "    get$capitalized_name$List() {\n"
     "  return java.util.Collections.unmodifiableList($name$_);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public int get$capitalized_name$Count() {\n"
     "  return $name$_.size();\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public java.lang.String get$capitalized_name$(int index) {\n"
     "  return $name$_.get(index);\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
+    "$deprecation$public com.google.protobuf.ByteString\n"
+    "    get$capitalized_name$Bytes(int index) {\n"
+    "  return $name$_.getByteString(index);\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder set$capitalized_name$(\n"
     "    int index, java.lang.String value) {\n"
     "$null_check$"
@@ -427,7 +518,9 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_.set(index, value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder add$capitalized_name$(\n"
     "    java.lang.String value) {\n"
     "$null_check$"
@@ -435,14 +528,18 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  $name$_.add(value);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder addAll$capitalized_name$(\n"
     "    java.lang.Iterable<java.lang.String> values) {\n"
     "  ensure$capitalized_name$IsMutable();\n"
     "  super.addAll(values, $name$_);\n"
     "  $on_changed$\n"
     "  return this;\n"
-    "}\n"
+    "}\n");
+  WriteFieldDocComment(printer, descriptor_);
+  printer->Print(variables_,
     "$deprecation$public Builder clear$capitalized_name$() {\n"
     "  $name$_ = $empty_list$;\n"
     "  $clear_mutable_bit_builder$;\n"
@@ -450,11 +547,15 @@ GenerateBuilderMembers(io::Printer* printer) const {
     "  return this;\n"
     "}\n");
 
+  WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
-    "void add$capitalized_name$(com.google.protobuf.ByteString value) {\n"
+    "$deprecation$public Builder add$capitalized_name$Bytes(\n"
+    "    com.google.protobuf.ByteString value) {\n"
+    "$null_check$"
     "  ensure$capitalized_name$IsMutable();\n"
     "  $name$_.add(value);\n"
     "  $on_changed$\n"
+    "  return this;\n"
     "}\n");
 }
 
@@ -512,7 +613,10 @@ GenerateBuildingCode(io::Printer* printer) const {
 void RepeatedStringFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "ensure$capitalized_name$IsMutable();\n"
+    "if (!$get_mutable_bit_parser$) {\n"
+    "  $name$_ = new com.google.protobuf.LazyStringArrayList();\n"
+    "  $set_mutable_bit_parser$;\n"
+    "}\n"
     "$name$_.add(input.readBytes());\n");
 }
 
@@ -521,13 +625,25 @@ GenerateParsingCodeFromPacked(io::Printer* printer) const {
   printer->Print(variables_,
     "int length = input.readRawVarint32();\n"
     "int limit = input.pushLimit(length);\n"
+    "if (!$get_mutable_bit_parser$ && input.getBytesUntilLimit() > 0) {\n"
+    "  $name$_ = new com.google.protobuf.LazyStringArrayList();\n"
+    "  $set_mutable_bit_parser$;\n"
+    "}\n"
     "while (input.getBytesUntilLimit() > 0) {\n"
-    "  add$capitalized_name$(input.read$capitalized_type$());\n"
+    "  $name$.add(input.read$capitalized_type$());\n"
     "}\n"
     "input.popLimit(limit);\n");
 }
 
 void RepeatedStringFieldGenerator::
+GenerateParsingDoneCode(io::Printer* printer) const {
+  printer->Print(variables_,
+    "if ($get_mutable_bit_parser$) {\n"
+    "  $name$_ = new com.google.protobuf.UnmodifiableLazyStringList($name$_);\n"
+    "}\n");
+}
+
+void RepeatedStringFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   if (descriptor_->options().packed()) {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/java/java_string_field.h b/src/google/protobuf/compiler/java/java_string_field.h
index 8cb41469..4f7532f4 100644
--- a/src/google/protobuf/compiler/java/java_string_field.h
+++ b/src/google/protobuf/compiler/java/java_string_field.h
@@ -62,6 +62,7 @@ class StringFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
@@ -96,6 +97,7 @@ class RepeatedStringFieldGenerator : public FieldGenerator {
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
   void GenerateParsingCodeFromPacked(io::Printer* printer) const;
+  void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
   void GenerateFieldBuilderInitializationCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/main.cc b/src/google/protobuf/compiler/main.cc
index d9b0c3f9..1afc5d61 100644
--- a/src/google/protobuf/compiler/main.cc
+++ b/src/google/protobuf/compiler/main.cc
@@ -43,7 +43,7 @@ int main(int argc, char* argv[]) {
 
   // Proto2 C++
   google::protobuf::compiler::cpp::CppGenerator cpp_generator;
-  cli.RegisterGenerator("--cpp_out", &cpp_generator,
+  cli.RegisterGenerator("--cpp_out", "--cpp_opt", &cpp_generator,
                         "Generate C++ header and source.");
 
   // Proto2 Java
diff --git a/src/google/protobuf/compiler/mock_code_generator.cc b/src/google/protobuf/compiler/mock_code_generator.cc
index 5b76af25..0e35ed19 100644
--- a/src/google/protobuf/compiler/mock_code_generator.cc
+++ b/src/google/protobuf/compiler/mock_code_generator.cc
@@ -33,13 +33,14 @@
 #include <google/protobuf/compiler/mock_code_generator.h>
 
 #include <google/protobuf/testing/file.h>
+#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -132,6 +133,15 @@ bool MockCodeGenerator::Generate(
       } else if (command == "Abort") {
         cerr << "Saw message type MockCodeGenerator_Abort." << endl;
         abort();
+      } else if (command == "HasSourceCodeInfo") {
+        FileDescriptorProto file_descriptor_proto;
+        file->CopySourceCodeInfoTo(&file_descriptor_proto);
+        bool has_source_code_info =
+            file_descriptor_proto.has_source_code_info() &&
+            file_descriptor_proto.source_code_info().location_size() > 0;
+        cerr << "Saw message type MockCodeGenerator_HasSourceCodeInfo: "
+             << has_source_code_info << "." << endl;
+        abort();
       } else {
         GOOGLE_LOG(FATAL) << "Unknown MockCodeGenerator command: " << command;
       }
diff --git a/src/google/protobuf/compiler/mock_code_generator.h b/src/google/protobuf/compiler/mock_code_generator.h
index 5c7942bd..506fd207 100644
--- a/src/google/protobuf/compiler/mock_code_generator.h
+++ b/src/google/protobuf/compiler/mock_code_generator.h
@@ -59,6 +59,10 @@ namespace compiler {
 //     MockCodeGenerator_Exit." to stderr and then calls exit(123).
 //   MockCodeGenerator_Abort:  Generate() prints "Saw message type
 //     MockCodeGenerator_Abort." to stderr and then calls abort().
+//   MockCodeGenerator_HasSourceCodeInfo:  Causes Generate() to abort after
+//     printing "Saw message type MockCodeGenerator_HasSourceCodeInfo: FOO." to
+//     stderr, where FOO is "1" if the supplied FileDescriptorProto has source
+//     code info, and "0" otherwise.
 class MockCodeGenerator : public CodeGenerator {
  public:
   MockCodeGenerator(const string& name);
diff --git a/src/google/protobuf/compiler/parser.cc b/src/google/protobuf/compiler/parser.cc
index 34317b1f..23aa01ce 100644
--- a/src/google/protobuf/compiler/parser.cc
+++ b/src/google/protobuf/compiler/parser.cc
@@ -174,6 +174,20 @@ bool Parser::ConsumeInteger(int* output, const char* error) {
   }
 }
 
+bool Parser::ConsumeSignedInteger(int* output, const char* error) {
+  bool is_negative = false;
+  uint64 max_value = kint32max;
+  if (TryConsume("-")) {
+    is_negative = true;
+    max_value += 1;
+  }
+  uint64 value = 0;
+  DO(ConsumeInteger64(max_value, &value, error));
+  if (is_negative) value *= -1;
+  *output = value;
+  return true;
+}
+
 bool Parser::ConsumeInteger64(uint64 max_value, uint64* output,
                               const char* error) {
   if (LookingAtType(io::Tokenizer::TYPE_INTEGER)) {
@@ -237,6 +251,35 @@ bool Parser::ConsumeString(string* output, const char* error) {
   }
 }
 
+bool Parser::TryConsumeEndOfDeclaration(const char* text,
+                                        const LocationRecorder* location) {
+  if (LookingAt(text)) {
+    string leading, trailing;
+    input_->NextWithComments(&trailing, NULL, &leading);
+
+    // Save the leading comments for next time, and recall the leading comments
+    // from last time.
+    leading.swap(upcoming_doc_comments_);
+
+    if (location != NULL) {
+      location->AttachComments(&leading, &trailing);
+    }
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool Parser::ConsumeEndOfDeclaration(const char* text,
+                                     const LocationRecorder* location) {
+  if (TryConsumeEndOfDeclaration(text, location)) {
+    return true;
+  } else {
+    AddError("Expected \"" + string(text) + "\".");
+    return false;
+  }
+}
+
 // -------------------------------------------------------------------
 
 void Parser::AddError(int line, int column, const string& error) {
@@ -315,6 +358,19 @@ void Parser::LocationRecorder::RecordLegacyLocation(const Message* descriptor,
   }
 }
 
+void Parser::LocationRecorder::AttachComments(
+    string* leading, string* trailing) const {
+  GOOGLE_CHECK(!location_->has_leading_comments());
+  GOOGLE_CHECK(!location_->has_trailing_comments());
+
+  if (!leading->empty()) {
+    location_->mutable_leading_comments()->swap(*leading);
+  }
+  if (!trailing->empty()) {
+    location_->mutable_trailing_comments()->swap(*trailing);
+  }
+}
+
 // -------------------------------------------------------------------
 
 void Parser::SkipStatement() {
@@ -322,7 +378,7 @@ void Parser::SkipStatement() {
     if (AtEnd()) {
       return;
     } else if (LookingAtType(io::Tokenizer::TYPE_SYMBOL)) {
-      if (TryConsume(";")) {
+      if (TryConsumeEndOfDeclaration(";", NULL)) {
         return;
       } else if (TryConsume("{")) {
         SkipRestOfBlock();
@@ -340,7 +396,7 @@ void Parser::SkipRestOfBlock() {
     if (AtEnd()) {
       return;
     } else if (LookingAtType(io::Tokenizer::TYPE_SYMBOL)) {
-      if (TryConsume("}")) {
+      if (TryConsumeEndOfDeclaration("}", NULL)) {
         return;
       } else if (TryConsume("{")) {
         SkipRestOfBlock();
@@ -366,7 +422,7 @@ bool Parser::Parse(io::Tokenizer* input, FileDescriptorProto* file) {
 
   if (LookingAtType(io::Tokenizer::TYPE_START)) {
     // Advance to first token.
-    input_->Next();
+    input_->NextWithComments(NULL, NULL, &upcoming_doc_comments_);
   }
 
   {
@@ -393,7 +449,7 @@ bool Parser::Parse(io::Tokenizer* input, FileDescriptorProto* file) {
 
         if (LookingAt("}")) {
           AddError("Unmatched \"}\".");
-          input_->Next();
+          input_->NextWithComments(NULL, NULL, &upcoming_doc_comments_);
         }
       }
     }
@@ -411,7 +467,7 @@ bool Parser::ParseSyntaxIdentifier() {
   io::Tokenizer::Token syntax_token = input_->current();
   string syntax;
   DO(ConsumeString(&syntax, "Expected syntax identifier."));
-  DO(Consume(";"));
+  DO(ConsumeEndOfDeclaration(";", NULL));
 
   syntax_identifier_ = syntax;
 
@@ -427,7 +483,7 @@ bool Parser::ParseSyntaxIdentifier() {
 
 bool Parser::ParseTopLevelStatement(FileDescriptorProto* file,
                                     const LocationRecorder& root_location) {
-  if (TryConsume(";")) {
+  if (TryConsumeEndOfDeclaration(";", NULL)) {
     // empty statement; ignore
     return true;
   } else if (LookingAt("message")) {
@@ -451,14 +507,16 @@ bool Parser::ParseTopLevelStatement(FileDescriptorProto* file,
                        FileDescriptorProto::kMessageTypeFieldNumber,
                        location);
   } else if (LookingAt("import")) {
-    int index = file->dependency_size();
-    return ParseImport(file->add_dependency(), root_location, index);
+    return ParseImport(file->mutable_dependency(),
+                       file->mutable_public_dependency(),
+                       file->mutable_weak_dependency(),
+                       root_location);
   } else if (LookingAt("package")) {
     return ParsePackage(file, root_location);
   } else if (LookingAt("option")) {
     LocationRecorder location(root_location,
         FileDescriptorProto::kOptionsFieldNumber);
-    return ParseOption(file->mutable_options(), location);
+    return ParseOption(file->mutable_options(), location, OPTION_STATEMENT);
   } else {
     AddError("Expected top-level statement (e.g. \"message\").");
     return false;
@@ -482,11 +540,45 @@ bool Parser::ParseMessageDefinition(DescriptorProto* message,
   return true;
 }
 
+namespace {
+
+const int kMaxExtensionRangeSentinel = -1;
+
+bool IsMessageSetWireFormatMessage(const DescriptorProto& message) {
+  const MessageOptions& options = message.options();
+  for (int i = 0; i < options.uninterpreted_option_size(); ++i) {
+    const UninterpretedOption& uninterpreted = options.uninterpreted_option(i);
+    if (uninterpreted.name_size() == 1 &&
+        uninterpreted.name(0).name_part() == "message_set_wire_format" &&
+        uninterpreted.identifier_value() == "true") {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Modifies any extension ranges that specified 'max' as the end of the
+// extension range, and sets them to the type-specific maximum. The actual max
+// tag number can only be determined after all options have been parsed.
+void AdjustExtensionRangesWithMaxEndNumber(DescriptorProto* message) {
+  const bool is_message_set = IsMessageSetWireFormatMessage(*message);
+  const int max_extension_number = is_message_set ?
+      kint32max :
+      FieldDescriptor::kMaxNumber + 1;
+  for (int i = 0; i < message->extension_range_size(); ++i) {
+    if (message->extension_range(i).end() == kMaxExtensionRangeSentinel) {
+      message->mutable_extension_range(i)->set_end(max_extension_number);
+    }
+  }
+}
+
+}  // namespace
+
 bool Parser::ParseMessageBlock(DescriptorProto* message,
                                const LocationRecorder& message_location) {
-  DO(Consume("{"));
+  DO(ConsumeEndOfDeclaration("{", &message_location));
 
-  while (!TryConsume("}")) {
+  while (!TryConsumeEndOfDeclaration("}", NULL)) {
     if (AtEnd()) {
       AddError("Reached end of input in message definition (missing '}').");
       return false;
@@ -499,12 +591,15 @@ bool Parser::ParseMessageBlock(DescriptorProto* message,
     }
   }
 
+  if (message->extension_range_size() > 0) {
+    AdjustExtensionRangesWithMaxEndNumber(message);
+  }
   return true;
 }
 
 bool Parser::ParseMessageStatement(DescriptorProto* message,
                                    const LocationRecorder& message_location) {
-  if (TryConsume(";")) {
+  if (TryConsumeEndOfDeclaration(";", NULL)) {
     // empty statement; ignore
     return true;
   } else if (LookingAt("message")) {
@@ -532,7 +627,7 @@ bool Parser::ParseMessageStatement(DescriptorProto* message,
   } else if (LookingAt("option")) {
     LocationRecorder location(message_location,
                               DescriptorProto::kOptionsFieldNumber);
-    return ParseOption(message->mutable_options(), location);
+    return ParseOption(message->mutable_options(), location, OPTION_STATEMENT);
   } else {
     LocationRecorder location(message_location,
                               DescriptorProto::kFieldFieldNumber,
@@ -647,7 +742,7 @@ bool Parser::ParseMessageField(FieldDescriptorProto* field,
       return false;
     }
   } else {
-    DO(Consume(";"));
+    DO(ConsumeEndOfDeclaration(";", &field_location));
   }
 
   return true;
@@ -669,7 +764,7 @@ bool Parser::ParseFieldOptions(FieldDescriptorProto* field,
       // the default value is not actually an option.
       DO(ParseDefaultAssignment(field, field_location));
     } else {
-      DO(ParseOptionAssignment(field->mutable_options(), location));
+      DO(ParseOption(field->mutable_options(), location, OPTION_ASSIGNMENT));
     }
   } while (TryConsume(","));
 
@@ -835,6 +930,8 @@ bool Parser::ParseOptionNamePart(UninterpretedOption* uninterpreted_option,
 
 bool Parser::ParseUninterpretedBlock(string* value) {
   // Note that enclosing braces are not added to *value.
+  // We do NOT use ConsumeEndOfStatement for this brace because it's delimiting
+  // an expression, not a block of statements.
   DO(Consume("{"));
   int brace_depth = 1;
   while (!AtEnd()) {
@@ -858,8 +955,9 @@ bool Parser::ParseUninterpretedBlock(string* value) {
 
 // We don't interpret the option here. Instead we store it in an
 // UninterpretedOption, to be interpreted later.
-bool Parser::ParseOptionAssignment(Message* options,
-                                   const LocationRecorder& options_location) {
+bool Parser::ParseOption(Message* options,
+                         const LocationRecorder& options_location,
+                         OptionStyle style) {
   // Create an entry in the uninterpreted_option field.
   const FieldDescriptor* uninterpreted_option_field = options->GetDescriptor()->
       FindFieldByName("uninterpreted_option");
@@ -872,6 +970,10 @@ bool Parser::ParseOptionAssignment(Message* options,
       options_location, uninterpreted_option_field->number(),
       reflection->FieldSize(*options, uninterpreted_option_field));
 
+  if (style == OPTION_STATEMENT) {
+    DO(Consume("option"));
+  }
+
   UninterpretedOption* uninterpreted_option = down_cast<UninterpretedOption*>(
       options->GetReflection()->AddMessage(options,
                                            uninterpreted_option_field));
@@ -899,82 +1001,91 @@ bool Parser::ParseOptionAssignment(Message* options,
 
   DO(Consume("="));
 
-  LocationRecorder value_location(location);
-  value_location.RecordLegacyLocation(
-      uninterpreted_option, DescriptorPool::ErrorCollector::OPTION_VALUE);
-
-  // All values are a single token, except for negative numbers, which consist
-  // of a single '-' symbol, followed by a positive number.
-  bool is_negative = TryConsume("-");
+  {
+    LocationRecorder value_location(location);
+    value_location.RecordLegacyLocation(
+        uninterpreted_option, DescriptorPool::ErrorCollector::OPTION_VALUE);
 
-  switch (input_->current().type) {
-    case io::Tokenizer::TYPE_START:
-      GOOGLE_LOG(FATAL) << "Trying to read value before any tokens have been read.";
-      return false;
+    // All values are a single token, except for negative numbers, which consist
+    // of a single '-' symbol, followed by a positive number.
+    bool is_negative = TryConsume("-");
 
-    case io::Tokenizer::TYPE_END:
-      AddError("Unexpected end of stream while parsing option value.");
-      return false;
+    switch (input_->current().type) {
+      case io::Tokenizer::TYPE_START:
+        GOOGLE_LOG(FATAL) << "Trying to read value before any tokens have been read.";
+        return false;
 
-    case io::Tokenizer::TYPE_IDENTIFIER: {
-      value_location.AddPath(UninterpretedOption::kIdentifierValueFieldNumber);
-      if (is_negative) {
-        AddError("Invalid '-' symbol before identifier.");
+      case io::Tokenizer::TYPE_END:
+        AddError("Unexpected end of stream while parsing option value.");
         return false;
-      }
-      string value;
-      DO(ConsumeIdentifier(&value, "Expected identifier."));
-      uninterpreted_option->set_identifier_value(value);
-      break;
-    }
 
-    case io::Tokenizer::TYPE_INTEGER: {
-      uint64 value;
-      uint64 max_value =
-          is_negative ? static_cast<uint64>(kint64max) + 1 : kuint64max;
-      DO(ConsumeInteger64(max_value, &value, "Expected integer."));
-      if (is_negative) {
+      case io::Tokenizer::TYPE_IDENTIFIER: {
         value_location.AddPath(
-            UninterpretedOption::kNegativeIntValueFieldNumber);
-        uninterpreted_option->set_negative_int_value(-static_cast<int64>(value));
-      } else {
-        value_location.AddPath(
-            UninterpretedOption::kPositiveIntValueFieldNumber);
-        uninterpreted_option->set_positive_int_value(value);
+            UninterpretedOption::kIdentifierValueFieldNumber);
+        if (is_negative) {
+          AddError("Invalid '-' symbol before identifier.");
+          return false;
+        }
+        string value;
+        DO(ConsumeIdentifier(&value, "Expected identifier."));
+        uninterpreted_option->set_identifier_value(value);
+        break;
       }
-      break;
-    }
 
-    case io::Tokenizer::TYPE_FLOAT: {
-      value_location.AddPath(UninterpretedOption::kDoubleValueFieldNumber);
-      double value;
-      DO(ConsumeNumber(&value, "Expected number."));
-      uninterpreted_option->set_double_value(is_negative ? -value : value);
-      break;
-    }
+      case io::Tokenizer::TYPE_INTEGER: {
+        uint64 value;
+        uint64 max_value =
+            is_negative ? static_cast<uint64>(kint64max) + 1 : kuint64max;
+        DO(ConsumeInteger64(max_value, &value, "Expected integer."));
+        if (is_negative) {
+          value_location.AddPath(
+              UninterpretedOption::kNegativeIntValueFieldNumber);
+          uninterpreted_option->set_negative_int_value(
+              -static_cast<int64>(value));
+        } else {
+          value_location.AddPath(
+              UninterpretedOption::kPositiveIntValueFieldNumber);
+          uninterpreted_option->set_positive_int_value(value);
+        }
+        break;
+      }
 
-    case io::Tokenizer::TYPE_STRING: {
-      value_location.AddPath(UninterpretedOption::kStringValueFieldNumber);
-      if (is_negative) {
-        AddError("Invalid '-' symbol before string.");
-        return false;
+      case io::Tokenizer::TYPE_FLOAT: {
+        value_location.AddPath(UninterpretedOption::kDoubleValueFieldNumber);
+        double value;
+        DO(ConsumeNumber(&value, "Expected number."));
+        uninterpreted_option->set_double_value(is_negative ? -value : value);
+        break;
       }
-      string value;
-      DO(ConsumeString(&value, "Expected string."));
-      uninterpreted_option->set_string_value(value);
-      break;
-    }
 
-    case io::Tokenizer::TYPE_SYMBOL:
-      if (LookingAt("{")) {
-        value_location.AddPath(UninterpretedOption::kAggregateValueFieldNumber);
-        DO(ParseUninterpretedBlock(
-            uninterpreted_option->mutable_aggregate_value()));
-      } else {
-        AddError("Expected option value.");
-        return false;
+      case io::Tokenizer::TYPE_STRING: {
+        value_location.AddPath(UninterpretedOption::kStringValueFieldNumber);
+        if (is_negative) {
+          AddError("Invalid '-' symbol before string.");
+          return false;
+        }
+        string value;
+        DO(ConsumeString(&value, "Expected string."));
+        uninterpreted_option->set_string_value(value);
+        break;
       }
-      break;
+
+      case io::Tokenizer::TYPE_SYMBOL:
+        if (LookingAt("{")) {
+          value_location.AddPath(
+              UninterpretedOption::kAggregateValueFieldNumber);
+          DO(ParseUninterpretedBlock(
+              uninterpreted_option->mutable_aggregate_value()));
+        } else {
+          AddError("Expected option value.");
+          return false;
+        }
+        break;
+    }
+  }
+
+  if (style == OPTION_STATEMENT) {
+    DO(ConsumeEndOfDeclaration(";", &location));
   }
 
   return true;
@@ -1008,7 +1119,10 @@ bool Parser::ParseExtensions(DescriptorProto* message,
       LocationRecorder end_location(
           location, DescriptorProto::ExtensionRange::kEndFieldNumber);
       if (TryConsume("max")) {
-        end = FieldDescriptor::kMaxNumber;
+        // Set to the sentinel value - 1 since we increment the value below.
+        // The actual value of the end of the range should be set with
+        // AdjustExtensionRangesWithMaxEndNumber.
+        end = kMaxExtensionRangeSentinel - 1;
       } else {
         DO(ConsumeInteger(&end, "Expected integer."));
       }
@@ -1028,7 +1142,7 @@ bool Parser::ParseExtensions(DescriptorProto* message,
     range->set_end(end);
   } while (TryConsume(","));
 
-  DO(Consume(";"));
+  DO(ConsumeEndOfDeclaration(";", &extensions_location));
   return true;
 }
 
@@ -1046,7 +1160,7 @@ bool Parser::ParseExtend(RepeatedPtrField<FieldDescriptorProto>* extensions,
   io::Tokenizer::Token extendee_end = input_->previous();
 
   // Parse the block.
-  DO(Consume("{"));
+  DO(ConsumeEndOfDeclaration("{", &extend_location));
 
   bool is_first = true;
 
@@ -1083,7 +1197,7 @@ bool Parser::ParseExtend(RepeatedPtrField<FieldDescriptorProto>* extensions,
       // other statements.
       SkipStatement();
     }
-  } while(!TryConsume("}"));
+  } while (!TryConsumeEndOfDeclaration("}", NULL));
 
   return true;
 }
@@ -1109,9 +1223,9 @@ bool Parser::ParseEnumDefinition(EnumDescriptorProto* enum_type,
 
 bool Parser::ParseEnumBlock(EnumDescriptorProto* enum_type,
                             const LocationRecorder& enum_location) {
-  DO(Consume("{"));
+  DO(ConsumeEndOfDeclaration("{", &enum_location));
 
-  while (!TryConsume("}")) {
+  while (!TryConsumeEndOfDeclaration("}", NULL)) {
     if (AtEnd()) {
       AddError("Reached end of input in enum definition (missing '}').");
       return false;
@@ -1129,13 +1243,14 @@ bool Parser::ParseEnumBlock(EnumDescriptorProto* enum_type,
 
 bool Parser::ParseEnumStatement(EnumDescriptorProto* enum_type,
                                 const LocationRecorder& enum_location) {
-  if (TryConsume(";")) {
+  if (TryConsumeEndOfDeclaration(";", NULL)) {
     // empty statement; ignore
     return true;
   } else if (LookingAt("option")) {
     LocationRecorder location(enum_location,
                               EnumDescriptorProto::kOptionsFieldNumber);
-    return ParseOption(enum_type->mutable_options(), location);
+    return ParseOption(enum_type->mutable_options(), location,
+                       OPTION_STATEMENT);
   } else {
     LocationRecorder location(enum_location,
         EnumDescriptorProto::kValueFieldNumber, enum_type->value_size());
@@ -1164,16 +1279,14 @@ bool Parser::ParseEnumConstant(EnumValueDescriptorProto* enum_value,
     location.RecordLegacyLocation(
         enum_value, DescriptorPool::ErrorCollector::NUMBER);
 
-    bool is_negative = TryConsume("-");
     int number;
-    DO(ConsumeInteger(&number, "Expected integer."));
-    if (is_negative) number *= -1;
+    DO(ConsumeSignedInteger(&number, "Expected integer."));
     enum_value->set_number(number);
   }
 
   DO(ParseEnumConstantOptions(enum_value, enum_value_location));
 
-  DO(Consume(";"));
+  DO(ConsumeEndOfDeclaration(";", &enum_value_location));
 
   return true;
 }
@@ -1189,7 +1302,7 @@ bool Parser::ParseEnumConstantOptions(
   DO(Consume("["));
 
   do {
-    DO(ParseOptionAssignment(value->mutable_options(), location));
+    DO(ParseOption(value->mutable_options(), location, OPTION_ASSIGNMENT));
   } while (TryConsume(","));
 
   DO(Consume("]"));
@@ -1217,9 +1330,9 @@ bool Parser::ParseServiceDefinition(ServiceDescriptorProto* service,
 
 bool Parser::ParseServiceBlock(ServiceDescriptorProto* service,
                                const LocationRecorder& service_location) {
-  DO(Consume("{"));
+  DO(ConsumeEndOfDeclaration("{", &service_location));
 
-  while (!TryConsume("}")) {
+  while (!TryConsumeEndOfDeclaration("}", NULL)) {
     if (AtEnd()) {
       AddError("Reached end of input in service definition (missing '}').");
       return false;
@@ -1237,13 +1350,13 @@ bool Parser::ParseServiceBlock(ServiceDescriptorProto* service,
 
 bool Parser::ParseServiceStatement(ServiceDescriptorProto* service,
                                    const LocationRecorder& service_location) {
-  if (TryConsume(";")) {
+  if (TryConsumeEndOfDeclaration(";", NULL)) {
     // empty statement; ignore
     return true;
   } else if (LookingAt("option")) {
     LocationRecorder location(
         service_location, ServiceDescriptorProto::kOptionsFieldNumber);
-    return ParseOption(service->mutable_options(), location);
+    return ParseOption(service->mutable_options(), location, OPTION_STATEMENT);
   } else {
     LocationRecorder location(service_location,
         ServiceDescriptorProto::kMethodFieldNumber, service->method_size());
@@ -1286,28 +1399,41 @@ bool Parser::ParseServiceMethod(MethodDescriptorProto* method,
   }
   DO(Consume(")"));
 
-  if (TryConsume("{")) {
+  if (LookingAt("{")) {
     // Options!
-    while (!TryConsume("}")) {
-      if (AtEnd()) {
-        AddError("Reached end of input in method options (missing '}').");
-        return false;
-      }
+    DO(ParseOptions(method_location,
+                    MethodDescriptorProto::kOptionsFieldNumber,
+                    method->mutable_options()));
+  } else {
+    DO(ConsumeEndOfDeclaration(";", &method_location));
+  }
 
-      if (TryConsume(";")) {
-        // empty statement; ignore
-      } else {
-        LocationRecorder location(method_location,
-                                  MethodDescriptorProto::kOptionsFieldNumber);
-        if (!ParseOption(method->mutable_options(), location)) {
-          // This statement failed to parse.  Skip it, but keep looping to
-          // parse other statements.
-          SkipStatement();
-        }
+  return true;
+}
+
+
+bool Parser::ParseOptions(const LocationRecorder& parent_location,
+                          const int optionsFieldNumber,
+                          Message* mutable_options) {
+  // Options!
+  ConsumeEndOfDeclaration("{", &parent_location);
+  while (!TryConsumeEndOfDeclaration("}", NULL)) {
+    if (AtEnd()) {
+      AddError("Reached end of input in method options (missing '}').");
+      return false;
+    }
+
+    if (TryConsumeEndOfDeclaration(";", NULL)) {
+      // empty statement; ignore
+    } else {
+      LocationRecorder location(parent_location,
+                                optionsFieldNumber);
+      if (!ParseOption(mutable_options, location, OPTION_STATEMENT)) {
+        // This statement failed to parse.  Skip it, but keep looping to
+        // parse other statements.
+        SkipStatement();
       }
     }
-  } else {
-    DO(Consume(";"));
   }
 
   return true;
@@ -1406,32 +1532,44 @@ bool Parser::ParsePackage(FileDescriptorProto* file,
       if (!TryConsume(".")) break;
       file->mutable_package()->append(".");
     }
+
+    location.EndAt(input_->previous());
+
+    DO(ConsumeEndOfDeclaration(";", &location));
   }
 
-  DO(Consume(";"));
   return true;
 }
 
-bool Parser::ParseImport(string* import_filename,
-                         const LocationRecorder& root_location,
-                         int index) {
+bool Parser::ParseImport(RepeatedPtrField<string>* dependency,
+                         RepeatedField<int32>* public_dependency,
+                         RepeatedField<int32>* weak_dependency,
+                         const LocationRecorder& root_location) {
   DO(Consume("import"));
+  if (LookingAt("public")) {
+    LocationRecorder location(
+        root_location, FileDescriptorProto::kPublicDependencyFieldNumber,
+        public_dependency->size());
+    DO(Consume("public"));
+    *public_dependency->Add() = dependency->size();
+  } else if (LookingAt("weak")) {
+    LocationRecorder location(
+        root_location, FileDescriptorProto::kWeakDependencyFieldNumber,
+        weak_dependency->size());
+    DO(Consume("weak"));
+    *weak_dependency->Add() = dependency->size();
+  }
   {
     LocationRecorder location(root_location,
                               FileDescriptorProto::kDependencyFieldNumber,
-                              index);
-    DO(ConsumeString(import_filename,
+                              dependency->size());
+    DO(ConsumeString(dependency->Add(),
       "Expected a string naming the file to import."));
-  }
-  DO(Consume(";"));
-  return true;
-}
 
-bool Parser::ParseOption(Message* options,
-                         const LocationRecorder& options_location) {
-  DO(Consume("option"));
-  DO(ParseOptionAssignment(options, options_location));
-  DO(Consume(";"));
+    location.EndAt(input_->previous());
+
+    DO(ConsumeEndOfDeclaration(";", &location));
+  }
   return true;
 }
 
diff --git a/src/google/protobuf/compiler/parser.h b/src/google/protobuf/compiler/parser.h
index 4cc90a29..cfd3649b 100644
--- a/src/google/protobuf/compiler/parser.h
+++ b/src/google/protobuf/compiler/parser.h
@@ -116,6 +116,8 @@ class LIBPROTOBUF_EXPORT Parser {
   }
 
  private:
+  class LocationRecorder;
+
   // =================================================================
   // Error recovery helpers
 
@@ -164,6 +166,8 @@ class LIBPROTOBUF_EXPORT Parser {
   bool ConsumeIdentifier(string* output, const char* error);
   // Consume an integer and store its value in "output".
   bool ConsumeInteger(int* output, const char* error);
+  // Consume a signed integer and store its value in "output".
+  bool ConsumeSignedInteger(int* output, const char* error);
   // Consume a 64-bit integer and store its value in "output".  If the value
   // is greater than max_value, an error will be reported.
   bool ConsumeInteger64(uint64 max_value, uint64* output, const char* error);
@@ -173,6 +177,20 @@ class LIBPROTOBUF_EXPORT Parser {
   // Consume a string literal and store its (unescaped) value in "output".
   bool ConsumeString(string* output, const char* error);
 
+  // Consume a token representing the end of the statement.  Comments between
+  // this token and the next will be harvested for documentation.  The given
+  // LocationRecorder should refer to the declaration that was just parsed;
+  // it will be populated with these comments.
+  //
+  // TODO(kenton):  The LocationRecorder is const because historically locations
+  //   have been passed around by const reference, for no particularly good
+  //   reason.  We should probably go through and change them all to mutable
+  //   pointer to make this more intuitive.
+  bool TryConsumeEndOfDeclaration(const char* text,
+                                  const LocationRecorder* location);
+  bool ConsumeEndOfDeclaration(const char* text,
+                               const LocationRecorder* location);
+
   // -----------------------------------------------------------------
   // Error logging helpers
 
@@ -227,6 +245,14 @@ class LIBPROTOBUF_EXPORT Parser {
     void RecordLegacyLocation(const Message* descriptor,
         DescriptorPool::ErrorCollector::ErrorLocation location);
 
+    // Attaches leading and trailing comments to the location.  The two strings
+    // will be swapped into place, so after this is called *leading and
+    // *trailing will be empty.
+    //
+    // TODO(kenton):  See comment on TryConsumeEndOfDeclaration(), above, for
+    //   why this is const.
+    void AttachComments(string* leading, string* trailing) const;
+
    private:
     Parser* parser_;
     SourceCodeInfo::Location* location_;
@@ -265,9 +291,10 @@ class LIBPROTOBUF_EXPORT Parser {
                               const LocationRecorder& service_location);
   bool ParsePackage(FileDescriptorProto* file,
                     const LocationRecorder& root_location);
-  bool ParseImport(string* import_filename,
-                   const LocationRecorder& root_location,
-                   int index);
+  bool ParseImport(RepeatedPtrField<string>* dependency,
+                   RepeatedField<int32>* public_dependency,
+                   RepeatedField<int32>* weak_dependency,
+                   const LocationRecorder& root_location);
   bool ParseOption(Message* options,
                    const LocationRecorder& options_location);
 
@@ -329,6 +356,12 @@ class LIBPROTOBUF_EXPORT Parser {
   bool ParseServiceMethod(MethodDescriptorProto* method,
                           const LocationRecorder& method_location);
 
+
+  // Parse options of a single method or stream.
+  bool ParseOptions(const LocationRecorder& parent_location,
+                    const int optionsFieldNumber,
+                    Message* mutable_options);
+
   // Parse "required", "optional", or "repeated" and fill in "label"
   // with the value.
   bool ParseLabel(FieldDescriptorProto::Label* label);
@@ -351,11 +384,17 @@ class LIBPROTOBUF_EXPORT Parser {
   bool ParseDefaultAssignment(FieldDescriptorProto* field,
                               const LocationRecorder& field_location);
 
+  enum OptionStyle {
+    OPTION_ASSIGNMENT,  // just "name = value"
+    OPTION_STATEMENT    // "option name = value;"
+  };
+
   // Parse a single option name/value pair, e.g. "ctype = CORD".  The name
   // identifies a field of the given Message, and the value of that field
   // is set to the parsed value.
-  bool ParseOptionAssignment(Message* options,
-                             const LocationRecorder& options_location);
+  bool ParseOption(Message* options,
+                   const LocationRecorder& options_location,
+                   OptionStyle style);
 
   // Parses a single part of a multipart option name. A multipart name consists
   // of names separated by dots. Each name is either an identifier or a series
@@ -387,6 +426,10 @@ class LIBPROTOBUF_EXPORT Parser {
   bool stop_after_syntax_identifier_;
   string syntax_identifier_;
 
+  // Leading doc comments for the next declaration.  These are not complete
+  // yet; use ConsumeEndOfDeclaration() to get the complete comments.
+  string upcoming_doc_comments_;
+
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Parser);
 };
 
diff --git a/src/google/protobuf/compiler/parser_unittest.cc b/src/google/protobuf/compiler/parser_unittest.cc
index 156c0dc3..c61ac60e 100644
--- a/src/google/protobuf/compiler/parser_unittest.cc
+++ b/src/google/protobuf/compiler/parser_unittest.cc
@@ -44,6 +44,7 @@
 #include <google/protobuf/wire_format.h>
 #include <google/protobuf/text_format.h>
 #include <google/protobuf/unittest.pb.h>
+#include <google/protobuf/unittest_custom_options.pb.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/stubs/map-util.h>
@@ -509,6 +510,31 @@ TEST_F(ParseMessageTest, CompoundExtensionRange) {
     "}");
 }
 
+TEST_F(ParseMessageTest, LargerMaxForMessageSetWireFormatMessages) {
+  // Messages using the message_set_wire_format option can accept larger
+  // extension numbers, as the numbers are not encoded as int32 field values
+  // rather than tags.
+  ExpectParsesTo(
+    "message TestMessage {\n"
+    "  extensions 4 to max;\n"
+    "  option message_set_wire_format = true;\n"
+    "}\n",
+
+    "message_type {"
+    "  name: \"TestMessage\""
+    "    extension_range { start:4 end: 0x7fffffff }"
+    "  options {\n"
+    "    uninterpreted_option { \n"
+    "      name {\n"
+    "        name_part: \"message_set_wire_format\"\n"
+    "        is_extension: false\n"
+    "      }\n"
+    "      identifier_value: \"true\"\n"
+    "    }\n"
+    "  }\n"
+    "}");
+}
+
 TEST_F(ParseMessageTest, Extensions) {
   ExpectParsesTo(
     "extend Extendee1 { optional int32 foo = 12; }\n"
@@ -571,6 +597,10 @@ TEST_F(ParseEnumTest, Values) {
     "  FOO = 13;\n"
     "  BAR = -10;\n"
     "  BAZ = 500;\n"
+    "  HEX_MAX = 0x7FFFFFFF;\n"
+    "  HEX_MIN = -0x80000000;\n"
+    "  INT_MAX = 2147483647;\n"
+    "  INT_MIN = -2147483648;\n"
     "}\n",
 
     "enum_type {"
@@ -578,6 +608,10 @@ TEST_F(ParseEnumTest, Values) {
     "  value { name:\"FOO\" number:13 }"
     "  value { name:\"BAR\" number:-10 }"
     "  value { name:\"BAZ\" number:500 }"
+    "  value { name:\"HEX_MAX\" number:2147483647 }"
+    "  value { name:\"HEX_MIN\" number:-2147483648 }"
+    "  value { name:\"INT_MAX\" number:2147483647 }"
+    "  value { name:\"INT_MIN\" number:-2147483648 }"
     "}");
 }
 
@@ -631,7 +665,7 @@ TEST_F(ParseServiceTest, SimpleService) {
     "}");
 }
 
-TEST_F(ParseServiceTest, Methods) {
+TEST_F(ParseServiceTest, MethodsAndStreams) {
   ExpectParsesTo(
     "service TestService {\n"
     "  rpc Foo(In1) returns (Out1);\n"
@@ -668,6 +702,20 @@ TEST_F(ParseMiscTest, ParseMultipleImports) {
     "dependency: \"baz.proto\"");
 }
 
+TEST_F(ParseMiscTest, ParsePublicImports) {
+  ExpectParsesTo(
+    "import \"foo.proto\";\n"
+    "import public \"bar.proto\";\n"
+    "import \"baz.proto\";\n"
+    "import public \"qux.proto\";\n",
+    "dependency: \"foo.proto\""
+    "dependency: \"bar.proto\""
+    "dependency: \"baz.proto\""
+    "dependency: \"qux.proto\""
+    "public_dependency: 1 "
+    "public_dependency: 3 ");
+}
+
 TEST_F(ParseMiscTest, ParsePackage) {
   ExpectParsesTo(
     "package foo.bar.baz;\n",
@@ -867,6 +915,20 @@ TEST_F(ParseErrorTest, DefaultValueTooLarge) {
     "6:36: Integer out of range.\n");
 }
 
+TEST_F(ParseErrorTest, EnumValueOutOfRange) {
+  ExpectHasErrors(
+    "enum TestEnum {\n"
+    "  HEX_TOO_BIG   =  0x80000000;\n"
+    "  HEX_TOO_SMALL = -0x80000001;\n"
+    "  INT_TOO_BIG   =  2147483648;\n"
+    "  INT_TOO_SMALL = -2147483649;\n"
+    "}\n",
+    "1:19: Integer out of range.\n"
+    "2:19: Integer out of range.\n"
+    "3:19: Integer out of range.\n"
+    "4:19: Integer out of range.\n");
+}
+
 TEST_F(ParseErrorTest, DefaultValueMissing) {
   ExpectHasErrors(
     "message TestMessage {\n"
@@ -976,6 +1038,7 @@ TEST_F(ParseErrorTest, ServiceMethodPrimitiveParams) {
     "1:26: Expected message type.\n");
 }
 
+
 TEST_F(ParseErrorTest, EofInMethodOptions) {
   ExpectHasErrors(
     "service TestService {\n"
@@ -984,6 +1047,7 @@ TEST_F(ParseErrorTest, EofInMethodOptions) {
     "1:29: Reached end of input in service definition (missing '}').\n");
 }
 
+
 TEST_F(ParseErrorTest, PrimitiveMethodInput) {
   ExpectHasErrors(
     "service TestService {\n"
@@ -992,6 +1056,7 @@ TEST_F(ParseErrorTest, PrimitiveMethodInput) {
     "1:10: Expected message type.\n");
 }
 
+
 TEST_F(ParseErrorTest, MethodOptionTypeError) {
   // This used to cause an infinite loop.
   ExpectHasErrors(
@@ -1002,6 +1067,7 @@ TEST_F(ParseErrorTest, MethodOptionTypeError) {
     "2:45: Expected \"=\".\n");
 }
 
+
 // -------------------------------------------------------------------
 // Import and package errors
 
@@ -1157,6 +1223,7 @@ TEST_F(ParserValidationErrorTest, MethodNameError) {
     "3:6: \"Bar\" is already defined in \"Foo\".\n");
 }
 
+
 TEST_F(ParserValidationErrorTest, MethodInputTypeError) {
   ExpectHasValidationErrors(
     "message Baz {}\n"
@@ -1166,6 +1233,7 @@ TEST_F(ParserValidationErrorTest, MethodInputTypeError) {
     "2:10: \"Qux\" is not defined.\n");
 }
 
+
 TEST_F(ParserValidationErrorTest, MethodOutputTypeError) {
   ExpectHasValidationErrors(
     "message Baz {}\n"
@@ -1175,6 +1243,7 @@ TEST_F(ParserValidationErrorTest, MethodOutputTypeError) {
     "2:23: \"Qux\" is not defined.\n");
 }
 
+
 // ===================================================================
 // Test that the output from FileDescriptor::DebugString() (and all other
 // descriptor types) is parseable, and results in the same Descriptor
@@ -1236,6 +1305,11 @@ TEST_F(ParseDecriptorDebugTest, TestAllDescriptorTypes) {
   // also need to give it the same name as the original.
   parsed.set_name("google/protobuf/unittest.proto");
   // We need the imported dependency before we can build our parsed proto
+  const FileDescriptor* public_import =
+      protobuf_unittest_import::PublicImportMessage::descriptor()->file();
+  FileDescriptorProto public_import_proto;
+  public_import->CopyTo(&public_import_proto);
+  ASSERT_TRUE(pool_.BuildFile(public_import_proto) != NULL);
   const FileDescriptor* import =
        protobuf_unittest_import::ImportMessage::descriptor()->file();
   FileDescriptorProto import_proto;
@@ -1258,6 +1332,45 @@ TEST_F(ParseDecriptorDebugTest, TestAllDescriptorTypes) {
   EXPECT_EQ(expected.DebugString(), parsed.DebugString());
 }
 
+TEST_F(ParseDecriptorDebugTest, TestCustomOptions) {
+  const FileDescriptor* original_file =
+     protobuf_unittest::AggregateMessage::descriptor()->file();
+  FileDescriptorProto expected;
+  original_file->CopyTo(&expected);
+
+  string debug_string = original_file->DebugString();
+
+  // Parse the debug string
+  SetupParser(debug_string.c_str());
+  FileDescriptorProto parsed;
+  parser_->Parse(input_.get(), &parsed);
+  EXPECT_EQ(io::Tokenizer::TYPE_END, input_->current().type);
+  ASSERT_EQ("", error_collector_.text_);
+
+  // We now have a FileDescriptorProto, but to compare with the expected we
+  // need to link to a FileDecriptor, then output back to a proto. We'll
+  // also need to give it the same name as the original.
+  parsed.set_name(original_file->name());
+
+  // unittest_custom_options.proto depends on descriptor.proto.
+  const FileDescriptor* import = FileDescriptorProto::descriptor()->file();
+  FileDescriptorProto import_proto;
+  import->CopyTo(&import_proto);
+  ASSERT_TRUE(pool_.BuildFile(import_proto) != NULL);
+  const FileDescriptor* actual = pool_.BuildFile(parsed);
+  ASSERT_TRUE(actual != NULL);
+  parsed.Clear();
+  actual->CopyTo(&parsed);
+
+  // The messages might be in different orders, making them hard to compare.
+  // So, sort the messages in the descriptor protos (including nested messages,
+  // recursively).
+  SortMessages(&expected);
+  SortMessages(&parsed);
+
+  EXPECT_EQ(expected.DebugString(), parsed.DebugString());
+}
+
 // ===================================================================
 // SourceCodeInfo tests.
 
@@ -1353,67 +1466,6 @@ bool FollowPath(const Message& root,
   }
 }
 
-// Split some text on line breaks.  The line breaks are retained in the output,
-// so each line (except the last) ends with a '\n', and the lines can be
-// concatenated to produce the original text.
-//
-// I couldn't find the proper string utility function for this.  Our
-// split-on-delimiter functions don't include the delimiter in the output.
-void SplitLines(const string& text, vector<string>* lines) {
-  string::size_type pos = 0;
-
-  while (pos != string::npos) {
-    string::size_type last_pos = pos;
-    pos = text.find_first_of('\n', pos);
-    if (pos != string::npos) ++pos;
-    lines->push_back(text.substr(last_pos, pos - last_pos));
-  }
-}
-
-// Look for the given tags in the given text and construct a span (as defined
-// by SourceCodeInfo.Location.span) from them.  E.g. for text like:
-//   /*a*/message /*b*/Foo/*c*/ {}/*d*/
-// There are four tags:  "a", "b", "c", and "d".  The constructed span starts
-// immediately after the start tag's trailing '/' and ends immediately before
-// the end tags leading '/'.
-void MakeExpectedSpan(const vector<string>& lines,
-                      const string& start_tag, const string& end_tag,
-                      RepeatedField<int>* output) {
-  string start_comment = "/*" + start_tag + "*/";
-  string end_comment = "/*" + end_tag + "*/";
-
-  int start_line = -1;
-  int start_column = -1;
-  for (int i = 0; i < lines.size(); i++) {
-    string::size_type pos = lines[i].find(start_comment);
-    if (pos != string::npos) {
-      start_line = i;
-      start_column = pos + start_comment.size();
-      break;
-    }
-  }
-  ASSERT_NE(start_line, -1)
-      << "Tag \"" << start_comment << "\" not found in text.";
-
-  int end_line = -1;
-  int end_column = -1;
-  for (int i = start_line; i < lines.size(); i++) {
-    string::size_type pos = lines[i].find(end_comment);
-    if (pos != string::npos) {
-      end_line = i;
-      end_column = pos;
-      break;
-    }
-  }
-  ASSERT_NE(end_line, -1)
-      << "Tag \"" << end_comment << "\" not found in text.";
-
-  output->Add(start_line);
-  output->Add(start_column);
-  if (end_line != start_line) output->Add(end_line);
-  output->Add(end_column);
-}
-
 // Check if two spans are equal.
 bool CompareSpans(const RepeatedField<int>& span1,
                   const RepeatedField<int>& span2) {
@@ -1434,8 +1486,8 @@ class SourceInfoTest : public ParserTest {
   // Parse the given text as a .proto file and populate the spans_ map with
   // all the source location spans in its SourceCodeInfo table.
   bool Parse(const char* text) {
-    SetupParser(text);
-    SplitLines(text, &lines_);
+    ExtractMarkers(text);
+    SetupParser(text_without_markers_.c_str());
     if (!parser_->Parse(input_.get(), &file_)) {
       return false;
     }
@@ -1470,19 +1522,38 @@ class SourceInfoTest : public ParserTest {
   // part of the FileDescriptorProto.  (If unclear, look at the actual tests;
   // it should quickly become obvious.)
 
-  bool HasSpan(const char* start_tag, const char* end_tag,
+  bool HasSpan(char start_marker, char end_marker,
                const Message& descriptor_proto) {
-    return HasSpan(start_tag, end_tag, descriptor_proto, NULL, -1);
+    return HasSpanWithComment(
+        start_marker, end_marker, descriptor_proto, NULL, -1, NULL, NULL);
   }
 
-  bool HasSpan(const char* start_tag, const char* end_tag,
+  bool HasSpanWithComment(char start_marker, char end_marker,
+                          const Message& descriptor_proto,
+                          const char* expected_leading_comments,
+                          const char* expected_trailing_comments) {
+    return HasSpanWithComment(
+        start_marker, end_marker, descriptor_proto, NULL, -1,
+        expected_leading_comments, expected_trailing_comments);
+  }
+
+  bool HasSpan(char start_marker, char end_marker,
                const Message& descriptor_proto, const string& field_name) {
-    return HasSpan(start_tag, end_tag, descriptor_proto, field_name, -1);
+    return HasSpan(start_marker, end_marker, descriptor_proto, field_name, -1);
   }
 
-  bool HasSpan(const char* start_tag, const char* end_tag,
+  bool HasSpan(char start_marker, char end_marker,
                const Message& descriptor_proto, const string& field_name,
                int index) {
+    return HasSpan(start_marker, end_marker, descriptor_proto,
+                   field_name, index, NULL, NULL);
+  }
+
+  bool HasSpan(char start_marker, char end_marker,
+               const Message& descriptor_proto,
+               const string& field_name, int index,
+               const char* expected_leading_comments,
+               const char* expected_trailing_comments) {
     const FieldDescriptor* field =
         descriptor_proto.GetDescriptor()->FindFieldByName(field_name);
     if (field == NULL) {
@@ -1491,29 +1562,34 @@ class SourceInfoTest : public ParserTest {
       return false;
     }
 
-    return HasSpan(start_tag, end_tag, descriptor_proto, field, index);
+    return HasSpanWithComment(
+        start_marker, end_marker, descriptor_proto, field, index,
+        expected_leading_comments, expected_trailing_comments);
   }
 
   bool HasSpan(const Message& descriptor_proto) {
-    return HasSpan(NULL, NULL, descriptor_proto, NULL, -1);
+    return HasSpanWithComment(
+        '\0', '\0', descriptor_proto, NULL, -1, NULL, NULL);
   }
 
   bool HasSpan(const Message& descriptor_proto, const string& field_name) {
-    return HasSpan(NULL, NULL, descriptor_proto, field_name, -1);
+    return HasSpan('\0', '\0', descriptor_proto, field_name, -1);
   }
 
   bool HasSpan(const Message& descriptor_proto, const string& field_name,
                int index) {
-    return HasSpan(NULL, NULL, descriptor_proto, field_name, index);
+    return HasSpan('\0', '\0', descriptor_proto, field_name, index);
   }
 
-  bool HasSpan(const char* start_tag, const char* end_tag,
-               const Message& descriptor_proto, const FieldDescriptor* field,
-               int index) {
+  bool HasSpanWithComment(char start_marker, char end_marker,
+                          const Message& descriptor_proto,
+                          const FieldDescriptor* field, int index,
+                          const char* expected_leading_comments,
+                          const char* expected_trailing_comments) {
     pair<SpanMap::iterator, SpanMap::iterator> range =
         spans_.equal_range(SpanKey(descriptor_proto, field, index));
 
-    if (start_tag == NULL) {
+    if (start_marker == '\0') {
       if (range.first == range.second) {
         return false;
       } else {
@@ -1521,11 +1597,34 @@ class SourceInfoTest : public ParserTest {
         return true;
       }
     } else {
+      pair<int, int> start_pos = FindOrDie(markers_, start_marker);
+      pair<int, int> end_pos = FindOrDie(markers_, end_marker);
+
       RepeatedField<int> expected_span;
-      MakeExpectedSpan(lines_, start_tag, end_tag, &expected_span);
+      expected_span.Add(start_pos.first);
+      expected_span.Add(start_pos.second);
+      if (end_pos.first != start_pos.first) {
+        expected_span.Add(end_pos.first);
+      }
+      expected_span.Add(end_pos.second);
 
       for (SpanMap::iterator iter = range.first; iter != range.second; ++iter) {
         if (CompareSpans(expected_span, iter->second->span())) {
+          if (expected_leading_comments == NULL) {
+            EXPECT_FALSE(iter->second->has_leading_comments());
+          } else {
+            EXPECT_TRUE(iter->second->has_leading_comments());
+            EXPECT_EQ(expected_leading_comments,
+                      iter->second->leading_comments());
+          }
+          if (expected_trailing_comments == NULL) {
+            EXPECT_FALSE(iter->second->has_trailing_comments());
+          } else {
+            EXPECT_TRUE(iter->second->has_trailing_comments());
+            EXPECT_EQ(expected_trailing_comments,
+                      iter->second->trailing_comments());
+          }
+
           spans_.erase(iter);
           return true;
         }
@@ -1542,10 +1641,11 @@ class SourceInfoTest : public ParserTest {
     int index;
 
     inline SpanKey() {}
-    inline SpanKey(const Message& descriptor_proto,
-                   const FieldDescriptor* field,
-                   int index)
-        : descriptor_proto(&descriptor_proto), field(field), index(index) {}
+    inline SpanKey(const Message& descriptor_proto_param,
+                   const FieldDescriptor* field_param,
+                   int index_param)
+        : descriptor_proto(&descriptor_proto_param), field(field_param),
+          index(index_param) {}
 
     inline bool operator<(const SpanKey& other) const {
       if (descriptor_proto < other.descriptor_proto) return true;
@@ -1558,32 +1658,63 @@ class SourceInfoTest : public ParserTest {
 
   typedef multimap<SpanKey, const SourceCodeInfo::Location*> SpanMap;
   SpanMap spans_;
-  vector<string> lines_;
+  map<char, pair<int, int> > markers_;
+  string text_without_markers_;
+
+  void ExtractMarkers(const char* text) {
+    markers_.clear();
+    text_without_markers_.clear();
+    int line = 0;
+    int column = 0;
+    while (*text != '\0') {
+      if (*text == '$') {
+        ++text;
+        GOOGLE_CHECK_NE('\0', *text);
+        if (*text == '$') {
+          text_without_markers_ += '$';
+          ++column;
+        } else {
+          markers_[*text] = make_pair(line, column);
+          ++text;
+          GOOGLE_CHECK_EQ('$', *text);
+        }
+      } else if (*text == '\n') {
+        ++line;
+        column = 0;
+        text_without_markers_ += *text;
+      } else {
+        text_without_markers_ += *text;
+        ++column;
+      }
+      ++text;
+    }
+  }
 };
 
 TEST_F(SourceInfoTest, BasicFileDecls) {
   EXPECT_TRUE(Parse(
-      "/*a*/syntax = \"proto2\";\n"
-      "package /*b*/foo.bar/*c*/;\n"
-      "import /*d*/\"baz.proto\"/*e*/;\n"
-      "import /*f*/\"qux.proto\"/*g*/;/*h*/\n"
+      "$a$syntax = \"proto2\";\n"
+      "package $b$foo.bar$c$;\n"
+      "import $d$\"baz.proto\"$e$;\n"
+      "import $f$\"qux.proto\"$g$;$h$\n"
+      "\n"
       "// comment ignored\n"));
 
-  EXPECT_TRUE(HasSpan("a", "h", file_));
-  EXPECT_TRUE(HasSpan("b", "c", file_, "package"));
-  EXPECT_TRUE(HasSpan("d", "e", file_, "dependency", 0));
-  EXPECT_TRUE(HasSpan("f", "g", file_, "dependency", 1));
+  EXPECT_TRUE(HasSpan('a', 'h', file_));
+  EXPECT_TRUE(HasSpan('b', 'c', file_, "package"));
+  EXPECT_TRUE(HasSpan('d', 'e', file_, "dependency", 0));
+  EXPECT_TRUE(HasSpan('f', 'g', file_, "dependency", 1));
 }
 
 TEST_F(SourceInfoTest, Messages) {
   EXPECT_TRUE(Parse(
-      "/*a*/message /*b*/Foo/*c*/ {}/*d*/\n"
-      "/*e*/message /*f*/Bar/*g*/ {}/*h*/\n"));
+      "$a$message $b$Foo$c$ {}$d$\n"
+      "$e$message $f$Bar$g$ {}$h$\n"));
 
-  EXPECT_TRUE(HasSpan("a", "d", file_.message_type(0)));
-  EXPECT_TRUE(HasSpan("b", "c", file_.message_type(0), "name"));
-  EXPECT_TRUE(HasSpan("e", "h", file_.message_type(1)));
-  EXPECT_TRUE(HasSpan("f", "g", file_.message_type(1), "name"));
+  EXPECT_TRUE(HasSpan('a', 'd', file_.message_type(0)));
+  EXPECT_TRUE(HasSpan('b', 'c', file_.message_type(0), "name"));
+  EXPECT_TRUE(HasSpan('e', 'h', file_.message_type(1)));
+  EXPECT_TRUE(HasSpan('f', 'g', file_.message_type(1), "name"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1592,24 +1723,24 @@ TEST_F(SourceInfoTest, Messages) {
 TEST_F(SourceInfoTest, Fields) {
   EXPECT_TRUE(Parse(
       "message Foo {\n"
-      "  /*a*/optional/*b*/ /*c*/int32/*d*/ /*e*/bar/*f*/ = /*g*/1/*h*/;/*i*/\n"
-      "  /*j*/repeated/*k*/ /*l*/X.Y/*m*/ /*n*/baz/*o*/ = /*p*/2/*q*/;/*r*/\n"
+      "  $a$optional$b$ $c$int32$d$ $e$bar$f$ = $g$1$h$;$i$\n"
+      "  $j$repeated$k$ $l$X.Y$m$ $n$baz$o$ = $p$2$q$;$r$\n"
       "}\n"));
 
   const FieldDescriptorProto& field1 = file_.message_type(0).field(0);
   const FieldDescriptorProto& field2 = file_.message_type(0).field(1);
 
-  EXPECT_TRUE(HasSpan("a", "i", field1));
-  EXPECT_TRUE(HasSpan("a", "b", field1, "label"));
-  EXPECT_TRUE(HasSpan("c", "d", field1, "type"));
-  EXPECT_TRUE(HasSpan("e", "f", field1, "name"));
-  EXPECT_TRUE(HasSpan("g", "h", field1, "number"));
+  EXPECT_TRUE(HasSpan('a', 'i', field1));
+  EXPECT_TRUE(HasSpan('a', 'b', field1, "label"));
+  EXPECT_TRUE(HasSpan('c', 'd', field1, "type"));
+  EXPECT_TRUE(HasSpan('e', 'f', field1, "name"));
+  EXPECT_TRUE(HasSpan('g', 'h', field1, "number"));
 
-  EXPECT_TRUE(HasSpan("j", "r", field2));
-  EXPECT_TRUE(HasSpan("j", "k", field2, "label"));
-  EXPECT_TRUE(HasSpan("l", "m", field2, "type_name"));
-  EXPECT_TRUE(HasSpan("n", "o", field2, "name"));
-  EXPECT_TRUE(HasSpan("p", "q", field2, "number"));
+  EXPECT_TRUE(HasSpan('j', 'r', field2));
+  EXPECT_TRUE(HasSpan('j', 'k', field2, "label"));
+  EXPECT_TRUE(HasSpan('l', 'm', field2, "type_name"));
+  EXPECT_TRUE(HasSpan('n', 'o', field2, "name"));
+  EXPECT_TRUE(HasSpan('p', 'q', field2, "number"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1619,31 +1750,31 @@ TEST_F(SourceInfoTest, Fields) {
 
 TEST_F(SourceInfoTest, Extensions) {
   EXPECT_TRUE(Parse(
-      "/*a*/extend /*b*/Foo/*c*/ {\n"
-      "  /*d*/optional/*e*/ int32 bar = 1;/*f*/\n"
-      "  /*g*/repeated/*h*/ X.Y baz = 2;/*i*/\n"
-      "}/*j*/\n"
-      "/*k*/extend /*l*/Bar/*m*/ {\n"
-      "  /*n*/optional int32 qux = 1;/*o*/\n"
-      "}/*p*/\n"));
+      "$a$extend $b$Foo$c$ {\n"
+      "  $d$optional$e$ int32 bar = 1;$f$\n"
+      "  $g$repeated$h$ X.Y baz = 2;$i$\n"
+      "}$j$\n"
+      "$k$extend $l$Bar$m$ {\n"
+      "  $n$optional int32 qux = 1;$o$\n"
+      "}$p$\n"));
 
   const FieldDescriptorProto& field1 = file_.extension(0);
   const FieldDescriptorProto& field2 = file_.extension(1);
   const FieldDescriptorProto& field3 = file_.extension(2);
 
-  EXPECT_TRUE(HasSpan("a", "j", file_, "extension"));
-  EXPECT_TRUE(HasSpan("k", "p", file_, "extension"));
+  EXPECT_TRUE(HasSpan('a', 'j', file_, "extension"));
+  EXPECT_TRUE(HasSpan('k', 'p', file_, "extension"));
 
-  EXPECT_TRUE(HasSpan("d", "f", field1));
-  EXPECT_TRUE(HasSpan("d", "e", field1, "label"));
-  EXPECT_TRUE(HasSpan("b", "c", field1, "extendee"));
+  EXPECT_TRUE(HasSpan('d', 'f', field1));
+  EXPECT_TRUE(HasSpan('d', 'e', field1, "label"));
+  EXPECT_TRUE(HasSpan('b', 'c', field1, "extendee"));
 
-  EXPECT_TRUE(HasSpan("g", "i", field2));
-  EXPECT_TRUE(HasSpan("g", "h", field2, "label"));
-  EXPECT_TRUE(HasSpan("b", "c", field2, "extendee"));
+  EXPECT_TRUE(HasSpan('g', 'i', field2));
+  EXPECT_TRUE(HasSpan('g', 'h', field2, "label"));
+  EXPECT_TRUE(HasSpan('b', 'c', field2, "extendee"));
 
-  EXPECT_TRUE(HasSpan("n", "o", field3));
-  EXPECT_TRUE(HasSpan("l", "m", field3, "extendee"));
+  EXPECT_TRUE(HasSpan('n', 'o', field3));
+  EXPECT_TRUE(HasSpan('l', 'm', field3, "extendee"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1662,32 +1793,32 @@ TEST_F(SourceInfoTest, Extensions) {
 TEST_F(SourceInfoTest, NestedExtensions) {
   EXPECT_TRUE(Parse(
       "message Message {\n"
-      "  /*a*/extend /*b*/Foo/*c*/ {\n"
-      "    /*d*/optional/*e*/ int32 bar = 1;/*f*/\n"
-      "    /*g*/repeated/*h*/ X.Y baz = 2;/*i*/\n"
-      "  }/*j*/\n"
-      "  /*k*/extend /*l*/Bar/*m*/ {\n"
-      "    /*n*/optional int32 qux = 1;/*o*/\n"
-      "  }/*p*/\n"
+      "  $a$extend $b$Foo$c$ {\n"
+      "    $d$optional$e$ int32 bar = 1;$f$\n"
+      "    $g$repeated$h$ X.Y baz = 2;$i$\n"
+      "  }$j$\n"
+      "  $k$extend $l$Bar$m$ {\n"
+      "    $n$optional int32 qux = 1;$o$\n"
+      "  }$p$\n"
       "}\n"));
 
   const FieldDescriptorProto& field1 = file_.message_type(0).extension(0);
   const FieldDescriptorProto& field2 = file_.message_type(0).extension(1);
   const FieldDescriptorProto& field3 = file_.message_type(0).extension(2);
 
-  EXPECT_TRUE(HasSpan("a", "j", file_.message_type(0), "extension"));
-  EXPECT_TRUE(HasSpan("k", "p", file_.message_type(0), "extension"));
+  EXPECT_TRUE(HasSpan('a', 'j', file_.message_type(0), "extension"));
+  EXPECT_TRUE(HasSpan('k', 'p', file_.message_type(0), "extension"));
 
-  EXPECT_TRUE(HasSpan("d", "f", field1));
-  EXPECT_TRUE(HasSpan("d", "e", field1, "label"));
-  EXPECT_TRUE(HasSpan("b", "c", field1, "extendee"));
+  EXPECT_TRUE(HasSpan('d', 'f', field1));
+  EXPECT_TRUE(HasSpan('d', 'e', field1, "label"));
+  EXPECT_TRUE(HasSpan('b', 'c', field1, "extendee"));
 
-  EXPECT_TRUE(HasSpan("g", "i", field2));
-  EXPECT_TRUE(HasSpan("g", "h", field2, "label"));
-  EXPECT_TRUE(HasSpan("b", "c", field2, "extendee"));
+  EXPECT_TRUE(HasSpan('g', 'i', field2));
+  EXPECT_TRUE(HasSpan('g', 'h', field2, "label"));
+  EXPECT_TRUE(HasSpan('b', 'c', field2, "extendee"));
 
-  EXPECT_TRUE(HasSpan("n", "o", field3));
-  EXPECT_TRUE(HasSpan("l", "m", field3, "extendee"));
+  EXPECT_TRUE(HasSpan('n', 'o', field3));
+  EXPECT_TRUE(HasSpan('l', 'm', field3, "extendee"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1708,8 +1839,8 @@ TEST_F(SourceInfoTest, NestedExtensions) {
 TEST_F(SourceInfoTest, ExtensionRanges) {
   EXPECT_TRUE(Parse(
       "message Message {\n"
-      "  /*a*/extensions /*b*/1/*c*/ to /*d*/4/*e*/, /*f*/6/*g*/;/*h*/\n"
-      "  /*i*/extensions /*j*/8/*k*/ to /*l*/max/*m*/;/*n*/\n"
+      "  $a$extensions $b$1$c$ to $d$4$e$, $f$6$g$;$h$\n"
+      "  $i$extensions $j$8$k$ to $l$max$m$;$n$\n"
       "}\n"));
 
   const DescriptorProto::ExtensionRange& range1 =
@@ -1719,20 +1850,20 @@ TEST_F(SourceInfoTest, ExtensionRanges) {
   const DescriptorProto::ExtensionRange& range3 =
       file_.message_type(0).extension_range(2);
 
-  EXPECT_TRUE(HasSpan("a", "h", file_.message_type(0), "extension_range"));
-  EXPECT_TRUE(HasSpan("i", "n", file_.message_type(0), "extension_range"));
+  EXPECT_TRUE(HasSpan('a', 'h', file_.message_type(0), "extension_range"));
+  EXPECT_TRUE(HasSpan('i', 'n', file_.message_type(0), "extension_range"));
 
-  EXPECT_TRUE(HasSpan("b", "e", range1));
-  EXPECT_TRUE(HasSpan("b", "c", range1, "start"));
-  EXPECT_TRUE(HasSpan("d", "e", range1, "end"));
+  EXPECT_TRUE(HasSpan('b', 'e', range1));
+  EXPECT_TRUE(HasSpan('b', 'c', range1, "start"));
+  EXPECT_TRUE(HasSpan('d', 'e', range1, "end"));
 
-  EXPECT_TRUE(HasSpan("f", "g", range2));
-  EXPECT_TRUE(HasSpan("f", "g", range2, "start"));
-  EXPECT_TRUE(HasSpan("f", "g", range2, "end"));
+  EXPECT_TRUE(HasSpan('f', 'g', range2));
+  EXPECT_TRUE(HasSpan('f', 'g', range2, "start"));
+  EXPECT_TRUE(HasSpan('f', 'g', range2, "end"));
 
-  EXPECT_TRUE(HasSpan("j", "m", range3));
-  EXPECT_TRUE(HasSpan("j", "k", range3, "start"));
-  EXPECT_TRUE(HasSpan("l", "m", range3, "end"));
+  EXPECT_TRUE(HasSpan('j', 'm', range3));
+  EXPECT_TRUE(HasSpan('j', 'k', range3, "start"));
+  EXPECT_TRUE(HasSpan('l', 'm', range3, "end"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1743,22 +1874,22 @@ TEST_F(SourceInfoTest, ExtensionRanges) {
 TEST_F(SourceInfoTest, NestedMessages) {
   EXPECT_TRUE(Parse(
       "message Foo {\n"
-      "  /*a*/message /*b*/Bar/*c*/ {\n"
-      "    /*d*/message /*e*/Baz/*f*/ {}/*g*/\n"
-      "  }/*h*/\n"
-      "  /*i*/message /*j*/Qux/*k*/ {}/*l*/\n"
+      "  $a$message $b$Bar$c$ {\n"
+      "    $d$message $e$Baz$f$ {}$g$\n"
+      "  }$h$\n"
+      "  $i$message $j$Qux$k$ {}$l$\n"
       "}\n"));
 
   const DescriptorProto& bar = file_.message_type(0).nested_type(0);
   const DescriptorProto& baz = bar.nested_type(0);
   const DescriptorProto& qux = file_.message_type(0).nested_type(1);
 
-  EXPECT_TRUE(HasSpan("a", "h", bar));
-  EXPECT_TRUE(HasSpan("b", "c", bar, "name"));
-  EXPECT_TRUE(HasSpan("d", "g", baz));
-  EXPECT_TRUE(HasSpan("e", "f", baz, "name"));
-  EXPECT_TRUE(HasSpan("i", "l", qux));
-  EXPECT_TRUE(HasSpan("j", "k", qux, "name"));
+  EXPECT_TRUE(HasSpan('a', 'h', bar));
+  EXPECT_TRUE(HasSpan('b', 'c', bar, "name"));
+  EXPECT_TRUE(HasSpan('d', 'g', baz));
+  EXPECT_TRUE(HasSpan('e', 'f', baz, "name"));
+  EXPECT_TRUE(HasSpan('i', 'l', qux));
+  EXPECT_TRUE(HasSpan('j', 'k', qux, "name"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1770,9 +1901,9 @@ TEST_F(SourceInfoTest, Groups) {
   EXPECT_TRUE(Parse(
       "message Foo {\n"
       "  message Bar {}\n"
-      "  /*a*/optional/*b*/ /*c*/group/*d*/ /*e*/Baz/*f*/ = /*g*/1/*h*/ {\n"
-      "    /*i*/message Qux {}/*j*/\n"
-      "  }/*k*/\n"
+      "  $a$optional$b$ $c$group$d$ $e$Baz$f$ = $g$1$h$ {\n"
+      "    $i$message Qux {}$j$\n"
+      "  }$k$\n"
       "}\n"));
 
   const DescriptorProto& bar = file_.message_type(0).nested_type(0);
@@ -1780,16 +1911,16 @@ TEST_F(SourceInfoTest, Groups) {
   const DescriptorProto& qux = baz.nested_type(0);
   const FieldDescriptorProto& field = file_.message_type(0).field(0);
 
-  EXPECT_TRUE(HasSpan("a", "k", field));
-  EXPECT_TRUE(HasSpan("a", "b", field, "label"));
-  EXPECT_TRUE(HasSpan("c", "d", field, "type"));
-  EXPECT_TRUE(HasSpan("e", "f", field, "name"));
-  EXPECT_TRUE(HasSpan("e", "f", field, "type_name"));
-  EXPECT_TRUE(HasSpan("g", "h", field, "number"));
+  EXPECT_TRUE(HasSpan('a', 'k', field));
+  EXPECT_TRUE(HasSpan('a', 'b', field, "label"));
+  EXPECT_TRUE(HasSpan('c', 'd', field, "type"));
+  EXPECT_TRUE(HasSpan('e', 'f', field, "name"));
+  EXPECT_TRUE(HasSpan('e', 'f', field, "type_name"));
+  EXPECT_TRUE(HasSpan('g', 'h', field, "number"));
 
-  EXPECT_TRUE(HasSpan("a", "k", baz));
-  EXPECT_TRUE(HasSpan("e", "f", baz, "name"));
-  EXPECT_TRUE(HasSpan("i", "j", qux));
+  EXPECT_TRUE(HasSpan('a', 'k', baz));
+  EXPECT_TRUE(HasSpan('e', 'f', baz, "name"));
+  EXPECT_TRUE(HasSpan('i', 'j', qux));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1802,13 +1933,13 @@ TEST_F(SourceInfoTest, Groups) {
 
 TEST_F(SourceInfoTest, Enums) {
   EXPECT_TRUE(Parse(
-      "/*a*/enum /*b*/Foo/*c*/ {}/*d*/\n"
-      "/*e*/enum /*f*/Bar/*g*/ {}/*h*/\n"));
+      "$a$enum $b$Foo$c$ {}$d$\n"
+      "$e$enum $f$Bar$g$ {}$h$\n"));
 
-  EXPECT_TRUE(HasSpan("a", "d", file_.enum_type(0)));
-  EXPECT_TRUE(HasSpan("b", "c", file_.enum_type(0), "name"));
-  EXPECT_TRUE(HasSpan("e", "h", file_.enum_type(1)));
-  EXPECT_TRUE(HasSpan("f", "g", file_.enum_type(1), "name"));
+  EXPECT_TRUE(HasSpan('a', 'd', file_.enum_type(0)));
+  EXPECT_TRUE(HasSpan('b', 'c', file_.enum_type(0), "name"));
+  EXPECT_TRUE(HasSpan('e', 'h', file_.enum_type(1)));
+  EXPECT_TRUE(HasSpan('f', 'g', file_.enum_type(1), "name"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1817,19 +1948,19 @@ TEST_F(SourceInfoTest, Enums) {
 TEST_F(SourceInfoTest, EnumValues) {
   EXPECT_TRUE(Parse(
       "enum Foo {\n"
-      "  /*a*/BAR/*b*/ = /*c*/1/*d*/;/*e*/\n"
-      "  /*f*/BAZ/*g*/ = /*h*/2/*i*/;/*j*/\n"
+      "  $a$BAR$b$ = $c$1$d$;$e$\n"
+      "  $f$BAZ$g$ = $h$2$i$;$j$\n"
       "}"));
 
   const EnumValueDescriptorProto& bar = file_.enum_type(0).value(0);
   const EnumValueDescriptorProto& baz = file_.enum_type(0).value(1);
 
-  EXPECT_TRUE(HasSpan("a", "e", bar));
-  EXPECT_TRUE(HasSpan("a", "b", bar, "name"));
-  EXPECT_TRUE(HasSpan("c", "d", bar, "number"));
-  EXPECT_TRUE(HasSpan("f", "j", baz));
-  EXPECT_TRUE(HasSpan("f", "g", baz, "name"));
-  EXPECT_TRUE(HasSpan("h", "i", baz, "number"));
+  EXPECT_TRUE(HasSpan('a', 'e', bar));
+  EXPECT_TRUE(HasSpan('a', 'b', bar, "name"));
+  EXPECT_TRUE(HasSpan('c', 'd', bar, "number"));
+  EXPECT_TRUE(HasSpan('f', 'j', baz));
+  EXPECT_TRUE(HasSpan('f', 'g', baz, "name"));
+  EXPECT_TRUE(HasSpan('h', 'i', baz, "number"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1840,17 +1971,17 @@ TEST_F(SourceInfoTest, EnumValues) {
 TEST_F(SourceInfoTest, NestedEnums) {
   EXPECT_TRUE(Parse(
       "message Foo {\n"
-      "  /*a*/enum /*b*/Bar/*c*/ {}/*d*/\n"
-      "  /*e*/enum /*f*/Baz/*g*/ {}/*h*/\n"
+      "  $a$enum $b$Bar$c$ {}$d$\n"
+      "  $e$enum $f$Baz$g$ {}$h$\n"
       "}\n"));
 
   const EnumDescriptorProto& bar = file_.message_type(0).enum_type(0);
   const EnumDescriptorProto& baz = file_.message_type(0).enum_type(1);
 
-  EXPECT_TRUE(HasSpan("a", "d", bar));
-  EXPECT_TRUE(HasSpan("b", "c", bar, "name"));
-  EXPECT_TRUE(HasSpan("e", "h", baz));
-  EXPECT_TRUE(HasSpan("f", "g", baz, "name"));
+  EXPECT_TRUE(HasSpan('a', 'd', bar));
+  EXPECT_TRUE(HasSpan('b', 'c', bar, "name"));
+  EXPECT_TRUE(HasSpan('e', 'h', baz));
+  EXPECT_TRUE(HasSpan('f', 'g', baz, "name"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1860,37 +1991,37 @@ TEST_F(SourceInfoTest, NestedEnums) {
 
 TEST_F(SourceInfoTest, Services) {
   EXPECT_TRUE(Parse(
-      "/*a*/service /*b*/Foo/*c*/ {}/*d*/\n"
-      "/*e*/service /*f*/Bar/*g*/ {}/*h*/\n"));
+      "$a$service $b$Foo$c$ {}$d$\n"
+      "$e$service $f$Bar$g$ {}$h$\n"));
 
-  EXPECT_TRUE(HasSpan("a", "d", file_.service(0)));
-  EXPECT_TRUE(HasSpan("b", "c", file_.service(0), "name"));
-  EXPECT_TRUE(HasSpan("e", "h", file_.service(1)));
-  EXPECT_TRUE(HasSpan("f", "g", file_.service(1), "name"));
+  EXPECT_TRUE(HasSpan('a', 'd', file_.service(0)));
+  EXPECT_TRUE(HasSpan('b', 'c', file_.service(0), "name"));
+  EXPECT_TRUE(HasSpan('e', 'h', file_.service(1)));
+  EXPECT_TRUE(HasSpan('f', 'g', file_.service(1), "name"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
 }
 
-TEST_F(SourceInfoTest, Methods) {
+TEST_F(SourceInfoTest, MethodsAndStreams) {
   EXPECT_TRUE(Parse(
       "service Foo {\n"
-      "  /*a*/rpc /*b*/Bar/*c*/(/*d*/X/*e*/) returns(/*f*/Y/*g*/);/*h*/"
-      "  /*i*/rpc /*j*/Baz/*k*/(/*l*/Z/*m*/) returns(/*n*/W/*o*/);/*p*/"
+      "  $a$rpc $b$Bar$c$($d$X$e$) returns($f$Y$g$);$h$"
+      "  $i$rpc $j$Baz$k$($l$Z$m$) returns($n$W$o$);$p$"
       "}"));
 
   const MethodDescriptorProto& bar = file_.service(0).method(0);
   const MethodDescriptorProto& baz = file_.service(0).method(1);
 
-  EXPECT_TRUE(HasSpan("a", "h", bar));
-  EXPECT_TRUE(HasSpan("b", "c", bar, "name"));
-  EXPECT_TRUE(HasSpan("d", "e", bar, "input_type"));
-  EXPECT_TRUE(HasSpan("f", "g", bar, "output_type"));
+  EXPECT_TRUE(HasSpan('a', 'h', bar));
+  EXPECT_TRUE(HasSpan('b', 'c', bar, "name"));
+  EXPECT_TRUE(HasSpan('d', 'e', bar, "input_type"));
+  EXPECT_TRUE(HasSpan('f', 'g', bar, "output_type"));
 
-  EXPECT_TRUE(HasSpan("i", "p", baz));
-  EXPECT_TRUE(HasSpan("j", "k", baz, "name"));
-  EXPECT_TRUE(HasSpan("l", "m", baz, "input_type"));
-  EXPECT_TRUE(HasSpan("n", "o", baz, "output_type"));
+  EXPECT_TRUE(HasSpan('i', 'p', baz));
+  EXPECT_TRUE(HasSpan('j', 'k', baz, "name"));
+  EXPECT_TRUE(HasSpan('l', 'm', baz, "input_type"));
+  EXPECT_TRUE(HasSpan('n', 'o', baz, "output_type"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1900,13 +2031,13 @@ TEST_F(SourceInfoTest, Methods) {
 
 TEST_F(SourceInfoTest, Options) {
   EXPECT_TRUE(Parse(
-      "/*a*/option /*b*/foo/*c*/./*d*/(/*e*/bar.baz/*f*/)/*g*/ = "
-          "/*h*/123/*i*/;/*j*/\n"
-      "/*k*/option qux = /*l*/-123/*m*/;/*n*/\n"
-      "/*o*/option corge = /*p*/abc/*q*/;/*r*/\n"
-      "/*s*/option grault = /*t*/'blah'/*u*/;/*v*/\n"
-      "/*w*/option garply = /*x*/{ yadda yadda }/*y*/;/*z*/\n"
-      "/*0*/option waldo = /*1*/123.0/*2*/;/*3*/\n"
+      "$a$option $b$foo$c$.$d$($e$bar.baz$f$)$g$ = "
+          "$h$123$i$;$j$\n"
+      "$k$option qux = $l$-123$m$;$n$\n"
+      "$o$option corge = $p$abc$q$;$r$\n"
+      "$s$option grault = $t$'blah'$u$;$v$\n"
+      "$w$option garply = $x${ yadda yadda }$y$;$z$\n"
+      "$0$option waldo = $1$123.0$2$;$3$\n"
   ));
 
   const UninterpretedOption& option1 = file_.options().uninterpreted_option(0);
@@ -1916,29 +2047,29 @@ TEST_F(SourceInfoTest, Options) {
   const UninterpretedOption& option5 = file_.options().uninterpreted_option(4);
   const UninterpretedOption& option6 = file_.options().uninterpreted_option(5);
 
-  EXPECT_TRUE(HasSpan("a", "j", file_.options()));
-  EXPECT_TRUE(HasSpan("b", "i", option1));
-  EXPECT_TRUE(HasSpan("b", "g", option1, "name"));
-  EXPECT_TRUE(HasSpan("b", "c", option1.name(0)));
-  EXPECT_TRUE(HasSpan("b", "c", option1.name(0), "name_part"));
-  EXPECT_TRUE(HasSpan("d", "g", option1.name(1)));
-  EXPECT_TRUE(HasSpan("e", "f", option1.name(1), "name_part"));
-  EXPECT_TRUE(HasSpan("h", "i", option1, "positive_int_value"));
+  EXPECT_TRUE(HasSpan('a', 'j', file_.options()));
+  EXPECT_TRUE(HasSpan('a', 'j', option1));
+  EXPECT_TRUE(HasSpan('b', 'g', option1, "name"));
+  EXPECT_TRUE(HasSpan('b', 'c', option1.name(0)));
+  EXPECT_TRUE(HasSpan('b', 'c', option1.name(0), "name_part"));
+  EXPECT_TRUE(HasSpan('d', 'g', option1.name(1)));
+  EXPECT_TRUE(HasSpan('e', 'f', option1.name(1), "name_part"));
+  EXPECT_TRUE(HasSpan('h', 'i', option1, "positive_int_value"));
 
-  EXPECT_TRUE(HasSpan("k", "n", file_.options()));
-  EXPECT_TRUE(HasSpan("l", "m", option2, "negative_int_value"));
+  EXPECT_TRUE(HasSpan('k', 'n', file_.options()));
+  EXPECT_TRUE(HasSpan('l', 'm', option2, "negative_int_value"));
 
-  EXPECT_TRUE(HasSpan("o", "r", file_.options()));
-  EXPECT_TRUE(HasSpan("p", "q", option3, "identifier_value"));
+  EXPECT_TRUE(HasSpan('o', 'r', file_.options()));
+  EXPECT_TRUE(HasSpan('p', 'q', option3, "identifier_value"));
 
-  EXPECT_TRUE(HasSpan("s", "v", file_.options()));
-  EXPECT_TRUE(HasSpan("t", "u", option4, "string_value"));
+  EXPECT_TRUE(HasSpan('s', 'v', file_.options()));
+  EXPECT_TRUE(HasSpan('t', 'u', option4, "string_value"));
 
-  EXPECT_TRUE(HasSpan("w", "z", file_.options()));
-  EXPECT_TRUE(HasSpan("x", "y", option5, "aggregate_value"));
+  EXPECT_TRUE(HasSpan('w', 'z', file_.options()));
+  EXPECT_TRUE(HasSpan('x', 'y', option5, "aggregate_value"));
 
-  EXPECT_TRUE(HasSpan("0", "3", file_.options()));
-  EXPECT_TRUE(HasSpan("1", "2", option6, "double_value"));
+  EXPECT_TRUE(HasSpan('0', '3', file_.options()));
+  EXPECT_TRUE(HasSpan('1', '2', option6, "double_value"));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -1967,22 +2098,22 @@ TEST_F(SourceInfoTest, Options) {
 TEST_F(SourceInfoTest, ScopedOptions) {
   EXPECT_TRUE(Parse(
     "message Foo {\n"
-    "  /*a*/option mopt = 1;/*b*/\n"
+    "  $a$option mopt = 1;$b$\n"
     "}\n"
     "enum Bar {\n"
-    "  /*c*/option eopt = 1;/*d*/\n"
+    "  $c$option eopt = 1;$d$\n"
     "}\n"
     "service Baz {\n"
-    "  /*e*/option sopt = 1;/*f*/\n"
+    "  $e$option sopt = 1;$f$\n"
     "  rpc M(X) returns(Y) {\n"
-    "    /*g*/option mopt = 1;/*h*/\n"
+    "    $g$option mopt = 1;$h$\n"
     "  }\n"
     "}\n"));
 
-  EXPECT_TRUE(HasSpan("a", "b", file_.message_type(0).options()));
-  EXPECT_TRUE(HasSpan("c", "d", file_.enum_type(0).options()));
-  EXPECT_TRUE(HasSpan("e", "f", file_.service(0).options()));
-  EXPECT_TRUE(HasSpan("g", "h", file_.service(0).method(0).options()));
+  EXPECT_TRUE(HasSpan('a', 'b', file_.message_type(0).options()));
+  EXPECT_TRUE(HasSpan('c', 'd', file_.enum_type(0).options()));
+  EXPECT_TRUE(HasSpan('e', 'f', file_.service(0).options()));
+  EXPECT_TRUE(HasSpan('g', 'h', file_.service(0).method(0).options()));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -2045,8 +2176,8 @@ TEST_F(SourceInfoTest, FieldOptions) {
   EXPECT_TRUE(Parse(
       "message Foo {"
       "  optional int32 bar = 1 "
-          "/*a*/[default=/*b*/123/*c*/,/*d*/opt1=123/*e*/,"
-          "/*f*/opt2='hi'/*g*/]/*h*/;"
+          "$a$[default=$b$123$c$,$d$opt1=123$e$,"
+          "$f$opt2='hi'$g$]$h$;"
       "}\n"
   ));
 
@@ -2054,10 +2185,10 @@ TEST_F(SourceInfoTest, FieldOptions) {
   const UninterpretedOption& option1 = field.options().uninterpreted_option(0);
   const UninterpretedOption& option2 = field.options().uninterpreted_option(1);
 
-  EXPECT_TRUE(HasSpan("a", "h", field.options()));
-  EXPECT_TRUE(HasSpan("b", "c", field, "default_value"));
-  EXPECT_TRUE(HasSpan("d", "e", option1));
-  EXPECT_TRUE(HasSpan("f", "g", option2));
+  EXPECT_TRUE(HasSpan('a', 'h', field.options()));
+  EXPECT_TRUE(HasSpan('b', 'c', field, "default_value"));
+  EXPECT_TRUE(HasSpan('d', 'e', option1));
+  EXPECT_TRUE(HasSpan('f', 'g', option2));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -2084,7 +2215,7 @@ TEST_F(SourceInfoTest, EnumValueOptions) {
   // syntax used for enum options is understood.
   EXPECT_TRUE(Parse(
       "enum Foo {"
-      "  BAR = 1 /*a*/[/*b*/opt1=123/*c*/,/*d*/opt2='hi'/*e*/]/*f*/;"
+      "  BAR = 1 $a$[$b$opt1=123$c$,$d$opt2='hi'$e$]$f$;"
       "}\n"
   ));
 
@@ -2092,9 +2223,9 @@ TEST_F(SourceInfoTest, EnumValueOptions) {
   const UninterpretedOption& option1 = value.options().uninterpreted_option(0);
   const UninterpretedOption& option2 = value.options().uninterpreted_option(1);
 
-  EXPECT_TRUE(HasSpan("a", "f", value.options()));
-  EXPECT_TRUE(HasSpan("b", "c", option1));
-  EXPECT_TRUE(HasSpan("d", "e", option2));
+  EXPECT_TRUE(HasSpan('a', 'f', value.options()));
+  EXPECT_TRUE(HasSpan('b', 'c', option1));
+  EXPECT_TRUE(HasSpan('d', 'e', option2));
 
   // Ignore these.
   EXPECT_TRUE(HasSpan(file_));
@@ -2113,6 +2244,127 @@ TEST_F(SourceInfoTest, EnumValueOptions) {
   EXPECT_TRUE(HasSpan(option2, "string_value"));
 }
 
+TEST_F(SourceInfoTest, DocComments) {
+  EXPECT_TRUE(Parse(
+      "// Foo leading\n"
+      "// line 2\n"
+      "$a$message Foo {\n"
+      "  // Foo trailing\n"
+      "  // line 2\n"
+      "\n"
+      "  // ignored\n"
+      "\n"
+      "  // bar leading\n"
+      "  $b$optional int32 bar = 1;$c$\n"
+      "  // bar trailing\n"
+      "}$d$\n"
+      "// ignored\n"
+  ));
+
+  const DescriptorProto& foo = file_.message_type(0);
+  const FieldDescriptorProto& bar = foo.field(0);
+
+  EXPECT_TRUE(HasSpanWithComment('a', 'd', foo,
+      " Foo leading\n line 2\n",
+      " Foo trailing\n line 2\n"));
+  EXPECT_TRUE(HasSpanWithComment('b', 'c', bar,
+      " bar leading\n",
+      " bar trailing\n"));
+
+  // Ignore these.
+  EXPECT_TRUE(HasSpan(file_));
+  EXPECT_TRUE(HasSpan(foo, "name"));
+  EXPECT_TRUE(HasSpan(bar, "label"));
+  EXPECT_TRUE(HasSpan(bar, "type"));
+  EXPECT_TRUE(HasSpan(bar, "name"));
+  EXPECT_TRUE(HasSpan(bar, "number"));
+}
+
+TEST_F(SourceInfoTest, DocComments2) {
+  EXPECT_TRUE(Parse(
+      "// ignored\n"
+      "syntax = \"proto2\";\n"
+      "// Foo leading\n"
+      "// line 2\n"
+      "$a$message Foo {\n"
+      "  /* Foo trailing\n"
+      "   * line 2 */\n"
+      "  // ignored\n"
+      "  /* bar leading\n"
+      "   */"
+      "  $b$optional int32 bar = 1;$c$  // bar trailing\n"
+      "  // ignored\n"
+      "}$d$\n"
+      "// ignored\n"
+      "\n"
+      "// option leading\n"
+      "$e$option baz = 123;$f$\n"
+      "// option trailing\n"
+  ));
+
+  const DescriptorProto& foo = file_.message_type(0);
+  const FieldDescriptorProto& bar = foo.field(0);
+  const UninterpretedOption& baz = file_.options().uninterpreted_option(0);
+
+  EXPECT_TRUE(HasSpanWithComment('a', 'd', foo,
+      " Foo leading\n line 2\n",
+      " Foo trailing\n line 2 "));
+  EXPECT_TRUE(HasSpanWithComment('b', 'c', bar,
+      " bar leading\n",
+      " bar trailing\n"));
+  EXPECT_TRUE(HasSpanWithComment('e', 'f', baz,
+      " option leading\n",
+      " option trailing\n"));
+
+  // Ignore these.
+  EXPECT_TRUE(HasSpan(file_));
+  EXPECT_TRUE(HasSpan(foo, "name"));
+  EXPECT_TRUE(HasSpan(bar, "label"));
+  EXPECT_TRUE(HasSpan(bar, "type"));
+  EXPECT_TRUE(HasSpan(bar, "name"));
+  EXPECT_TRUE(HasSpan(bar, "number"));
+  EXPECT_TRUE(HasSpan(file_.options()));
+  EXPECT_TRUE(HasSpan(baz, "name"));
+  EXPECT_TRUE(HasSpan(baz.name(0)));
+  EXPECT_TRUE(HasSpan(baz.name(0), "name_part"));
+  EXPECT_TRUE(HasSpan(baz, "positive_int_value"));
+}
+
+TEST_F(SourceInfoTest, DocComments3) {
+  EXPECT_TRUE(Parse(
+      "$a$message Foo {\n"
+      "  // bar leading\n"
+      "  $b$optional int32 bar = 1 [(baz.qux) = {}];$c$\n"
+      "  // bar trailing\n"
+      "}$d$\n"
+      "// ignored\n"
+  ));
+
+  const DescriptorProto& foo = file_.message_type(0);
+  const FieldDescriptorProto& bar = foo.field(0);
+
+  EXPECT_TRUE(HasSpanWithComment('b', 'c', bar,
+      " bar leading\n",
+      " bar trailing\n"));
+
+  // Ignore these.
+  EXPECT_TRUE(HasSpan(file_));
+  EXPECT_TRUE(HasSpan(foo));
+  EXPECT_TRUE(HasSpan(foo, "name"));
+  EXPECT_TRUE(HasSpan(bar, "label"));
+  EXPECT_TRUE(HasSpan(bar, "type"));
+  EXPECT_TRUE(HasSpan(bar, "name"));
+  EXPECT_TRUE(HasSpan(bar, "number"));
+  EXPECT_TRUE(HasSpan(bar.options()));
+  EXPECT_TRUE(HasSpan(bar.options().uninterpreted_option(0)));
+  EXPECT_TRUE(HasSpan(bar.options().uninterpreted_option(0), "name"));
+  EXPECT_TRUE(HasSpan(bar.options().uninterpreted_option(0).name(0)));
+  EXPECT_TRUE(HasSpan(
+      bar.options().uninterpreted_option(0).name(0), "name_part"));
+  EXPECT_TRUE(HasSpan(
+      bar.options().uninterpreted_option(0), "aggregate_value"));
+}
+
 // ===================================================================
 
 }  // anonymous namespace
diff --git a/src/google/protobuf/compiler/plugin.h b/src/google/protobuf/compiler/plugin.h
index 7c403332..6fa2de12 100644
--- a/src/google/protobuf/compiler/plugin.h
+++ b/src/google/protobuf/compiler/plugin.h
@@ -56,7 +56,6 @@
 #define GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__
 
 #include <google/protobuf/stubs/common.h>
-
 namespace google {
 namespace protobuf {
 namespace compiler {
diff --git a/src/google/protobuf/compiler/plugin.pb.cc b/src/google/protobuf/compiler/plugin.pb.cc
index 05ff2f04..bc0c1f17 100644
--- a/src/google/protobuf/compiler/plugin.pb.cc
+++ b/src/google/protobuf/compiler/plugin.pb.cc
@@ -1,4 +1,5 @@
 // Generated by the protocol buffer compiler.  DO NOT EDIT!
+// source: google/protobuf/compiler/plugin.proto
 
 #define INTERNAL_SUPPRESS_PROTOBUF_FIELD_DEPRECATION
 #include "google/protobuf/compiler/plugin.pb.h"
@@ -9,6 +10,7 @@
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/generated_message_reflection.h>
 #include <google/protobuf/reflection_ops.h>
 #include <google/protobuf/wire_format.h>
 // @@protoc_insertion_point(includes)
@@ -124,6 +126,7 @@ void protobuf_AddDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto() {
   if (already_here) return;
   already_here = true;
   GOOGLE_PROTOBUF_VERIFY_VERSION;
+
   ::google::protobuf::protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n%google/protobuf/compiler/plugin.proto\022"
@@ -253,7 +256,7 @@ bool CodeGeneratorRequest::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_parameter;
         break;
       }
-      
+
       // optional string parameter = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -270,7 +273,7 @@ bool CodeGeneratorRequest::MergePartialFromCodedStream(
         if (input->ExpectTag(122)) goto parse_proto_file;
         break;
       }
-      
+
       // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
       case 15: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -285,7 +288,7 @@ bool CodeGeneratorRequest::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -312,7 +315,7 @@ void CodeGeneratorRequest::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->file_to_generate(i), output);
   }
-  
+
   // optional string parameter = 2;
   if (has_parameter()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -321,13 +324,13 @@ void CodeGeneratorRequest::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       2, this->parameter(), output);
   }
-  
+
   // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
   for (int i = 0; i < this->proto_file_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       15, this->proto_file(i), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -344,7 +347,7 @@ void CodeGeneratorRequest::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::
       WriteStringToArray(1, this->file_to_generate(i), target);
   }
-  
+
   // optional string parameter = 2;
   if (has_parameter()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -354,14 +357,14 @@ void CodeGeneratorRequest::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         2, this->parameter(), target);
   }
-  
+
   // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
   for (int i = 0; i < this->proto_file_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         15, this->proto_file(i), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -371,7 +374,7 @@ void CodeGeneratorRequest::SerializeWithCachedSizes(
 
 int CodeGeneratorRequest::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[1 / 32] & (0xffu << (1 % 32))) {
     // optional string parameter = 2;
     if (has_parameter()) {
@@ -379,7 +382,7 @@ int CodeGeneratorRequest::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->parameter());
     }
-    
+
   }
   // repeated string file_to_generate = 1;
   total_size += 1 * this->file_to_generate_size();
@@ -387,7 +390,7 @@ int CodeGeneratorRequest::ByteSize() const {
     total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
       this->file_to_generate(i));
   }
-  
+
   // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
   total_size += 1 * this->proto_file_size();
   for (int i = 0; i < this->proto_file_size(); i++) {
@@ -395,7 +398,7 @@ int CodeGeneratorRequest::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->proto_file(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -444,7 +447,7 @@ void CodeGeneratorRequest::CopyFrom(const CodeGeneratorRequest& from) {
 }
 
 bool CodeGeneratorRequest::IsInitialized() const {
-  
+
   for (int i = 0; i < proto_file_size(); i++) {
     if (!this->proto_file(i).IsInitialized()) return false;
   }
@@ -583,7 +586,7 @@ bool CodeGeneratorResponse_File::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_insertion_point;
         break;
       }
-      
+
       // optional string insertion_point = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -600,7 +603,7 @@ bool CodeGeneratorResponse_File::MergePartialFromCodedStream(
         if (input->ExpectTag(122)) goto parse_content;
         break;
       }
-      
+
       // optional string content = 15;
       case 15: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -617,7 +620,7 @@ bool CodeGeneratorResponse_File::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -644,7 +647,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // optional string insertion_point = 2;
   if (has_insertion_point()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -653,7 +656,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       2, this->insertion_point(), output);
   }
-  
+
   // optional string content = 15;
   if (has_content()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -662,7 +665,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       15, this->content(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -680,7 +683,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // optional string insertion_point = 2;
   if (has_insertion_point()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -690,7 +693,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         2, this->insertion_point(), target);
   }
-  
+
   // optional string content = 15;
   if (has_content()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -700,7 +703,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         15, this->content(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -710,7 +713,7 @@ void CodeGeneratorResponse_File::SerializeWithCachedSizes(
 
 int CodeGeneratorResponse_File::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -718,21 +721,21 @@ int CodeGeneratorResponse_File::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional string insertion_point = 2;
     if (has_insertion_point()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->insertion_point());
     }
-    
+
     // optional string content = 15;
     if (has_content()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->content());
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -786,7 +789,7 @@ void CodeGeneratorResponse_File::CopyFrom(const CodeGeneratorResponse_File& from
 }
 
 bool CodeGeneratorResponse_File::IsInitialized() const {
-  
+
   return true;
 }
 
@@ -904,7 +907,7 @@ bool CodeGeneratorResponse::MergePartialFromCodedStream(
         if (input->ExpectTag(122)) goto parse_file;
         break;
       }
-      
+
       // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
       case 15: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -919,7 +922,7 @@ bool CodeGeneratorResponse::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -946,13 +949,13 @@ void CodeGeneratorResponse::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->error(), output);
   }
-  
+
   // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
   for (int i = 0; i < this->file_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       15, this->file(i), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -970,14 +973,14 @@ void CodeGeneratorResponse::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->error(), target);
   }
-  
+
   // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
   for (int i = 0; i < this->file_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         15, this->file(i), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -987,7 +990,7 @@ void CodeGeneratorResponse::SerializeWithCachedSizes(
 
 int CodeGeneratorResponse::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string error = 1;
     if (has_error()) {
@@ -995,7 +998,7 @@ int CodeGeneratorResponse::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->error());
     }
-    
+
   }
   // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
   total_size += 1 * this->file_size();
@@ -1004,7 +1007,7 @@ int CodeGeneratorResponse::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->file(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -1052,7 +1055,7 @@ void CodeGeneratorResponse::CopyFrom(const CodeGeneratorResponse& from) {
 }
 
 bool CodeGeneratorResponse::IsInitialized() const {
-  
+
   return true;
 }
 
diff --git a/src/google/protobuf/compiler/plugin.pb.h b/src/google/protobuf/compiler/plugin.pb.h
index 1cf8a556..46478c73 100644
--- a/src/google/protobuf/compiler/plugin.pb.h
+++ b/src/google/protobuf/compiler/plugin.pb.h
@@ -20,9 +20,10 @@
 #endif
 
 #include <google/protobuf/generated_message_util.h>
+#include <google/protobuf/message.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/extension_set.h>
-#include <google/protobuf/generated_message_reflection.h>
+#include <google/protobuf/unknown_field_set.h>
 #include "google/protobuf/descriptor.pb.h"
 // @@protoc_insertion_point(includes)
 
@@ -45,29 +46,29 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
  public:
   CodeGeneratorRequest();
   virtual ~CodeGeneratorRequest();
-  
+
   CodeGeneratorRequest(const CodeGeneratorRequest& from);
-  
+
   inline CodeGeneratorRequest& operator=(const CodeGeneratorRequest& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const CodeGeneratorRequest& default_instance();
-  
+
   void Swap(CodeGeneratorRequest* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   CodeGeneratorRequest* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -75,7 +76,7 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
   void MergeFrom(const CodeGeneratorRequest& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -88,13 +89,13 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated string file_to_generate = 1;
   inline int file_to_generate_size() const;
   inline void clear_file_to_generate();
@@ -110,7 +111,7 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
   inline void add_file_to_generate(const char* value, size_t size);
   inline const ::google::protobuf::RepeatedPtrField< ::std::string>& file_to_generate() const;
   inline ::google::protobuf::RepeatedPtrField< ::std::string>* mutable_file_to_generate();
-  
+
   // optional string parameter = 2;
   inline bool has_parameter() const;
   inline void clear_parameter();
@@ -121,7 +122,8 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
   inline void set_parameter(const char* value, size_t size);
   inline ::std::string* mutable_parameter();
   inline ::std::string* release_parameter();
-  
+  inline void set_allocated_parameter(::std::string* parameter);
+
   // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
   inline int proto_file_size() const;
   inline void clear_proto_file();
@@ -133,25 +135,25 @@ class LIBPROTOC_EXPORT CodeGeneratorRequest : public ::google::protobuf::Message
       proto_file() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::FileDescriptorProto >*
       mutable_proto_file();
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorRequest)
  private:
   inline void set_has_parameter();
   inline void clear_has_parameter();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::std::string> file_to_generate_;
   ::std::string* parameter_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::FileDescriptorProto > proto_file_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOC_EXPORT protobuf_AddDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
-  
+
   void InitAsDefaultInstance();
   static CodeGeneratorRequest* default_instance_;
 };
@@ -161,29 +163,29 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
  public:
   CodeGeneratorResponse_File();
   virtual ~CodeGeneratorResponse_File();
-  
+
   CodeGeneratorResponse_File(const CodeGeneratorResponse_File& from);
-  
+
   inline CodeGeneratorResponse_File& operator=(const CodeGeneratorResponse_File& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const CodeGeneratorResponse_File& default_instance();
-  
+
   void Swap(CodeGeneratorResponse_File* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   CodeGeneratorResponse_File* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -191,7 +193,7 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   void MergeFrom(const CodeGeneratorResponse_File& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -204,13 +206,13 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -221,7 +223,8 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // optional string insertion_point = 2;
   inline bool has_insertion_point() const;
   inline void clear_insertion_point();
@@ -232,7 +235,8 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   inline void set_insertion_point(const char* value, size_t size);
   inline ::std::string* mutable_insertion_point();
   inline ::std::string* release_insertion_point();
-  
+  inline void set_allocated_insertion_point(::std::string* insertion_point);
+
   // optional string content = 15;
   inline bool has_content() const;
   inline void clear_content();
@@ -243,7 +247,8 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   inline void set_content(const char* value, size_t size);
   inline ::std::string* mutable_content();
   inline ::std::string* release_content();
-  
+  inline void set_allocated_content(::std::string* content);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorResponse.File)
  private:
   inline void set_has_name();
@@ -252,20 +257,20 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse_File : public ::google::protobuf::M
   inline void clear_has_insertion_point();
   inline void set_has_content();
   inline void clear_has_content();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::std::string* insertion_point_;
   ::std::string* content_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOC_EXPORT protobuf_AddDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
-  
+
   void InitAsDefaultInstance();
   static CodeGeneratorResponse_File* default_instance_;
 };
@@ -275,29 +280,29 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse : public ::google::protobuf::Messag
  public:
   CodeGeneratorResponse();
   virtual ~CodeGeneratorResponse();
-  
+
   CodeGeneratorResponse(const CodeGeneratorResponse& from);
-  
+
   inline CodeGeneratorResponse& operator=(const CodeGeneratorResponse& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const CodeGeneratorResponse& default_instance();
-  
+
   void Swap(CodeGeneratorResponse* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   CodeGeneratorResponse* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -305,7 +310,7 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse : public ::google::protobuf::Messag
   void MergeFrom(const CodeGeneratorResponse& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -318,15 +323,15 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse : public ::google::protobuf::Messag
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef CodeGeneratorResponse_File File;
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string error = 1;
   inline bool has_error() const;
   inline void clear_error();
@@ -337,7 +342,8 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse : public ::google::protobuf::Messag
   inline void set_error(const char* value, size_t size);
   inline ::std::string* mutable_error();
   inline ::std::string* release_error();
-  
+  inline void set_allocated_error(::std::string* error);
+
   // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
   inline int file_size() const;
   inline void clear_file();
@@ -349,24 +355,24 @@ class LIBPROTOC_EXPORT CodeGeneratorResponse : public ::google::protobuf::Messag
       file() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::compiler::CodeGeneratorResponse_File >*
       mutable_file();
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorResponse)
  private:
   inline void set_has_error();
   inline void clear_has_error();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* error_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::compiler::CodeGeneratorResponse_File > file_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];
-  
+
   friend void LIBPROTOC_EXPORT protobuf_AddDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fcompiler_2fplugin_2eproto();
-  
+
   void InitAsDefaultInstance();
   static CodeGeneratorResponse* default_instance_;
 };
@@ -478,6 +484,18 @@ inline ::std::string* CodeGeneratorRequest::release_parameter() {
     return temp;
   }
 }
+inline void CodeGeneratorRequest::set_allocated_parameter(::std::string* parameter) {
+  if (parameter_ != &::google::protobuf::internal::kEmptyString) {
+    delete parameter_;
+  }
+  if (parameter) {
+    set_has_parameter();
+    parameter_ = parameter;
+  } else {
+    clear_has_parameter();
+    parameter_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
 inline int CodeGeneratorRequest::proto_file_size() const {
@@ -565,6 +583,18 @@ inline ::std::string* CodeGeneratorResponse_File::release_name() {
     return temp;
   }
 }
+inline void CodeGeneratorResponse_File::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string insertion_point = 2;
 inline bool CodeGeneratorResponse_File::has_insertion_point() const {
@@ -623,6 +653,18 @@ inline ::std::string* CodeGeneratorResponse_File::release_insertion_point() {
     return temp;
   }
 }
+inline void CodeGeneratorResponse_File::set_allocated_insertion_point(::std::string* insertion_point) {
+  if (insertion_point_ != &::google::protobuf::internal::kEmptyString) {
+    delete insertion_point_;
+  }
+  if (insertion_point) {
+    set_has_insertion_point();
+    insertion_point_ = insertion_point;
+  } else {
+    clear_has_insertion_point();
+    insertion_point_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string content = 15;
 inline bool CodeGeneratorResponse_File::has_content() const {
@@ -681,6 +723,18 @@ inline ::std::string* CodeGeneratorResponse_File::release_content() {
     return temp;
   }
 }
+inline void CodeGeneratorResponse_File::set_allocated_content(::std::string* content) {
+  if (content_ != &::google::protobuf::internal::kEmptyString) {
+    delete content_;
+  }
+  if (content) {
+    set_has_content();
+    content_ = content;
+  } else {
+    clear_has_content();
+    content_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -743,6 +797,18 @@ inline ::std::string* CodeGeneratorResponse::release_error() {
     return temp;
   }
 }
+inline void CodeGeneratorResponse::set_allocated_error(::std::string* error) {
+  if (error_ != &::google::protobuf::internal::kEmptyString) {
+    delete error_;
+  }
+  if (error) {
+    set_has_error();
+    error_ = error;
+  } else {
+    clear_has_error();
+    error_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
 inline int CodeGeneratorResponse::file_size() const {
diff --git a/src/google/protobuf/compiler/python/python_generator.cc b/src/google/protobuf/compiler/python/python_generator.cc
index 9b109378..211ac70c 100644
--- a/src/google/protobuf/compiler/python/python_generator.cc
+++ b/src/google/protobuf/compiler/python/python_generator.cc
@@ -52,6 +52,7 @@
 #include <google/protobuf/descriptor.pb.h>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/io/zero_copy_stream.h>
@@ -106,6 +107,12 @@ string NamePrefixedWithNestedTypes(const DescriptorT& descriptor,
 const char kDescriptorKey[] = "DESCRIPTOR";
 
 
+// Does the file have top-level enums?
+inline bool HasTopLevelEnums(const FileDescriptor *file) {
+  return file->enum_type_count() > 0;
+}
+
+
 // Should we generate generic services for this file?
 inline bool HasGenericServices(const FileDescriptor *file) {
   return file->service_count() > 0 &&
@@ -120,13 +127,21 @@ void PrintTopBoilerplate(
   // TODO(robinson): Allow parameterization of Python version?
   printer->Print(
       "# Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
-      "\n"
-      "from google.protobuf import descriptor\n"
-      "from google.protobuf import message\n"
-      "from google.protobuf import reflection\n");
+      "# source: $filename$\n"
+      "\n",
+      "filename", file->name());
+  if (HasTopLevelEnums(file)) {
+    printer->Print(
+        "from google.protobuf.internal import enum_type_wrapper\n");
+  }
+  printer->Print(
+      "from google.protobuf import descriptor as _descriptor\n"
+      "from google.protobuf import message as _message\n"
+      "from google.protobuf import reflection as _reflection\n"
+      );
   if (HasGenericServices(file)) {
     printer->Print(
-        "from google.protobuf import service\n"
+        "from google.protobuf import service as _service\n"
         "from google.protobuf import service_reflection\n");
   }
 
@@ -204,12 +219,12 @@ string StringifyDefaultValue(const FieldDescriptor& field) {
     case FieldDescriptor::CPPTYPE_STRING:
       if (field.type() == FieldDescriptor::TYPE_STRING) {
         return "unicode(\"" + CEscape(field.default_value_string()) +
-            "\", \"utf-8\")";
+                        "\", \"utf-8\")";
       } else {
         return "\"" + CEscape(field.default_value_string()) + "\"";
       }
-    case FieldDescriptor::CPPTYPE_MESSAGE:
-      return "None";
+      case FieldDescriptor::CPPTYPE_MESSAGE:
+          return "None";
   }
   // (We could add a default case above but then we wouldn't get the nice
   // compiler warning when a new type is added.)
@@ -270,6 +285,11 @@ bool Generator::Generate(const FileDescriptor* file,
   // since they need to call static RegisterExtension() methods on these
   // classes.
   FixForeignFieldsInExtensions();
+  // Descriptor options may have custom extensions. These custom options
+  // can only be successfully parsed after we register corresponding
+  // extensions. Therefore we parse all options again here to recognize
+  // custom options that may be unknown when we define the descriptors.
+  FixAllDescriptorOptions();
   if (HasGenericServices(file)) {
     PrintServices();
   }
@@ -288,6 +308,13 @@ void Generator::PrintImports() const {
                     module_name);
   }
   printer_->Print("\n");
+
+  // Print public imports.
+  for (int i = 0; i < file_->public_dependency_count(); ++i) {
+    string module_name = ModuleName(file_->public_dependency(i)->name());
+    printer_->Print("from $module$ import *\n", "module", module_name);
+  }
+  printer_->Print("\n");
 }
 
 // Prints the single file descriptor for this file.
@@ -297,7 +324,7 @@ void Generator::PrintFileDescriptor() const {
   m["name"] = file_->name();
   m["package"] = file_->package();
   const char file_descriptor_template[] =
-      "$descriptor_name$ = descriptor.FileDescriptor(\n"
+      "$descriptor_name$ = _descriptor.FileDescriptor(\n"
       "  name='$name$',\n"
       "  package='$package$',\n";
   printer_->Print(m, file_descriptor_template);
@@ -321,6 +348,11 @@ void Generator::PrintTopLevelEnums() const {
   for (int i = 0; i < file_->enum_type_count(); ++i) {
     const EnumDescriptor& enum_descriptor = *file_->enum_type(i);
     PrintEnum(enum_descriptor);
+    printer_->Print("$name$ = "
+                    "enum_type_wrapper.EnumTypeWrapper($descriptor_name$)",
+                    "name", enum_descriptor.name(),
+                    "descriptor_name",
+                    ModuleLevelDescriptorName(enum_descriptor));
     printer_->Print("\n");
 
     for (int j = 0; j < enum_descriptor.value_count(); ++j) {
@@ -355,7 +387,7 @@ void Generator::PrintEnum(const EnumDescriptor& enum_descriptor) const {
   m["full_name"] = enum_descriptor.full_name();
   m["file"] = kDescriptorKey;
   const char enum_descriptor_template[] =
-      "$descriptor_name$ = descriptor.EnumDescriptor(\n"
+      "$descriptor_name$ = _descriptor.EnumDescriptor(\n"
       "  name='$name$',\n"
       "  full_name='$full_name$',\n"
       "  filename=None,\n"
@@ -436,7 +468,7 @@ void Generator::PrintServiceDescriptor(
   descriptor.options().SerializeToString(&options_string);
 
   printer_->Print(
-      "$service_name$ = descriptor.ServiceDescriptor(\n",
+      "$service_name$ = _descriptor.ServiceDescriptor(\n",
       "service_name", service_name);
   printer_->Indent();
   map<string, string> m;
@@ -459,7 +491,6 @@ void Generator::PrintServiceDescriptor(
   printer_->Print("methods=[\n");
   for (int i = 0; i < descriptor.method_count(); ++i) {
     const MethodDescriptor* method = descriptor.method(i);
-    string options_string;
     method->options().SerializeToString(&options_string);
 
     m.clear();
@@ -470,7 +501,7 @@ void Generator::PrintServiceDescriptor(
     m["input_type"] = ModuleLevelDescriptorName(*(method->input_type()));
     m["output_type"] = ModuleLevelDescriptorName(*(method->output_type()));
     m["options_value"] = OptionsValue("MethodOptions", options_string);
-    printer_->Print("descriptor.MethodDescriptor(\n");
+    printer_->Print("_descriptor.MethodDescriptor(\n");
     printer_->Indent();
     printer_->Print(
         m,
@@ -491,7 +522,7 @@ void Generator::PrintServiceDescriptor(
 
 void Generator::PrintServiceClass(const ServiceDescriptor& descriptor) const {
   // Print the service.
-  printer_->Print("class $class_name$(service.Service):\n",
+  printer_->Print("class $class_name$(_service.Service):\n",
                   "class_name", descriptor.name());
   printer_->Indent();
   printer_->Print(
@@ -523,7 +554,7 @@ void Generator::PrintDescriptor(const Descriptor& message_descriptor) const {
   PrintNestedDescriptors(message_descriptor);
 
   printer_->Print("\n");
-  printer_->Print("$descriptor_name$ = descriptor.Descriptor(\n",
+  printer_->Print("$descriptor_name$ = _descriptor.Descriptor(\n",
                   "descriptor_name",
                   ModuleLevelDescriptorName(message_descriptor));
   printer_->Indent();
@@ -618,10 +649,10 @@ void Generator::PrintMessages() const {
 // Mutually recursive with PrintNestedMessages().
 void Generator::PrintMessage(
     const Descriptor& message_descriptor) const {
-  printer_->Print("class $name$(message.Message):\n", "name",
+  printer_->Print("class $name$(_message.Message):\n", "name",
                   message_descriptor.name());
   printer_->Indent();
-  printer_->Print("__metaclass__ = reflection.GeneratedProtocolMessageType\n");
+  printer_->Print("__metaclass__ = _reflection.GeneratedProtocolMessageType\n");
   PrintNestedMessages(message_descriptor);
   map<string, string> m;
   m["descriptor_key"] = kDescriptorKey;
@@ -779,6 +810,7 @@ void Generator::FixForeignFieldsInExtensions() const {
   for (int i = 0; i < file_->message_type_count(); ++i) {
     FixForeignFieldsInNestedExtensions(*file_->message_type(i));
   }
+  printer_->Print("\n");
 }
 
 void Generator::FixForeignFieldsInExtension(
@@ -829,7 +861,7 @@ void Generator::PrintEnumValueDescriptor(
   m["options"] = OptionsValue("EnumValueOptions", options_string);
   printer_->Print(
       m,
-      "descriptor.EnumValueDescriptor(\n"
+      "_descriptor.EnumValueDescriptor(\n"
       "  name='$name$', index=$index$, number=$number$,\n"
       "  options=$options$,\n"
       "  type=None)");
@@ -843,7 +875,7 @@ string Generator::OptionsValue(
     return "None";
   } else {
     string full_class_name = "descriptor_pb2." + class_name;
-    return "descriptor._ParseOptions(" + full_class_name + "(), '"
+    return "_descriptor._ParseOptions(" + full_class_name + "(), '"
         + CEscape(serialized_options)+ "')";
   }
 }
@@ -869,7 +901,7 @@ void Generator::PrintFieldDescriptor(
   // these fields in correctly after all referenced descriptors have been
   // defined and/or imported (see FixForeignFieldsInDescriptors()).
   const char field_descriptor_decl[] =
-    "descriptor.FieldDescriptor(\n"
+    "_descriptor.FieldDescriptor(\n"
     "  name='$name$', full_name='$full_name$', index=$index$,\n"
     "  number=$number$, type=$type$, cpp_type=$cpp_type$, label=$label$,\n"
     "  has_default_value=$has_default_value$, default_value=$default_value$,\n"
@@ -1000,6 +1032,125 @@ void Generator::PrintSerializedPbInterval(
                   "serialized_end", SimpleItoa(offset + sp.size()));
 }
 
+namespace {
+void PrintDescriptorOptionsFixingCode(const string& descriptor,
+                                      const string& options,
+                                      io::Printer* printer) {
+  // TODO(xiaofeng): I have added a method _SetOptions() to DescriptorBase
+  // in proto2 python runtime but it couldn't be used here because appengine
+  // uses a snapshot version of the library in which the new method is not
+  // yet present. After appengine has synced their runtime library, the code
+  // below should be cleaned up to use _SetOptions().
+  printer->Print(
+      "$descriptor$.has_options = True\n"
+      "$descriptor$._options = $options$\n",
+      "descriptor", descriptor, "options", options);
+}
+}  // namespace
+
+// Prints expressions that set the options field of all descriptors.
+void Generator::FixAllDescriptorOptions() const {
+  // Prints an expression that sets the file descriptor's options.
+  string file_options = OptionsValue(
+      "FileOptions", file_->options().SerializeAsString());
+  if (file_options != "None") {
+    PrintDescriptorOptionsFixingCode(kDescriptorKey, file_options, printer_);
+  }
+  // Prints expressions that set the options for all top level enums.
+  for (int i = 0; i < file_->enum_type_count(); ++i) {
+    const EnumDescriptor& enum_descriptor = *file_->enum_type(i);
+    FixOptionsForEnum(enum_descriptor);
+  }
+  // Prints expressions that set the options for all top level extensions.
+  for (int i = 0; i < file_->extension_count(); ++i) {
+    const FieldDescriptor& field = *file_->extension(i);
+    FixOptionsForField(field);
+  }
+  // Prints expressions that set the options for all messages, nested enums,
+  // nested extensions and message fields.
+  for (int i = 0; i < file_->message_type_count(); ++i) {
+    FixOptionsForMessage(*file_->message_type(i));
+  }
+}
+
+// Prints expressions that set the options for an enum descriptor and its
+// value descriptors.
+void Generator::FixOptionsForEnum(const EnumDescriptor& enum_descriptor) const {
+  string descriptor_name = ModuleLevelDescriptorName(enum_descriptor);
+  string enum_options = OptionsValue(
+      "EnumOptions", enum_descriptor.options().SerializeAsString());
+  if (enum_options != "None") {
+    PrintDescriptorOptionsFixingCode(descriptor_name, enum_options, printer_);
+  }
+  for (int i = 0; i < enum_descriptor.value_count(); ++i) {
+    const EnumValueDescriptor& value_descriptor = *enum_descriptor.value(i);
+    string value_options = OptionsValue(
+        "EnumValueOptions", value_descriptor.options().SerializeAsString());
+    if (value_options != "None") {
+      PrintDescriptorOptionsFixingCode(
+          StringPrintf("%s.values_by_name[\"%s\"]", descriptor_name.c_str(),
+                       value_descriptor.name().c_str()),
+          value_options, printer_);
+    }
+  }
+}
+
+// Prints expressions that set the options for field descriptors (including
+// extensions).
+void Generator::FixOptionsForField(
+    const FieldDescriptor& field) const {
+  string field_options = OptionsValue(
+      "FieldOptions", field.options().SerializeAsString());
+  if (field_options != "None") {
+    string field_name;
+    if (field.is_extension()) {
+      if (field.extension_scope() == NULL) {
+        // Top level extensions.
+        field_name = field.name();
+      } else {
+        field_name = FieldReferencingExpression(
+            field.extension_scope(), field, "extensions_by_name");
+      }
+    } else {
+      field_name = FieldReferencingExpression(
+          field.containing_type(), field, "fields_by_name");
+    }
+    PrintDescriptorOptionsFixingCode(field_name, field_options, printer_);
+  }
+}
+
+// Prints expressions that set the options for a message and all its inner
+// types (nested messages, nested enums, extensions, fields).
+void Generator::FixOptionsForMessage(const Descriptor& descriptor) const {
+  // Nested messages.
+  for (int i = 0; i < descriptor.nested_type_count(); ++i) {
+    FixOptionsForMessage(*descriptor.nested_type(i));
+  }
+  // Enums.
+  for (int i = 0; i < descriptor.enum_type_count(); ++i) {
+    FixOptionsForEnum(*descriptor.enum_type(i));
+  }
+  // Fields.
+  for (int i = 0; i < descriptor.field_count(); ++i) {
+    const FieldDescriptor& field = *descriptor.field(i);
+    FixOptionsForField(field);
+  }
+  // Extensions.
+  for (int i = 0; i < descriptor.extension_count(); ++i) {
+    const FieldDescriptor& field = *descriptor.extension(i);
+    FixOptionsForField(field);
+  }
+  // Message option for this message.
+  string message_options = OptionsValue(
+      "MessageOptions", descriptor.options().SerializeAsString());
+  if (message_options != "None") {
+    string descriptor_name = ModuleLevelDescriptorName(descriptor);
+    PrintDescriptorOptionsFixingCode(descriptor_name,
+                                     message_options,
+                                     printer_);
+  }
+}
+
 }  // namespace python
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/python/python_generator.h b/src/google/protobuf/compiler/python/python_generator.h
index 84eaf8ab..a3f22cee 100644
--- a/src/google/protobuf/compiler/python/python_generator.h
+++ b/src/google/protobuf/compiler/python/python_generator.h
@@ -138,6 +138,11 @@ class LIBPROTOC_EXPORT Generator : public CodeGenerator {
   void PrintSerializedPbInterval(
       const DescriptorT& descriptor, DescriptorProtoT& proto) const;
 
+  void FixAllDescriptorOptions() const;
+  void FixOptionsForField(const FieldDescriptor& field) const;
+  void FixOptionsForEnum(const EnumDescriptor& descriptor) const;
+  void FixOptionsForMessage(const Descriptor& descriptor) const;
+
   // Very coarse-grained lock to ensure that Generate() is reentrant.
   // Guards file_, printer_ and file_descriptor_serialized_.
   mutable Mutex mutex_;
diff --git a/src/google/protobuf/compiler/subprocess.cc b/src/google/protobuf/compiler/subprocess.cc
index 5fb5d5cb..860fc875 100644
--- a/src/google/protobuf/compiler/subprocess.cc
+++ b/src/google/protobuf/compiler/subprocess.cc
@@ -33,6 +33,7 @@
 #include <google/protobuf/compiler/subprocess.h>
 
 #include <algorithm>
+#include <iostream>
 
 #ifndef _WIN32
 #include <errno.h>
diff --git a/src/google/protobuf/compiler/subprocess.h b/src/google/protobuf/compiler/subprocess.h
index 00564964..de9fce9e 100644
--- a/src/google/protobuf/compiler/subprocess.h
+++ b/src/google/protobuf/compiler/subprocess.h
@@ -53,7 +53,7 @@ class Message;
 namespace compiler {
 
 // Utility class for launching sub-processes.
-class LIBPROTOC_EXPORT Subprocess {
+class Subprocess {
  public:
   Subprocess();
   ~Subprocess();
diff --git a/src/google/protobuf/descriptor.cc b/src/google/protobuf/descriptor.cc
index 754b5628..a60abf43 100644
--- a/src/google/protobuf/descriptor.cc
+++ b/src/google/protobuf/descriptor.cc
@@ -54,7 +54,7 @@
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/stubs/map-util.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 #undef PACKAGE  // autoheader #defines this.  :(
 
@@ -108,6 +108,21 @@ const char * const FieldDescriptor::kTypeToName[MAX_TYPE + 1] = {
   "sint64",    // TYPE_SINT64
 };
 
+const char * const FieldDescriptor::kCppTypeToName[MAX_CPPTYPE + 1] = {
+  "ERROR",     // 0 is reserved for errors
+
+  "int32",     // CPPTYPE_INT32
+  "int64",     // CPPTYPE_INT64
+  "uint32",    // CPPTYPE_UINT32
+  "uint64",    // CPPTYPE_UINT64
+  "double",    // CPPTYPE_DOUBLE
+  "float",     // CPPTYPE_FLOAT
+  "bool",      // CPPTYPE_BOOL
+  "enum",      // CPPTYPE_ENUM
+  "string",    // CPPTYPE_STRING
+  "message",   // CPPTYPE_MESSAGE
+};
+
 const char * const FieldDescriptor::kLabelToName[MAX_LABEL + 1] = {
   "ERROR",     // 0 is reserved for errors
 
@@ -221,7 +236,8 @@ struct PointerStringPairHash {
 
 struct Symbol {
   enum Type {
-    NULL_SYMBOL, MESSAGE, FIELD, ENUM, ENUM_VALUE, SERVICE, METHOD, PACKAGE
+    NULL_SYMBOL, MESSAGE, FIELD, ENUM, ENUM_VALUE, SERVICE, METHOD,
+    PACKAGE
   };
   Type type;
   union {
@@ -311,17 +327,42 @@ class DescriptorPool::Tables {
   Tables();
   ~Tables();
 
-  // Checkpoint the state of the tables.  Future calls to Rollback() will
-  // return the Tables to this state.  This is used when building files, since
-  // some kinds of validation errors cannot be detected until the file's
-  // descriptors have already been added to the tables.  BuildFile() calls
-  // Checkpoint() before it starts building and Rollback() if it encounters
-  // an error.
-  void Checkpoint();
+  // Record the current state of the tables to the stack of checkpoints.
+  // Each call to AddCheckpoint() must be paired with exactly one call to either
+  // ClearLastCheckpoint() or RollbackToLastCheckpoint().
+  //
+  // This is used when building files, since some kinds of validation errors
+  // cannot be detected until the file's descriptors have already been added to
+  // the tables.
+  //
+  // This supports recursive checkpoints, since building a file may trigger
+  // recursive building of other files. Note that recursive checkpoints are not
+  // normally necessary; explicit dependencies are built prior to checkpointing.
+  // So although we recursively build transitive imports, there is at most one
+  // checkpoint in the stack during dependency building.
+  //
+  // Recursive checkpoints only arise during cross-linking of the descriptors.
+  // Symbol references must be resolved, via DescriptorBuilder::FindSymbol and
+  // friends. If the pending file references an unknown symbol
+  // (e.g., it is not defined in the pending file's explicit dependencies), and
+  // the pool is using a fallback database, and that database contains a file
+  // defining that symbol, and that file has not yet been built by the pool,
+  // the pool builds the file during cross-linking, leading to another
+  // checkpoint.
+  void AddCheckpoint();
+
+  // Mark the last checkpoint as having cleared successfully, removing it from
+  // the stack. If the stack is empty, all pending symbols will be committed.
+  //
+  // Note that this does not guarantee that the symbols added since the last
+  // checkpoint won't be rolled back: if a checkpoint gets rolled back,
+  // everything past that point gets rolled back, including symbols added after
+  // checkpoints that were pushed onto the stack after it and marked as cleared.
+  void ClearLastCheckpoint();
 
-  // Roll back the Tables to the state of the last Checkpoint(), removing
-  // everything that was added after that point.
-  void Rollback();
+  // Roll back the Tables to the state of the checkpoint at the top of the
+  // stack, removing everything that was added after that point.
+  void RollbackToLastCheckpoint();
 
   // The stack of files which are currently being built.  Used to detect
   // cyclic dependencies when loading files from a DescriptorDatabase.  Not
@@ -405,10 +446,28 @@ class DescriptorPool::Tables {
   FilesByNameMap        files_by_name_;
   ExtensionsGroupedByDescriptorMap extensions_;
 
-  int strings_before_checkpoint_;
-  int messages_before_checkpoint_;
-  int file_tables_before_checkpoint_;
-  int allocations_before_checkpoint_;
+  struct CheckPoint {
+    explicit CheckPoint(const Tables* tables)
+      : strings_before_checkpoint(tables->strings_.size()),
+        messages_before_checkpoint(tables->messages_.size()),
+        file_tables_before_checkpoint(tables->file_tables_.size()),
+        allocations_before_checkpoint(tables->allocations_.size()),
+        pending_symbols_before_checkpoint(
+            tables->symbols_after_checkpoint_.size()),
+        pending_files_before_checkpoint(
+            tables->files_after_checkpoint_.size()),
+        pending_extensions_before_checkpoint(
+            tables->extensions_after_checkpoint_.size()) {
+    }
+    int strings_before_checkpoint;
+    int messages_before_checkpoint;
+    int file_tables_before_checkpoint;
+    int allocations_before_checkpoint;
+    int pending_symbols_before_checkpoint;
+    int pending_files_before_checkpoint;
+    int pending_extensions_before_checkpoint;
+  };
+  vector<CheckPoint> checkpoints_;
   vector<const char*      > symbols_after_checkpoint_;
   vector<const char*      > files_after_checkpoint_;
   vector<DescriptorIntPair> extensions_after_checkpoint_;
@@ -481,11 +540,15 @@ class FileDescriptorTables {
 };
 
 DescriptorPool::Tables::Tables()
-  : strings_before_checkpoint_(0),
-    messages_before_checkpoint_(0),
-    allocations_before_checkpoint_(0) {}
+    // Start some hash_map and hash_set objects with a small # of buckets
+    : known_bad_files_(3),
+      extensions_loaded_from_db_(3),
+      symbols_by_name_(3),
+      files_by_name_(3) {}
+
 
 DescriptorPool::Tables::~Tables() {
+  GOOGLE_DCHECK(checkpoints_.empty());
   // Note that the deletion order is important, since the destructors of some
   // messages may refer to objects in allocations_.
   STLDeleteElements(&messages_);
@@ -496,51 +559,80 @@ DescriptorPool::Tables::~Tables() {
   STLDeleteElements(&file_tables_);
 }
 
-FileDescriptorTables::FileDescriptorTables() {}
+FileDescriptorTables::FileDescriptorTables()
+    // Initialize all the hash tables to start out with a small # of buckets
+    : symbols_by_parent_(3),
+      fields_by_lowercase_name_(3),
+      fields_by_camelcase_name_(3),
+      fields_by_number_(3),
+      enum_values_by_number_(3) {
+}
+
 FileDescriptorTables::~FileDescriptorTables() {}
 
 const FileDescriptorTables FileDescriptorTables::kEmpty;
 
-void DescriptorPool::Tables::Checkpoint() {
-  strings_before_checkpoint_ = strings_.size();
-  messages_before_checkpoint_ = messages_.size();
-  file_tables_before_checkpoint_ = file_tables_.size();
-  allocations_before_checkpoint_ = allocations_.size();
+void DescriptorPool::Tables::AddCheckpoint() {
+  checkpoints_.push_back(CheckPoint(this));
+}
 
-  symbols_after_checkpoint_.clear();
-  files_after_checkpoint_.clear();
-  extensions_after_checkpoint_.clear();
+void DescriptorPool::Tables::ClearLastCheckpoint() {
+  GOOGLE_DCHECK(!checkpoints_.empty());
+  checkpoints_.pop_back();
+  if (checkpoints_.empty()) {
+    // All checkpoints have been cleared: we can now commit all of the pending
+    // data.
+    symbols_after_checkpoint_.clear();
+    files_after_checkpoint_.clear();
+    extensions_after_checkpoint_.clear();
+  }
 }
 
-void DescriptorPool::Tables::Rollback() {
-  for (int i = 0; i < symbols_after_checkpoint_.size(); i++) {
+void DescriptorPool::Tables::RollbackToLastCheckpoint() {
+  GOOGLE_DCHECK(!checkpoints_.empty());
+  const CheckPoint& checkpoint = checkpoints_.back();
+
+  for (int i = checkpoint.pending_symbols_before_checkpoint;
+       i < symbols_after_checkpoint_.size();
+       i++) {
     symbols_by_name_.erase(symbols_after_checkpoint_[i]);
   }
-  for (int i = 0; i < files_after_checkpoint_.size(); i++) {
+  for (int i = checkpoint.pending_files_before_checkpoint;
+       i < files_after_checkpoint_.size();
+       i++) {
     files_by_name_.erase(files_after_checkpoint_[i]);
   }
-  for (int i = 0; i < extensions_after_checkpoint_.size(); i++) {
+  for (int i = checkpoint.pending_extensions_before_checkpoint;
+       i < extensions_after_checkpoint_.size();
+       i++) {
     extensions_.erase(extensions_after_checkpoint_[i]);
   }
 
-  symbols_after_checkpoint_.clear();
-  files_after_checkpoint_.clear();
-  extensions_after_checkpoint_.clear();
+  symbols_after_checkpoint_.resize(
+      checkpoint.pending_symbols_before_checkpoint);
+  files_after_checkpoint_.resize(checkpoint.pending_files_before_checkpoint);
+  extensions_after_checkpoint_.resize(
+      checkpoint.pending_extensions_before_checkpoint);
 
   STLDeleteContainerPointers(
-    strings_.begin() + strings_before_checkpoint_, strings_.end());
+      strings_.begin() + checkpoint.strings_before_checkpoint, strings_.end());
   STLDeleteContainerPointers(
-    messages_.begin() + messages_before_checkpoint_, messages_.end());
+      messages_.begin() + checkpoint.messages_before_checkpoint,
+      messages_.end());
   STLDeleteContainerPointers(
-    file_tables_.begin() + file_tables_before_checkpoint_, file_tables_.end());
-  for (int i = allocations_before_checkpoint_; i < allocations_.size(); i++) {
+      file_tables_.begin() + checkpoint.file_tables_before_checkpoint,
+      file_tables_.end());
+  for (int i = checkpoint.allocations_before_checkpoint;
+       i < allocations_.size();
+       i++) {
     operator delete(allocations_[i]);
   }
 
-  strings_.resize(strings_before_checkpoint_);
-  messages_.resize(messages_before_checkpoint_);
-  file_tables_.resize(file_tables_before_checkpoint_);
-  allocations_.resize(allocations_before_checkpoint_);
+  strings_.resize(checkpoint.strings_before_checkpoint);
+  messages_.resize(checkpoint.messages_before_checkpoint);
+  file_tables_.resize(checkpoint.file_tables_before_checkpoint);
+  allocations_.resize(checkpoint.allocations_before_checkpoint);
+  checkpoints_.pop_back();
 }
 
 // -------------------------------------------------------------------
@@ -811,7 +903,7 @@ void DeleteGeneratedPool() {
   generated_pool_ = NULL;
 }
 
-void InitGeneratedPool() {
+static void InitGeneratedPool() {
   generated_database_ = new EncodedDescriptorDatabase;
   generated_pool_ = new DescriptorPool(generated_database_);
 
@@ -874,11 +966,11 @@ const FileDescriptor* DescriptorPool::FindFileByName(const string& name) const {
   const FileDescriptor* result = tables_->FindFile(name);
   if (result != NULL) return result;
   if (underlay_ != NULL) {
-    const FileDescriptor* result = underlay_->FindFileByName(name);
+    result = underlay_->FindFileByName(name);
     if (result != NULL) return result;
   }
   if (TryFindFileInFallbackDatabase(name)) {
-    const FileDescriptor* result = tables_->FindFile(name);
+    result = tables_->FindFile(name);
     if (result != NULL) return result;
   }
   return NULL;
@@ -890,12 +982,12 @@ const FileDescriptor* DescriptorPool::FindFileContainingSymbol(
   Symbol result = tables_->FindSymbol(symbol_name);
   if (!result.IsNull()) return result.GetFile();
   if (underlay_ != NULL) {
-    const FileDescriptor* result =
+    const FileDescriptor* file_result =
       underlay_->FindFileContainingSymbol(symbol_name);
-    if (result != NULL) return result;
+    if (file_result != NULL) return file_result;
   }
   if (TryFindSymbolInFallbackDatabase(symbol_name)) {
-    Symbol result = tables_->FindSymbol(symbol_name);
+    result = tables_->FindSymbol(symbol_name);
     if (!result.IsNull()) return result.GetFile();
   }
   return NULL;
@@ -962,12 +1054,11 @@ const FieldDescriptor* DescriptorPool::FindExtensionByNumber(
     return result;
   }
   if (underlay_ != NULL) {
-    const FieldDescriptor* result =
-      underlay_->FindExtensionByNumber(extendee, number);
+    result = underlay_->FindExtensionByNumber(extendee, number);
     if (result != NULL) return result;
   }
   if (TryFindExtensionInFallbackDatabase(extendee, number)) {
-    const FieldDescriptor* result = tables_->FindExtension(extendee, number);
+    result = tables_->FindExtension(extendee, number);
     if (result != NULL) {
       return result;
     }
@@ -1241,9 +1332,48 @@ bool DescriptorPool::TryFindFileInFallbackDatabase(const string& name) const {
   return true;
 }
 
+bool DescriptorPool::IsSubSymbolOfBuiltType(const string& name) const {
+  string prefix = name;
+  for (;;) {
+    string::size_type dot_pos = prefix.find_last_of('.');
+    if (dot_pos == string::npos) {
+      break;
+    }
+    prefix = prefix.substr(0, dot_pos);
+    Symbol symbol = tables_->FindSymbol(prefix);
+    // If the symbol type is anything other than PACKAGE, then its complete
+    // definition is already known.
+    if (!symbol.IsNull() && symbol.type != Symbol::PACKAGE) {
+      return true;
+    }
+  }
+  if (underlay_ != NULL) {
+    // Check to see if any prefix of this symbol exists in the underlay.
+    return underlay_->IsSubSymbolOfBuiltType(name);
+  }
+  return false;
+}
+
 bool DescriptorPool::TryFindSymbolInFallbackDatabase(const string& name) const {
   if (fallback_database_ == NULL) return false;
 
+  // We skip looking in the fallback database if the name is a sub-symbol of
+  // any descriptor that already exists in the descriptor pool (except for
+  // package descriptors).  This is valid because all symbols except for
+  // packages are defined in a single file, so if the symbol exists then we
+  // should already have its definition.
+  //
+  // The other reason to do this is to support "overriding" type definitions
+  // by merging two databases that define the same type.  (Yes, people do
+  // this.)  The main difficulty with making this work is that
+  // FindFileContainingSymbol() is allowed to return both false positives
+  // (e.g., SimpleDescriptorDatabase, UpgradedDescriptorDatabase) and false
+  // negatives (e.g. ProtoFileParser, SourceTreeDescriptorDatabase).  When two
+  // such databases are merged, looking up a non-existent sub-symbol of a type
+  // that already exists in the descriptor pool can result in an attempt to
+  // load multiple definitions of the same type.  The check below avoids this.
+  if (IsSubSymbolOfBuiltType(name)) return false;
+
   FileDescriptorProto file_proto;
   if (!fallback_database_->FindFileContainingSymbol(name, &file_proto)) {
     return false;
@@ -1345,6 +1475,14 @@ void FileDescriptor::CopyTo(FileDescriptorProto* proto) const {
     proto->add_dependency(dependency(i)->name());
   }
 
+  for (int i = 0; i < public_dependency_count(); i++) {
+    proto->add_public_dependency(public_dependencies_[i]);
+  }
+
+  for (int i = 0; i < weak_dependency_count(); i++) {
+    proto->add_weak_dependency(weak_dependencies_[i]);
+  }
+
   for (int i = 0; i < message_type_count(); i++) {
     message_type(i)->CopyTo(proto->add_message_type());
   }
@@ -1363,6 +1501,12 @@ void FileDescriptor::CopyTo(FileDescriptorProto* proto) const {
   }
 }
 
+void FileDescriptor::CopySourceCodeInfoTo(FileDescriptorProto* proto) const {
+  if (source_code_info_ != &SourceCodeInfo::default_instance()) {
+    proto->mutable_source_code_info()->CopyFrom(*source_code_info_);
+  }
+}
+
 void Descriptor::CopyTo(DescriptorProto* proto) const {
   proto->set_name(name());
 
@@ -1490,16 +1634,14 @@ void MethodDescriptor::CopyTo(MethodDescriptorProto* proto) const {
 namespace {
 
 // Used by each of the option formatters.
-bool RetrieveOptions(const Message &options, vector<string> *option_entries) {
+bool RetrieveOptions(int depth,
+                     const Message &options,
+                     vector<string> *option_entries) {
   option_entries->clear();
   const Reflection* reflection = options.GetReflection();
   vector<const FieldDescriptor*> fields;
   reflection->ListFields(options, &fields);
   for (int i = 0; i < fields.size(); i++) {
-    // Doesn't make sense to have message type fields here
-    if (fields[i]->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
-      continue;
-    }
     int count = 1;
     bool repeated = false;
     if (fields[i]->is_repeated()) {
@@ -1508,9 +1650,27 @@ bool RetrieveOptions(const Message &options, vector<string> *option_entries) {
     }
     for (int j = 0; j < count; j++) {
       string fieldval;
-      TextFormat::PrintFieldValueToString(options, fields[i],
-                                          repeated ? count : -1, &fieldval);
-      option_entries->push_back(fields[i]->name() + " = " + fieldval);
+      if (fields[i]->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+        string tmp;
+        TextFormat::Printer printer;
+        printer.SetInitialIndentLevel(depth + 1);
+        printer.PrintFieldValueToString(options, fields[i],
+                                        repeated ? j : -1, &tmp);
+        fieldval.append("{\n");
+        fieldval.append(tmp);
+        fieldval.append(depth * 2, ' ');
+        fieldval.append("}");
+      } else {
+        TextFormat::PrintFieldValueToString(options, fields[i],
+                                            repeated ? j : -1, &fieldval);
+      }
+      string name;
+      if (fields[i]->is_extension()) {
+        name = "(." + fields[i]->full_name() + ")";
+      } else {
+        name = fields[i]->name();
+      }
+      option_entries->push_back(name + " = " + fieldval);
     }
   }
   return !option_entries->empty();
@@ -1518,9 +1678,9 @@ bool RetrieveOptions(const Message &options, vector<string> *option_entries) {
 
 // Formats options that all appear together in brackets. Does not include
 // brackets.
-bool FormatBracketedOptions(const Message &options, string *output) {
+bool FormatBracketedOptions(int depth, const Message &options, string *output) {
   vector<string> all_options;
-  if (RetrieveOptions(options, &all_options)) {
+  if (RetrieveOptions(depth, options, &all_options)) {
     output->append(JoinStrings(all_options, ", "));
   }
   return !all_options.empty();
@@ -1530,7 +1690,7 @@ bool FormatBracketedOptions(const Message &options, string *output) {
 bool FormatLineOptions(int depth, const Message &options, string *output) {
   string prefix(depth * 2, ' ');
   vector<string> all_options;
-  if (RetrieveOptions(options, &all_options)) {
+  if (RetrieveOptions(depth, options, &all_options)) {
     for (int i = 0; i < all_options.size(); i++) {
       strings::SubstituteAndAppend(output, "$0option $1;\n",
                                    prefix, all_options[i]);
@@ -1544,9 +1704,24 @@ bool FormatLineOptions(int depth, const Message &options, string *output) {
 string FileDescriptor::DebugString() const {
   string contents = "syntax = \"proto2\";\n\n";
 
+  set<int> public_dependencies;
+  set<int> weak_dependencies;
+  public_dependencies.insert(public_dependencies_,
+                             public_dependencies_ + public_dependency_count_);
+  weak_dependencies.insert(weak_dependencies_,
+                           weak_dependencies_ + weak_dependency_count_);
+
   for (int i = 0; i < dependency_count(); i++) {
-    strings::SubstituteAndAppend(&contents, "import \"$0\";\n",
-                                 dependency(i)->name());
+    if (public_dependencies.count(i) > 0) {
+      strings::SubstituteAndAppend(&contents, "import public \"$0\";\n",
+                                   dependency(i)->name());
+    } else if (weak_dependencies.count(i) > 0) {
+      strings::SubstituteAndAppend(&contents, "import weak \"$0\";\n",
+                                   dependency(i)->name());
+    } else {
+      strings::SubstituteAndAppend(&contents, "import \"$0\";\n",
+                                   dependency(i)->name());
+    }
   }
 
   if (!package().empty()) {
@@ -1712,7 +1887,7 @@ void FieldDescriptor::DebugString(int depth, string *contents) const {
   }
 
   string formatted_options;
-  if (FormatBracketedOptions(options(), &formatted_options)) {
+  if (FormatBracketedOptions(depth, options(), &formatted_options)) {
     contents->append(bracketed ? ", " : " [");
     bracketed = true;
     contents->append(formatted_options);
@@ -1761,7 +1936,7 @@ void EnumValueDescriptor::DebugString(int depth, string *contents) const {
                                prefix, name(), number());
 
   string formatted_options;
-  if (FormatBracketedOptions(options(), &formatted_options)) {
+  if (FormatBracketedOptions(depth, options(), &formatted_options)) {
     strings::SubstituteAndAppend(contents, " [$0]", formatted_options);
   }
   contents->append(";\n");
@@ -1807,6 +1982,126 @@ void MethodDescriptor::DebugString(int depth, string *contents) const {
     contents->append(";\n");
   }
 }
+
+
+// Location methods ===============================================
+
+static bool PathsEqual(const vector<int>& x, const RepeatedField<int32>& y) {
+  if (x.size() != y.size()) return false;
+  for (int i = 0; i < x.size(); ++i) {
+    if (x[i] != y.Get(i)) return false;
+  }
+  return true;
+}
+
+bool FileDescriptor::GetSourceLocation(const vector<int>& path,
+                                       SourceLocation* out_location) const {
+  GOOGLE_CHECK_NOTNULL(out_location);
+  const SourceCodeInfo* info = source_code_info_;
+  for (int i = 0; info && i < info->location_size(); ++i) {
+    if (PathsEqual(path, info->location(i).path())) {
+      const RepeatedField<int32>& span = info->location(i).span();
+      if (span.size() == 3 || span.size() == 4) {
+        out_location->start_line   = span.Get(0);
+        out_location->start_column = span.Get(1);
+        out_location->end_line     = span.Get(span.size() == 3 ? 0 : 2);
+        out_location->end_column   = span.Get(span.size() - 1);
+
+        out_location->leading_comments = info->location(i).leading_comments();
+        out_location->trailing_comments = info->location(i).trailing_comments();
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+bool FieldDescriptor::is_packed() const {
+  return is_packable() && (options_ != NULL) && options_->packed();
+}
+
+bool Descriptor::GetSourceLocation(SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return file()->GetSourceLocation(path, out_location);
+}
+
+bool FieldDescriptor::GetSourceLocation(SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return file()->GetSourceLocation(path, out_location);
+}
+
+bool EnumDescriptor::GetSourceLocation(SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return file()->GetSourceLocation(path, out_location);
+}
+
+bool MethodDescriptor::GetSourceLocation(SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return service()->file()->GetSourceLocation(path, out_location);
+}
+
+bool ServiceDescriptor::GetSourceLocation(SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return file()->GetSourceLocation(path, out_location);
+}
+
+bool EnumValueDescriptor::GetSourceLocation(
+    SourceLocation* out_location) const {
+  vector<int> path;
+  GetLocationPath(&path);
+  return type()->file()->GetSourceLocation(path, out_location);
+}
+
+void Descriptor::GetLocationPath(vector<int>* output) const {
+  if (containing_type()) {
+    containing_type()->GetLocationPath(output);
+    output->push_back(DescriptorProto::kNestedTypeFieldNumber);
+    output->push_back(index());
+  } else {
+    output->push_back(FileDescriptorProto::kMessageTypeFieldNumber);
+    output->push_back(index());
+  }
+}
+
+void FieldDescriptor::GetLocationPath(vector<int>* output) const {
+  containing_type()->GetLocationPath(output);
+  output->push_back(DescriptorProto::kFieldFieldNumber);
+  output->push_back(index());
+}
+
+void EnumDescriptor::GetLocationPath(vector<int>* output) const {
+  if (containing_type()) {
+    containing_type()->GetLocationPath(output);
+    output->push_back(DescriptorProto::kEnumTypeFieldNumber);
+    output->push_back(index());
+  } else {
+    output->push_back(FileDescriptorProto::kEnumTypeFieldNumber);
+    output->push_back(index());
+  }
+}
+
+void EnumValueDescriptor::GetLocationPath(vector<int>* output) const {
+  type()->GetLocationPath(output);
+  output->push_back(EnumDescriptorProto::kValueFieldNumber);
+  output->push_back(index());
+}
+
+void ServiceDescriptor::GetLocationPath(vector<int>* output) const {
+  output->push_back(FileDescriptorProto::kServiceFieldNumber);
+  output->push_back(index());
+}
+
+void MethodDescriptor::GetLocationPath(vector<int>* output) const {
+  service()->GetLocationPath(output);
+  output->push_back(ServiceDescriptorProto::kMethodFieldNumber);
+  output->push_back(index());
+}
+
 // ===================================================================
 
 namespace {
@@ -1859,6 +2154,7 @@ class DescriptorBuilder {
   string filename_;
   FileDescriptor* file_;
   FileDescriptorTables* file_tables_;
+  set<const FileDescriptor*> dependencies_;
 
   // If LookupSymbol() finds a symbol that is in a file which is not a declared
   // dependency of this file, it will fail, but will set
@@ -1888,6 +2184,10 @@ class DescriptorBuilder {
   // nested package within package_name.
   bool IsInPackage(const FileDescriptor* file, const string& package_name);
 
+  // Helper function which finds all public dependencies of the given file, and
+  // stores the them in the dependencies_ set in the builder.
+  void RecordPublicDependencies(const FileDescriptor* file);
+
   // Like tables_->FindSymbol(), but additionally:
   // - Search the pool's underlay if not found in tables_.
   // - Insure that the resulting Symbol is from one of the file's declared
@@ -1898,6 +2198,10 @@ class DescriptorBuilder {
   // file's declared dependencies.
   Symbol FindSymbolNotEnforcingDeps(const string& name);
 
+  // This implements the body of FindSymbolNotEnforcingDeps().
+  Symbol FindSymbolNotEnforcingDepsHelper(const DescriptorPool* pool,
+                                          const string& name);
+
   // Like FindSymbol(), but looks up the name relative to some other symbol
   // name.  This first searches siblings of relative_to, then siblings of its
   // parents, etc.  For example, LookupSymbol("foo.bar", "baz.qux.corge") makes
@@ -2189,6 +2493,7 @@ class DescriptorBuilder {
 
   void ValidateMapKey(FieldDescriptor* field,
                       const FieldDescriptorProto& proto);
+
 };
 
 const FileDescriptor* DescriptorPool::BuildFile(
@@ -2275,31 +2580,48 @@ bool DescriptorBuilder::IsInPackage(const FileDescriptor* file,
             file->package()[package_name.size()] == '.');
 }
 
-Symbol DescriptorBuilder::FindSymbolNotEnforcingDeps(const string& name) {
-  Symbol result;
+void DescriptorBuilder::RecordPublicDependencies(const FileDescriptor* file) {
+  if (file == NULL || !dependencies_.insert(file).second) return;
+  for (int i = 0; file != NULL && i < file->public_dependency_count(); i++) {
+    RecordPublicDependencies(file->public_dependency(i));
+  }
+}
 
-  // We need to search our pool and all its underlays.
-  const DescriptorPool* pool = pool_;
-  while (true) {
-    // If we are looking at an underlay, we must lock its mutex_, since we are
-    // accessing the underlay's tables_ dircetly.
-    MutexLockMaybe lock((pool == pool_) ? NULL : pool->mutex_);
+Symbol DescriptorBuilder::FindSymbolNotEnforcingDepsHelper(
+    const DescriptorPool* pool, const string& name) {
+  // If we are looking at an underlay, we must lock its mutex_, since we are
+  // accessing the underlay's tables_ directly.
+  MutexLockMaybe lock((pool == pool_) ? NULL : pool->mutex_);
+
+  Symbol result = pool->tables_->FindSymbol(name);
+  if (result.IsNull() && pool->underlay_ != NULL) {
+    // Symbol not found; check the underlay.
+    result = FindSymbolNotEnforcingDepsHelper(pool->underlay_, name);
+  }
 
-    // Note that we don't have to check fallback_database_ here because the
-    // symbol has to be in one of its file's direct dependencies, and we have
-    // already loaded those by the time we get here.
-    result = pool->tables_->FindSymbol(name);
-    if (!result.IsNull()) break;
-    if (pool->underlay_ == NULL) return kNullSymbol;
-    pool = pool->underlay_;
+  if (result.IsNull()) {
+    // In theory, we shouldn't need to check fallback_database_ because the
+    // symbol should be in one of its file's direct dependencies, and we have
+    // already loaded those by the time we get here.  But we check anyway so
+    // that we can generate better error message when dependencies are missing
+    // (i.e., "missing dependency" rather than "type is not defined").
+    if (pool->TryFindSymbolInFallbackDatabase(name)) {
+      result = pool->tables_->FindSymbol(name);
+    }
   }
 
   return result;
 }
 
+Symbol DescriptorBuilder::FindSymbolNotEnforcingDeps(const string& name) {
+  return FindSymbolNotEnforcingDepsHelper(pool_, name);
+}
+
 Symbol DescriptorBuilder::FindSymbol(const string& name) {
   Symbol result = FindSymbolNotEnforcingDeps(name);
 
+  if (result.IsNull()) return result;
+
   if (!pool_->enforce_dependencies_) {
     // Hack for CompilerUpgrader.
     return result;
@@ -2308,10 +2630,7 @@ Symbol DescriptorBuilder::FindSymbol(const string& name) {
   // Only find symbols which were defined in this file or one of its
   // dependencies.
   const FileDescriptor* file = result.GetFile();
-  if (file == file_) return result;
-  for (int i = 0; i < file_->dependency_count(); i++) {
-    if (file == file_->dependency(i)) return result;
-  }
+  if (file == file_ || dependencies_.count(file) > 0) return result;
 
   if (result.type == Symbol::PACKAGE) {
     // Arg, this is overcomplicated.  The symbol is a package name.  It could
@@ -2322,12 +2641,10 @@ Symbol DescriptorBuilder::FindSymbol(const string& name) {
     // dependency also defines the same package.  We can't really rule out this
     // symbol unless none of the dependencies define it.
     if (IsInPackage(file_, name)) return result;
-    for (int i = 0; i < file_->dependency_count(); i++) {
+    for (set<const FileDescriptor*>::const_iterator it = dependencies_.begin();
+         it != dependencies_.end(); ++it) {
       // Note:  A dependency may be NULL if it was not found or had errors.
-      if (file_->dependency(i) != NULL &&
-          IsInPackage(file_->dependency(i), name)) {
-        return result;
-      }
+      if (*it != NULL && IsInPackage(*it, name)) return result;
     }
   }
 
@@ -2448,6 +2765,8 @@ Symbol DescriptorBuilder::NewPlaceholder(const string& name,
   FileDescriptor* placeholder_file = tables_->Allocate<FileDescriptor>();
   memset(placeholder_file, 0, sizeof(*placeholder_file));
 
+  placeholder_file->source_code_info_ = &SourceCodeInfo::default_instance();
+
   placeholder_file->name_ =
     tables_->AllocateString(*placeholder_full_name + ".placeholder.proto");
   placeholder_file->package_ = placeholder_package;
@@ -2757,11 +3076,19 @@ const FileDescriptor* DescriptorBuilder::BuildFile(
   }
 
   // Checkpoint the tables so that we can roll back if something goes wrong.
-  tables_->Checkpoint();
+  tables_->AddCheckpoint();
 
   FileDescriptor* result = tables_->Allocate<FileDescriptor>();
   file_ = result;
 
+  if (proto.has_source_code_info()) {
+    SourceCodeInfo *info = tables_->AllocateMessage<SourceCodeInfo>();
+    info->CopyFrom(proto.source_code_info());
+    result->source_code_info_ = info;
+  } else {
+    result->source_code_info_ = &SourceCodeInfo::default_instance();
+  }
+
   file_tables_ = tables_->AllocateFileTables();
   file_->tables_ = file_tables_;
 
@@ -2788,7 +3115,7 @@ const FileDescriptor* DescriptorBuilder::BuildFile(
              "A file with this name is already in the pool.");
     // Bail out early so that if this is actually the exact same file, we
     // don't end up reporting that every single symbol is already defined.
-    tables_->Rollback();
+    tables_->RollbackToLastCheckpoint();
     return NULL;
   }
   if (!result->package().empty()) {
@@ -2833,6 +3160,45 @@ const FileDescriptor* DescriptorBuilder::BuildFile(
     result->dependencies_[i] = dependency;
   }
 
+  // Check public dependencies.
+  int public_dependency_count = 0;
+  result->public_dependencies_ = tables_->AllocateArray<int>(
+      proto.public_dependency_size());
+  for (int i = 0; i < proto.public_dependency_size(); i++) {
+    // Only put valid public dependency indexes.
+    int index = proto.public_dependency(i);
+    if (index >= 0 && index < proto.dependency_size()) {
+      result->public_dependencies_[public_dependency_count++] = index;
+    } else {
+      AddError(proto.name(), proto,
+               DescriptorPool::ErrorCollector::OTHER,
+               "Invalid public dependency index.");
+    }
+  }
+  result->public_dependency_count_ = public_dependency_count;
+
+  // Build dependency set
+  dependencies_.clear();
+  for (int i = 0; i < result->dependency_count(); i++) {
+    RecordPublicDependencies(result->dependency(i));
+  }
+
+  // Check weak dependencies.
+  int weak_dependency_count = 0;
+  result->weak_dependencies_ = tables_->AllocateArray<int>(
+      proto.weak_dependency_size());
+  for (int i = 0; i < proto.weak_dependency_size(); i++) {
+    int index = proto.weak_dependency(i);
+    if (index >= 0 && index < proto.dependency_size()) {
+      result->weak_dependencies_[weak_dependency_count++] = index;
+    } else {
+      AddError(proto.name(), proto,
+               DescriptorPool::ErrorCollector::OTHER,
+               "Invalid weak dependency index.");
+    }
+  }
+  result->weak_dependency_count_ = weak_dependency_count;
+
   // Convert children.
   BUILD_ARRAY(proto, result, message_type, BuildMessage  , NULL);
   BUILD_ARRAY(proto, result, enum_type   , BuildEnum     , NULL);
@@ -2870,10 +3236,10 @@ const FileDescriptor* DescriptorBuilder::BuildFile(
   }
 
   if (had_errors_) {
-    tables_->Rollback();
+    tables_->RollbackToLastCheckpoint();
     return NULL;
   } else {
-    tables_->Checkpoint();
+    tables_->ClearLastCheckpoint();
     return result;
   }
 }
@@ -3065,7 +3431,7 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
               UnescapeCEscapeString(proto.default_value()));
           } else {
             result->default_value_string_ =
-              tables_->AllocateString(proto.default_value());
+                tables_->AllocateString(proto.default_value());
           }
           break;
         case FieldDescriptor::CPPTYPE_MESSAGE:
@@ -3126,7 +3492,15 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
   if (result->number() <= 0) {
     AddError(result->full_name(), proto, DescriptorPool::ErrorCollector::NUMBER,
              "Field numbers must be positive integers.");
-  } else if (result->number() > FieldDescriptor::kMaxNumber) {
+  } else if (!is_extension && result->number() > FieldDescriptor::kMaxNumber) {
+    // Only validate that the number is within the valid field range if it is
+    // not an extension. Since extension numbers are validated with the
+    // extendee's valid set of extension numbers, and those are in turn
+    // validated against the max allowed number, the check is unnecessary for
+    // extension fields.
+    // This avoids cross-linking issues that arise when attempting to check if
+    // the extendee is a message_set_wire_format message, which has a higher max
+    // on extension numbers.
     AddError(result->full_name(), proto, DescriptorPool::ErrorCollector::NUMBER,
              strings::Substitute("Field numbers cannot be greater than $0.",
                                  FieldDescriptor::kMaxNumber));
@@ -3181,12 +3555,10 @@ void DescriptorBuilder::BuildExtensionRange(
              "Extension numbers must be positive integers.");
   }
 
-  if (result->end > FieldDescriptor::kMaxNumber + 1) {
-    AddError(parent->full_name(), proto,
-             DescriptorPool::ErrorCollector::NUMBER,
-             strings::Substitute("Extension numbers cannot be greater than $0.",
-                                 FieldDescriptor::kMaxNumber));
-  }
+  // Checking of the upper bound of the extension range is deferred until after
+  // options interpreting. This allows messages with message_set_wire_format to
+  // have extensions beyond FieldDescriptor::kMaxNumber, since the extension
+  // numbers are actually used as int32s in the message_set_wire_format.
 
   if (result->start >= result->end) {
     AddError(parent->full_name(), proto,
@@ -3681,6 +4053,20 @@ void DescriptorBuilder::ValidateMessageOptions(Descriptor* message,
   VALIDATE_OPTIONS_FROM_ARRAY(message, nested_type, Message);
   VALIDATE_OPTIONS_FROM_ARRAY(message, enum_type, Enum);
   VALIDATE_OPTIONS_FROM_ARRAY(message, extension, Field);
+
+  const int64 max_extension_range =
+      static_cast<int64>(message->options().message_set_wire_format() ?
+                         kint32max :
+                         FieldDescriptor::kMaxNumber);
+  for (int i = 0; i < message->extension_range_count(); ++i) {
+    if (message->extension_range(i)->end > max_extension_range + 1) {
+      AddError(
+          message->full_name(), proto.extension_range(i),
+          DescriptorPool::ErrorCollector::NUMBER,
+          strings::Substitute("Extension numbers cannot be greater than $0.",
+                              max_extension_range));
+    }
+  }
 }
 
 void DescriptorBuilder::ValidateFieldOptions(FieldDescriptor* field,
@@ -3689,6 +4075,15 @@ void DescriptorBuilder::ValidateFieldOptions(FieldDescriptor* field,
     ValidateMapKey(field, proto);
   }
 
+  // Only message type fields may be lazy.
+  if (field->options().lazy()) {
+    if (field->type() != FieldDescriptor::TYPE_MESSAGE) {
+      AddError(field->full_name(), proto,
+               DescriptorPool::ErrorCollector::TYPE,
+               "[lazy = true] can only be specified for submessage fields.");
+    }
+  }
+
   // Only repeated primitive fields may be packed.
   if (field->options().packed() && !field->is_packable()) {
     AddError(
@@ -3727,11 +4122,27 @@ void DescriptorBuilder::ValidateFieldOptions(FieldDescriptor* field,
              "files.  Note that you cannot extend a non-lite type to contain "
              "a lite type, but the reverse is allowed.");
   }
+
 }
 
 void DescriptorBuilder::ValidateEnumOptions(EnumDescriptor* enm,
                                             const EnumDescriptorProto& proto) {
   VALIDATE_OPTIONS_FROM_ARRAY(enm, value, EnumValue);
+  if (!enm->options().allow_alias()) {
+    map<int, string> used_values;
+    for (int i = 0; i < enm->value_count(); ++i) {
+      const EnumValueDescriptor* enum_value = enm->value(i);
+      if (used_values.find(enum_value->number()) != used_values.end()) {
+        AddError(enm->full_name(), proto,
+                 DescriptorPool::ErrorCollector::NUMBER,
+                 "\"" + enum_value->full_name() +
+                 "\" uses the same enum value as \"" +
+                 used_values[enum_value->number()] + "\"");
+      } else {
+        used_values[enum_value->number()] = enum_value->full_name();
+      }
+    }
+  }
 }
 
 void DescriptorBuilder::ValidateEnumValueOptions(
@@ -3811,6 +4222,7 @@ void DescriptorBuilder::ValidateMapKey(FieldDescriptor* field,
   field->experimental_map_key_ = key_field;
 }
 
+
 #undef VALIDATE_OPTIONS_FROM_ARRAY
 
 // -------------------------------------------------------------------
@@ -3901,9 +4313,11 @@ bool DescriptorBuilder::OptionInterpreter::InterpretSingleOption(
   // file we're currently building. The descriptor should be there as long as
   // the file we're building imported "google/protobuf/descriptors.proto".
 
-  // Note that we use DescriptorBuilder::FindSymbol(), not
+  // Note that we use DescriptorBuilder::FindSymbolNotEnforcingDeps(), not
   // DescriptorPool::FindMessageTypeByName() because we're already holding the
-  // pool's mutex, and the latter method locks it again.
+  // pool's mutex, and the latter method locks it again.  We don't use
+  // FindSymbol() because files that use custom options only need to depend on
+  // the file that defines the option, not descriptor.proto itself.
   Symbol symbol = builder_->FindSymbolNotEnforcingDeps(
     options->GetDescriptor()->full_name());
   if (!symbol.IsNull() && symbol.type == Symbol::MESSAGE) {
@@ -3939,8 +4353,8 @@ bool DescriptorBuilder::OptionInterpreter::InterpretSingleOption(
       // DescriptorPool::FindExtensionByName(), for two reasons: 1) It allows
       // relative lookups, and 2) because we're already holding the pool's
       // mutex, and the latter method locks it again.
-      Symbol symbol = builder_->LookupSymbol(name_part,
-                                             options_to_interpret_->name_scope);
+      symbol = builder_->LookupSymbol(name_part,
+                                      options_to_interpret_->name_scope);
       if (!symbol.IsNull() && symbol.type == Symbol::FIELD) {
         field = symbol.field_descriptor;
       }
@@ -4344,14 +4758,32 @@ class DescriptorBuilder::OptionInterpreter::AggregateOptionFinder
   virtual const FieldDescriptor* FindExtension(
       Message* message, const string& name) const {
     assert_mutex_held(builder_->pool_);
+    const Descriptor* descriptor = message->GetDescriptor();
     Symbol result = builder_->LookupSymbolNoPlaceholder(
-        name, message->GetDescriptor()->full_name());
+        name, descriptor->full_name());
     if (result.type == Symbol::FIELD &&
         result.field_descriptor->is_extension()) {
       return result.field_descriptor;
-    } else {
-      return NULL;
+    } else if (result.type == Symbol::MESSAGE &&
+               descriptor->options().message_set_wire_format()) {
+      const Descriptor* foreign_type = result.descriptor;
+      // The text format allows MessageSet items to be specified using
+      // the type name, rather than the extension identifier. If the symbol
+      // lookup returned a Message, and the enclosing Message has
+      // message_set_wire_format = true, then return the message set
+      // extension, if one exists.
+      for (int i = 0; i < foreign_type->extension_count(); i++) {
+        const FieldDescriptor* extension = foreign_type->extension(i);
+        if (extension->containing_type() == descriptor &&
+            extension->type() == FieldDescriptor::TYPE_MESSAGE &&
+            extension->is_optional() &&
+            extension->message_type() == foreign_type) {
+          // Found it.
+          return extension;
+        }
+      }
     }
+    return NULL;
   }
 };
 
@@ -4409,7 +4841,13 @@ bool DescriptorBuilder::OptionInterpreter::SetAggregateOption(
   } else {
     string serial;
     dynamic->SerializeToString(&serial);  // Never fails
-    unknown_fields->AddLengthDelimited(option_field->number(), serial);
+    if (option_field->type() == FieldDescriptor::TYPE_MESSAGE) {
+      unknown_fields->AddLengthDelimited(option_field->number(), serial);
+    } else {
+      GOOGLE_CHECK_EQ(option_field->type(),  FieldDescriptor::TYPE_GROUP);
+      UnknownFieldSet* group = unknown_fields->AddGroup(option_field->number());
+      group->ParseFromString(serial);
+    }
     return true;
   }
 }
diff --git a/src/google/protobuf/descriptor.h b/src/google/protobuf/descriptor.h
index 7f87dd80..410d3ed4 100644
--- a/src/google/protobuf/descriptor.h
+++ b/src/google/protobuf/descriptor.h
@@ -89,6 +89,7 @@ class ServiceOptions;
 class MethodOptions;
 class FileOptions;
 class UninterpretedOption;
+class SourceCodeInfo;
 
 // Defined in message.h
 class Message;
@@ -100,6 +101,20 @@ class FileDescriptorTables;
 // Defined in unknown_field_set.h.
 class UnknownField;
 
+// NB, all indices are zero-based.
+struct SourceLocation {
+  int start_line;
+  int end_line;
+  int start_column;
+  int end_column;
+
+  // Doc comments found at the source location.
+  // TODO(kenton):  Maybe this struct should have been named SourceInfo or
+  //   something instead.  Oh well.
+  string leading_comments;
+  string trailing_comments;
+};
+
 // Describes a type of protocol message, or a particular group within a
 // message.  To obtain the Descriptor for a given message object, call
 // Message::GetDescriptor().  Generated message classes also have a
@@ -236,6 +251,13 @@ class LIBPROTOBUF_EXPORT Descriptor {
   // this message type's scope.
   const FieldDescriptor* FindExtensionByCamelcaseName(const string& name) const;
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this message declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef MessageOptions OptionsType;
 
@@ -243,6 +265,10 @@ class LIBPROTOBUF_EXPORT Descriptor {
   // correct depth
   void DebugString(int depth, string *contents) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   const FileDescriptor* file_;
@@ -388,15 +414,19 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
   // when parsing formats which prefer to use camel-case naming style.
   const string& camelcase_name() const;
 
-  Type type() const;                 // Declared type of this field.
-  CppType cpp_type() const;          // C++ type of this field.
-  Label label() const;               // optional/required/repeated
+  Type type() const;                  // Declared type of this field.
+  const char* type_name() const;      // Name of the declared type.
+  CppType cpp_type() const;           // C++ type of this field.
+  const char* cpp_type_name() const;  // Name of the C++ type.
+  Label label() const;                // optional/required/repeated
 
   bool is_required() const;      // shorthand for label() == LABEL_REQUIRED
   bool is_optional() const;      // shorthand for label() == LABEL_OPTIONAL
   bool is_repeated() const;      // shorthand for label() == LABEL_REPEATED
   bool is_packable() const;      // shorthand for is_repeated() &&
                                  //               IsTypePackable(type())
+  bool is_packed() const;        // shorthand for is_packable() &&
+                                 //               options().packed()
 
   // Index of this field within the message's field array, or the file or
   // extension scope's extensions array.
@@ -479,6 +509,13 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
   // Return true iff [packed = true] is valid for fields of this type.
   static inline bool IsTypePackable(Type field_type);
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this field declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef FieldOptions OptionsType;
 
@@ -490,6 +527,10 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
   // types of CPPTYPE_STRING whill be surrounded by quotes and CEscaped.
   string DefaultValueAsString(bool quote_string_type) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   const string* lowercase_name_;
@@ -527,6 +568,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
 
   static const char * const kTypeToName[MAX_TYPE + 1];
 
+  static const char * const kCppTypeToName[MAX_CPPTYPE + 1];
+
   static const char * const kLabelToName[MAX_LABEL + 1];
 
   // Must be constructed using DescriptorPool.
@@ -583,12 +626,23 @@ class LIBPROTOBUF_EXPORT EnumDescriptor {
   // See Descriptor::DebugString().
   string DebugString() const;
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this enum declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef EnumOptions OptionsType;
 
   // See Descriptor::DebugString().
   void DebugString(int depth, string *contents) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   const FileDescriptor* file_;
@@ -650,12 +704,23 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptor {
   // See Descriptor::DebugString().
   string DebugString() const;
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this enum value declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef EnumValueOptions OptionsType;
 
   // See Descriptor::DebugString().
   void DebugString(int depth, string *contents) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   int number_;
@@ -703,19 +768,29 @@ class LIBPROTOBUF_EXPORT ServiceDescriptor {
 
   // Look up a MethodDescriptor by name.
   const MethodDescriptor* FindMethodByName(const string& name) const;
-
   // See Descriptor::CopyTo().
   void CopyTo(ServiceDescriptorProto* proto) const;
 
   // See Descriptor::DebugString().
   string DebugString() const;
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this service declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef ServiceOptions OptionsType;
 
   // See Descriptor::DebugString().
   void DebugString(string *contents) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   const FileDescriptor* file_;
@@ -768,12 +843,23 @@ class LIBPROTOBUF_EXPORT MethodDescriptor {
   // See Descriptor::DebugString().
   string DebugString() const;
 
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of this method declaration.  Returns false and leaves
+  // |*out_location| unchanged iff location information was not available.
+  bool GetSourceLocation(SourceLocation* out_location) const;
+
  private:
   typedef MethodOptions OptionsType;
 
   // See Descriptor::DebugString().
   void DebugString(int depth, string *contents) const;
 
+  // Walks up the descriptor tree to generate the source location path
+  // to this descriptor from the file root.
+  void GetLocationPath(vector<int>* output) const;
+
   const string* name_;
   const string* full_name_;
   const ServiceDescriptor* service_;
@@ -791,6 +877,7 @@ class LIBPROTOBUF_EXPORT MethodDescriptor {
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MethodDescriptor);
 };
 
+
 // Describes a whole .proto file.  To get the FileDescriptor for a compiled-in
 // file, get the descriptor for something defined in that file and call
 // descriptor->file().  Use DescriptorPool to construct your own descriptors.
@@ -813,6 +900,22 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   // These are returned in the order they were defined in the .proto file.
   const FileDescriptor* dependency(int index) const;
 
+  // The number of files public imported by this one.
+  // The public dependency list is a subset of the dependency list.
+  int public_dependency_count() const;
+  // Gets a public imported file by index, where 0 <= index <
+  // public_dependency_count().
+  // These are returned in the order they were defined in the .proto file.
+  const FileDescriptor* public_dependency(int index) const;
+
+  // The number of files that are imported for weak fields.
+  // The weak dependency list is a subset of the dependency list.
+  int weak_dependency_count() const;
+  // Gets a weak imported file by index, where 0 <= index <
+  // weak_dependency_count().
+  // These are returned in the order they were defined in the .proto file.
+  const FileDescriptor* weak_dependency(int index) const;
+
   // Number of top-level message types defined in this file.  (This does not
   // include nested types.)
   int message_type_count() const;
@@ -866,12 +969,28 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   const FieldDescriptor* FindExtensionByCamelcaseName(const string& name) const;
 
   // See Descriptor::CopyTo().
+  // Notes:
+  // - This method does NOT copy source code information since it is relatively
+  //   large and rarely needed.  See CopySourceCodeInfoTo() below.
   void CopyTo(FileDescriptorProto* proto) const;
+  // Write the source code information of this FileDescriptor into the given
+  // FileDescriptorProto.  See CopyTo() above.
+  void CopySourceCodeInfoTo(FileDescriptorProto* proto) const;
 
   // See Descriptor::DebugString().
   string DebugString() const;
 
  private:
+  // Source Location ---------------------------------------------------
+
+  // Updates |*out_location| to the source location of the complete
+  // extent of the declaration or declaration-part denoted by |path|.
+  // Returns false and leaves |*out_location| unchanged iff location
+  // information was not available.  (See SourceCodeInfo for
+  // description of path encoding.)
+  bool GetSourceLocation(const vector<int>& path,
+                         SourceLocation* out_location) const;
+
   typedef FileOptions OptionsType;
 
   const string* name_;
@@ -879,6 +998,10 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   const DescriptorPool* pool_;
   int dependency_count_;
   const FileDescriptor** dependencies_;
+  int public_dependency_count_;
+  int* public_dependencies_;
+  int weak_dependency_count_;
+  int* weak_dependencies_;
   int message_type_count_;
   Descriptor* message_types_;
   int enum_type_count_;
@@ -890,6 +1013,7 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   const FileOptions* options_;
 
   const FileDescriptorTables* tables_;
+  const SourceCodeInfo* source_code_info_;
   // IMPORTANT:  If you add a new field, make sure to search for all instances
   // of Allocate<FileDescriptor>() and AllocateArray<FileDescriptor>() in
   // descriptor.cc and update them to initialize the field.
@@ -899,6 +1023,8 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   friend class Descriptor;
   friend class FieldDescriptor;
   friend class EnumDescriptor;
+  friend class EnumValueDescriptor;
+  friend class MethodDescriptor;
   friend class ServiceDescriptor;
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileDescriptor);
 };
@@ -1106,7 +1232,7 @@ class LIBPROTOBUF_EXPORT DescriptorPool {
   // For internal use only:  Gets a non-const pointer to the generated pool.
   // This is called at static-initialization time only, so thread-safety is
   // not a concern.  If both an underlay and a fallback database are present,
-  // the fallback database takes precedence.
+  // the underlay takes precedence.
   static DescriptorPool* internal_generated_pool();
 
   // For internal use only:  Changes the behavior of BuildFile() such that it
@@ -1132,6 +1258,11 @@ class LIBPROTOBUF_EXPORT DescriptorPool {
   friend class FileDescriptor;
   friend class DescriptorBuilder;
 
+  // Return true if the given name is a sub-symbol of any non-package
+  // descriptor that already exists in the descriptor pool.  (The full
+  // definition of such types is already known.)
+  bool IsSubSymbolOfBuiltType(const string& name) const;
+
   // Tries to find something in the fallback database and link in the
   // corresponding proto file.  Returns true if successful, in which case
   // the caller should search for the thing again.  These are declared
@@ -1262,11 +1393,12 @@ PROTOBUF_DEFINE_ACCESSOR(MethodDescriptor, service, const ServiceDescriptor*)
 PROTOBUF_DEFINE_ACCESSOR(MethodDescriptor, input_type, const Descriptor*)
 PROTOBUF_DEFINE_ACCESSOR(MethodDescriptor, output_type, const Descriptor*)
 PROTOBUF_DEFINE_OPTIONS_ACCESSOR(MethodDescriptor, MethodOptions);
-
 PROTOBUF_DEFINE_STRING_ACCESSOR(FileDescriptor, name)
 PROTOBUF_DEFINE_STRING_ACCESSOR(FileDescriptor, package)
 PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, pool, const DescriptorPool*)
 PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, dependency_count, int)
+PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, public_dependency_count, int)
+PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, weak_dependency_count, int)
 PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, message_type_count, int)
 PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, enum_type_count, int)
 PROTOBUF_DEFINE_ACCESSOR(FileDescriptor, service_count, int)
@@ -1342,10 +1474,18 @@ inline int MethodDescriptor::index() const {
   return this - service_->methods_;
 }
 
+inline const char* FieldDescriptor::type_name() const {
+  return kTypeToName[type_];
+}
+
 inline FieldDescriptor::CppType FieldDescriptor::cpp_type() const {
   return kTypeToCppTypeMap[type_];
 }
 
+inline const char* FieldDescriptor::cpp_type_name() const {
+  return kCppTypeToName[kTypeToCppTypeMap[type_]];
+}
+
 inline FieldDescriptor::CppType FieldDescriptor::TypeToCppType(Type type) {
   return kTypeToCppTypeMap[type];
 }
@@ -1361,6 +1501,16 @@ inline const FileDescriptor* FileDescriptor::dependency(int index) const {
   return dependencies_[index];
 }
 
+inline const FileDescriptor* FileDescriptor::public_dependency(
+    int index) const {
+  return dependencies_[public_dependencies_[index]];
+}
+
+inline const FileDescriptor* FileDescriptor::weak_dependency(
+    int index) const {
+  return dependencies_[weak_dependencies_[index]];
+}
+
 }  // namespace protobuf
 
 }  // namespace google
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index b0f0e90e..bb438f25 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -1,4 +1,5 @@
 // Generated by the protocol buffer compiler.  DO NOT EDIT!
+// source: google/protobuf/descriptor.proto
 
 #define INTERNAL_SUPPRESS_PROTOBUF_FIELD_DEPRECATION
 #include "google/protobuf/descriptor.pb.h"
@@ -9,6 +10,7 @@
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/generated_message_reflection.h>
 #include <google/protobuf/reflection_ops.h>
 #include <google/protobuf/wire_format.h>
 // @@protoc_insertion_point(includes)
@@ -108,10 +110,12 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       ::google::protobuf::MessageFactory::generated_factory(),
       sizeof(FileDescriptorSet));
   FileDescriptorProto_descriptor_ = file->message_type(1);
-  static const int FileDescriptorProto_offsets_[9] = {
+  static const int FileDescriptorProto_offsets_[11] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, name_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, package_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, dependency_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, public_dependency_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, weak_dependency_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, message_type_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, enum_type_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileDescriptorProto, service_),
@@ -261,12 +265,13 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       ::google::protobuf::MessageFactory::generated_factory(),
       sizeof(MethodDescriptorProto));
   FileOptions_descriptor_ = file->message_type(8);
-  static const int FileOptions_offsets_[9] = {
+  static const int FileOptions_offsets_[10] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, java_package_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, java_outer_classname_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, java_multiple_files_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, java_generate_equals_and_hash_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, optimize_for_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, go_package_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, cc_generic_services_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, java_generic_services_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FileOptions, py_generic_services_),
@@ -302,11 +307,13 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       ::google::protobuf::MessageFactory::generated_factory(),
       sizeof(MessageOptions));
   FieldOptions_descriptor_ = file->message_type(10);
-  static const int FieldOptions_offsets_[5] = {
+  static const int FieldOptions_offsets_[7] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, ctype_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, packed_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, lazy_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, deprecated_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, experimental_map_key_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, weak_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldOptions, uninterpreted_option_),
   };
   FieldOptions_reflection_ =
@@ -322,7 +329,8 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       sizeof(FieldOptions));
   FieldOptions_CType_descriptor_ = FieldOptions_descriptor_->enum_type(0);
   EnumOptions_descriptor_ = file->message_type(11);
-  static const int EnumOptions_offsets_[1] = {
+  static const int EnumOptions_offsets_[2] = {
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(EnumOptions, allow_alias_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(EnumOptions, uninterpreted_option_),
   };
   EnumOptions_reflection_ =
@@ -434,9 +442,11 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       ::google::protobuf::MessageFactory::generated_factory(),
       sizeof(SourceCodeInfo));
   SourceCodeInfo_Location_descriptor_ = SourceCodeInfo_descriptor_->nested_type(0);
-  static const int SourceCodeInfo_Location_offsets_[2] = {
+  static const int SourceCodeInfo_Location_offsets_[4] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(SourceCodeInfo_Location, path_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(SourceCodeInfo_Location, span_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(SourceCodeInfo_Location, leading_comments_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(SourceCodeInfo_Location, trailing_comments_),
   };
   SourceCodeInfo_Location_reflection_ =
     new ::google::protobuf::internal::GeneratedMessageReflection(
@@ -553,106 +563,112 @@ void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() {
   if (already_here) return;
   already_here = true;
   GOOGLE_PROTOBUF_VERIFY_VERSION;
+
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
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+    "\020\200\200\200\200\002\"_\n\rMethodOptions\022C\n\024uninterpreted"
+    "_option\030\347\007 \003(\0132$.google.protobuf.Uninter"
+    "pretedOption*\t\010\350\007\020\200\200\200\200\002\"\236\002\n\023Uninterprete"
+    "dOption\022;\n\004name\030\002 \003(\0132-.google.protobuf."
+    "UninterpretedOption.NamePart\022\030\n\020identifi"
+    "er_value\030\003 \001(\t\022\032\n\022positive_int_value\030\004 \001"
+    "(\004\022\032\n\022negative_int_value\030\005 \001(\003\022\024\n\014double"
+    "_value\030\006 \001(\001\022\024\n\014string_value\030\007 \001(\014\022\027\n\017ag"
+    "gregate_value\030\010 \001(\t\0323\n\010NamePart\022\021\n\tname_"
+    "part\030\001 \002(\t\022\024\n\014is_extension\030\002 \002(\010\"\261\001\n\016Sou"
+    "rceCodeInfo\022:\n\010location\030\001 \003(\0132(.google.p"
+    "rotobuf.SourceCodeInfo.Location\032c\n\010Locat"
+    "ion\022\020\n\004path\030\001 \003(\005B\002\020\001\022\020\n\004span\030\002 \003(\005B\002\020\001\022"
+    "\030\n\020leading_comments\030\003 \001(\t\022\031\n\021trailing_co"
+    "mments\030\004 \001(\tB)\n\023com.google.protobufB\020Des"
+    "criptorProtosH\001", 4135);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/descriptor.proto", &protobuf_RegisterTypes);
   FileDescriptorSet::default_instance_ = new FileDescriptorSet();
@@ -786,7 +802,7 @@ bool FileDescriptorSet::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -810,7 +826,7 @@ void FileDescriptorSet::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       1, this->file(i), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -825,7 +841,7 @@ void FileDescriptorSet::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         1, this->file(i), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -835,7 +851,7 @@ void FileDescriptorSet::SerializeWithCachedSizes(
 
 int FileDescriptorSet::ByteSize() const {
   int total_size = 0;
-  
+
   // repeated .google.protobuf.FileDescriptorProto file = 1;
   total_size += 1 * this->file_size();
   for (int i = 0; i < this->file_size(); i++) {
@@ -843,7 +859,7 @@ int FileDescriptorSet::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->file(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -886,7 +902,7 @@ void FileDescriptorSet::CopyFrom(const FileDescriptorSet& from) {
 }
 
 bool FileDescriptorSet::IsInitialized() const {
-  
+
   for (int i = 0; i < file_size(); i++) {
     if (!this->file(i).IsInitialized()) return false;
   }
@@ -917,6 +933,8 @@ void FileDescriptorSet::Swap(FileDescriptorSet* other) {
 const int FileDescriptorProto::kNameFieldNumber;
 const int FileDescriptorProto::kPackageFieldNumber;
 const int FileDescriptorProto::kDependencyFieldNumber;
+const int FileDescriptorProto::kPublicDependencyFieldNumber;
+const int FileDescriptorProto::kWeakDependencyFieldNumber;
 const int FileDescriptorProto::kMessageTypeFieldNumber;
 const int FileDescriptorProto::kEnumTypeFieldNumber;
 const int FileDescriptorProto::kServiceFieldNumber;
@@ -1000,16 +1018,18 @@ void FileDescriptorProto::Clear() {
         package_->clear();
       }
     }
+  }
+  if (_has_bits_[9 / 32] & (0xffu << (9 % 32))) {
     if (has_options()) {
       if (options_ != NULL) options_->::google::protobuf::FileOptions::Clear();
     }
-  }
-  if (_has_bits_[8 / 32] & (0xffu << (8 % 32))) {
     if (has_source_code_info()) {
       if (source_code_info_ != NULL) source_code_info_->::google::protobuf::SourceCodeInfo::Clear();
     }
   }
   dependency_.Clear();
+  public_dependency_.Clear();
+  weak_dependency_.Clear();
   message_type_.Clear();
   enum_type_.Clear();
   service_.Clear();
@@ -1039,7 +1059,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_package;
         break;
       }
-      
+
       // optional string package = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1056,7 +1076,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_dependency;
         break;
       }
-      
+
       // repeated string dependency = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1075,7 +1095,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(34)) goto parse_message_type;
         break;
       }
-      
+
       // repeated .google.protobuf.DescriptorProto message_type = 4;
       case 4: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1090,7 +1110,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(42)) goto parse_enum_type;
         break;
       }
-      
+
       // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
       case 5: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1105,7 +1125,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(50)) goto parse_service;
         break;
       }
-      
+
       // repeated .google.protobuf.ServiceDescriptorProto service = 6;
       case 6: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1120,7 +1140,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(58)) goto parse_extension;
         break;
       }
-      
+
       // repeated .google.protobuf.FieldDescriptorProto extension = 7;
       case 7: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1135,7 +1155,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(66)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.FileOptions options = 8;
       case 8: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1149,7 +1169,7 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(74)) goto parse_source_code_info;
         break;
       }
-      
+
       // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
       case 9: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1160,10 +1180,54 @@ bool FileDescriptorProto::MergePartialFromCodedStream(
         } else {
           goto handle_uninterpreted;
         }
+        if (input->ExpectTag(80)) goto parse_public_dependency;
+        break;
+      }
+
+      // repeated int32 public_dependency = 10;
+      case 10: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
+         parse_public_dependency:
+          DO_((::google::protobuf::internal::WireFormatLite::ReadRepeatedPrimitive<
+                   ::google::protobuf::int32, ::google::protobuf::internal::WireFormatLite::TYPE_INT32>(
+                 1, 80, input, this->mutable_public_dependency())));
+        } else if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag)
+                   == ::google::protobuf::internal::WireFormatLite::
+                      WIRETYPE_LENGTH_DELIMITED) {
+          DO_((::google::protobuf::internal::WireFormatLite::ReadPackedPrimitiveNoInline<
+                   ::google::protobuf::int32, ::google::protobuf::internal::WireFormatLite::TYPE_INT32>(
+                 input, this->mutable_public_dependency())));
+        } else {
+          goto handle_uninterpreted;
+        }
+        if (input->ExpectTag(80)) goto parse_public_dependency;
+        if (input->ExpectTag(88)) goto parse_weak_dependency;
+        break;
+      }
+
+      // repeated int32 weak_dependency = 11;
+      case 11: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
+         parse_weak_dependency:
+          DO_((::google::protobuf::internal::WireFormatLite::ReadRepeatedPrimitive<
+                   ::google::protobuf::int32, ::google::protobuf::internal::WireFormatLite::TYPE_INT32>(
+                 1, 88, input, this->mutable_weak_dependency())));
+        } else if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag)
+                   == ::google::protobuf::internal::WireFormatLite::
+                      WIRETYPE_LENGTH_DELIMITED) {
+          DO_((::google::protobuf::internal::WireFormatLite::ReadPackedPrimitiveNoInline<
+                   ::google::protobuf::int32, ::google::protobuf::internal::WireFormatLite::TYPE_INT32>(
+                 input, this->mutable_weak_dependency())));
+        } else {
+          goto handle_uninterpreted;
+        }
+        if (input->ExpectTag(88)) goto parse_weak_dependency;
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1190,7 +1254,7 @@ void FileDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // optional string package = 2;
   if (has_package()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -1199,7 +1263,7 @@ void FileDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       2, this->package(), output);
   }
-  
+
   // repeated string dependency = 3;
   for (int i = 0; i < this->dependency_size(); i++) {
   ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -1208,43 +1272,55 @@ void FileDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       3, this->dependency(i), output);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto message_type = 4;
   for (int i = 0; i < this->message_type_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       4, this->message_type(i), output);
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
   for (int i = 0; i < this->enum_type_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       5, this->enum_type(i), output);
   }
-  
+
   // repeated .google.protobuf.ServiceDescriptorProto service = 6;
   for (int i = 0; i < this->service_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       6, this->service(i), output);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 7;
   for (int i = 0; i < this->extension_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       7, this->extension(i), output);
   }
-  
+
   // optional .google.protobuf.FileOptions options = 8;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       8, this->options(), output);
   }
-  
+
   // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
   if (has_source_code_info()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       9, this->source_code_info(), output);
   }
-  
+
+  // repeated int32 public_dependency = 10;
+  for (int i = 0; i < this->public_dependency_size(); i++) {
+    ::google::protobuf::internal::WireFormatLite::WriteInt32(
+      10, this->public_dependency(i), output);
+  }
+
+  // repeated int32 weak_dependency = 11;
+  for (int i = 0; i < this->weak_dependency_size(); i++) {
+    ::google::protobuf::internal::WireFormatLite::WriteInt32(
+      11, this->weak_dependency(i), output);
+  }
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -1262,7 +1338,7 @@ void FileDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // optional string package = 2;
   if (has_package()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -1272,7 +1348,7 @@ void FileDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         2, this->package(), target);
   }
-  
+
   // repeated string dependency = 3;
   for (int i = 0; i < this->dependency_size(); i++) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -1281,49 +1357,61 @@ void FileDescriptorProto::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::
       WriteStringToArray(3, this->dependency(i), target);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto message_type = 4;
   for (int i = 0; i < this->message_type_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         4, this->message_type(i), target);
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
   for (int i = 0; i < this->enum_type_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         5, this->enum_type(i), target);
   }
-  
+
   // repeated .google.protobuf.ServiceDescriptorProto service = 6;
   for (int i = 0; i < this->service_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         6, this->service(i), target);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 7;
   for (int i = 0; i < this->extension_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         7, this->extension(i), target);
   }
-  
+
   // optional .google.protobuf.FileOptions options = 8;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         8, this->options(), target);
   }
-  
+
   // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
   if (has_source_code_info()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         9, this->source_code_info(), target);
   }
-  
+
+  // repeated int32 public_dependency = 10;
+  for (int i = 0; i < this->public_dependency_size(); i++) {
+    target = ::google::protobuf::internal::WireFormatLite::
+      WriteInt32ToArray(10, this->public_dependency(i), target);
+  }
+
+  // repeated int32 weak_dependency = 11;
+  for (int i = 0; i < this->weak_dependency_size(); i++) {
+    target = ::google::protobuf::internal::WireFormatLite::
+      WriteInt32ToArray(11, this->weak_dependency(i), target);
+  }
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -1333,7 +1421,7 @@ void FileDescriptorProto::SerializeWithCachedSizes(
 
 int FileDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -1341,30 +1429,30 @@ int FileDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional string package = 2;
     if (has_package()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->package());
     }
-    
+
+  }
+  if (_has_bits_[9 / 32] & (0xffu << (9 % 32))) {
     // optional .google.protobuf.FileOptions options = 8;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
-  }
-  if (_has_bits_[8 / 32] & (0xffu << (8 % 32))) {
+
     // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
     if (has_source_code_info()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->source_code_info());
     }
-    
+
   }
   // repeated string dependency = 3;
   total_size += 1 * this->dependency_size();
@@ -1372,7 +1460,27 @@ int FileDescriptorProto::ByteSize() const {
     total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
       this->dependency(i));
   }
-  
+
+  // repeated int32 public_dependency = 10;
+  {
+    int data_size = 0;
+    for (int i = 0; i < this->public_dependency_size(); i++) {
+      data_size += ::google::protobuf::internal::WireFormatLite::
+        Int32Size(this->public_dependency(i));
+    }
+    total_size += 1 * this->public_dependency_size() + data_size;
+  }
+
+  // repeated int32 weak_dependency = 11;
+  {
+    int data_size = 0;
+    for (int i = 0; i < this->weak_dependency_size(); i++) {
+      data_size += ::google::protobuf::internal::WireFormatLite::
+        Int32Size(this->weak_dependency(i));
+    }
+    total_size += 1 * this->weak_dependency_size() + data_size;
+  }
+
   // repeated .google.protobuf.DescriptorProto message_type = 4;
   total_size += 1 * this->message_type_size();
   for (int i = 0; i < this->message_type_size(); i++) {
@@ -1380,7 +1488,7 @@ int FileDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->message_type(i));
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
   total_size += 1 * this->enum_type_size();
   for (int i = 0; i < this->enum_type_size(); i++) {
@@ -1388,7 +1496,7 @@ int FileDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->enum_type(i));
   }
-  
+
   // repeated .google.protobuf.ServiceDescriptorProto service = 6;
   total_size += 1 * this->service_size();
   for (int i = 0; i < this->service_size(); i++) {
@@ -1396,7 +1504,7 @@ int FileDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->service(i));
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 7;
   total_size += 1 * this->extension_size();
   for (int i = 0; i < this->extension_size(); i++) {
@@ -1404,7 +1512,7 @@ int FileDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->extension(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -1431,6 +1539,8 @@ void FileDescriptorProto::MergeFrom(const ::google::protobuf::Message& from) {
 void FileDescriptorProto::MergeFrom(const FileDescriptorProto& from) {
   GOOGLE_CHECK_NE(&from, this);
   dependency_.MergeFrom(from.dependency_);
+  public_dependency_.MergeFrom(from.public_dependency_);
+  weak_dependency_.MergeFrom(from.weak_dependency_);
   message_type_.MergeFrom(from.message_type_);
   enum_type_.MergeFrom(from.enum_type_);
   service_.MergeFrom(from.service_);
@@ -1442,11 +1552,11 @@ void FileDescriptorProto::MergeFrom(const FileDescriptorProto& from) {
     if (from.has_package()) {
       set_package(from.package());
     }
+  }
+  if (from._has_bits_[9 / 32] & (0xffu << (9 % 32))) {
     if (from.has_options()) {
       mutable_options()->::google::protobuf::FileOptions::MergeFrom(from.options());
     }
-  }
-  if (from._has_bits_[8 / 32] & (0xffu << (8 % 32))) {
     if (from.has_source_code_info()) {
       mutable_source_code_info()->::google::protobuf::SourceCodeInfo::MergeFrom(from.source_code_info());
     }
@@ -1467,7 +1577,7 @@ void FileDescriptorProto::CopyFrom(const FileDescriptorProto& from) {
 }
 
 bool FileDescriptorProto::IsInitialized() const {
-  
+
   for (int i = 0; i < message_type_size(); i++) {
     if (!this->message_type(i).IsInitialized()) return false;
   }
@@ -1491,6 +1601,8 @@ void FileDescriptorProto::Swap(FileDescriptorProto* other) {
     std::swap(name_, other->name_);
     std::swap(package_, other->package_);
     dependency_.Swap(&other->dependency_);
+    public_dependency_.Swap(&other->public_dependency_);
+    weak_dependency_.Swap(&other->weak_dependency_);
     message_type_.Swap(&other->message_type_);
     enum_type_.Swap(&other->enum_type_);
     service_.Swap(&other->service_);
@@ -1599,7 +1711,7 @@ bool DescriptorProto_ExtensionRange::MergePartialFromCodedStream(
         if (input->ExpectTag(16)) goto parse_end;
         break;
       }
-      
+
       // optional int32 end = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1615,7 +1727,7 @@ bool DescriptorProto_ExtensionRange::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1638,12 +1750,12 @@ void DescriptorProto_ExtensionRange::SerializeWithCachedSizes(
   if (has_start()) {
     ::google::protobuf::internal::WireFormatLite::WriteInt32(1, this->start(), output);
   }
-  
+
   // optional int32 end = 2;
   if (has_end()) {
     ::google::protobuf::internal::WireFormatLite::WriteInt32(2, this->end(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -1656,12 +1768,12 @@ void DescriptorProto_ExtensionRange::SerializeWithCachedSizes(
   if (has_start()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(1, this->start(), target);
   }
-  
+
   // optional int32 end = 2;
   if (has_end()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(2, this->end(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -1671,7 +1783,7 @@ void DescriptorProto_ExtensionRange::SerializeWithCachedSizes(
 
 int DescriptorProto_ExtensionRange::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional int32 start = 1;
     if (has_start()) {
@@ -1679,14 +1791,14 @@ int DescriptorProto_ExtensionRange::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::Int32Size(
           this->start());
     }
-    
+
     // optional int32 end = 2;
     if (has_end()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int32Size(
           this->end());
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -1737,7 +1849,7 @@ void DescriptorProto_ExtensionRange::CopyFrom(const DescriptorProto_ExtensionRan
 }
 
 bool DescriptorProto_ExtensionRange::IsInitialized() const {
-  
+
   return true;
 }
 
@@ -1869,7 +1981,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_field;
         break;
       }
-      
+
       // repeated .google.protobuf.FieldDescriptorProto field = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1884,7 +1996,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_nested_type;
         break;
       }
-      
+
       // repeated .google.protobuf.DescriptorProto nested_type = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1899,7 +2011,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(34)) goto parse_enum_type;
         break;
       }
-      
+
       // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
       case 4: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1914,7 +2026,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(42)) goto parse_extension_range;
         break;
       }
-      
+
       // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
       case 5: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1929,7 +2041,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(50)) goto parse_extension;
         break;
       }
-      
+
       // repeated .google.protobuf.FieldDescriptorProto extension = 6;
       case 6: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1944,7 +2056,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(58)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.MessageOptions options = 7;
       case 7: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1958,7 +2070,7 @@ bool DescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -1985,43 +2097,43 @@ void DescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto field = 2;
   for (int i = 0; i < this->field_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       2, this->field(i), output);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto nested_type = 3;
   for (int i = 0; i < this->nested_type_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       3, this->nested_type(i), output);
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
   for (int i = 0; i < this->enum_type_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       4, this->enum_type(i), output);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
   for (int i = 0; i < this->extension_range_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       5, this->extension_range(i), output);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 6;
   for (int i = 0; i < this->extension_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       6, this->extension(i), output);
   }
-  
+
   // optional .google.protobuf.MessageOptions options = 7;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       7, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -2039,49 +2151,49 @@ void DescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto field = 2;
   for (int i = 0; i < this->field_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         2, this->field(i), target);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto nested_type = 3;
   for (int i = 0; i < this->nested_type_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         3, this->nested_type(i), target);
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
   for (int i = 0; i < this->enum_type_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         4, this->enum_type(i), target);
   }
-  
+
   // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
   for (int i = 0; i < this->extension_range_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         5, this->extension_range(i), target);
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 6;
   for (int i = 0; i < this->extension_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         6, this->extension(i), target);
   }
-  
+
   // optional .google.protobuf.MessageOptions options = 7;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         7, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -2091,7 +2203,7 @@ void DescriptorProto::SerializeWithCachedSizes(
 
 int DescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -2099,14 +2211,14 @@ int DescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional .google.protobuf.MessageOptions options = 7;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   // repeated .google.protobuf.FieldDescriptorProto field = 2;
   total_size += 1 * this->field_size();
@@ -2115,7 +2227,7 @@ int DescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->field(i));
   }
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 6;
   total_size += 1 * this->extension_size();
   for (int i = 0; i < this->extension_size(); i++) {
@@ -2123,7 +2235,7 @@ int DescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->extension(i));
   }
-  
+
   // repeated .google.protobuf.DescriptorProto nested_type = 3;
   total_size += 1 * this->nested_type_size();
   for (int i = 0; i < this->nested_type_size(); i++) {
@@ -2131,7 +2243,7 @@ int DescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->nested_type(i));
   }
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
   total_size += 1 * this->enum_type_size();
   for (int i = 0; i < this->enum_type_size(); i++) {
@@ -2139,7 +2251,7 @@ int DescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->enum_type(i));
   }
-  
+
   // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
   total_size += 1 * this->extension_range_size();
   for (int i = 0; i < this->extension_range_size(); i++) {
@@ -2147,7 +2259,7 @@ int DescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->extension_range(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -2202,7 +2314,7 @@ void DescriptorProto::CopyFrom(const DescriptorProto& from) {
 }
 
 bool DescriptorProto::IsInitialized() const {
-  
+
   for (int i = 0; i < field_size(); i++) {
     if (!this->field(i).IsInitialized()) return false;
   }
@@ -2459,7 +2571,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_extendee;
         break;
       }
-      
+
       // optional string extendee = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2476,7 +2588,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(24)) goto parse_number;
         break;
       }
-      
+
       // optional int32 number = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2492,7 +2604,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(32)) goto parse_label;
         break;
       }
-      
+
       // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
       case 4: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2513,7 +2625,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(40)) goto parse_type;
         break;
       }
-      
+
       // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
       case 5: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2534,7 +2646,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(50)) goto parse_type_name;
         break;
       }
-      
+
       // optional string type_name = 6;
       case 6: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2551,7 +2663,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(58)) goto parse_default_value;
         break;
       }
-      
+
       // optional string default_value = 7;
       case 7: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2568,7 +2680,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(66)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.FieldOptions options = 8;
       case 8: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2582,7 +2694,7 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -2609,7 +2721,7 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // optional string extendee = 2;
   if (has_extendee()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2618,24 +2730,24 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       2, this->extendee(), output);
   }
-  
+
   // optional int32 number = 3;
   if (has_number()) {
     ::google::protobuf::internal::WireFormatLite::WriteInt32(3, this->number(), output);
   }
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
   if (has_label()) {
     ::google::protobuf::internal::WireFormatLite::WriteEnum(
       4, this->label(), output);
   }
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
   if (has_type()) {
     ::google::protobuf::internal::WireFormatLite::WriteEnum(
       5, this->type(), output);
   }
-  
+
   // optional string type_name = 6;
   if (has_type_name()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2644,7 +2756,7 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       6, this->type_name(), output);
   }
-  
+
   // optional string default_value = 7;
   if (has_default_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2653,13 +2765,13 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       7, this->default_value(), output);
   }
-  
+
   // optional .google.protobuf.FieldOptions options = 8;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       8, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -2677,7 +2789,7 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // optional string extendee = 2;
   if (has_extendee()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2687,24 +2799,24 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         2, this->extendee(), target);
   }
-  
+
   // optional int32 number = 3;
   if (has_number()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(3, this->number(), target);
   }
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
   if (has_label()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteEnumToArray(
       4, this->label(), target);
   }
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
   if (has_type()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteEnumToArray(
       5, this->type(), target);
   }
-  
+
   // optional string type_name = 6;
   if (has_type_name()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2714,7 +2826,7 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         6, this->type_name(), target);
   }
-  
+
   // optional string default_value = 7;
   if (has_default_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -2724,14 +2836,14 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         7, this->default_value(), target);
   }
-  
+
   // optional .google.protobuf.FieldOptions options = 8;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         8, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -2741,7 +2853,7 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
 
 int FieldDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -2749,54 +2861,54 @@ int FieldDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional int32 number = 3;
     if (has_number()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int32Size(
           this->number());
     }
-    
+
     // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
     if (has_label()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::EnumSize(this->label());
     }
-    
+
     // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
     if (has_type()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::EnumSize(this->type());
     }
-    
+
     // optional string type_name = 6;
     if (has_type_name()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->type_name());
     }
-    
+
     // optional string extendee = 2;
     if (has_extendee()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->extendee());
     }
-    
+
     // optional string default_value = 7;
     if (has_default_value()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->default_value());
     }
-    
+
     // optional .google.protobuf.FieldOptions options = 8;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -2865,7 +2977,7 @@ void FieldDescriptorProto::CopyFrom(const FieldDescriptorProto& from) {
 }
 
 bool FieldDescriptorProto::IsInitialized() const {
-  
+
   if (has_options()) {
     if (!this->options().IsInitialized()) return false;
   }
@@ -2998,7 +3110,7 @@ bool EnumDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_value;
         break;
       }
-      
+
       // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3013,7 +3125,7 @@ bool EnumDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.EnumOptions options = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3027,7 +3139,7 @@ bool EnumDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3054,19 +3166,19 @@ void EnumDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
   for (int i = 0; i < this->value_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       2, this->value(i), output);
   }
-  
+
   // optional .google.protobuf.EnumOptions options = 3;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       3, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -3084,21 +3196,21 @@ void EnumDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
   for (int i = 0; i < this->value_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         2, this->value(i), target);
   }
-  
+
   // optional .google.protobuf.EnumOptions options = 3;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         3, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -3108,7 +3220,7 @@ void EnumDescriptorProto::SerializeWithCachedSizes(
 
 int EnumDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -3116,14 +3228,14 @@ int EnumDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional .google.protobuf.EnumOptions options = 3;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
   total_size += 1 * this->value_size();
@@ -3132,7 +3244,7 @@ int EnumDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->value(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -3183,7 +3295,7 @@ void EnumDescriptorProto::CopyFrom(const EnumDescriptorProto& from) {
 }
 
 bool EnumDescriptorProto::IsInitialized() const {
-  
+
   for (int i = 0; i < value_size(); i++) {
     if (!this->value(i).IsInitialized()) return false;
   }
@@ -3315,7 +3427,7 @@ bool EnumValueDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(16)) goto parse_number;
         break;
       }
-      
+
       // optional int32 number = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3331,7 +3443,7 @@ bool EnumValueDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.EnumValueOptions options = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3345,7 +3457,7 @@ bool EnumValueDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3372,18 +3484,18 @@ void EnumValueDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // optional int32 number = 2;
   if (has_number()) {
     ::google::protobuf::internal::WireFormatLite::WriteInt32(2, this->number(), output);
   }
-  
+
   // optional .google.protobuf.EnumValueOptions options = 3;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       3, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -3401,19 +3513,19 @@ void EnumValueDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // optional int32 number = 2;
   if (has_number()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(2, this->number(), target);
   }
-  
+
   // optional .google.protobuf.EnumValueOptions options = 3;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         3, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -3423,7 +3535,7 @@ void EnumValueDescriptorProto::SerializeWithCachedSizes(
 
 int EnumValueDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -3431,21 +3543,21 @@ int EnumValueDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional int32 number = 2;
     if (has_number()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int32Size(
           this->number());
     }
-    
+
     // optional .google.protobuf.EnumValueOptions options = 3;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -3499,7 +3611,7 @@ void EnumValueDescriptorProto::CopyFrom(const EnumValueDescriptorProto& from) {
 }
 
 bool EnumValueDescriptorProto::IsInitialized() const {
-  
+
   if (has_options()) {
     if (!this->options().IsInitialized()) return false;
   }
@@ -3627,7 +3739,7 @@ bool ServiceDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_method;
         break;
       }
-      
+
       // repeated .google.protobuf.MethodDescriptorProto method = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3642,7 +3754,7 @@ bool ServiceDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.ServiceOptions options = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3656,7 +3768,7 @@ bool ServiceDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3683,19 +3795,19 @@ void ServiceDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // repeated .google.protobuf.MethodDescriptorProto method = 2;
   for (int i = 0; i < this->method_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       2, this->method(i), output);
   }
-  
+
   // optional .google.protobuf.ServiceOptions options = 3;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       3, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -3713,21 +3825,21 @@ void ServiceDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // repeated .google.protobuf.MethodDescriptorProto method = 2;
   for (int i = 0; i < this->method_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         2, this->method(i), target);
   }
-  
+
   // optional .google.protobuf.ServiceOptions options = 3;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         3, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -3737,7 +3849,7 @@ void ServiceDescriptorProto::SerializeWithCachedSizes(
 
 int ServiceDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -3745,14 +3857,14 @@ int ServiceDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional .google.protobuf.ServiceOptions options = 3;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   // repeated .google.protobuf.MethodDescriptorProto method = 2;
   total_size += 1 * this->method_size();
@@ -3761,7 +3873,7 @@ int ServiceDescriptorProto::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->method(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -3812,7 +3924,7 @@ void ServiceDescriptorProto::CopyFrom(const ServiceDescriptorProto& from) {
 }
 
 bool ServiceDescriptorProto::IsInitialized() const {
-  
+
   for (int i = 0; i < method_size(); i++) {
     if (!this->method(i).IsInitialized()) return false;
   }
@@ -3961,7 +4073,7 @@ bool MethodDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_input_type;
         break;
       }
-      
+
       // optional string input_type = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3978,7 +4090,7 @@ bool MethodDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_output_type;
         break;
       }
-      
+
       // optional string output_type = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -3995,7 +4107,7 @@ bool MethodDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectTag(34)) goto parse_options;
         break;
       }
-      
+
       // optional .google.protobuf.MethodOptions options = 4;
       case 4: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4009,7 +4121,7 @@ bool MethodDescriptorProto::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4036,7 +4148,7 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name(), output);
   }
-  
+
   // optional string input_type = 2;
   if (has_input_type()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4045,7 +4157,7 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       2, this->input_type(), output);
   }
-  
+
   // optional string output_type = 3;
   if (has_output_type()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4054,13 +4166,13 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       3, this->output_type(), output);
   }
-  
+
   // optional .google.protobuf.MethodOptions options = 4;
   if (has_options()) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       4, this->options(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -4078,7 +4190,7 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name(), target);
   }
-  
+
   // optional string input_type = 2;
   if (has_input_type()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4088,7 +4200,7 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         2, this->input_type(), target);
   }
-  
+
   // optional string output_type = 3;
   if (has_output_type()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4098,14 +4210,14 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         3, this->output_type(), target);
   }
-  
+
   // optional .google.protobuf.MethodOptions options = 4;
   if (has_options()) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         4, this->options(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -4115,7 +4227,7 @@ void MethodDescriptorProto::SerializeWithCachedSizes(
 
 int MethodDescriptorProto::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string name = 1;
     if (has_name()) {
@@ -4123,28 +4235,28 @@ int MethodDescriptorProto::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name());
     }
-    
+
     // optional string input_type = 2;
     if (has_input_type()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->input_type());
     }
-    
+
     // optional string output_type = 3;
     if (has_output_type()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->output_type());
     }
-    
+
     // optional .google.protobuf.MethodOptions options = 4;
     if (has_options()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
           this->options());
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -4201,7 +4313,7 @@ void MethodDescriptorProto::CopyFrom(const MethodDescriptorProto& from) {
 }
 
 bool MethodDescriptorProto::IsInitialized() const {
-  
+
   if (has_options()) {
     if (!this->options().IsInitialized()) return false;
   }
@@ -4260,6 +4372,7 @@ const int FileOptions::kJavaOuterClassnameFieldNumber;
 const int FileOptions::kJavaMultipleFilesFieldNumber;
 const int FileOptions::kJavaGenerateEqualsAndHashFieldNumber;
 const int FileOptions::kOptimizeForFieldNumber;
+const int FileOptions::kGoPackageFieldNumber;
 const int FileOptions::kCcGenericServicesFieldNumber;
 const int FileOptions::kJavaGenericServicesFieldNumber;
 const int FileOptions::kPyGenericServicesFieldNumber;
@@ -4287,6 +4400,7 @@ void FileOptions::SharedCtor() {
   java_multiple_files_ = false;
   java_generate_equals_and_hash_ = false;
   optimize_for_ = 1;
+  go_package_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
   cc_generic_services_ = false;
   java_generic_services_ = false;
   py_generic_services_ = false;
@@ -4304,6 +4418,9 @@ void FileOptions::SharedDtor() {
   if (java_outer_classname_ != &::google::protobuf::internal::kEmptyString) {
     delete java_outer_classname_;
   }
+  if (go_package_ != &::google::protobuf::internal::kEmptyString) {
+    delete go_package_;
+  }
   if (this != default_instance_) {
   }
 }
@@ -4345,8 +4462,15 @@ void FileOptions::Clear() {
     java_multiple_files_ = false;
     java_generate_equals_and_hash_ = false;
     optimize_for_ = 1;
+    if (has_go_package()) {
+      if (go_package_ != &::google::protobuf::internal::kEmptyString) {
+        go_package_->clear();
+      }
+    }
     cc_generic_services_ = false;
     java_generic_services_ = false;
+  }
+  if (_has_bits_[8 / 32] & (0xffu << (8 % 32))) {
     py_generic_services_ = false;
   }
   uninterpreted_option_.Clear();
@@ -4375,7 +4499,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(66)) goto parse_java_outer_classname;
         break;
       }
-      
+
       // optional string java_outer_classname = 8;
       case 8: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4392,7 +4516,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(72)) goto parse_optimize_for;
         break;
       }
-      
+
       // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
       case 9: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4413,7 +4537,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(80)) goto parse_java_multiple_files;
         break;
       }
-      
+
       // optional bool java_multiple_files = 10 [default = false];
       case 10: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4426,10 +4550,27 @@ bool FileOptions::MergePartialFromCodedStream(
         } else {
           goto handle_uninterpreted;
         }
+        if (input->ExpectTag(90)) goto parse_go_package;
+        break;
+      }
+
+      // optional string go_package = 11;
+      case 11: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {
+         parse_go_package:
+          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
+                input, this->mutable_go_package()));
+          ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+            this->go_package().data(), this->go_package().length(),
+            ::google::protobuf::internal::WireFormat::PARSE);
+        } else {
+          goto handle_uninterpreted;
+        }
         if (input->ExpectTag(128)) goto parse_cc_generic_services;
         break;
       }
-      
+
       // optional bool cc_generic_services = 16 [default = false];
       case 16: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4445,7 +4586,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(136)) goto parse_java_generic_services;
         break;
       }
-      
+
       // optional bool java_generic_services = 17 [default = false];
       case 17: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4461,7 +4602,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(144)) goto parse_py_generic_services;
         break;
       }
-      
+
       // optional bool py_generic_services = 18 [default = false];
       case 18: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4477,7 +4618,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(160)) goto parse_java_generate_equals_and_hash;
         break;
       }
-      
+
       // optional bool java_generate_equals_and_hash = 20 [default = false];
       case 20: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4493,7 +4634,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(7994)) goto parse_uninterpreted_option;
         break;
       }
-      
+
       // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
       case 999: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4508,7 +4649,7 @@ bool FileOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4540,7 +4681,7 @@ void FileOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->java_package(), output);
   }
-  
+
   // optional string java_outer_classname = 8;
   if (has_java_outer_classname()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4549,48 +4690,57 @@ void FileOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       8, this->java_outer_classname(), output);
   }
-  
+
   // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
   if (has_optimize_for()) {
     ::google::protobuf::internal::WireFormatLite::WriteEnum(
       9, this->optimize_for(), output);
   }
-  
+
   // optional bool java_multiple_files = 10 [default = false];
   if (has_java_multiple_files()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(10, this->java_multiple_files(), output);
   }
-  
+
+  // optional string go_package = 11;
+  if (has_go_package()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->go_package().data(), this->go_package().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    ::google::protobuf::internal::WireFormatLite::WriteString(
+      11, this->go_package(), output);
+  }
+
   // optional bool cc_generic_services = 16 [default = false];
   if (has_cc_generic_services()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(16, this->cc_generic_services(), output);
   }
-  
+
   // optional bool java_generic_services = 17 [default = false];
   if (has_java_generic_services()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(17, this->java_generic_services(), output);
   }
-  
+
   // optional bool py_generic_services = 18 [default = false];
   if (has_py_generic_services()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(18, this->py_generic_services(), output);
   }
-  
+
   // optional bool java_generate_equals_and_hash = 20 [default = false];
   if (has_java_generate_equals_and_hash()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(20, this->java_generate_equals_and_hash(), output);
   }
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -4608,7 +4758,7 @@ void FileOptions::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->java_package(), target);
   }
-  
+
   // optional string java_outer_classname = 8;
   if (has_java_outer_classname()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -4618,49 +4768,59 @@ void FileOptions::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         8, this->java_outer_classname(), target);
   }
-  
+
   // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
   if (has_optimize_for()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteEnumToArray(
       9, this->optimize_for(), target);
   }
-  
+
   // optional bool java_multiple_files = 10 [default = false];
   if (has_java_multiple_files()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(10, this->java_multiple_files(), target);
   }
-  
+
+  // optional string go_package = 11;
+  if (has_go_package()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->go_package().data(), this->go_package().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    target =
+      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
+        11, this->go_package(), target);
+  }
+
   // optional bool cc_generic_services = 16 [default = false];
   if (has_cc_generic_services()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(16, this->cc_generic_services(), target);
   }
-  
+
   // optional bool java_generic_services = 17 [default = false];
   if (has_java_generic_services()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(17, this->java_generic_services(), target);
   }
-  
+
   // optional bool py_generic_services = 18 [default = false];
   if (has_py_generic_services()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(18, this->py_generic_services(), target);
   }
-  
+
   // optional bool java_generate_equals_and_hash = 20 [default = false];
   if (has_java_generate_equals_and_hash()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(20, this->java_generate_equals_and_hash(), target);
   }
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -4670,7 +4830,7 @@ void FileOptions::SerializeWithCachedSizes(
 
 int FileOptions::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional string java_package = 1;
     if (has_java_package()) {
@@ -4678,45 +4838,54 @@ int FileOptions::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->java_package());
     }
-    
+
     // optional string java_outer_classname = 8;
     if (has_java_outer_classname()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->java_outer_classname());
     }
-    
+
     // optional bool java_multiple_files = 10 [default = false];
     if (has_java_multiple_files()) {
       total_size += 1 + 1;
     }
-    
+
     // optional bool java_generate_equals_and_hash = 20 [default = false];
     if (has_java_generate_equals_and_hash()) {
       total_size += 2 + 1;
     }
-    
+
     // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
     if (has_optimize_for()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::EnumSize(this->optimize_for());
     }
-    
+
+    // optional string go_package = 11;
+    if (has_go_package()) {
+      total_size += 1 +
+        ::google::protobuf::internal::WireFormatLite::StringSize(
+          this->go_package());
+    }
+
     // optional bool cc_generic_services = 16 [default = false];
     if (has_cc_generic_services()) {
       total_size += 2 + 1;
     }
-    
+
     // optional bool java_generic_services = 17 [default = false];
     if (has_java_generic_services()) {
       total_size += 2 + 1;
     }
-    
+
+  }
+  if (_has_bits_[8 / 32] & (0xffu << (8 % 32))) {
     // optional bool py_generic_services = 18 [default = false];
     if (has_py_generic_services()) {
       total_size += 2 + 1;
     }
-    
+
   }
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
@@ -4725,9 +4894,9 @@ int FileOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -4770,12 +4939,17 @@ void FileOptions::MergeFrom(const FileOptions& from) {
     if (from.has_optimize_for()) {
       set_optimize_for(from.optimize_for());
     }
+    if (from.has_go_package()) {
+      set_go_package(from.go_package());
+    }
     if (from.has_cc_generic_services()) {
       set_cc_generic_services(from.cc_generic_services());
     }
     if (from.has_java_generic_services()) {
       set_java_generic_services(from.java_generic_services());
     }
+  }
+  if (from._has_bits_[8 / 32] & (0xffu << (8 % 32))) {
     if (from.has_py_generic_services()) {
       set_py_generic_services(from.py_generic_services());
     }
@@ -4797,11 +4971,11 @@ void FileOptions::CopyFrom(const FileOptions& from) {
 }
 
 bool FileOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -4812,6 +4986,7 @@ void FileOptions::Swap(FileOptions* other) {
     std::swap(java_multiple_files_, other->java_multiple_files_);
     std::swap(java_generate_equals_and_hash_, other->java_generate_equals_and_hash_);
     std::swap(optimize_for_, other->optimize_for_);
+    std::swap(go_package_, other->go_package_);
     std::swap(cc_generic_services_, other->cc_generic_services_);
     std::swap(java_generic_services_, other->java_generic_services_);
     std::swap(py_generic_services_, other->py_generic_services_);
@@ -4922,7 +5097,7 @@ bool MessageOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(16)) goto parse_no_standard_descriptor_accessor;
         break;
       }
-      
+
       // optional bool no_standard_descriptor_accessor = 2 [default = false];
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4938,7 +5113,7 @@ bool MessageOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(7994)) goto parse_uninterpreted_option;
         break;
       }
-      
+
       // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
       case 999: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4953,7 +5128,7 @@ bool MessageOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -4981,22 +5156,22 @@ void MessageOptions::SerializeWithCachedSizes(
   if (has_message_set_wire_format()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(1, this->message_set_wire_format(), output);
   }
-  
+
   // optional bool no_standard_descriptor_accessor = 2 [default = false];
   if (has_no_standard_descriptor_accessor()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(2, this->no_standard_descriptor_accessor(), output);
   }
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -5009,23 +5184,23 @@ void MessageOptions::SerializeWithCachedSizes(
   if (has_message_set_wire_format()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(1, this->message_set_wire_format(), target);
   }
-  
+
   // optional bool no_standard_descriptor_accessor = 2 [default = false];
   if (has_no_standard_descriptor_accessor()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(2, this->no_standard_descriptor_accessor(), target);
   }
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -5035,18 +5210,18 @@ void MessageOptions::SerializeWithCachedSizes(
 
 int MessageOptions::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional bool message_set_wire_format = 1 [default = false];
     if (has_message_set_wire_format()) {
       total_size += 1 + 1;
     }
-    
+
     // optional bool no_standard_descriptor_accessor = 2 [default = false];
     if (has_no_standard_descriptor_accessor()) {
       total_size += 1 + 1;
     }
-    
+
   }
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
@@ -5055,9 +5230,9 @@ int MessageOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -5109,11 +5284,11 @@ void MessageOptions::CopyFrom(const MessageOptions& from) {
 }
 
 bool MessageOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -5166,8 +5341,10 @@ const int FieldOptions::CType_ARRAYSIZE;
 #ifndef _MSC_VER
 const int FieldOptions::kCtypeFieldNumber;
 const int FieldOptions::kPackedFieldNumber;
+const int FieldOptions::kLazyFieldNumber;
 const int FieldOptions::kDeprecatedFieldNumber;
 const int FieldOptions::kExperimentalMapKeyFieldNumber;
+const int FieldOptions::kWeakFieldNumber;
 const int FieldOptions::kUninterpretedOptionFieldNumber;
 #endif  // !_MSC_VER
 
@@ -5189,8 +5366,10 @@ void FieldOptions::SharedCtor() {
   _cached_size_ = 0;
   ctype_ = 0;
   packed_ = false;
+  lazy_ = false;
   deprecated_ = false;
   experimental_map_key_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  weak_ = false;
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
 }
 
@@ -5232,12 +5411,14 @@ void FieldOptions::Clear() {
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     ctype_ = 0;
     packed_ = false;
+    lazy_ = false;
     deprecated_ = false;
     if (has_experimental_map_key()) {
       if (experimental_map_key_ != &::google::protobuf::internal::kEmptyString) {
         experimental_map_key_->clear();
       }
     }
+    weak_ = false;
   }
   uninterpreted_option_.Clear();
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
@@ -5269,7 +5450,7 @@ bool FieldOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(16)) goto parse_packed;
         break;
       }
-      
+
       // optional bool packed = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5285,7 +5466,7 @@ bool FieldOptions::MergePartialFromCodedStream(
         if (input->ExpectTag(24)) goto parse_deprecated;
         break;
       }
-      
+
       // optional bool deprecated = 3 [default = false];
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5298,10 +5479,26 @@ bool FieldOptions::MergePartialFromCodedStream(
         } else {
           goto handle_uninterpreted;
         }
+        if (input->ExpectTag(40)) goto parse_lazy;
+        break;
+      }
+
+      // optional bool lazy = 5 [default = false];
+      case 5: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
+         parse_lazy:
+          DO_((::google::protobuf::internal::WireFormatLite::ReadPrimitive<
+                   bool, ::google::protobuf::internal::WireFormatLite::TYPE_BOOL>(
+                 input, &lazy_)));
+          set_has_lazy();
+        } else {
+          goto handle_uninterpreted;
+        }
         if (input->ExpectTag(74)) goto parse_experimental_map_key;
         break;
       }
-      
+
       // optional string experimental_map_key = 9;
       case 9: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5315,10 +5512,26 @@ bool FieldOptions::MergePartialFromCodedStream(
         } else {
           goto handle_uninterpreted;
         }
+        if (input->ExpectTag(80)) goto parse_weak;
+        break;
+      }
+
+      // optional bool weak = 10 [default = false];
+      case 10: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
+         parse_weak:
+          DO_((::google::protobuf::internal::WireFormatLite::ReadPrimitive<
+                   bool, ::google::protobuf::internal::WireFormatLite::TYPE_BOOL>(
+                 input, &weak_)));
+          set_has_weak();
+        } else {
+          goto handle_uninterpreted;
+        }
         if (input->ExpectTag(7994)) goto parse_uninterpreted_option;
         break;
       }
-      
+
       // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
       case 999: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5333,7 +5546,7 @@ bool FieldOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5362,17 +5575,22 @@ void FieldOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteEnum(
       1, this->ctype(), output);
   }
-  
+
   // optional bool packed = 2;
   if (has_packed()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(2, this->packed(), output);
   }
-  
+
   // optional bool deprecated = 3 [default = false];
   if (has_deprecated()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(3, this->deprecated(), output);
   }
-  
+
+  // optional bool lazy = 5 [default = false];
+  if (has_lazy()) {
+    ::google::protobuf::internal::WireFormatLite::WriteBool(5, this->lazy(), output);
+  }
+
   // optional string experimental_map_key = 9;
   if (has_experimental_map_key()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -5381,17 +5599,22 @@ void FieldOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       9, this->experimental_map_key(), output);
   }
-  
+
+  // optional bool weak = 10 [default = false];
+  if (has_weak()) {
+    ::google::protobuf::internal::WireFormatLite::WriteBool(10, this->weak(), output);
+  }
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -5405,17 +5628,22 @@ void FieldOptions::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::WriteEnumToArray(
       1, this->ctype(), target);
   }
-  
+
   // optional bool packed = 2;
   if (has_packed()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(2, this->packed(), target);
   }
-  
+
   // optional bool deprecated = 3 [default = false];
   if (has_deprecated()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(3, this->deprecated(), target);
   }
-  
+
+  // optional bool lazy = 5 [default = false];
+  if (has_lazy()) {
+    target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(5, this->lazy(), target);
+  }
+
   // optional string experimental_map_key = 9;
   if (has_experimental_map_key()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -5425,18 +5653,23 @@ void FieldOptions::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         9, this->experimental_map_key(), target);
   }
-  
+
+  // optional bool weak = 10 [default = false];
+  if (has_weak()) {
+    target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(10, this->weak(), target);
+  }
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -5446,31 +5679,41 @@ void FieldOptions::SerializeWithCachedSizes(
 
 int FieldOptions::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // optional .google.protobuf.FieldOptions.CType ctype = 1 [default = STRING];
     if (has_ctype()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::EnumSize(this->ctype());
     }
-    
+
     // optional bool packed = 2;
     if (has_packed()) {
       total_size += 1 + 1;
     }
-    
+
+    // optional bool lazy = 5 [default = false];
+    if (has_lazy()) {
+      total_size += 1 + 1;
+    }
+
     // optional bool deprecated = 3 [default = false];
     if (has_deprecated()) {
       total_size += 1 + 1;
     }
-    
+
     // optional string experimental_map_key = 9;
     if (has_experimental_map_key()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->experimental_map_key());
     }
-    
+
+    // optional bool weak = 10 [default = false];
+    if (has_weak()) {
+      total_size += 1 + 1;
+    }
+
   }
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
@@ -5479,9 +5722,9 @@ int FieldOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -5515,12 +5758,18 @@ void FieldOptions::MergeFrom(const FieldOptions& from) {
     if (from.has_packed()) {
       set_packed(from.packed());
     }
+    if (from.has_lazy()) {
+      set_lazy(from.lazy());
+    }
     if (from.has_deprecated()) {
       set_deprecated(from.deprecated());
     }
     if (from.has_experimental_map_key()) {
       set_experimental_map_key(from.experimental_map_key());
     }
+    if (from.has_weak()) {
+      set_weak(from.weak());
+    }
   }
   _extensions_.MergeFrom(from._extensions_);
   mutable_unknown_fields()->MergeFrom(from.unknown_fields());
@@ -5539,11 +5788,11 @@ void FieldOptions::CopyFrom(const FieldOptions& from) {
 }
 
 bool FieldOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -5551,8 +5800,10 @@ void FieldOptions::Swap(FieldOptions* other) {
   if (other != this) {
     std::swap(ctype_, other->ctype_);
     std::swap(packed_, other->packed_);
+    std::swap(lazy_, other->lazy_);
     std::swap(deprecated_, other->deprecated_);
     std::swap(experimental_map_key_, other->experimental_map_key_);
+    std::swap(weak_, other->weak_);
     uninterpreted_option_.Swap(&other->uninterpreted_option_);
     std::swap(_has_bits_[0], other->_has_bits_[0]);
     _unknown_fields_.Swap(&other->_unknown_fields_);
@@ -5573,6 +5824,7 @@ void FieldOptions::Swap(FieldOptions* other) {
 // ===================================================================
 
 #ifndef _MSC_VER
+const int EnumOptions::kAllowAliasFieldNumber;
 const int EnumOptions::kUninterpretedOptionFieldNumber;
 #endif  // !_MSC_VER
 
@@ -5592,6 +5844,7 @@ EnumOptions::EnumOptions(const EnumOptions& from)
 
 void EnumOptions::SharedCtor() {
   _cached_size_ = 0;
+  allow_alias_ = true;
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
 }
 
@@ -5627,6 +5880,9 @@ EnumOptions* EnumOptions::New() const {
 
 void EnumOptions::Clear() {
   _extensions_.Clear();
+  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
+    allow_alias_ = true;
+  }
   uninterpreted_option_.Clear();
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
   mutable_unknown_fields()->Clear();
@@ -5638,6 +5894,21 @@ bool EnumOptions::MergePartialFromCodedStream(
   ::google::protobuf::uint32 tag;
   while ((tag = input->ReadTag()) != 0) {
     switch (::google::protobuf::internal::WireFormatLite::GetTagFieldNumber(tag)) {
+      // optional bool allow_alias = 2 [default = true];
+      case 2: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
+          DO_((::google::protobuf::internal::WireFormatLite::ReadPrimitive<
+                   bool, ::google::protobuf::internal::WireFormatLite::TYPE_BOOL>(
+                 input, &allow_alias_)));
+          set_has_allow_alias();
+        } else {
+          goto handle_uninterpreted;
+        }
+        if (input->ExpectTag(7994)) goto parse_uninterpreted_option;
+        break;
+      }
+
       // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
       case 999: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5652,7 +5923,7 @@ bool EnumOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5676,16 +5947,21 @@ bool EnumOptions::MergePartialFromCodedStream(
 
 void EnumOptions::SerializeWithCachedSizes(
     ::google::protobuf::io::CodedOutputStream* output) const {
+  // optional bool allow_alias = 2 [default = true];
+  if (has_allow_alias()) {
+    ::google::protobuf::internal::WireFormatLite::WriteBool(2, this->allow_alias(), output);
+  }
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -5694,17 +5970,22 @@ void EnumOptions::SerializeWithCachedSizes(
 
 ::google::protobuf::uint8* EnumOptions::SerializeWithCachedSizesToArray(
     ::google::protobuf::uint8* target) const {
+  // optional bool allow_alias = 2 [default = true];
+  if (has_allow_alias()) {
+    target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(2, this->allow_alias(), target);
+  }
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
     target = ::google::protobuf::internal::WireFormatLite::
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -5714,7 +5995,14 @@ void EnumOptions::SerializeWithCachedSizes(
 
 int EnumOptions::ByteSize() const {
   int total_size = 0;
-  
+
+  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
+    // optional bool allow_alias = 2 [default = true];
+    if (has_allow_alias()) {
+      total_size += 1 + 1;
+    }
+
+  }
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
@@ -5722,9 +6010,9 @@ int EnumOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -5751,6 +6039,11 @@ void EnumOptions::MergeFrom(const ::google::protobuf::Message& from) {
 void EnumOptions::MergeFrom(const EnumOptions& from) {
   GOOGLE_CHECK_NE(&from, this);
   uninterpreted_option_.MergeFrom(from.uninterpreted_option_);
+  if (from._has_bits_[0 / 32] & (0xffu << (0 % 32))) {
+    if (from.has_allow_alias()) {
+      set_allow_alias(from.allow_alias());
+    }
+  }
   _extensions_.MergeFrom(from._extensions_);
   mutable_unknown_fields()->MergeFrom(from.unknown_fields());
 }
@@ -5768,16 +6061,17 @@ void EnumOptions::CopyFrom(const EnumOptions& from) {
 }
 
 bool EnumOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
 void EnumOptions::Swap(EnumOptions* other) {
   if (other != this) {
+    std::swap(allow_alias_, other->allow_alias_);
     uninterpreted_option_.Swap(&other->uninterpreted_option_);
     std::swap(_has_bits_[0], other->_has_bits_[0]);
     _unknown_fields_.Swap(&other->_unknown_fields_);
@@ -5877,7 +6171,7 @@ bool EnumValueOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -5906,11 +6200,11 @@ void EnumValueOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -5925,11 +6219,11 @@ void EnumValueOptions::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -5939,7 +6233,7 @@ void EnumValueOptions::SerializeWithCachedSizes(
 
 int EnumValueOptions::ByteSize() const {
   int total_size = 0;
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
@@ -5947,9 +6241,9 @@ int EnumValueOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -5993,11 +6287,11 @@ void EnumValueOptions::CopyFrom(const EnumValueOptions& from) {
 }
 
 bool EnumValueOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -6102,7 +6396,7 @@ bool ServiceOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6131,11 +6425,11 @@ void ServiceOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -6150,11 +6444,11 @@ void ServiceOptions::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -6164,7 +6458,7 @@ void ServiceOptions::SerializeWithCachedSizes(
 
 int ServiceOptions::ByteSize() const {
   int total_size = 0;
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
@@ -6172,9 +6466,9 @@ int ServiceOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -6218,11 +6512,11 @@ void ServiceOptions::CopyFrom(const ServiceOptions& from) {
 }
 
 bool ServiceOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -6327,7 +6621,7 @@ bool MethodOptions::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6356,11 +6650,11 @@ void MethodOptions::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       999, this->uninterpreted_option(i), output);
   }
-  
+
   // Extension range [1000, 536870912)
   _extensions_.SerializeWithCachedSizes(
       1000, 536870912, output);
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -6375,11 +6669,11 @@ void MethodOptions::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         999, this->uninterpreted_option(i), target);
   }
-  
+
   // Extension range [1000, 536870912)
   target = _extensions_.SerializeWithCachedSizesToArray(
       1000, 536870912, target);
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -6389,7 +6683,7 @@ void MethodOptions::SerializeWithCachedSizes(
 
 int MethodOptions::ByteSize() const {
   int total_size = 0;
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   total_size += 2 * this->uninterpreted_option_size();
   for (int i = 0; i < this->uninterpreted_option_size(); i++) {
@@ -6397,9 +6691,9 @@ int MethodOptions::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->uninterpreted_option(i));
   }
-  
+
   total_size += _extensions_.ByteSize();
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -6443,11 +6737,11 @@ void MethodOptions::CopyFrom(const MethodOptions& from) {
 }
 
 bool MethodOptions::IsInitialized() const {
-  
+
   for (int i = 0; i < uninterpreted_option_size(); i++) {
     if (!this->uninterpreted_option(i).IsInitialized()) return false;
   }
-  
+
   if (!_extensions_.IsInitialized()) return false;  return true;
 }
 
@@ -6565,7 +6859,7 @@ bool UninterpretedOption_NamePart::MergePartialFromCodedStream(
         if (input->ExpectTag(16)) goto parse_is_extension;
         break;
       }
-      
+
       // required bool is_extension = 2;
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6581,7 +6875,7 @@ bool UninterpretedOption_NamePart::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6608,12 +6902,12 @@ void UninterpretedOption_NamePart::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       1, this->name_part(), output);
   }
-  
+
   // required bool is_extension = 2;
   if (has_is_extension()) {
     ::google::protobuf::internal::WireFormatLite::WriteBool(2, this->is_extension(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -6631,12 +6925,12 @@ void UninterpretedOption_NamePart::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         1, this->name_part(), target);
   }
-  
+
   // required bool is_extension = 2;
   if (has_is_extension()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteBoolToArray(2, this->is_extension(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -6646,7 +6940,7 @@ void UninterpretedOption_NamePart::SerializeWithCachedSizes(
 
 int UninterpretedOption_NamePart::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
     // required string name_part = 1;
     if (has_name_part()) {
@@ -6654,12 +6948,12 @@ int UninterpretedOption_NamePart::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->name_part());
     }
-    
+
     // required bool is_extension = 2;
     if (has_is_extension()) {
       total_size += 1 + 1;
     }
-    
+
   }
   if (!unknown_fields().empty()) {
     total_size +=
@@ -6711,7 +7005,7 @@ void UninterpretedOption_NamePart::CopyFrom(const UninterpretedOption_NamePart&
 
 bool UninterpretedOption_NamePart::IsInitialized() const {
   if ((_has_bits_[0] & 0x00000003) != 0x00000003) return false;
-  
+
   return true;
 }
 
@@ -6856,7 +7150,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(26)) goto parse_identifier_value;
         break;
       }
-      
+
       // optional string identifier_value = 3;
       case 3: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6873,7 +7167,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(32)) goto parse_positive_int_value;
         break;
       }
-      
+
       // optional uint64 positive_int_value = 4;
       case 4: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6889,7 +7183,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(40)) goto parse_negative_int_value;
         break;
       }
-      
+
       // optional int64 negative_int_value = 5;
       case 5: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6905,7 +7199,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(49)) goto parse_double_value;
         break;
       }
-      
+
       // optional double double_value = 6;
       case 6: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6921,7 +7215,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(58)) goto parse_string_value;
         break;
       }
-      
+
       // optional bytes string_value = 7;
       case 7: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6935,7 +7229,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectTag(66)) goto parse_aggregate_value;
         break;
       }
-      
+
       // optional string aggregate_value = 8;
       case 8: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6952,7 +7246,7 @@ bool UninterpretedOption::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -6976,7 +7270,7 @@ void UninterpretedOption::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       2, this->name(i), output);
   }
-  
+
   // optional string identifier_value = 3;
   if (has_identifier_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -6985,28 +7279,28 @@ void UninterpretedOption::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       3, this->identifier_value(), output);
   }
-  
+
   // optional uint64 positive_int_value = 4;
   if (has_positive_int_value()) {
     ::google::protobuf::internal::WireFormatLite::WriteUInt64(4, this->positive_int_value(), output);
   }
-  
+
   // optional int64 negative_int_value = 5;
   if (has_negative_int_value()) {
     ::google::protobuf::internal::WireFormatLite::WriteInt64(5, this->negative_int_value(), output);
   }
-  
+
   // optional double double_value = 6;
   if (has_double_value()) {
     ::google::protobuf::internal::WireFormatLite::WriteDouble(6, this->double_value(), output);
   }
-  
+
   // optional bytes string_value = 7;
   if (has_string_value()) {
     ::google::protobuf::internal::WireFormatLite::WriteBytes(
       7, this->string_value(), output);
   }
-  
+
   // optional string aggregate_value = 8;
   if (has_aggregate_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -7015,7 +7309,7 @@ void UninterpretedOption::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteString(
       8, this->aggregate_value(), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -7030,7 +7324,7 @@ void UninterpretedOption::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         2, this->name(i), target);
   }
-  
+
   // optional string identifier_value = 3;
   if (has_identifier_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -7040,29 +7334,29 @@ void UninterpretedOption::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         3, this->identifier_value(), target);
   }
-  
+
   // optional uint64 positive_int_value = 4;
   if (has_positive_int_value()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteUInt64ToArray(4, this->positive_int_value(), target);
   }
-  
+
   // optional int64 negative_int_value = 5;
   if (has_negative_int_value()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteInt64ToArray(5, this->negative_int_value(), target);
   }
-  
+
   // optional double double_value = 6;
   if (has_double_value()) {
     target = ::google::protobuf::internal::WireFormatLite::WriteDoubleToArray(6, this->double_value(), target);
   }
-  
+
   // optional bytes string_value = 7;
   if (has_string_value()) {
     target =
       ::google::protobuf::internal::WireFormatLite::WriteBytesToArray(
         7, this->string_value(), target);
   }
-  
+
   // optional string aggregate_value = 8;
   if (has_aggregate_value()) {
     ::google::protobuf::internal::WireFormat::VerifyUTF8String(
@@ -7072,7 +7366,7 @@ void UninterpretedOption::SerializeWithCachedSizes(
       ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
         8, this->aggregate_value(), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -7082,7 +7376,7 @@ void UninterpretedOption::SerializeWithCachedSizes(
 
 int UninterpretedOption::ByteSize() const {
   int total_size = 0;
-  
+
   if (_has_bits_[1 / 32] & (0xffu << (1 % 32))) {
     // optional string identifier_value = 3;
     if (has_identifier_value()) {
@@ -7090,40 +7384,40 @@ int UninterpretedOption::ByteSize() const {
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->identifier_value());
     }
-    
+
     // optional uint64 positive_int_value = 4;
     if (has_positive_int_value()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::UInt64Size(
           this->positive_int_value());
     }
-    
+
     // optional int64 negative_int_value = 5;
     if (has_negative_int_value()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int64Size(
           this->negative_int_value());
     }
-    
+
     // optional double double_value = 6;
     if (has_double_value()) {
       total_size += 1 + 8;
     }
-    
+
     // optional bytes string_value = 7;
     if (has_string_value()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::BytesSize(
           this->string_value());
     }
-    
+
     // optional string aggregate_value = 8;
     if (has_aggregate_value()) {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::StringSize(
           this->aggregate_value());
     }
-    
+
   }
   // repeated .google.protobuf.UninterpretedOption.NamePart name = 2;
   total_size += 1 * this->name_size();
@@ -7132,7 +7426,7 @@ int UninterpretedOption::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->name(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -7195,7 +7489,7 @@ void UninterpretedOption::CopyFrom(const UninterpretedOption& from) {
 }
 
 bool UninterpretedOption::IsInitialized() const {
-  
+
   for (int i = 0; i < name_size(); i++) {
     if (!this->name(i).IsInitialized()) return false;
   }
@@ -7231,6 +7525,8 @@ void UninterpretedOption::Swap(UninterpretedOption* other) {
 #ifndef _MSC_VER
 const int SourceCodeInfo_Location::kPathFieldNumber;
 const int SourceCodeInfo_Location::kSpanFieldNumber;
+const int SourceCodeInfo_Location::kLeadingCommentsFieldNumber;
+const int SourceCodeInfo_Location::kTrailingCommentsFieldNumber;
 #endif  // !_MSC_VER
 
 SourceCodeInfo_Location::SourceCodeInfo_Location()
@@ -7249,6 +7545,8 @@ SourceCodeInfo_Location::SourceCodeInfo_Location(const SourceCodeInfo_Location&
 
 void SourceCodeInfo_Location::SharedCtor() {
   _cached_size_ = 0;
+  leading_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  trailing_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
 }
 
@@ -7257,6 +7555,12 @@ SourceCodeInfo_Location::~SourceCodeInfo_Location() {
 }
 
 void SourceCodeInfo_Location::SharedDtor() {
+  if (leading_comments_ != &::google::protobuf::internal::kEmptyString) {
+    delete leading_comments_;
+  }
+  if (trailing_comments_ != &::google::protobuf::internal::kEmptyString) {
+    delete trailing_comments_;
+  }
   if (this != default_instance_) {
   }
 }
@@ -7283,6 +7587,18 @@ SourceCodeInfo_Location* SourceCodeInfo_Location::New() const {
 }
 
 void SourceCodeInfo_Location::Clear() {
+  if (_has_bits_[2 / 32] & (0xffu << (2 % 32))) {
+    if (has_leading_comments()) {
+      if (leading_comments_ != &::google::protobuf::internal::kEmptyString) {
+        leading_comments_->clear();
+      }
+    }
+    if (has_trailing_comments()) {
+      if (trailing_comments_ != &::google::protobuf::internal::kEmptyString) {
+        trailing_comments_->clear();
+      }
+    }
+  }
   path_.Clear();
   span_.Clear();
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
@@ -7314,7 +7630,7 @@ bool SourceCodeInfo_Location::MergePartialFromCodedStream(
         if (input->ExpectTag(18)) goto parse_span;
         break;
       }
-      
+
       // repeated int32 span = 2 [packed = true];
       case 2: {
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -7332,10 +7648,44 @@ bool SourceCodeInfo_Location::MergePartialFromCodedStream(
         } else {
           goto handle_uninterpreted;
         }
+        if (input->ExpectTag(26)) goto parse_leading_comments;
+        break;
+      }
+
+      // optional string leading_comments = 3;
+      case 3: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {
+         parse_leading_comments:
+          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
+                input, this->mutable_leading_comments()));
+          ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+            this->leading_comments().data(), this->leading_comments().length(),
+            ::google::protobuf::internal::WireFormat::PARSE);
+        } else {
+          goto handle_uninterpreted;
+        }
+        if (input->ExpectTag(34)) goto parse_trailing_comments;
+        break;
+      }
+
+      // optional string trailing_comments = 4;
+      case 4: {
+        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
+            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {
+         parse_trailing_comments:
+          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
+                input, this->mutable_trailing_comments()));
+          ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+            this->trailing_comments().data(), this->trailing_comments().length(),
+            ::google::protobuf::internal::WireFormat::PARSE);
+        } else {
+          goto handle_uninterpreted;
+        }
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -7363,7 +7713,7 @@ void SourceCodeInfo_Location::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteInt32NoTag(
       this->path(i), output);
   }
-  
+
   // repeated int32 span = 2 [packed = true];
   if (this->span_size() > 0) {
     ::google::protobuf::internal::WireFormatLite::WriteTag(2, ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED, output);
@@ -7373,7 +7723,25 @@ void SourceCodeInfo_Location::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteInt32NoTag(
       this->span(i), output);
   }
-  
+
+  // optional string leading_comments = 3;
+  if (has_leading_comments()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->leading_comments().data(), this->leading_comments().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    ::google::protobuf::internal::WireFormatLite::WriteString(
+      3, this->leading_comments(), output);
+  }
+
+  // optional string trailing_comments = 4;
+  if (has_trailing_comments()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->trailing_comments().data(), this->trailing_comments().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    ::google::protobuf::internal::WireFormatLite::WriteString(
+      4, this->trailing_comments(), output);
+  }
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -7395,7 +7763,7 @@ void SourceCodeInfo_Location::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::
       WriteInt32NoTagToArray(this->path(i), target);
   }
-  
+
   // repeated int32 span = 2 [packed = true];
   if (this->span_size() > 0) {
     target = ::google::protobuf::internal::WireFormatLite::WriteTagToArray(
@@ -7409,7 +7777,27 @@ void SourceCodeInfo_Location::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::
       WriteInt32NoTagToArray(this->span(i), target);
   }
-  
+
+  // optional string leading_comments = 3;
+  if (has_leading_comments()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->leading_comments().data(), this->leading_comments().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    target =
+      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
+        3, this->leading_comments(), target);
+  }
+
+  // optional string trailing_comments = 4;
+  if (has_trailing_comments()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
+      this->trailing_comments().data(), this->trailing_comments().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE);
+    target =
+      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
+        4, this->trailing_comments(), target);
+  }
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -7419,7 +7807,23 @@ void SourceCodeInfo_Location::SerializeWithCachedSizes(
 
 int SourceCodeInfo_Location::ByteSize() const {
   int total_size = 0;
-  
+
+  if (_has_bits_[2 / 32] & (0xffu << (2 % 32))) {
+    // optional string leading_comments = 3;
+    if (has_leading_comments()) {
+      total_size += 1 +
+        ::google::protobuf::internal::WireFormatLite::StringSize(
+          this->leading_comments());
+    }
+
+    // optional string trailing_comments = 4;
+    if (has_trailing_comments()) {
+      total_size += 1 +
+        ::google::protobuf::internal::WireFormatLite::StringSize(
+          this->trailing_comments());
+    }
+
+  }
   // repeated int32 path = 1 [packed = true];
   {
     int data_size = 0;
@@ -7431,10 +7835,12 @@ int SourceCodeInfo_Location::ByteSize() const {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int32Size(data_size);
     }
+    GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
     _path_cached_byte_size_ = data_size;
+    GOOGLE_SAFE_CONCURRENT_WRITES_END();
     total_size += data_size;
   }
-  
+
   // repeated int32 span = 2 [packed = true];
   {
     int data_size = 0;
@@ -7446,10 +7852,12 @@ int SourceCodeInfo_Location::ByteSize() const {
       total_size += 1 +
         ::google::protobuf::internal::WireFormatLite::Int32Size(data_size);
     }
+    GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
     _span_cached_byte_size_ = data_size;
+    GOOGLE_SAFE_CONCURRENT_WRITES_END();
     total_size += data_size;
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -7477,6 +7885,14 @@ void SourceCodeInfo_Location::MergeFrom(const SourceCodeInfo_Location& from) {
   GOOGLE_CHECK_NE(&from, this);
   path_.MergeFrom(from.path_);
   span_.MergeFrom(from.span_);
+  if (from._has_bits_[2 / 32] & (0xffu << (2 % 32))) {
+    if (from.has_leading_comments()) {
+      set_leading_comments(from.leading_comments());
+    }
+    if (from.has_trailing_comments()) {
+      set_trailing_comments(from.trailing_comments());
+    }
+  }
   mutable_unknown_fields()->MergeFrom(from.unknown_fields());
 }
 
@@ -7493,7 +7909,7 @@ void SourceCodeInfo_Location::CopyFrom(const SourceCodeInfo_Location& from) {
 }
 
 bool SourceCodeInfo_Location::IsInitialized() const {
-  
+
   return true;
 }
 
@@ -7501,6 +7917,8 @@ void SourceCodeInfo_Location::Swap(SourceCodeInfo_Location* other) {
   if (other != this) {
     path_.Swap(&other->path_);
     span_.Swap(&other->span_);
+    std::swap(leading_comments_, other->leading_comments_);
+    std::swap(trailing_comments_, other->trailing_comments_);
     std::swap(_has_bits_[0], other->_has_bits_[0]);
     _unknown_fields_.Swap(&other->_unknown_fields_);
     std::swap(_cached_size_, other->_cached_size_);
@@ -7597,7 +8015,7 @@ bool SourceCodeInfo::MergePartialFromCodedStream(
         if (input->ExpectAtEnd()) return true;
         break;
       }
-      
+
       default: {
       handle_uninterpreted:
         if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
@@ -7621,7 +8039,7 @@ void SourceCodeInfo::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteMessageMaybeToArray(
       1, this->location(i), output);
   }
-  
+
   if (!unknown_fields().empty()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -7636,7 +8054,7 @@ void SourceCodeInfo::SerializeWithCachedSizes(
       WriteMessageNoVirtualToArray(
         1, this->location(i), target);
   }
-  
+
   if (!unknown_fields().empty()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -7646,7 +8064,7 @@ void SourceCodeInfo::SerializeWithCachedSizes(
 
 int SourceCodeInfo::ByteSize() const {
   int total_size = 0;
-  
+
   // repeated .google.protobuf.SourceCodeInfo.Location location = 1;
   total_size += 1 * this->location_size();
   for (int i = 0; i < this->location_size(); i++) {
@@ -7654,7 +8072,7 @@ int SourceCodeInfo::ByteSize() const {
       ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
         this->location(i));
   }
-  
+
   if (!unknown_fields().empty()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -7697,7 +8115,7 @@ void SourceCodeInfo::CopyFrom(const SourceCodeInfo& from) {
 }
 
 bool SourceCodeInfo::IsInitialized() const {
-  
+
   return true;
 }
 
diff --git a/src/google/protobuf/descriptor.pb.h b/src/google/protobuf/descriptor.pb.h
index 267d0d35..b7ea1b28 100644
--- a/src/google/protobuf/descriptor.pb.h
+++ b/src/google/protobuf/descriptor.pb.h
@@ -20,9 +20,11 @@
 #endif
 
 #include <google/protobuf/generated_message_util.h>
+#include <google/protobuf/message.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/extension_set.h>
-#include <google/protobuf/generated_message_reflection.h>
+#include <google/protobuf/generated_enum_reflection.h>
+#include <google/protobuf/unknown_field_set.h>
 // @@protoc_insertion_point(includes)
 
 namespace google {
@@ -155,29 +157,29 @@ class LIBPROTOBUF_EXPORT FileDescriptorSet : public ::google::protobuf::Message
  public:
   FileDescriptorSet();
   virtual ~FileDescriptorSet();
-  
+
   FileDescriptorSet(const FileDescriptorSet& from);
-  
+
   inline FileDescriptorSet& operator=(const FileDescriptorSet& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const FileDescriptorSet& default_instance();
-  
+
   void Swap(FileDescriptorSet* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   FileDescriptorSet* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -185,7 +187,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorSet : public ::google::protobuf::Message
   void MergeFrom(const FileDescriptorSet& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -198,13 +200,13 @@ class LIBPROTOBUF_EXPORT FileDescriptorSet : public ::google::protobuf::Message
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.FileDescriptorProto file = 1;
   inline int file_size() const;
   inline void clear_file();
@@ -216,21 +218,21 @@ class LIBPROTOBUF_EXPORT FileDescriptorSet : public ::google::protobuf::Message
       file() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::FileDescriptorProto >*
       mutable_file();
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.FileDescriptorSet)
  private:
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::FileDescriptorProto > file_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static FileDescriptorSet* default_instance_;
 };
@@ -240,29 +242,29 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
  public:
   FileDescriptorProto();
   virtual ~FileDescriptorProto();
-  
+
   FileDescriptorProto(const FileDescriptorProto& from);
-  
+
   inline FileDescriptorProto& operator=(const FileDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const FileDescriptorProto& default_instance();
-  
+
   void Swap(FileDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   FileDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -270,7 +272,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   void MergeFrom(const FileDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -283,13 +285,13 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -300,7 +302,8 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // optional string package = 2;
   inline bool has_package() const;
   inline void clear_package();
@@ -311,7 +314,8 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline void set_package(const char* value, size_t size);
   inline ::std::string* mutable_package();
   inline ::std::string* release_package();
-  
+  inline void set_allocated_package(::std::string* package);
+
   // repeated string dependency = 3;
   inline int dependency_size() const;
   inline void clear_dependency();
@@ -327,7 +331,31 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline void add_dependency(const char* value, size_t size);
   inline const ::google::protobuf::RepeatedPtrField< ::std::string>& dependency() const;
   inline ::google::protobuf::RepeatedPtrField< ::std::string>* mutable_dependency();
-  
+
+  // repeated int32 public_dependency = 10;
+  inline int public_dependency_size() const;
+  inline void clear_public_dependency();
+  static const int kPublicDependencyFieldNumber = 10;
+  inline ::google::protobuf::int32 public_dependency(int index) const;
+  inline void set_public_dependency(int index, ::google::protobuf::int32 value);
+  inline void add_public_dependency(::google::protobuf::int32 value);
+  inline const ::google::protobuf::RepeatedField< ::google::protobuf::int32 >&
+      public_dependency() const;
+  inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
+      mutable_public_dependency();
+
+  // repeated int32 weak_dependency = 11;
+  inline int weak_dependency_size() const;
+  inline void clear_weak_dependency();
+  static const int kWeakDependencyFieldNumber = 11;
+  inline ::google::protobuf::int32 weak_dependency(int index) const;
+  inline void set_weak_dependency(int index, ::google::protobuf::int32 value);
+  inline void add_weak_dependency(::google::protobuf::int32 value);
+  inline const ::google::protobuf::RepeatedField< ::google::protobuf::int32 >&
+      weak_dependency() const;
+  inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
+      mutable_weak_dependency();
+
   // repeated .google.protobuf.DescriptorProto message_type = 4;
   inline int message_type_size() const;
   inline void clear_message_type();
@@ -339,7 +367,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
       message_type() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::DescriptorProto >*
       mutable_message_type();
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
   inline int enum_type_size() const;
   inline void clear_enum_type();
@@ -351,7 +379,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
       enum_type() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumDescriptorProto >*
       mutable_enum_type();
-  
+
   // repeated .google.protobuf.ServiceDescriptorProto service = 6;
   inline int service_size() const;
   inline void clear_service();
@@ -363,7 +391,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
       service() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::ServiceDescriptorProto >*
       mutable_service();
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 7;
   inline int extension_size() const;
   inline void clear_extension();
@@ -375,7 +403,7 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
       extension() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto >*
       mutable_extension();
-  
+
   // optional .google.protobuf.FileOptions options = 8;
   inline bool has_options() const;
   inline void clear_options();
@@ -383,7 +411,8 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline const ::google::protobuf::FileOptions& options() const;
   inline ::google::protobuf::FileOptions* mutable_options();
   inline ::google::protobuf::FileOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::FileOptions* options);
+
   // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
   inline bool has_source_code_info() const;
   inline void clear_source_code_info();
@@ -391,7 +420,8 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline const ::google::protobuf::SourceCodeInfo& source_code_info() const;
   inline ::google::protobuf::SourceCodeInfo* mutable_source_code_info();
   inline ::google::protobuf::SourceCodeInfo* release_source_code_info();
-  
+  inline void set_allocated_source_code_info(::google::protobuf::SourceCodeInfo* source_code_info);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.FileDescriptorProto)
  private:
   inline void set_has_name();
@@ -402,26 +432,28 @@ class LIBPROTOBUF_EXPORT FileDescriptorProto : public ::google::protobuf::Messag
   inline void clear_has_options();
   inline void set_has_source_code_info();
   inline void clear_has_source_code_info();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::std::string* package_;
   ::google::protobuf::RepeatedPtrField< ::std::string> dependency_;
+  ::google::protobuf::RepeatedField< ::google::protobuf::int32 > public_dependency_;
+  ::google::protobuf::RepeatedField< ::google::protobuf::int32 > weak_dependency_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::DescriptorProto > message_type_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumDescriptorProto > enum_type_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::ServiceDescriptorProto > service_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto > extension_;
   ::google::protobuf::FileOptions* options_;
   ::google::protobuf::SourceCodeInfo* source_code_info_;
-  
+
   mutable int _cached_size_;
-  ::google::protobuf::uint32 _has_bits_[(9 + 31) / 32];
-  
+  ::google::protobuf::uint32 _has_bits_[(11 + 31) / 32];
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static FileDescriptorProto* default_instance_;
 };
@@ -431,29 +463,29 @@ class LIBPROTOBUF_EXPORT DescriptorProto_ExtensionRange : public ::google::proto
  public:
   DescriptorProto_ExtensionRange();
   virtual ~DescriptorProto_ExtensionRange();
-  
+
   DescriptorProto_ExtensionRange(const DescriptorProto_ExtensionRange& from);
-  
+
   inline DescriptorProto_ExtensionRange& operator=(const DescriptorProto_ExtensionRange& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const DescriptorProto_ExtensionRange& default_instance();
-  
+
   void Swap(DescriptorProto_ExtensionRange* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   DescriptorProto_ExtensionRange* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -461,7 +493,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto_ExtensionRange : public ::google::proto
   void MergeFrom(const DescriptorProto_ExtensionRange& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -474,46 +506,46 @@ class LIBPROTOBUF_EXPORT DescriptorProto_ExtensionRange : public ::google::proto
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional int32 start = 1;
   inline bool has_start() const;
   inline void clear_start();
   static const int kStartFieldNumber = 1;
   inline ::google::protobuf::int32 start() const;
   inline void set_start(::google::protobuf::int32 value);
-  
+
   // optional int32 end = 2;
   inline bool has_end() const;
   inline void clear_end();
   static const int kEndFieldNumber = 2;
   inline ::google::protobuf::int32 end() const;
   inline void set_end(::google::protobuf::int32 value);
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.DescriptorProto.ExtensionRange)
  private:
   inline void set_has_start();
   inline void clear_has_start();
   inline void set_has_end();
   inline void clear_has_end();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::int32 start_;
   ::google::protobuf::int32 end_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static DescriptorProto_ExtensionRange* default_instance_;
 };
@@ -523,29 +555,29 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
  public:
   DescriptorProto();
   virtual ~DescriptorProto();
-  
+
   DescriptorProto(const DescriptorProto& from);
-  
+
   inline DescriptorProto& operator=(const DescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const DescriptorProto& default_instance();
-  
+
   void Swap(DescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   DescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -553,7 +585,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
   void MergeFrom(const DescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -566,15 +598,15 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef DescriptorProto_ExtensionRange ExtensionRange;
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -585,7 +617,8 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // repeated .google.protobuf.FieldDescriptorProto field = 2;
   inline int field_size() const;
   inline void clear_field();
@@ -597,7 +630,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
       field() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto >*
       mutable_field();
-  
+
   // repeated .google.protobuf.FieldDescriptorProto extension = 6;
   inline int extension_size() const;
   inline void clear_extension();
@@ -609,7 +642,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
       extension() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto >*
       mutable_extension();
-  
+
   // repeated .google.protobuf.DescriptorProto nested_type = 3;
   inline int nested_type_size() const;
   inline void clear_nested_type();
@@ -621,7 +654,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
       nested_type() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::DescriptorProto >*
       mutable_nested_type();
-  
+
   // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
   inline int enum_type_size() const;
   inline void clear_enum_type();
@@ -633,7 +666,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
       enum_type() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumDescriptorProto >*
       mutable_enum_type();
-  
+
   // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
   inline int extension_range_size() const;
   inline void clear_extension_range();
@@ -645,7 +678,7 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
       extension_range() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::DescriptorProto_ExtensionRange >*
       mutable_extension_range();
-  
+
   // optional .google.protobuf.MessageOptions options = 7;
   inline bool has_options() const;
   inline void clear_options();
@@ -653,16 +686,17 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
   inline const ::google::protobuf::MessageOptions& options() const;
   inline ::google::protobuf::MessageOptions* mutable_options();
   inline ::google::protobuf::MessageOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::MessageOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.DescriptorProto)
  private:
   inline void set_has_name();
   inline void clear_has_name();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto > field_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::FieldDescriptorProto > extension_;
@@ -670,14 +704,14 @@ class LIBPROTOBUF_EXPORT DescriptorProto : public ::google::protobuf::Message {
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumDescriptorProto > enum_type_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::DescriptorProto_ExtensionRange > extension_range_;
   ::google::protobuf::MessageOptions* options_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(7 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static DescriptorProto* default_instance_;
 };
@@ -687,29 +721,29 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
  public:
   FieldDescriptorProto();
   virtual ~FieldDescriptorProto();
-  
+
   FieldDescriptorProto(const FieldDescriptorProto& from);
-  
+
   inline FieldDescriptorProto& operator=(const FieldDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const FieldDescriptorProto& default_instance();
-  
+
   void Swap(FieldDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   FieldDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -717,7 +751,7 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   void MergeFrom(const FieldDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -730,11 +764,11 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef FieldDescriptorProto_Type Type;
   static const Type TYPE_DOUBLE = FieldDescriptorProto_Type_TYPE_DOUBLE;
   static const Type TYPE_FLOAT = FieldDescriptorProto_Type_TYPE_FLOAT;
@@ -774,7 +808,7 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
       Type* value) {
     return FieldDescriptorProto_Type_Parse(name, value);
   }
-  
+
   typedef FieldDescriptorProto_Label Label;
   static const Label LABEL_OPTIONAL = FieldDescriptorProto_Label_LABEL_OPTIONAL;
   static const Label LABEL_REQUIRED = FieldDescriptorProto_Label_LABEL_REQUIRED;
@@ -799,9 +833,9 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
       Label* value) {
     return FieldDescriptorProto_Label_Parse(name, value);
   }
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -812,28 +846,29 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // optional int32 number = 3;
   inline bool has_number() const;
   inline void clear_number();
   static const int kNumberFieldNumber = 3;
   inline ::google::protobuf::int32 number() const;
   inline void set_number(::google::protobuf::int32 value);
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
   inline bool has_label() const;
   inline void clear_label();
   static const int kLabelFieldNumber = 4;
   inline ::google::protobuf::FieldDescriptorProto_Label label() const;
   inline void set_label(::google::protobuf::FieldDescriptorProto_Label value);
-  
+
   // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
   inline bool has_type() const;
   inline void clear_type();
   static const int kTypeFieldNumber = 5;
   inline ::google::protobuf::FieldDescriptorProto_Type type() const;
   inline void set_type(::google::protobuf::FieldDescriptorProto_Type value);
-  
+
   // optional string type_name = 6;
   inline bool has_type_name() const;
   inline void clear_type_name();
@@ -844,7 +879,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void set_type_name(const char* value, size_t size);
   inline ::std::string* mutable_type_name();
   inline ::std::string* release_type_name();
-  
+  inline void set_allocated_type_name(::std::string* type_name);
+
   // optional string extendee = 2;
   inline bool has_extendee() const;
   inline void clear_extendee();
@@ -855,7 +891,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void set_extendee(const char* value, size_t size);
   inline ::std::string* mutable_extendee();
   inline ::std::string* release_extendee();
-  
+  inline void set_allocated_extendee(::std::string* extendee);
+
   // optional string default_value = 7;
   inline bool has_default_value() const;
   inline void clear_default_value();
@@ -866,7 +903,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void set_default_value(const char* value, size_t size);
   inline ::std::string* mutable_default_value();
   inline ::std::string* release_default_value();
-  
+  inline void set_allocated_default_value(::std::string* default_value);
+
   // optional .google.protobuf.FieldOptions options = 8;
   inline bool has_options() const;
   inline void clear_options();
@@ -874,7 +912,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline const ::google::protobuf::FieldOptions& options() const;
   inline ::google::protobuf::FieldOptions* mutable_options();
   inline ::google::protobuf::FieldOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::FieldOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.FieldDescriptorProto)
  private:
   inline void set_has_name();
@@ -893,9 +932,9 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void clear_has_default_value();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::google::protobuf::int32 number_;
   int label_;
@@ -904,14 +943,14 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   ::std::string* default_value_;
   ::google::protobuf::FieldOptions* options_;
   int type_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(8 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static FieldDescriptorProto* default_instance_;
 };
@@ -921,29 +960,29 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
  public:
   EnumDescriptorProto();
   virtual ~EnumDescriptorProto();
-  
+
   EnumDescriptorProto(const EnumDescriptorProto& from);
-  
+
   inline EnumDescriptorProto& operator=(const EnumDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const EnumDescriptorProto& default_instance();
-  
+
   void Swap(EnumDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   EnumDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -951,7 +990,7 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
   void MergeFrom(const EnumDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -964,13 +1003,13 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -981,7 +1020,8 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
   inline int value_size() const;
   inline void clear_value();
@@ -993,7 +1033,7 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
       value() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumValueDescriptorProto >*
       mutable_value();
-  
+
   // optional .google.protobuf.EnumOptions options = 3;
   inline bool has_options() const;
   inline void clear_options();
@@ -1001,27 +1041,28 @@ class LIBPROTOBUF_EXPORT EnumDescriptorProto : public ::google::protobuf::Messag
   inline const ::google::protobuf::EnumOptions& options() const;
   inline ::google::protobuf::EnumOptions* mutable_options();
   inline ::google::protobuf::EnumOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::EnumOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.EnumDescriptorProto)
  private:
   inline void set_has_name();
   inline void clear_has_name();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::EnumValueDescriptorProto > value_;
   ::google::protobuf::EnumOptions* options_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static EnumDescriptorProto* default_instance_;
 };
@@ -1031,29 +1072,29 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
  public:
   EnumValueDescriptorProto();
   virtual ~EnumValueDescriptorProto();
-  
+
   EnumValueDescriptorProto(const EnumValueDescriptorProto& from);
-  
+
   inline EnumValueDescriptorProto& operator=(const EnumValueDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const EnumValueDescriptorProto& default_instance();
-  
+
   void Swap(EnumValueDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   EnumValueDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1061,7 +1102,7 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
   void MergeFrom(const EnumValueDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1074,13 +1115,13 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -1091,14 +1132,15 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // optional int32 number = 2;
   inline bool has_number() const;
   inline void clear_number();
   static const int kNumberFieldNumber = 2;
   inline ::google::protobuf::int32 number() const;
   inline void set_number(::google::protobuf::int32 value);
-  
+
   // optional .google.protobuf.EnumValueOptions options = 3;
   inline bool has_options() const;
   inline void clear_options();
@@ -1106,7 +1148,8 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
   inline const ::google::protobuf::EnumValueOptions& options() const;
   inline ::google::protobuf::EnumValueOptions* mutable_options();
   inline ::google::protobuf::EnumValueOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::EnumValueOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.EnumValueDescriptorProto)
  private:
   inline void set_has_name();
@@ -1115,20 +1158,20 @@ class LIBPROTOBUF_EXPORT EnumValueDescriptorProto : public ::google::protobuf::M
   inline void clear_has_number();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::google::protobuf::EnumValueOptions* options_;
   ::google::protobuf::int32 number_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static EnumValueDescriptorProto* default_instance_;
 };
@@ -1138,29 +1181,29 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
  public:
   ServiceDescriptorProto();
   virtual ~ServiceDescriptorProto();
-  
+
   ServiceDescriptorProto(const ServiceDescriptorProto& from);
-  
+
   inline ServiceDescriptorProto& operator=(const ServiceDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const ServiceDescriptorProto& default_instance();
-  
+
   void Swap(ServiceDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   ServiceDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1168,7 +1211,7 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
   void MergeFrom(const ServiceDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1181,13 +1224,13 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -1198,7 +1241,8 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // repeated .google.protobuf.MethodDescriptorProto method = 2;
   inline int method_size() const;
   inline void clear_method();
@@ -1210,7 +1254,7 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
       method() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::MethodDescriptorProto >*
       mutable_method();
-  
+
   // optional .google.protobuf.ServiceOptions options = 3;
   inline bool has_options() const;
   inline void clear_options();
@@ -1218,27 +1262,28 @@ class LIBPROTOBUF_EXPORT ServiceDescriptorProto : public ::google::protobuf::Mes
   inline const ::google::protobuf::ServiceOptions& options() const;
   inline ::google::protobuf::ServiceOptions* mutable_options();
   inline ::google::protobuf::ServiceOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::ServiceOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.ServiceDescriptorProto)
  private:
   inline void set_has_name();
   inline void clear_has_name();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::MethodDescriptorProto > method_;
   ::google::protobuf::ServiceOptions* options_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static ServiceDescriptorProto* default_instance_;
 };
@@ -1248,29 +1293,29 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
  public:
   MethodDescriptorProto();
   virtual ~MethodDescriptorProto();
-  
+
   MethodDescriptorProto(const MethodDescriptorProto& from);
-  
+
   inline MethodDescriptorProto& operator=(const MethodDescriptorProto& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const MethodDescriptorProto& default_instance();
-  
+
   void Swap(MethodDescriptorProto* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   MethodDescriptorProto* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1278,7 +1323,7 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   void MergeFrom(const MethodDescriptorProto& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1291,13 +1336,13 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string name = 1;
   inline bool has_name() const;
   inline void clear_name();
@@ -1308,7 +1353,8 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   inline void set_name(const char* value, size_t size);
   inline ::std::string* mutable_name();
   inline ::std::string* release_name();
-  
+  inline void set_allocated_name(::std::string* name);
+
   // optional string input_type = 2;
   inline bool has_input_type() const;
   inline void clear_input_type();
@@ -1319,7 +1365,8 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   inline void set_input_type(const char* value, size_t size);
   inline ::std::string* mutable_input_type();
   inline ::std::string* release_input_type();
-  
+  inline void set_allocated_input_type(::std::string* input_type);
+
   // optional string output_type = 3;
   inline bool has_output_type() const;
   inline void clear_output_type();
@@ -1330,7 +1377,8 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   inline void set_output_type(const char* value, size_t size);
   inline ::std::string* mutable_output_type();
   inline ::std::string* release_output_type();
-  
+  inline void set_allocated_output_type(::std::string* output_type);
+
   // optional .google.protobuf.MethodOptions options = 4;
   inline bool has_options() const;
   inline void clear_options();
@@ -1338,7 +1386,8 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   inline const ::google::protobuf::MethodOptions& options() const;
   inline ::google::protobuf::MethodOptions* mutable_options();
   inline ::google::protobuf::MethodOptions* release_options();
-  
+  inline void set_allocated_options(::google::protobuf::MethodOptions* options);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.MethodDescriptorProto)
  private:
   inline void set_has_name();
@@ -1349,21 +1398,21 @@ class LIBPROTOBUF_EXPORT MethodDescriptorProto : public ::google::protobuf::Mess
   inline void clear_has_output_type();
   inline void set_has_options();
   inline void clear_has_options();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_;
   ::std::string* input_type_;
   ::std::string* output_type_;
   ::google::protobuf::MethodOptions* options_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(4 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static MethodDescriptorProto* default_instance_;
 };
@@ -1373,29 +1422,29 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
  public:
   FileOptions();
   virtual ~FileOptions();
-  
+
   FileOptions(const FileOptions& from);
-  
+
   inline FileOptions& operator=(const FileOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const FileOptions& default_instance();
-  
+
   void Swap(FileOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   FileOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1403,7 +1452,7 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   void MergeFrom(const FileOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1416,11 +1465,11 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef FileOptions_OptimizeMode OptimizeMode;
   static const OptimizeMode SPEED = FileOptions_OptimizeMode_SPEED;
   static const OptimizeMode CODE_SIZE = FileOptions_OptimizeMode_CODE_SIZE;
@@ -1445,9 +1494,9 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
       OptimizeMode* value) {
     return FileOptions_OptimizeMode_Parse(name, value);
   }
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional string java_package = 1;
   inline bool has_java_package() const;
   inline void clear_java_package();
@@ -1458,7 +1507,8 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   inline void set_java_package(const char* value, size_t size);
   inline ::std::string* mutable_java_package();
   inline ::std::string* release_java_package();
-  
+  inline void set_allocated_java_package(::std::string* java_package);
+
   // optional string java_outer_classname = 8;
   inline bool has_java_outer_classname() const;
   inline void clear_java_outer_classname();
@@ -1469,49 +1519,62 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   inline void set_java_outer_classname(const char* value, size_t size);
   inline ::std::string* mutable_java_outer_classname();
   inline ::std::string* release_java_outer_classname();
-  
+  inline void set_allocated_java_outer_classname(::std::string* java_outer_classname);
+
   // optional bool java_multiple_files = 10 [default = false];
   inline bool has_java_multiple_files() const;
   inline void clear_java_multiple_files();
   static const int kJavaMultipleFilesFieldNumber = 10;
   inline bool java_multiple_files() const;
   inline void set_java_multiple_files(bool value);
-  
+
   // optional bool java_generate_equals_and_hash = 20 [default = false];
   inline bool has_java_generate_equals_and_hash() const;
   inline void clear_java_generate_equals_and_hash();
   static const int kJavaGenerateEqualsAndHashFieldNumber = 20;
   inline bool java_generate_equals_and_hash() const;
   inline void set_java_generate_equals_and_hash(bool value);
-  
+
   // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
   inline bool has_optimize_for() const;
   inline void clear_optimize_for();
   static const int kOptimizeForFieldNumber = 9;
   inline ::google::protobuf::FileOptions_OptimizeMode optimize_for() const;
   inline void set_optimize_for(::google::protobuf::FileOptions_OptimizeMode value);
-  
+
+  // optional string go_package = 11;
+  inline bool has_go_package() const;
+  inline void clear_go_package();
+  static const int kGoPackageFieldNumber = 11;
+  inline const ::std::string& go_package() const;
+  inline void set_go_package(const ::std::string& value);
+  inline void set_go_package(const char* value);
+  inline void set_go_package(const char* value, size_t size);
+  inline ::std::string* mutable_go_package();
+  inline ::std::string* release_go_package();
+  inline void set_allocated_go_package(::std::string* go_package);
+
   // optional bool cc_generic_services = 16 [default = false];
   inline bool has_cc_generic_services() const;
   inline void clear_cc_generic_services();
   static const int kCcGenericServicesFieldNumber = 16;
   inline bool cc_generic_services() const;
   inline void set_cc_generic_services(bool value);
-  
+
   // optional bool java_generic_services = 17 [default = false];
   inline bool has_java_generic_services() const;
   inline void clear_java_generic_services();
   static const int kJavaGenericServicesFieldNumber = 17;
   inline bool java_generic_services() const;
   inline void set_java_generic_services(bool value);
-  
+
   // optional bool py_generic_services = 18 [default = false];
   inline bool has_py_generic_services() const;
   inline void clear_py_generic_services();
   static const int kPyGenericServicesFieldNumber = 18;
   inline bool py_generic_services() const;
   inline void set_py_generic_services(bool value);
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -1523,7 +1586,7 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(FileOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.FileOptions)
  private:
@@ -1537,17 +1600,19 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   inline void clear_has_java_generate_equals_and_hash();
   inline void set_has_optimize_for();
   inline void clear_has_optimize_for();
+  inline void set_has_go_package();
+  inline void clear_has_go_package();
   inline void set_has_cc_generic_services();
   inline void clear_has_cc_generic_services();
   inline void set_has_java_generic_services();
   inline void clear_has_java_generic_services();
   inline void set_has_py_generic_services();
   inline void clear_has_py_generic_services();
-  
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* java_package_;
   ::std::string* java_outer_classname_;
   int optimize_for_;
@@ -1555,16 +1620,17 @@ class LIBPROTOBUF_EXPORT FileOptions : public ::google::protobuf::Message {
   bool java_generate_equals_and_hash_;
   bool cc_generic_services_;
   bool java_generic_services_;
+  ::std::string* go_package_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
   bool py_generic_services_;
-  
+
   mutable int _cached_size_;
-  ::google::protobuf::uint32 _has_bits_[(9 + 31) / 32];
-  
+  ::google::protobuf::uint32 _has_bits_[(10 + 31) / 32];
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static FileOptions* default_instance_;
 };
@@ -1574,29 +1640,29 @@ class LIBPROTOBUF_EXPORT MessageOptions : public ::google::protobuf::Message {
  public:
   MessageOptions();
   virtual ~MessageOptions();
-  
+
   MessageOptions(const MessageOptions& from);
-  
+
   inline MessageOptions& operator=(const MessageOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const MessageOptions& default_instance();
-  
+
   void Swap(MessageOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   MessageOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1604,7 +1670,7 @@ class LIBPROTOBUF_EXPORT MessageOptions : public ::google::protobuf::Message {
   void MergeFrom(const MessageOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1617,27 +1683,27 @@ class LIBPROTOBUF_EXPORT MessageOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional bool message_set_wire_format = 1 [default = false];
   inline bool has_message_set_wire_format() const;
   inline void clear_message_set_wire_format();
   static const int kMessageSetWireFormatFieldNumber = 1;
   inline bool message_set_wire_format() const;
   inline void set_message_set_wire_format(bool value);
-  
+
   // optional bool no_standard_descriptor_accessor = 2 [default = false];
   inline bool has_no_standard_descriptor_accessor() const;
   inline void clear_no_standard_descriptor_accessor();
   static const int kNoStandardDescriptorAccessorFieldNumber = 2;
   inline bool no_standard_descriptor_accessor() const;
   inline void set_no_standard_descriptor_accessor(bool value);
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -1649,7 +1715,7 @@ class LIBPROTOBUF_EXPORT MessageOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(MessageOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.MessageOptions)
  private:
@@ -1657,22 +1723,22 @@ class LIBPROTOBUF_EXPORT MessageOptions : public ::google::protobuf::Message {
   inline void clear_has_message_set_wire_format();
   inline void set_has_no_standard_descriptor_accessor();
   inline void clear_has_no_standard_descriptor_accessor();
-  
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
   bool message_set_wire_format_;
   bool no_standard_descriptor_accessor_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static MessageOptions* default_instance_;
 };
@@ -1682,29 +1748,29 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
  public:
   FieldOptions();
   virtual ~FieldOptions();
-  
+
   FieldOptions(const FieldOptions& from);
-  
+
   inline FieldOptions& operator=(const FieldOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const FieldOptions& default_instance();
-  
+
   void Swap(FieldOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   FieldOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1712,7 +1778,7 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
   void MergeFrom(const FieldOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1725,11 +1791,11 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef FieldOptions_CType CType;
   static const CType STRING = FieldOptions_CType_STRING;
   static const CType CORD = FieldOptions_CType_CORD;
@@ -1754,30 +1820,37 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
       CType* value) {
     return FieldOptions_CType_Parse(name, value);
   }
-  
+
   // accessors -------------------------------------------------------
-  
+
   // optional .google.protobuf.FieldOptions.CType ctype = 1 [default = STRING];
   inline bool has_ctype() const;
   inline void clear_ctype();
   static const int kCtypeFieldNumber = 1;
   inline ::google::protobuf::FieldOptions_CType ctype() const;
   inline void set_ctype(::google::protobuf::FieldOptions_CType value);
-  
+
   // optional bool packed = 2;
   inline bool has_packed() const;
   inline void clear_packed();
   static const int kPackedFieldNumber = 2;
   inline bool packed() const;
   inline void set_packed(bool value);
-  
+
+  // optional bool lazy = 5 [default = false];
+  inline bool has_lazy() const;
+  inline void clear_lazy();
+  static const int kLazyFieldNumber = 5;
+  inline bool lazy() const;
+  inline void set_lazy(bool value);
+
   // optional bool deprecated = 3 [default = false];
   inline bool has_deprecated() const;
   inline void clear_deprecated();
   static const int kDeprecatedFieldNumber = 3;
   inline bool deprecated() const;
   inline void set_deprecated(bool value);
-  
+
   // optional string experimental_map_key = 9;
   inline bool has_experimental_map_key() const;
   inline void clear_experimental_map_key();
@@ -1788,7 +1861,15 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
   inline void set_experimental_map_key(const char* value, size_t size);
   inline ::std::string* mutable_experimental_map_key();
   inline ::std::string* release_experimental_map_key();
-  
+  inline void set_allocated_experimental_map_key(::std::string* experimental_map_key);
+
+  // optional bool weak = 10 [default = false];
+  inline bool has_weak() const;
+  inline void clear_weak();
+  static const int kWeakFieldNumber = 10;
+  inline bool weak() const;
+  inline void set_weak(bool value);
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -1800,7 +1881,7 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(FieldOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.FieldOptions)
  private:
@@ -1808,28 +1889,34 @@ class LIBPROTOBUF_EXPORT FieldOptions : public ::google::protobuf::Message {
   inline void clear_has_ctype();
   inline void set_has_packed();
   inline void clear_has_packed();
+  inline void set_has_lazy();
+  inline void clear_has_lazy();
   inline void set_has_deprecated();
   inline void clear_has_deprecated();
   inline void set_has_experimental_map_key();
   inline void clear_has_experimental_map_key();
-  
+  inline void set_has_weak();
+  inline void clear_has_weak();
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   int ctype_;
   bool packed_;
+  bool lazy_;
   bool deprecated_;
+  bool weak_;
   ::std::string* experimental_map_key_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
-  
+
   mutable int _cached_size_;
-  ::google::protobuf::uint32 _has_bits_[(5 + 31) / 32];
-  
+  ::google::protobuf::uint32 _has_bits_[(7 + 31) / 32];
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static FieldOptions* default_instance_;
 };
@@ -1839,29 +1926,29 @@ class LIBPROTOBUF_EXPORT EnumOptions : public ::google::protobuf::Message {
  public:
   EnumOptions();
   virtual ~EnumOptions();
-  
+
   EnumOptions(const EnumOptions& from);
-  
+
   inline EnumOptions& operator=(const EnumOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const EnumOptions& default_instance();
-  
+
   void Swap(EnumOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   EnumOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1869,7 +1956,7 @@ class LIBPROTOBUF_EXPORT EnumOptions : public ::google::protobuf::Message {
   void MergeFrom(const EnumOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1882,13 +1969,20 @@ class LIBPROTOBUF_EXPORT EnumOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
+  // optional bool allow_alias = 2 [default = true];
+  inline bool has_allow_alias() const;
+  inline void clear_allow_alias();
+  static const int kAllowAliasFieldNumber = 2;
+  inline bool allow_alias() const;
+  inline void set_allow_alias(bool value);
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -1900,24 +1994,27 @@ class LIBPROTOBUF_EXPORT EnumOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(EnumOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.EnumOptions)
  private:
-  
+  inline void set_has_allow_alias();
+  inline void clear_has_allow_alias();
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
-  
+  bool allow_alias_;
+
   mutable int _cached_size_;
-  ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+  ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static EnumOptions* default_instance_;
 };
@@ -1927,29 +2024,29 @@ class LIBPROTOBUF_EXPORT EnumValueOptions : public ::google::protobuf::Message {
  public:
   EnumValueOptions();
   virtual ~EnumValueOptions();
-  
+
   EnumValueOptions(const EnumValueOptions& from);
-  
+
   inline EnumValueOptions& operator=(const EnumValueOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const EnumValueOptions& default_instance();
-  
+
   void Swap(EnumValueOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   EnumValueOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -1957,7 +2054,7 @@ class LIBPROTOBUF_EXPORT EnumValueOptions : public ::google::protobuf::Message {
   void MergeFrom(const EnumValueOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -1970,13 +2067,13 @@ class LIBPROTOBUF_EXPORT EnumValueOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -1988,24 +2085,24 @@ class LIBPROTOBUF_EXPORT EnumValueOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(EnumValueOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.EnumValueOptions)
  private:
-  
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static EnumValueOptions* default_instance_;
 };
@@ -2015,29 +2112,29 @@ class LIBPROTOBUF_EXPORT ServiceOptions : public ::google::protobuf::Message {
  public:
   ServiceOptions();
   virtual ~ServiceOptions();
-  
+
   ServiceOptions(const ServiceOptions& from);
-  
+
   inline ServiceOptions& operator=(const ServiceOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const ServiceOptions& default_instance();
-  
+
   void Swap(ServiceOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   ServiceOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2045,7 +2142,7 @@ class LIBPROTOBUF_EXPORT ServiceOptions : public ::google::protobuf::Message {
   void MergeFrom(const ServiceOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2058,13 +2155,13 @@ class LIBPROTOBUF_EXPORT ServiceOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -2076,24 +2173,24 @@ class LIBPROTOBUF_EXPORT ServiceOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(ServiceOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.ServiceOptions)
  private:
-  
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static ServiceOptions* default_instance_;
 };
@@ -2103,29 +2200,29 @@ class LIBPROTOBUF_EXPORT MethodOptions : public ::google::protobuf::Message {
  public:
   MethodOptions();
   virtual ~MethodOptions();
-  
+
   MethodOptions(const MethodOptions& from);
-  
+
   inline MethodOptions& operator=(const MethodOptions& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const MethodOptions& default_instance();
-  
+
   void Swap(MethodOptions* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   MethodOptions* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2133,7 +2230,7 @@ class LIBPROTOBUF_EXPORT MethodOptions : public ::google::protobuf::Message {
   void MergeFrom(const MethodOptions& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2146,13 +2243,13 @@ class LIBPROTOBUF_EXPORT MethodOptions : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
   inline int uninterpreted_option_size() const;
   inline void clear_uninterpreted_option();
@@ -2164,24 +2261,24 @@ class LIBPROTOBUF_EXPORT MethodOptions : public ::google::protobuf::Message {
       uninterpreted_option() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption >*
       mutable_uninterpreted_option();
-  
+
   GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(MethodOptions)
   // @@protoc_insertion_point(class_scope:google.protobuf.MethodOptions)
  private:
-  
+
   ::google::protobuf::internal::ExtensionSet _extensions_;
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption > uninterpreted_option_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static MethodOptions* default_instance_;
 };
@@ -2191,29 +2288,29 @@ class LIBPROTOBUF_EXPORT UninterpretedOption_NamePart : public ::google::protobu
  public:
   UninterpretedOption_NamePart();
   virtual ~UninterpretedOption_NamePart();
-  
+
   UninterpretedOption_NamePart(const UninterpretedOption_NamePart& from);
-  
+
   inline UninterpretedOption_NamePart& operator=(const UninterpretedOption_NamePart& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const UninterpretedOption_NamePart& default_instance();
-  
+
   void Swap(UninterpretedOption_NamePart* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   UninterpretedOption_NamePart* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2221,7 +2318,7 @@ class LIBPROTOBUF_EXPORT UninterpretedOption_NamePart : public ::google::protobu
   void MergeFrom(const UninterpretedOption_NamePart& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2234,13 +2331,13 @@ class LIBPROTOBUF_EXPORT UninterpretedOption_NamePart : public ::google::protobu
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // required string name_part = 1;
   inline bool has_name_part() const;
   inline void clear_name_part();
@@ -2251,33 +2348,34 @@ class LIBPROTOBUF_EXPORT UninterpretedOption_NamePart : public ::google::protobu
   inline void set_name_part(const char* value, size_t size);
   inline ::std::string* mutable_name_part();
   inline ::std::string* release_name_part();
-  
+  inline void set_allocated_name_part(::std::string* name_part);
+
   // required bool is_extension = 2;
   inline bool has_is_extension() const;
   inline void clear_is_extension();
   static const int kIsExtensionFieldNumber = 2;
   inline bool is_extension() const;
   inline void set_is_extension(bool value);
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.UninterpretedOption.NamePart)
  private:
   inline void set_has_name_part();
   inline void clear_has_name_part();
   inline void set_has_is_extension();
   inline void clear_has_is_extension();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::std::string* name_part_;
   bool is_extension_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static UninterpretedOption_NamePart* default_instance_;
 };
@@ -2287,29 +2385,29 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
  public:
   UninterpretedOption();
   virtual ~UninterpretedOption();
-  
+
   UninterpretedOption(const UninterpretedOption& from);
-  
+
   inline UninterpretedOption& operator=(const UninterpretedOption& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const UninterpretedOption& default_instance();
-  
+
   void Swap(UninterpretedOption* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   UninterpretedOption* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2317,7 +2415,7 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   void MergeFrom(const UninterpretedOption& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2330,15 +2428,15 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef UninterpretedOption_NamePart NamePart;
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.UninterpretedOption.NamePart name = 2;
   inline int name_size() const;
   inline void clear_name();
@@ -2350,7 +2448,7 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
       name() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption_NamePart >*
       mutable_name();
-  
+
   // optional string identifier_value = 3;
   inline bool has_identifier_value() const;
   inline void clear_identifier_value();
@@ -2361,28 +2459,29 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   inline void set_identifier_value(const char* value, size_t size);
   inline ::std::string* mutable_identifier_value();
   inline ::std::string* release_identifier_value();
-  
+  inline void set_allocated_identifier_value(::std::string* identifier_value);
+
   // optional uint64 positive_int_value = 4;
   inline bool has_positive_int_value() const;
   inline void clear_positive_int_value();
   static const int kPositiveIntValueFieldNumber = 4;
   inline ::google::protobuf::uint64 positive_int_value() const;
   inline void set_positive_int_value(::google::protobuf::uint64 value);
-  
+
   // optional int64 negative_int_value = 5;
   inline bool has_negative_int_value() const;
   inline void clear_negative_int_value();
   static const int kNegativeIntValueFieldNumber = 5;
   inline ::google::protobuf::int64 negative_int_value() const;
   inline void set_negative_int_value(::google::protobuf::int64 value);
-  
+
   // optional double double_value = 6;
   inline bool has_double_value() const;
   inline void clear_double_value();
   static const int kDoubleValueFieldNumber = 6;
   inline double double_value() const;
   inline void set_double_value(double value);
-  
+
   // optional bytes string_value = 7;
   inline bool has_string_value() const;
   inline void clear_string_value();
@@ -2393,7 +2492,8 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   inline void set_string_value(const void* value, size_t size);
   inline ::std::string* mutable_string_value();
   inline ::std::string* release_string_value();
-  
+  inline void set_allocated_string_value(::std::string* string_value);
+
   // optional string aggregate_value = 8;
   inline bool has_aggregate_value() const;
   inline void clear_aggregate_value();
@@ -2404,7 +2504,8 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   inline void set_aggregate_value(const char* value, size_t size);
   inline ::std::string* mutable_aggregate_value();
   inline ::std::string* release_aggregate_value();
-  
+  inline void set_allocated_aggregate_value(::std::string* aggregate_value);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.UninterpretedOption)
  private:
   inline void set_has_identifier_value();
@@ -2419,9 +2520,9 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   inline void clear_has_string_value();
   inline void set_has_aggregate_value();
   inline void clear_has_aggregate_value();
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::UninterpretedOption_NamePart > name_;
   ::std::string* identifier_value_;
   ::google::protobuf::uint64 positive_int_value_;
@@ -2429,14 +2530,14 @@ class LIBPROTOBUF_EXPORT UninterpretedOption : public ::google::protobuf::Messag
   double double_value_;
   ::std::string* string_value_;
   ::std::string* aggregate_value_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(7 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static UninterpretedOption* default_instance_;
 };
@@ -2446,29 +2547,29 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo_Location : public ::google::protobuf::Me
  public:
   SourceCodeInfo_Location();
   virtual ~SourceCodeInfo_Location();
-  
+
   SourceCodeInfo_Location(const SourceCodeInfo_Location& from);
-  
+
   inline SourceCodeInfo_Location& operator=(const SourceCodeInfo_Location& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const SourceCodeInfo_Location& default_instance();
-  
+
   void Swap(SourceCodeInfo_Location* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   SourceCodeInfo_Location* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2476,7 +2577,7 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo_Location : public ::google::protobuf::Me
   void MergeFrom(const SourceCodeInfo_Location& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2489,13 +2590,13 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo_Location : public ::google::protobuf::Me
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated int32 path = 1 [packed = true];
   inline int path_size() const;
   inline void clear_path();
@@ -2507,7 +2608,7 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo_Location : public ::google::protobuf::Me
       path() const;
   inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
       mutable_path();
-  
+
   // repeated int32 span = 2 [packed = true];
   inline int span_size() const;
   inline void clear_span();
@@ -2519,24 +2620,54 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo_Location : public ::google::protobuf::Me
       span() const;
   inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
       mutable_span();
-  
+
+  // optional string leading_comments = 3;
+  inline bool has_leading_comments() const;
+  inline void clear_leading_comments();
+  static const int kLeadingCommentsFieldNumber = 3;
+  inline const ::std::string& leading_comments() const;
+  inline void set_leading_comments(const ::std::string& value);
+  inline void set_leading_comments(const char* value);
+  inline void set_leading_comments(const char* value, size_t size);
+  inline ::std::string* mutable_leading_comments();
+  inline ::std::string* release_leading_comments();
+  inline void set_allocated_leading_comments(::std::string* leading_comments);
+
+  // optional string trailing_comments = 4;
+  inline bool has_trailing_comments() const;
+  inline void clear_trailing_comments();
+  static const int kTrailingCommentsFieldNumber = 4;
+  inline const ::std::string& trailing_comments() const;
+  inline void set_trailing_comments(const ::std::string& value);
+  inline void set_trailing_comments(const char* value);
+  inline void set_trailing_comments(const char* value, size_t size);
+  inline ::std::string* mutable_trailing_comments();
+  inline ::std::string* release_trailing_comments();
+  inline void set_allocated_trailing_comments(::std::string* trailing_comments);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.SourceCodeInfo.Location)
  private:
-  
+  inline void set_has_leading_comments();
+  inline void clear_has_leading_comments();
+  inline void set_has_trailing_comments();
+  inline void clear_has_trailing_comments();
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedField< ::google::protobuf::int32 > path_;
   mutable int _path_cached_byte_size_;
   ::google::protobuf::RepeatedField< ::google::protobuf::int32 > span_;
   mutable int _span_cached_byte_size_;
-  
+  ::std::string* leading_comments_;
+  ::std::string* trailing_comments_;
+
   mutable int _cached_size_;
-  ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];
-  
+  ::google::protobuf::uint32 _has_bits_[(4 + 31) / 32];
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static SourceCodeInfo_Location* default_instance_;
 };
@@ -2546,29 +2677,29 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo : public ::google::protobuf::Message {
  public:
   SourceCodeInfo();
   virtual ~SourceCodeInfo();
-  
+
   SourceCodeInfo(const SourceCodeInfo& from);
-  
+
   inline SourceCodeInfo& operator=(const SourceCodeInfo& from) {
     CopyFrom(from);
     return *this;
   }
-  
+
   inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
     return _unknown_fields_;
   }
-  
+
   inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
     return &_unknown_fields_;
   }
-  
+
   static const ::google::protobuf::Descriptor* descriptor();
   static const SourceCodeInfo& default_instance();
-  
+
   void Swap(SourceCodeInfo* other);
-  
+
   // implements Message ----------------------------------------------
-  
+
   SourceCodeInfo* New() const;
   void CopyFrom(const ::google::protobuf::Message& from);
   void MergeFrom(const ::google::protobuf::Message& from);
@@ -2576,7 +2707,7 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo : public ::google::protobuf::Message {
   void MergeFrom(const SourceCodeInfo& from);
   void Clear();
   bool IsInitialized() const;
-  
+
   int ByteSize() const;
   bool MergePartialFromCodedStream(
       ::google::protobuf::io::CodedInputStream* input);
@@ -2589,15 +2720,15 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   public:
-  
+
   ::google::protobuf::Metadata GetMetadata() const;
-  
+
   // nested types ----------------------------------------------------
-  
+
   typedef SourceCodeInfo_Location Location;
-  
+
   // accessors -------------------------------------------------------
-  
+
   // repeated .google.protobuf.SourceCodeInfo.Location location = 1;
   inline int location_size() const;
   inline void clear_location();
@@ -2609,21 +2740,21 @@ class LIBPROTOBUF_EXPORT SourceCodeInfo : public ::google::protobuf::Message {
       location() const;
   inline ::google::protobuf::RepeatedPtrField< ::google::protobuf::SourceCodeInfo_Location >*
       mutable_location();
-  
+
   // @@protoc_insertion_point(class_scope:google.protobuf.SourceCodeInfo)
  private:
-  
+
   ::google::protobuf::UnknownFieldSet _unknown_fields_;
-  
+
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::SourceCodeInfo_Location > location_;
-  
+
   mutable int _cached_size_;
   ::google::protobuf::uint32 _has_bits_[(1 + 31) / 32];
-  
+
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto();
-  
+
   void InitAsDefaultInstance();
   static SourceCodeInfo* default_instance_;
 };
@@ -2720,6 +2851,18 @@ inline ::std::string* FileDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void FileDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string package = 2;
 inline bool FileDescriptorProto::has_package() const {
@@ -2778,6 +2921,18 @@ inline ::std::string* FileDescriptorProto::release_package() {
     return temp;
   }
 }
+inline void FileDescriptorProto::set_allocated_package(::std::string* package) {
+  if (package_ != &::google::protobuf::internal::kEmptyString) {
+    delete package_;
+  }
+  if (package) {
+    set_has_package();
+    package_ = package;
+  } else {
+    clear_has_package();
+    package_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated string dependency = 3;
 inline int FileDescriptorProto::dependency_size() const {
@@ -2823,6 +2978,56 @@ FileDescriptorProto::mutable_dependency() {
   return &dependency_;
 }
 
+// repeated int32 public_dependency = 10;
+inline int FileDescriptorProto::public_dependency_size() const {
+  return public_dependency_.size();
+}
+inline void FileDescriptorProto::clear_public_dependency() {
+  public_dependency_.Clear();
+}
+inline ::google::protobuf::int32 FileDescriptorProto::public_dependency(int index) const {
+  return public_dependency_.Get(index);
+}
+inline void FileDescriptorProto::set_public_dependency(int index, ::google::protobuf::int32 value) {
+  public_dependency_.Set(index, value);
+}
+inline void FileDescriptorProto::add_public_dependency(::google::protobuf::int32 value) {
+  public_dependency_.Add(value);
+}
+inline const ::google::protobuf::RepeatedField< ::google::protobuf::int32 >&
+FileDescriptorProto::public_dependency() const {
+  return public_dependency_;
+}
+inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
+FileDescriptorProto::mutable_public_dependency() {
+  return &public_dependency_;
+}
+
+// repeated int32 weak_dependency = 11;
+inline int FileDescriptorProto::weak_dependency_size() const {
+  return weak_dependency_.size();
+}
+inline void FileDescriptorProto::clear_weak_dependency() {
+  weak_dependency_.Clear();
+}
+inline ::google::protobuf::int32 FileDescriptorProto::weak_dependency(int index) const {
+  return weak_dependency_.Get(index);
+}
+inline void FileDescriptorProto::set_weak_dependency(int index, ::google::protobuf::int32 value) {
+  weak_dependency_.Set(index, value);
+}
+inline void FileDescriptorProto::add_weak_dependency(::google::protobuf::int32 value) {
+  weak_dependency_.Add(value);
+}
+inline const ::google::protobuf::RepeatedField< ::google::protobuf::int32 >&
+FileDescriptorProto::weak_dependency() const {
+  return weak_dependency_;
+}
+inline ::google::protobuf::RepeatedField< ::google::protobuf::int32 >*
+FileDescriptorProto::mutable_weak_dependency() {
+  return &weak_dependency_;
+}
+
 // repeated .google.protobuf.DescriptorProto message_type = 4;
 inline int FileDescriptorProto::message_type_size() const {
   return message_type_.size();
@@ -2925,13 +3130,13 @@ FileDescriptorProto::mutable_extension() {
 
 // optional .google.protobuf.FileOptions options = 8;
 inline bool FileDescriptorProto::has_options() const {
-  return (_has_bits_[0] & 0x00000080u) != 0;
+  return (_has_bits_[0] & 0x00000200u) != 0;
 }
 inline void FileDescriptorProto::set_has_options() {
-  _has_bits_[0] |= 0x00000080u;
+  _has_bits_[0] |= 0x00000200u;
 }
 inline void FileDescriptorProto::clear_has_options() {
-  _has_bits_[0] &= ~0x00000080u;
+  _has_bits_[0] &= ~0x00000200u;
 }
 inline void FileDescriptorProto::clear_options() {
   if (options_ != NULL) options_->::google::protobuf::FileOptions::Clear();
@@ -2951,16 +3156,25 @@ inline ::google::protobuf::FileOptions* FileDescriptorProto::release_options() {
   options_ = NULL;
   return temp;
 }
+inline void FileDescriptorProto::set_allocated_options(::google::protobuf::FileOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
 inline bool FileDescriptorProto::has_source_code_info() const {
-  return (_has_bits_[0] & 0x00000100u) != 0;
+  return (_has_bits_[0] & 0x00000400u) != 0;
 }
 inline void FileDescriptorProto::set_has_source_code_info() {
-  _has_bits_[0] |= 0x00000100u;
+  _has_bits_[0] |= 0x00000400u;
 }
 inline void FileDescriptorProto::clear_has_source_code_info() {
-  _has_bits_[0] &= ~0x00000100u;
+  _has_bits_[0] &= ~0x00000400u;
 }
 inline void FileDescriptorProto::clear_source_code_info() {
   if (source_code_info_ != NULL) source_code_info_->::google::protobuf::SourceCodeInfo::Clear();
@@ -2980,6 +3194,15 @@ inline ::google::protobuf::SourceCodeInfo* FileDescriptorProto::release_source_c
   source_code_info_ = NULL;
   return temp;
 }
+inline void FileDescriptorProto::set_allocated_source_code_info(::google::protobuf::SourceCodeInfo* source_code_info) {
+  delete source_code_info_;
+  source_code_info_ = source_code_info;
+  if (source_code_info) {
+    set_has_source_code_info();
+  } else {
+    clear_has_source_code_info();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3090,6 +3313,18 @@ inline ::std::string* DescriptorProto::release_name() {
     return temp;
   }
 }
+inline void DescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated .google.protobuf.FieldDescriptorProto field = 2;
 inline int DescriptorProto::field_size() const {
@@ -3244,6 +3479,15 @@ inline ::google::protobuf::MessageOptions* DescriptorProto::release_options() {
   options_ = NULL;
   return temp;
 }
+inline void DescriptorProto::set_allocated_options(::google::protobuf::MessageOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3306,6 +3550,18 @@ inline ::std::string* FieldDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void FieldDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional int32 number = 3;
 inline bool FieldDescriptorProto::has_number() const {
@@ -3347,7 +3603,7 @@ inline ::google::protobuf::FieldDescriptorProto_Label FieldDescriptorProto::labe
   return static_cast< ::google::protobuf::FieldDescriptorProto_Label >(label_);
 }
 inline void FieldDescriptorProto::set_label(::google::protobuf::FieldDescriptorProto_Label value) {
-  GOOGLE_DCHECK(::google::protobuf::FieldDescriptorProto_Label_IsValid(value));
+  assert(::google::protobuf::FieldDescriptorProto_Label_IsValid(value));
   set_has_label();
   label_ = value;
 }
@@ -3370,7 +3626,7 @@ inline ::google::protobuf::FieldDescriptorProto_Type FieldDescriptorProto::type(
   return static_cast< ::google::protobuf::FieldDescriptorProto_Type >(type_);
 }
 inline void FieldDescriptorProto::set_type(::google::protobuf::FieldDescriptorProto_Type value) {
-  GOOGLE_DCHECK(::google::protobuf::FieldDescriptorProto_Type_IsValid(value));
+  assert(::google::protobuf::FieldDescriptorProto_Type_IsValid(value));
   set_has_type();
   type_ = value;
 }
@@ -3432,6 +3688,18 @@ inline ::std::string* FieldDescriptorProto::release_type_name() {
     return temp;
   }
 }
+inline void FieldDescriptorProto::set_allocated_type_name(::std::string* type_name) {
+  if (type_name_ != &::google::protobuf::internal::kEmptyString) {
+    delete type_name_;
+  }
+  if (type_name) {
+    set_has_type_name();
+    type_name_ = type_name;
+  } else {
+    clear_has_type_name();
+    type_name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string extendee = 2;
 inline bool FieldDescriptorProto::has_extendee() const {
@@ -3490,6 +3758,18 @@ inline ::std::string* FieldDescriptorProto::release_extendee() {
     return temp;
   }
 }
+inline void FieldDescriptorProto::set_allocated_extendee(::std::string* extendee) {
+  if (extendee_ != &::google::protobuf::internal::kEmptyString) {
+    delete extendee_;
+  }
+  if (extendee) {
+    set_has_extendee();
+    extendee_ = extendee;
+  } else {
+    clear_has_extendee();
+    extendee_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string default_value = 7;
 inline bool FieldDescriptorProto::has_default_value() const {
@@ -3548,6 +3828,18 @@ inline ::std::string* FieldDescriptorProto::release_default_value() {
     return temp;
   }
 }
+inline void FieldDescriptorProto::set_allocated_default_value(::std::string* default_value) {
+  if (default_value_ != &::google::protobuf::internal::kEmptyString) {
+    delete default_value_;
+  }
+  if (default_value) {
+    set_has_default_value();
+    default_value_ = default_value;
+  } else {
+    clear_has_default_value();
+    default_value_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional .google.protobuf.FieldOptions options = 8;
 inline bool FieldDescriptorProto::has_options() const {
@@ -3577,6 +3869,15 @@ inline ::google::protobuf::FieldOptions* FieldDescriptorProto::release_options()
   options_ = NULL;
   return temp;
 }
+inline void FieldDescriptorProto::set_allocated_options(::google::protobuf::FieldOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3639,6 +3940,18 @@ inline ::std::string* EnumDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void EnumDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
 inline int EnumDescriptorProto::value_size() const {
@@ -3693,6 +4006,15 @@ inline ::google::protobuf::EnumOptions* EnumDescriptorProto::release_options() {
   options_ = NULL;
   return temp;
 }
+inline void EnumDescriptorProto::set_allocated_options(::google::protobuf::EnumOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3755,6 +4077,18 @@ inline ::std::string* EnumValueDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void EnumValueDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional int32 number = 2;
 inline bool EnumValueDescriptorProto::has_number() const {
@@ -3806,6 +4140,15 @@ inline ::google::protobuf::EnumValueOptions* EnumValueDescriptorProto::release_o
   options_ = NULL;
   return temp;
 }
+inline void EnumValueDescriptorProto::set_allocated_options(::google::protobuf::EnumValueOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3868,6 +4211,18 @@ inline ::std::string* ServiceDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void ServiceDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // repeated .google.protobuf.MethodDescriptorProto method = 2;
 inline int ServiceDescriptorProto::method_size() const {
@@ -3922,6 +4277,15 @@ inline ::google::protobuf::ServiceOptions* ServiceDescriptorProto::release_optio
   options_ = NULL;
   return temp;
 }
+inline void ServiceDescriptorProto::set_allocated_options(::google::protobuf::ServiceOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -3984,6 +4348,18 @@ inline ::std::string* MethodDescriptorProto::release_name() {
     return temp;
   }
 }
+inline void MethodDescriptorProto::set_allocated_name(::std::string* name) {
+  if (name_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_;
+  }
+  if (name) {
+    set_has_name();
+    name_ = name;
+  } else {
+    clear_has_name();
+    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string input_type = 2;
 inline bool MethodDescriptorProto::has_input_type() const {
@@ -4042,6 +4418,18 @@ inline ::std::string* MethodDescriptorProto::release_input_type() {
     return temp;
   }
 }
+inline void MethodDescriptorProto::set_allocated_input_type(::std::string* input_type) {
+  if (input_type_ != &::google::protobuf::internal::kEmptyString) {
+    delete input_type_;
+  }
+  if (input_type) {
+    set_has_input_type();
+    input_type_ = input_type;
+  } else {
+    clear_has_input_type();
+    input_type_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string output_type = 3;
 inline bool MethodDescriptorProto::has_output_type() const {
@@ -4100,6 +4488,18 @@ inline ::std::string* MethodDescriptorProto::release_output_type() {
     return temp;
   }
 }
+inline void MethodDescriptorProto::set_allocated_output_type(::std::string* output_type) {
+  if (output_type_ != &::google::protobuf::internal::kEmptyString) {
+    delete output_type_;
+  }
+  if (output_type) {
+    set_has_output_type();
+    output_type_ = output_type;
+  } else {
+    clear_has_output_type();
+    output_type_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional .google.protobuf.MethodOptions options = 4;
 inline bool MethodDescriptorProto::has_options() const {
@@ -4129,6 +4529,15 @@ inline ::google::protobuf::MethodOptions* MethodDescriptorProto::release_options
   options_ = NULL;
   return temp;
 }
+inline void MethodDescriptorProto::set_allocated_options(::google::protobuf::MethodOptions* options) {
+  delete options_;
+  options_ = options;
+  if (options) {
+    set_has_options();
+  } else {
+    clear_has_options();
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -4191,6 +4600,18 @@ inline ::std::string* FileOptions::release_java_package() {
     return temp;
   }
 }
+inline void FileOptions::set_allocated_java_package(::std::string* java_package) {
+  if (java_package_ != &::google::protobuf::internal::kEmptyString) {
+    delete java_package_;
+  }
+  if (java_package) {
+    set_has_java_package();
+    java_package_ = java_package;
+  } else {
+    clear_has_java_package();
+    java_package_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string java_outer_classname = 8;
 inline bool FileOptions::has_java_outer_classname() const {
@@ -4249,6 +4670,18 @@ inline ::std::string* FileOptions::release_java_outer_classname() {
     return temp;
   }
 }
+inline void FileOptions::set_allocated_java_outer_classname(::std::string* java_outer_classname) {
+  if (java_outer_classname_ != &::google::protobuf::internal::kEmptyString) {
+    delete java_outer_classname_;
+  }
+  if (java_outer_classname) {
+    set_has_java_outer_classname();
+    java_outer_classname_ = java_outer_classname;
+  } else {
+    clear_has_java_outer_classname();
+    java_outer_classname_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional bool java_multiple_files = 10 [default = false];
 inline bool FileOptions::has_java_multiple_files() const {
@@ -4312,20 +4745,90 @@ inline ::google::protobuf::FileOptions_OptimizeMode FileOptions::optimize_for()
   return static_cast< ::google::protobuf::FileOptions_OptimizeMode >(optimize_for_);
 }
 inline void FileOptions::set_optimize_for(::google::protobuf::FileOptions_OptimizeMode value) {
-  GOOGLE_DCHECK(::google::protobuf::FileOptions_OptimizeMode_IsValid(value));
+  assert(::google::protobuf::FileOptions_OptimizeMode_IsValid(value));
   set_has_optimize_for();
   optimize_for_ = value;
 }
 
+// optional string go_package = 11;
+inline bool FileOptions::has_go_package() const {
+  return (_has_bits_[0] & 0x00000020u) != 0;
+}
+inline void FileOptions::set_has_go_package() {
+  _has_bits_[0] |= 0x00000020u;
+}
+inline void FileOptions::clear_has_go_package() {
+  _has_bits_[0] &= ~0x00000020u;
+}
+inline void FileOptions::clear_go_package() {
+  if (go_package_ != &::google::protobuf::internal::kEmptyString) {
+    go_package_->clear();
+  }
+  clear_has_go_package();
+}
+inline const ::std::string& FileOptions::go_package() const {
+  return *go_package_;
+}
+inline void FileOptions::set_go_package(const ::std::string& value) {
+  set_has_go_package();
+  if (go_package_ == &::google::protobuf::internal::kEmptyString) {
+    go_package_ = new ::std::string;
+  }
+  go_package_->assign(value);
+}
+inline void FileOptions::set_go_package(const char* value) {
+  set_has_go_package();
+  if (go_package_ == &::google::protobuf::internal::kEmptyString) {
+    go_package_ = new ::std::string;
+  }
+  go_package_->assign(value);
+}
+inline void FileOptions::set_go_package(const char* value, size_t size) {
+  set_has_go_package();
+  if (go_package_ == &::google::protobuf::internal::kEmptyString) {
+    go_package_ = new ::std::string;
+  }
+  go_package_->assign(reinterpret_cast<const char*>(value), size);
+}
+inline ::std::string* FileOptions::mutable_go_package() {
+  set_has_go_package();
+  if (go_package_ == &::google::protobuf::internal::kEmptyString) {
+    go_package_ = new ::std::string;
+  }
+  return go_package_;
+}
+inline ::std::string* FileOptions::release_go_package() {
+  clear_has_go_package();
+  if (go_package_ == &::google::protobuf::internal::kEmptyString) {
+    return NULL;
+  } else {
+    ::std::string* temp = go_package_;
+    go_package_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+    return temp;
+  }
+}
+inline void FileOptions::set_allocated_go_package(::std::string* go_package) {
+  if (go_package_ != &::google::protobuf::internal::kEmptyString) {
+    delete go_package_;
+  }
+  if (go_package) {
+    set_has_go_package();
+    go_package_ = go_package;
+  } else {
+    clear_has_go_package();
+    go_package_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
+
 // optional bool cc_generic_services = 16 [default = false];
 inline bool FileOptions::has_cc_generic_services() const {
-  return (_has_bits_[0] & 0x00000020u) != 0;
+  return (_has_bits_[0] & 0x00000040u) != 0;
 }
 inline void FileOptions::set_has_cc_generic_services() {
-  _has_bits_[0] |= 0x00000020u;
+  _has_bits_[0] |= 0x00000040u;
 }
 inline void FileOptions::clear_has_cc_generic_services() {
-  _has_bits_[0] &= ~0x00000020u;
+  _has_bits_[0] &= ~0x00000040u;
 }
 inline void FileOptions::clear_cc_generic_services() {
   cc_generic_services_ = false;
@@ -4341,13 +4844,13 @@ inline void FileOptions::set_cc_generic_services(bool value) {
 
 // optional bool java_generic_services = 17 [default = false];
 inline bool FileOptions::has_java_generic_services() const {
-  return (_has_bits_[0] & 0x00000040u) != 0;
+  return (_has_bits_[0] & 0x00000080u) != 0;
 }
 inline void FileOptions::set_has_java_generic_services() {
-  _has_bits_[0] |= 0x00000040u;
+  _has_bits_[0] |= 0x00000080u;
 }
 inline void FileOptions::clear_has_java_generic_services() {
-  _has_bits_[0] &= ~0x00000040u;
+  _has_bits_[0] &= ~0x00000080u;
 }
 inline void FileOptions::clear_java_generic_services() {
   java_generic_services_ = false;
@@ -4363,13 +4866,13 @@ inline void FileOptions::set_java_generic_services(bool value) {
 
 // optional bool py_generic_services = 18 [default = false];
 inline bool FileOptions::has_py_generic_services() const {
-  return (_has_bits_[0] & 0x00000080u) != 0;
+  return (_has_bits_[0] & 0x00000100u) != 0;
 }
 inline void FileOptions::set_has_py_generic_services() {
-  _has_bits_[0] |= 0x00000080u;
+  _has_bits_[0] |= 0x00000100u;
 }
 inline void FileOptions::clear_has_py_generic_services() {
-  _has_bits_[0] &= ~0x00000080u;
+  _has_bits_[0] &= ~0x00000100u;
 }
 inline void FileOptions::clear_py_generic_services() {
   py_generic_services_ = false;
@@ -4503,7 +5006,7 @@ inline ::google::protobuf::FieldOptions_CType FieldOptions::ctype() const {
   return static_cast< ::google::protobuf::FieldOptions_CType >(ctype_);
 }
 inline void FieldOptions::set_ctype(::google::protobuf::FieldOptions_CType value) {
-  GOOGLE_DCHECK(::google::protobuf::FieldOptions_CType_IsValid(value));
+  assert(::google::protobuf::FieldOptions_CType_IsValid(value));
   set_has_ctype();
   ctype_ = value;
 }
@@ -4530,15 +5033,37 @@ inline void FieldOptions::set_packed(bool value) {
   packed_ = value;
 }
 
+// optional bool lazy = 5 [default = false];
+inline bool FieldOptions::has_lazy() const {
+  return (_has_bits_[0] & 0x00000004u) != 0;
+}
+inline void FieldOptions::set_has_lazy() {
+  _has_bits_[0] |= 0x00000004u;
+}
+inline void FieldOptions::clear_has_lazy() {
+  _has_bits_[0] &= ~0x00000004u;
+}
+inline void FieldOptions::clear_lazy() {
+  lazy_ = false;
+  clear_has_lazy();
+}
+inline bool FieldOptions::lazy() const {
+  return lazy_;
+}
+inline void FieldOptions::set_lazy(bool value) {
+  set_has_lazy();
+  lazy_ = value;
+}
+
 // optional bool deprecated = 3 [default = false];
 inline bool FieldOptions::has_deprecated() const {
-  return (_has_bits_[0] & 0x00000004u) != 0;
+  return (_has_bits_[0] & 0x00000008u) != 0;
 }
 inline void FieldOptions::set_has_deprecated() {
-  _has_bits_[0] |= 0x00000004u;
+  _has_bits_[0] |= 0x00000008u;
 }
 inline void FieldOptions::clear_has_deprecated() {
-  _has_bits_[0] &= ~0x00000004u;
+  _has_bits_[0] &= ~0x00000008u;
 }
 inline void FieldOptions::clear_deprecated() {
   deprecated_ = false;
@@ -4554,13 +5079,13 @@ inline void FieldOptions::set_deprecated(bool value) {
 
 // optional string experimental_map_key = 9;
 inline bool FieldOptions::has_experimental_map_key() const {
-  return (_has_bits_[0] & 0x00000008u) != 0;
+  return (_has_bits_[0] & 0x00000010u) != 0;
 }
 inline void FieldOptions::set_has_experimental_map_key() {
-  _has_bits_[0] |= 0x00000008u;
+  _has_bits_[0] |= 0x00000010u;
 }
 inline void FieldOptions::clear_has_experimental_map_key() {
-  _has_bits_[0] &= ~0x00000008u;
+  _has_bits_[0] &= ~0x00000010u;
 }
 inline void FieldOptions::clear_experimental_map_key() {
   if (experimental_map_key_ != &::google::protobuf::internal::kEmptyString) {
@@ -4609,6 +5134,40 @@ inline ::std::string* FieldOptions::release_experimental_map_key() {
     return temp;
   }
 }
+inline void FieldOptions::set_allocated_experimental_map_key(::std::string* experimental_map_key) {
+  if (experimental_map_key_ != &::google::protobuf::internal::kEmptyString) {
+    delete experimental_map_key_;
+  }
+  if (experimental_map_key) {
+    set_has_experimental_map_key();
+    experimental_map_key_ = experimental_map_key;
+  } else {
+    clear_has_experimental_map_key();
+    experimental_map_key_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
+
+// optional bool weak = 10 [default = false];
+inline bool FieldOptions::has_weak() const {
+  return (_has_bits_[0] & 0x00000020u) != 0;
+}
+inline void FieldOptions::set_has_weak() {
+  _has_bits_[0] |= 0x00000020u;
+}
+inline void FieldOptions::clear_has_weak() {
+  _has_bits_[0] &= ~0x00000020u;
+}
+inline void FieldOptions::clear_weak() {
+  weak_ = false;
+  clear_has_weak();
+}
+inline bool FieldOptions::weak() const {
+  return weak_;
+}
+inline void FieldOptions::set_weak(bool value) {
+  set_has_weak();
+  weak_ = value;
+}
 
 // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
 inline int FieldOptions::uninterpreted_option_size() const {
@@ -4639,6 +5198,28 @@ FieldOptions::mutable_uninterpreted_option() {
 
 // EnumOptions
 
+// optional bool allow_alias = 2 [default = true];
+inline bool EnumOptions::has_allow_alias() const {
+  return (_has_bits_[0] & 0x00000001u) != 0;
+}
+inline void EnumOptions::set_has_allow_alias() {
+  _has_bits_[0] |= 0x00000001u;
+}
+inline void EnumOptions::clear_has_allow_alias() {
+  _has_bits_[0] &= ~0x00000001u;
+}
+inline void EnumOptions::clear_allow_alias() {
+  allow_alias_ = true;
+  clear_has_allow_alias();
+}
+inline bool EnumOptions::allow_alias() const {
+  return allow_alias_;
+}
+inline void EnumOptions::set_allow_alias(bool value) {
+  set_has_allow_alias();
+  allow_alias_ = value;
+}
+
 // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
 inline int EnumOptions::uninterpreted_option_size() const {
   return uninterpreted_option_.size();
@@ -4812,6 +5393,18 @@ inline ::std::string* UninterpretedOption_NamePart::release_name_part() {
     return temp;
   }
 }
+inline void UninterpretedOption_NamePart::set_allocated_name_part(::std::string* name_part) {
+  if (name_part_ != &::google::protobuf::internal::kEmptyString) {
+    delete name_part_;
+  }
+  if (name_part) {
+    set_has_name_part();
+    name_part_ = name_part;
+  } else {
+    clear_has_name_part();
+    name_part_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // required bool is_extension = 2;
 inline bool UninterpretedOption_NamePart::has_is_extension() const {
@@ -4921,6 +5514,18 @@ inline ::std::string* UninterpretedOption::release_identifier_value() {
     return temp;
   }
 }
+inline void UninterpretedOption::set_allocated_identifier_value(::std::string* identifier_value) {
+  if (identifier_value_ != &::google::protobuf::internal::kEmptyString) {
+    delete identifier_value_;
+  }
+  if (identifier_value) {
+    set_has_identifier_value();
+    identifier_value_ = identifier_value;
+  } else {
+    clear_has_identifier_value();
+    identifier_value_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional uint64 positive_int_value = 4;
 inline bool UninterpretedOption::has_positive_int_value() const {
@@ -5045,6 +5650,18 @@ inline ::std::string* UninterpretedOption::release_string_value() {
     return temp;
   }
 }
+inline void UninterpretedOption::set_allocated_string_value(::std::string* string_value) {
+  if (string_value_ != &::google::protobuf::internal::kEmptyString) {
+    delete string_value_;
+  }
+  if (string_value) {
+    set_has_string_value();
+    string_value_ = string_value;
+  } else {
+    clear_has_string_value();
+    string_value_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // optional string aggregate_value = 8;
 inline bool UninterpretedOption::has_aggregate_value() const {
@@ -5103,6 +5720,18 @@ inline ::std::string* UninterpretedOption::release_aggregate_value() {
     return temp;
   }
 }
+inline void UninterpretedOption::set_allocated_aggregate_value(::std::string* aggregate_value) {
+  if (aggregate_value_ != &::google::protobuf::internal::kEmptyString) {
+    delete aggregate_value_;
+  }
+  if (aggregate_value) {
+    set_has_aggregate_value();
+    aggregate_value_ = aggregate_value;
+  } else {
+    clear_has_aggregate_value();
+    aggregate_value_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
 
 // -------------------------------------------------------------------
 
@@ -5158,6 +5787,146 @@ SourceCodeInfo_Location::mutable_span() {
   return &span_;
 }
 
+// optional string leading_comments = 3;
+inline bool SourceCodeInfo_Location::has_leading_comments() const {
+  return (_has_bits_[0] & 0x00000004u) != 0;
+}
+inline void SourceCodeInfo_Location::set_has_leading_comments() {
+  _has_bits_[0] |= 0x00000004u;
+}
+inline void SourceCodeInfo_Location::clear_has_leading_comments() {
+  _has_bits_[0] &= ~0x00000004u;
+}
+inline void SourceCodeInfo_Location::clear_leading_comments() {
+  if (leading_comments_ != &::google::protobuf::internal::kEmptyString) {
+    leading_comments_->clear();
+  }
+  clear_has_leading_comments();
+}
+inline const ::std::string& SourceCodeInfo_Location::leading_comments() const {
+  return *leading_comments_;
+}
+inline void SourceCodeInfo_Location::set_leading_comments(const ::std::string& value) {
+  set_has_leading_comments();
+  if (leading_comments_ == &::google::protobuf::internal::kEmptyString) {
+    leading_comments_ = new ::std::string;
+  }
+  leading_comments_->assign(value);
+}
+inline void SourceCodeInfo_Location::set_leading_comments(const char* value) {
+  set_has_leading_comments();
+  if (leading_comments_ == &::google::protobuf::internal::kEmptyString) {
+    leading_comments_ = new ::std::string;
+  }
+  leading_comments_->assign(value);
+}
+inline void SourceCodeInfo_Location::set_leading_comments(const char* value, size_t size) {
+  set_has_leading_comments();
+  if (leading_comments_ == &::google::protobuf::internal::kEmptyString) {
+    leading_comments_ = new ::std::string;
+  }
+  leading_comments_->assign(reinterpret_cast<const char*>(value), size);
+}
+inline ::std::string* SourceCodeInfo_Location::mutable_leading_comments() {
+  set_has_leading_comments();
+  if (leading_comments_ == &::google::protobuf::internal::kEmptyString) {
+    leading_comments_ = new ::std::string;
+  }
+  return leading_comments_;
+}
+inline ::std::string* SourceCodeInfo_Location::release_leading_comments() {
+  clear_has_leading_comments();
+  if (leading_comments_ == &::google::protobuf::internal::kEmptyString) {
+    return NULL;
+  } else {
+    ::std::string* temp = leading_comments_;
+    leading_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+    return temp;
+  }
+}
+inline void SourceCodeInfo_Location::set_allocated_leading_comments(::std::string* leading_comments) {
+  if (leading_comments_ != &::google::protobuf::internal::kEmptyString) {
+    delete leading_comments_;
+  }
+  if (leading_comments) {
+    set_has_leading_comments();
+    leading_comments_ = leading_comments;
+  } else {
+    clear_has_leading_comments();
+    leading_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
+
+// optional string trailing_comments = 4;
+inline bool SourceCodeInfo_Location::has_trailing_comments() const {
+  return (_has_bits_[0] & 0x00000008u) != 0;
+}
+inline void SourceCodeInfo_Location::set_has_trailing_comments() {
+  _has_bits_[0] |= 0x00000008u;
+}
+inline void SourceCodeInfo_Location::clear_has_trailing_comments() {
+  _has_bits_[0] &= ~0x00000008u;
+}
+inline void SourceCodeInfo_Location::clear_trailing_comments() {
+  if (trailing_comments_ != &::google::protobuf::internal::kEmptyString) {
+    trailing_comments_->clear();
+  }
+  clear_has_trailing_comments();
+}
+inline const ::std::string& SourceCodeInfo_Location::trailing_comments() const {
+  return *trailing_comments_;
+}
+inline void SourceCodeInfo_Location::set_trailing_comments(const ::std::string& value) {
+  set_has_trailing_comments();
+  if (trailing_comments_ == &::google::protobuf::internal::kEmptyString) {
+    trailing_comments_ = new ::std::string;
+  }
+  trailing_comments_->assign(value);
+}
+inline void SourceCodeInfo_Location::set_trailing_comments(const char* value) {
+  set_has_trailing_comments();
+  if (trailing_comments_ == &::google::protobuf::internal::kEmptyString) {
+    trailing_comments_ = new ::std::string;
+  }
+  trailing_comments_->assign(value);
+}
+inline void SourceCodeInfo_Location::set_trailing_comments(const char* value, size_t size) {
+  set_has_trailing_comments();
+  if (trailing_comments_ == &::google::protobuf::internal::kEmptyString) {
+    trailing_comments_ = new ::std::string;
+  }
+  trailing_comments_->assign(reinterpret_cast<const char*>(value), size);
+}
+inline ::std::string* SourceCodeInfo_Location::mutable_trailing_comments() {
+  set_has_trailing_comments();
+  if (trailing_comments_ == &::google::protobuf::internal::kEmptyString) {
+    trailing_comments_ = new ::std::string;
+  }
+  return trailing_comments_;
+}
+inline ::std::string* SourceCodeInfo_Location::release_trailing_comments() {
+  clear_has_trailing_comments();
+  if (trailing_comments_ == &::google::protobuf::internal::kEmptyString) {
+    return NULL;
+  } else {
+    ::std::string* temp = trailing_comments_;
+    trailing_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+    return temp;
+  }
+}
+inline void SourceCodeInfo_Location::set_allocated_trailing_comments(::std::string* trailing_comments) {
+  if (trailing_comments_ != &::google::protobuf::internal::kEmptyString) {
+    delete trailing_comments_;
+  }
+  if (trailing_comments) {
+    set_has_trailing_comments();
+    trailing_comments_ = trailing_comments;
+  } else {
+    clear_has_trailing_comments();
+    trailing_comments_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
+  }
+}
+
 // -------------------------------------------------------------------
 
 // SourceCodeInfo
diff --git a/src/google/protobuf/descriptor.proto b/src/google/protobuf/descriptor.proto
index 4eeb43b5..a785f79f 100644
--- a/src/google/protobuf/descriptor.proto
+++ b/src/google/protobuf/descriptor.proto
@@ -59,6 +59,11 @@ message FileDescriptorProto {
 
   // Names of files imported by this file.
   repeated string dependency = 3;
+  // Indexes of the public imported files in the dependency list above.
+  repeated int32 public_dependency = 10;
+  // Indexes of the weak imported files in the dependency list.
+  // For Google-internal migration only. Do not use.
+  repeated int32 weak_dependency = 11;
 
   // All top-level definitions in this file.
   repeated DescriptorProto message_type = 4;
@@ -101,13 +106,13 @@ message FieldDescriptorProto {
     // Order is weird for historical reasons.
     TYPE_DOUBLE         = 1;
     TYPE_FLOAT          = 2;
-    TYPE_INT64          = 3;   // Not ZigZag encoded.  Negative numbers
-                               // take 10 bytes.  Use TYPE_SINT64 if negative
-                               // values are likely.
+    // Not ZigZag encoded.  Negative numbers take 10 bytes.  Use TYPE_SINT64 if
+    // negative values are likely.
+    TYPE_INT64          = 3;
     TYPE_UINT64         = 4;
-    TYPE_INT32          = 5;   // Not ZigZag encoded.  Negative numbers
-                               // take 10 bytes.  Use TYPE_SINT32 if negative
-                               // values are likely.
+    // Not ZigZag encoded.  Negative numbers take 10 bytes.  Use TYPE_SINT32 if
+    // negative values are likely.
+    TYPE_INT32          = 5;
     TYPE_FIXED64        = 6;
     TYPE_FIXED32        = 7;
     TYPE_BOOL           = 8;
@@ -199,6 +204,7 @@ message MethodDescriptorProto {
   optional MethodOptions options = 4;
 }
 
+
 // ===================================================================
 // Options
 
@@ -271,6 +277,9 @@ message FileOptions {
   }
   optional OptimizeMode optimize_for = 9 [default=SPEED];
 
+  // Sets the Go package where structs generated from this .proto will be
+  // placed.  There is no default.
+  optional string go_package = 11;
 
 
 
@@ -349,6 +358,37 @@ message FieldOptions {
   optional bool packed = 2;
 
 
+
+  // Should this field be parsed lazily?  Lazy applies only to message-type
+  // fields.  It means that when the outer message is initially parsed, the
+  // inner message's contents will not be parsed but instead stored in encoded
+  // form.  The inner message will actually be parsed when it is first accessed.
+  //
+  // This is only a hint.  Implementations are free to choose whether to use
+  // eager or lazy parsing regardless of the value of this option.  However,
+  // setting this option true suggests that the protocol author believes that
+  // using lazy parsing on this field is worth the additional bookkeeping
+  // overhead typically needed to implement it.
+  //
+  // This option does not affect the public interface of any generated code;
+  // all method signatures remain the same.  Furthermore, thread-safety of the
+  // interface is not affected by this option; const methods remain safe to
+  // call from multiple threads concurrently, while non-const methods continue
+  // to require exclusive access.
+  //
+  //
+  // Note that implementations may choose not to check required fields within
+  // a lazy sub-message.  That is, calling IsInitialized() on the outher message
+  // may return true even if the inner message has missing required fields.
+  // This is necessary because otherwise the inner message would have to be
+  // parsed in order to perform the check, defeating the purpose of lazy
+  // parsing.  An implementation which chooses not to check required fields
+  // must be consistent about it.  That is, for any particular sub-message, the
+  // implementation must either *always* check its required fields, or *never*
+  // check its required fields, regardless of whether or not the message has
+  // been parsed.
+  optional bool lazy = 5 [default=false];
+
   // Is this field deprecated?
   // Depending on the target platform, this can emit Deprecated annotations
   // for accessors, or it will be completely ignored; in the very least, this
@@ -369,6 +409,9 @@ message FieldOptions {
   // TODO: Fully-implement this, then remove the "experimental_" prefix.
   optional string experimental_map_key = 9;
 
+  // For Google-internal migration only. Do not use.
+  optional bool weak = 10 [default=false];
+
   // The parser stores options it doesn't recognize here. See above.
   repeated UninterpretedOption uninterpreted_option = 999;
 
@@ -378,6 +421,10 @@ message FieldOptions {
 
 message EnumOptions {
 
+  // Set this option to false to disallow mapping different tag names to a same
+  // value.
+  optional bool allow_alias = 2 [default=true];
+
   // The parser stores options it doesn't recognize here. See above.
   repeated UninterpretedOption uninterpreted_option = 999;
 
@@ -421,6 +468,7 @@ message MethodOptions {
   extensions 1000 to max;
 }
 
+
 // A message representing a option the parser does not recognize. This only
 // appears in options protos created by the compiler::Parser class.
 // DescriptorPool resolves these when building Descriptor objects. Therefore,
@@ -532,7 +580,41 @@ message SourceCodeInfo {
     // 1 to each before displaying to a user.
     repeated int32 span = 2 [packed=true];
 
-    // TODO(kenton):  Record comments appearing before and after the
-    // declaration.
+    // If this SourceCodeInfo represents a complete declaration, these are any
+    // comments appearing before and after the declaration which appear to be
+    // attached to the declaration.
+    //
+    // A series of line comments appearing on consecutive lines, with no other
+    // tokens appearing on those lines, will be treated as a single comment.
+    //
+    // Only the comment content is provided; comment markers (e.g. //) are
+    // stripped out.  For block comments, leading whitespace and an asterisk
+    // will be stripped from the beginning of each line other than the first.
+    // Newlines are included in the output.
+    //
+    // Examples:
+    //
+    //   optional int32 foo = 1;  // Comment attached to foo.
+    //   // Comment attached to bar.
+    //   optional int32 bar = 2;
+    //
+    //   optional string baz = 3;
+    //   // Comment attached to baz.
+    //   // Another line attached to baz.
+    //
+    //   // Comment attached to qux.
+    //   //
+    //   // Another line attached to qux.
+    //   optional double qux = 4;
+    //
+    //   optional string corge = 5;
+    //   /* Block comment attached
+    //    * to corge.  Leading asterisks
+    //    * will be removed. */
+    //   /* Block comment attached to
+    //    * grault. */
+    //   optional int32 grault = 6;
+    optional string leading_comments = 3;
+    optional string trailing_comments = 4;
   }
 }
diff --git a/src/google/protobuf/descriptor_database.cc b/src/google/protobuf/descriptor_database.cc
index 23e48a67..35e459d5 100644
--- a/src/google/protobuf/descriptor_database.cc
+++ b/src/google/protobuf/descriptor_database.cc
@@ -39,7 +39,7 @@
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/wire_format_lite_inl.h>
 #include <google/protobuf/stubs/strutil.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 #include <google/protobuf/stubs/map-util.h>
 
 namespace google {
diff --git a/src/google/protobuf/descriptor_database.h b/src/google/protobuf/descriptor_database.h
index f32b1db9..2ccb1458 100644
--- a/src/google/protobuf/descriptor_database.h
+++ b/src/google/protobuf/descriptor_database.h
@@ -41,6 +41,7 @@
 #include <string>
 #include <utility>
 #include <vector>
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/descriptor.h>
 
 namespace google {
diff --git a/src/google/protobuf/descriptor_unittest.cc b/src/google/protobuf/descriptor_unittest.cc
index 55aebfd1..3503f13e 100644
--- a/src/google/protobuf/descriptor_unittest.cc
+++ b/src/google/protobuf/descriptor_unittest.cc
@@ -36,13 +36,15 @@
 
 #include <vector>
 
+#include <google/protobuf/compiler/importer.h>
+#include <google/protobuf/unittest.pb.h>
+#include <google/protobuf/unittest_custom_options.pb.h>
+#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/descriptor_database.h>
 #include <google/protobuf/dynamic_message.h>
-#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/text_format.h>
-#include <google/protobuf/unittest.pb.h>
-#include <google/protobuf/unittest_custom_options.pb.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 
@@ -1518,9 +1520,8 @@ TEST_F(ExtensionDescriptorTest, FindAllExtensions) {
 
 class MiscTest : public testing::Test {
  protected:
-  // Function which makes a field of the given type just to find out what its
-  // cpp_type is.
-  FieldDescriptor::CppType GetCppTypeForFieldType(FieldDescriptor::Type type) {
+  // Function which makes a field descriptor of the given type.
+  const FieldDescriptor* GetFieldDescriptorOfType(FieldDescriptor::Type type) {
     FileDescriptorProto file_proto;
     file_proto.set_name("foo.proto");
     AddEmptyEnum(&file_proto, "DummyEnum");
@@ -1538,19 +1539,62 @@ class MiscTest : public testing::Test {
     }
 
     // Build the descriptors and get the pointers.
-    DescriptorPool pool;
-    const FileDescriptor* file = pool.BuildFile(file_proto);
+    pool_.reset(new DescriptorPool());
+    const FileDescriptor* file = pool_->BuildFile(file_proto);
 
     if (file != NULL &&
         file->message_type_count() == 1 &&
         file->message_type(0)->field_count() == 1) {
-      return file->message_type(0)->field(0)->cpp_type();
+      return file->message_type(0)->field(0);
     } else {
-      return static_cast<FieldDescriptor::CppType>(0);
+      return NULL;
     }
   }
+
+  const char* GetTypeNameForFieldType(FieldDescriptor::Type type) {
+    const FieldDescriptor* field = GetFieldDescriptorOfType(type);
+    return field != NULL ? field->type_name() : "";
+  }
+
+  FieldDescriptor::CppType GetCppTypeForFieldType(FieldDescriptor::Type type) {
+    const FieldDescriptor* field = GetFieldDescriptorOfType(type);
+    return field != NULL ? field->cpp_type() :
+        static_cast<FieldDescriptor::CppType>(0);
+  }
+
+  const char* GetCppTypeNameForFieldType(FieldDescriptor::Type type) {
+    const FieldDescriptor* field = GetFieldDescriptorOfType(type);
+    return field != NULL ? field->cpp_type_name() : "";
+  }
+
+  scoped_ptr<DescriptorPool> pool_;
 };
 
+TEST_F(MiscTest, TypeNames) {
+  // Test that correct type names are returned.
+
+  typedef FieldDescriptor FD;  // avoid ugly line wrapping
+
+  EXPECT_STREQ("double"  , GetTypeNameForFieldType(FD::TYPE_DOUBLE  ));
+  EXPECT_STREQ("float"   , GetTypeNameForFieldType(FD::TYPE_FLOAT   ));
+  EXPECT_STREQ("int64"   , GetTypeNameForFieldType(FD::TYPE_INT64   ));
+  EXPECT_STREQ("uint64"  , GetTypeNameForFieldType(FD::TYPE_UINT64  ));
+  EXPECT_STREQ("int32"   , GetTypeNameForFieldType(FD::TYPE_INT32   ));
+  EXPECT_STREQ("fixed64" , GetTypeNameForFieldType(FD::TYPE_FIXED64 ));
+  EXPECT_STREQ("fixed32" , GetTypeNameForFieldType(FD::TYPE_FIXED32 ));
+  EXPECT_STREQ("bool"    , GetTypeNameForFieldType(FD::TYPE_BOOL    ));
+  EXPECT_STREQ("string"  , GetTypeNameForFieldType(FD::TYPE_STRING  ));
+  EXPECT_STREQ("group"   , GetTypeNameForFieldType(FD::TYPE_GROUP   ));
+  EXPECT_STREQ("message" , GetTypeNameForFieldType(FD::TYPE_MESSAGE ));
+  EXPECT_STREQ("bytes"   , GetTypeNameForFieldType(FD::TYPE_BYTES   ));
+  EXPECT_STREQ("uint32"  , GetTypeNameForFieldType(FD::TYPE_UINT32  ));
+  EXPECT_STREQ("enum"    , GetTypeNameForFieldType(FD::TYPE_ENUM    ));
+  EXPECT_STREQ("sfixed32", GetTypeNameForFieldType(FD::TYPE_SFIXED32));
+  EXPECT_STREQ("sfixed64", GetTypeNameForFieldType(FD::TYPE_SFIXED64));
+  EXPECT_STREQ("sint32"  , GetTypeNameForFieldType(FD::TYPE_SINT32  ));
+  EXPECT_STREQ("sint64"  , GetTypeNameForFieldType(FD::TYPE_SINT64  ));
+}
+
 TEST_F(MiscTest, CppTypes) {
   // Test that CPP types are assigned correctly.
 
@@ -1576,6 +1620,31 @@ TEST_F(MiscTest, CppTypes) {
   EXPECT_EQ(FD::CPPTYPE_INT64  , GetCppTypeForFieldType(FD::TYPE_SINT64  ));
 }
 
+TEST_F(MiscTest, CppTypeNames) {
+  // Test that correct CPP type names are returned.
+
+  typedef FieldDescriptor FD;  // avoid ugly line wrapping
+
+  EXPECT_STREQ("double" , GetCppTypeNameForFieldType(FD::TYPE_DOUBLE  ));
+  EXPECT_STREQ("float"  , GetCppTypeNameForFieldType(FD::TYPE_FLOAT   ));
+  EXPECT_STREQ("int64"  , GetCppTypeNameForFieldType(FD::TYPE_INT64   ));
+  EXPECT_STREQ("uint64" , GetCppTypeNameForFieldType(FD::TYPE_UINT64  ));
+  EXPECT_STREQ("int32"  , GetCppTypeNameForFieldType(FD::TYPE_INT32   ));
+  EXPECT_STREQ("uint64" , GetCppTypeNameForFieldType(FD::TYPE_FIXED64 ));
+  EXPECT_STREQ("uint32" , GetCppTypeNameForFieldType(FD::TYPE_FIXED32 ));
+  EXPECT_STREQ("bool"   , GetCppTypeNameForFieldType(FD::TYPE_BOOL    ));
+  EXPECT_STREQ("string" , GetCppTypeNameForFieldType(FD::TYPE_STRING  ));
+  EXPECT_STREQ("message", GetCppTypeNameForFieldType(FD::TYPE_GROUP   ));
+  EXPECT_STREQ("message", GetCppTypeNameForFieldType(FD::TYPE_MESSAGE ));
+  EXPECT_STREQ("string" , GetCppTypeNameForFieldType(FD::TYPE_BYTES   ));
+  EXPECT_STREQ("uint32" , GetCppTypeNameForFieldType(FD::TYPE_UINT32  ));
+  EXPECT_STREQ("enum"   , GetCppTypeNameForFieldType(FD::TYPE_ENUM    ));
+  EXPECT_STREQ("int32"  , GetCppTypeNameForFieldType(FD::TYPE_SFIXED32));
+  EXPECT_STREQ("int64"  , GetCppTypeNameForFieldType(FD::TYPE_SFIXED64));
+  EXPECT_STREQ("int32"  , GetCppTypeNameForFieldType(FD::TYPE_SINT32  ));
+  EXPECT_STREQ("int64"  , GetCppTypeNameForFieldType(FD::TYPE_SINT64  ));
+}
+
 TEST_F(MiscTest, DefaultValues) {
   // Test that setting default values works.
   FileDescriptorProto file_proto;
@@ -1739,13 +1808,31 @@ TEST_F(MiscTest, FieldOptions) {
 }
 
 // ===================================================================
+enum DescriptorPoolMode {
+  NO_DATABASE,
+  FALLBACK_DATABASE
+};
 
-class AllowUnknownDependenciesTest : public testing::Test {
+class AllowUnknownDependenciesTest
+    : public testing::TestWithParam<DescriptorPoolMode> {
  protected:
+  DescriptorPoolMode mode() {
+    return GetParam();
+   }
+
   virtual void SetUp() {
     FileDescriptorProto foo_proto, bar_proto;
 
-    pool_.AllowUnknownDependencies();
+    switch (mode()) {
+      case NO_DATABASE:
+        pool_.reset(new DescriptorPool);
+        break;
+      case FALLBACK_DATABASE:
+        pool_.reset(new DescriptorPool(&db_));
+        break;
+    }
+
+    pool_->AllowUnknownDependencies();
 
     ASSERT_TRUE(TextFormat::ParseFromString(
       "name: 'foo.proto'"
@@ -1776,13 +1863,13 @@ class AllowUnknownDependenciesTest : public testing::Test {
       &bar_proto));
 
     // Collect pointers to stuff.
-    bar_file_ = pool_.BuildFile(bar_proto);
+    bar_file_ = BuildFile(bar_proto);
     ASSERT_TRUE(bar_file_ != NULL);
 
     ASSERT_EQ(1, bar_file_->message_type_count());
     bar_type_ = bar_file_->message_type(0);
 
-    foo_file_ = pool_.BuildFile(foo_proto);
+    foo_file_ = BuildFile(foo_proto);
     ASSERT_TRUE(foo_file_ != NULL);
 
     ASSERT_EQ(1, foo_file_->message_type_count());
@@ -1794,6 +1881,20 @@ class AllowUnknownDependenciesTest : public testing::Test {
     qux_field_ = foo_type_->field(2);
   }
 
+  const FileDescriptor* BuildFile(const FileDescriptorProto& proto) {
+    switch (mode()) {
+      case NO_DATABASE:
+        return pool_->BuildFile(proto);
+        break;
+      case FALLBACK_DATABASE: {
+        EXPECT_TRUE(db_.Add(proto));
+        return pool_->FindFileByName(proto.name());
+      }
+    }
+    GOOGLE_LOG(FATAL) << "Can't get here.";
+    return NULL;
+  }
+
   const FileDescriptor* bar_file_;
   const Descriptor* bar_type_;
   const FileDescriptor* foo_file_;
@@ -1802,10 +1903,11 @@ class AllowUnknownDependenciesTest : public testing::Test {
   const FieldDescriptor* baz_field_;
   const FieldDescriptor* qux_field_;
 
-  DescriptorPool pool_;
+  SimpleDescriptorDatabase db_;        // used if in FALLBACK_DATABASE mode.
+  scoped_ptr<DescriptorPool> pool_;
 };
 
-TEST_F(AllowUnknownDependenciesTest, PlaceholderFile) {
+TEST_P(AllowUnknownDependenciesTest, PlaceholderFile) {
   ASSERT_EQ(2, foo_file_->dependency_count());
   EXPECT_EQ(bar_file_, foo_file_->dependency(0));
 
@@ -1814,11 +1916,11 @@ TEST_F(AllowUnknownDependenciesTest, PlaceholderFile) {
   EXPECT_EQ(0, baz_file->message_type_count());
 
   // Placeholder files should not be findable.
-  EXPECT_EQ(bar_file_, pool_.FindFileByName(bar_file_->name()));
-  EXPECT_TRUE(pool_.FindFileByName(baz_file->name()) == NULL);
+  EXPECT_EQ(bar_file_, pool_->FindFileByName(bar_file_->name()));
+  EXPECT_TRUE(pool_->FindFileByName(baz_file->name()) == NULL);
 }
 
-TEST_F(AllowUnknownDependenciesTest, PlaceholderTypes) {
+TEST_P(AllowUnknownDependenciesTest, PlaceholderTypes) {
   ASSERT_EQ(FieldDescriptor::TYPE_MESSAGE, bar_field_->type());
   EXPECT_EQ(bar_type_, bar_field_->message_type());
 
@@ -1836,12 +1938,12 @@ TEST_F(AllowUnknownDependenciesTest, PlaceholderTypes) {
   EXPECT_EQ("corge.Qux.placeholder.proto", qux_type->file()->name());
 
   // Placeholder types should not be findable.
-  EXPECT_EQ(bar_type_, pool_.FindMessageTypeByName(bar_type_->full_name()));
-  EXPECT_TRUE(pool_.FindMessageTypeByName(baz_type->full_name()) == NULL);
-  EXPECT_TRUE(pool_.FindEnumTypeByName(qux_type->full_name()) == NULL);
+  EXPECT_EQ(bar_type_, pool_->FindMessageTypeByName(bar_type_->full_name()));
+  EXPECT_TRUE(pool_->FindMessageTypeByName(baz_type->full_name()) == NULL);
+  EXPECT_TRUE(pool_->FindEnumTypeByName(qux_type->full_name()) == NULL);
 }
 
-TEST_F(AllowUnknownDependenciesTest, CopyTo) {
+TEST_P(AllowUnknownDependenciesTest, CopyTo) {
   // FieldDescriptor::CopyTo() should write non-fully-qualified type names
   // for placeholder types which were not originally fully-qualified.
   FieldDescriptorProto proto;
@@ -1864,7 +1966,7 @@ TEST_F(AllowUnknownDependenciesTest, CopyTo) {
   EXPECT_EQ(FieldDescriptorProto::TYPE_ENUM, proto.type());
 }
 
-TEST_F(AllowUnknownDependenciesTest, CustomOptions) {
+TEST_P(AllowUnknownDependenciesTest, CustomOptions) {
   // Qux should still have the uninterpreted option attached.
   ASSERT_EQ(1, qux_field_->options().uninterpreted_option_size());
   const UninterpretedOption& option =
@@ -1873,7 +1975,7 @@ TEST_F(AllowUnknownDependenciesTest, CustomOptions) {
   EXPECT_EQ("grault", option.name(0).name_part());
 }
 
-TEST_F(AllowUnknownDependenciesTest, UnknownExtendee) {
+TEST_P(AllowUnknownDependenciesTest, UnknownExtendee) {
   // Test that we can extend an unknown type.  This is slightly tricky because
   // it means that the placeholder type must have an extension range.
 
@@ -1884,7 +1986,7 @@ TEST_F(AllowUnknownDependenciesTest, UnknownExtendee) {
     "extension { extendee: 'UnknownType' name:'some_extension' number:123"
     "            label:LABEL_OPTIONAL type:TYPE_INT32 }",
     &extension_proto));
-  const FileDescriptor* file = pool_.BuildFile(extension_proto);
+  const FileDescriptor* file = BuildFile(extension_proto);
 
   ASSERT_TRUE(file != NULL);
 
@@ -1896,7 +1998,7 @@ TEST_F(AllowUnknownDependenciesTest, UnknownExtendee) {
   EXPECT_EQ(FieldDescriptor::kMaxNumber + 1, extendee->extension_range(0)->end);
 }
 
-TEST_F(AllowUnknownDependenciesTest, CustomOption) {
+TEST_P(AllowUnknownDependenciesTest, CustomOption) {
   // Test that we can use a custom option without having parsed
   // descriptor.proto.
 
@@ -1937,7 +2039,7 @@ TEST_F(AllowUnknownDependenciesTest, CustomOption) {
     "}",
     &option_proto));
 
-  const FileDescriptor* file = pool_.BuildFile(option_proto);
+  const FileDescriptor* file = BuildFile(option_proto);
   ASSERT_TRUE(file != NULL);
 
   // Verify that no extension options were set, but they were left as
@@ -1949,6 +2051,81 @@ TEST_F(AllowUnknownDependenciesTest, CustomOption) {
   EXPECT_EQ(2, file->options().uninterpreted_option_size());
 }
 
+TEST_P(AllowUnknownDependenciesTest,
+       UndeclaredDependencyTriggersBuildOfDependency) {
+  // Crazy case: suppose foo.proto refers to a symbol without declaring the
+  // dependency that finds it. In the event that the pool is backed by a
+  // DescriptorDatabase, the pool will attempt to find the symbol in the
+  // database. If successful, it will build the undeclared dependency to verify
+  // that the file does indeed contain the symbol. If that file fails to build,
+  // then its descriptors must be rolled back. However, we still want foo.proto
+  // to build successfully, since we are allowing unknown dependencies.
+
+  FileDescriptorProto undeclared_dep_proto;
+  // We make this file fail to build by giving it two fields with tag 1.
+  ASSERT_TRUE(TextFormat::ParseFromString(
+    "name: \"invalid_file_as_undeclared_dep.proto\" "
+    "package: \"undeclared\" "
+    "message_type: {  "
+    "  name: \"Quux\"  "
+    "  field { "
+    "    name:'qux' number:1 label:LABEL_OPTIONAL type: TYPE_INT32 "
+    "  }"
+    "  field { "
+    "    name:'quux' number:1 label:LABEL_OPTIONAL type: TYPE_INT64 "
+    "  }"
+    "}",
+    &undeclared_dep_proto));
+  // We can't use the BuildFile() helper because we don't actually want to build
+  // it into the descriptor pool in the fallback database case: it just needs to
+  // be sitting in the database so that it gets built during the building of
+  // test.proto below.
+  switch (mode()) {
+    case NO_DATABASE: {
+      ASSERT_TRUE(pool_->BuildFile(undeclared_dep_proto) == NULL);
+      break;
+    }
+    case FALLBACK_DATABASE: {
+      ASSERT_TRUE(db_.Add(undeclared_dep_proto));
+    }
+  }
+
+  FileDescriptorProto test_proto;
+  ASSERT_TRUE(TextFormat::ParseFromString(
+    "name: \"test.proto\" "
+    "message_type: { "
+    "  name: \"Corge\" "
+    "  field { "
+    "    name:'quux' number:1 label: LABEL_OPTIONAL "
+    "    type_name:'undeclared.Quux' type: TYPE_MESSAGE "
+    "  }"
+    "}",
+    &test_proto));
+
+  const FileDescriptor* file = BuildFile(test_proto);
+  ASSERT_TRUE(file != NULL);
+  GOOGLE_LOG(INFO) << file->DebugString();
+
+  EXPECT_EQ(0, file->dependency_count());
+  ASSERT_EQ(1, file->message_type_count());
+  const Descriptor* corge_desc = file->message_type(0);
+  ASSERT_EQ("Corge", corge_desc->name());
+  ASSERT_EQ(1, corge_desc->field_count());
+
+  const FieldDescriptor* quux_field = corge_desc->field(0);
+  ASSERT_EQ(FieldDescriptor::TYPE_MESSAGE, quux_field->type());
+  ASSERT_EQ("Quux", quux_field->message_type()->name());
+  ASSERT_EQ("undeclared.Quux", quux_field->message_type()->full_name());
+  EXPECT_EQ("undeclared.Quux.placeholder.proto",
+            quux_field->message_type()->file()->name());
+  // The place holder type should not be findable.
+  ASSERT_TRUE(pool_->FindMessageTypeByName("undeclared.Quux") == NULL);
+}
+
+INSTANTIATE_TEST_CASE_P(DatabaseSource,
+                        AllowUnknownDependenciesTest,
+                        testing::Values(NO_DATABASE, FALLBACK_DATABASE));
+
 // ===================================================================
 
 TEST(CustomOptions, OptionLocations) {
@@ -2451,6 +2628,15 @@ TEST_F(ValidationErrorTest, UnknownDependency) {
     "bar.proto: bar.proto: OTHER: Import \"foo.proto\" has not been loaded.\n");
 }
 
+TEST_F(ValidationErrorTest, InvalidPublicDependencyIndex) {
+  BuildFile("name: \"foo.proto\"");
+  BuildFileWithErrors(
+    "name: \"bar.proto\" "
+    "dependency: \"foo.proto\" "
+    "public_dependency: 1",
+    "bar.proto: bar.proto: OTHER: Invalid public dependency index.\n");
+}
+
 TEST_F(ValidationErrorTest, ForeignUnimportedPackageNoCrash) {
   // Used to crash:  If we depend on a non-existent file and then refer to a
   // package defined in a file that we didn't import, and that package is
@@ -2829,6 +3015,164 @@ TEST_F(ValidationErrorTest, FieldTypeDefinedInUndeclaredDependency) {
       "necessary import.\n");
 }
 
+TEST_F(ValidationErrorTest, FieldTypeDefinedInIndirectDependency) {
+  // Test for hidden dependencies.
+  //
+  // // bar.proto
+  // message Bar{}
+  //
+  // // forward.proto
+  // import "bar.proto"
+  //
+  // // foo.proto
+  // import "forward.proto"
+  // message Foo {
+  //   optional Bar foo = 1;  // Error, needs to import bar.proto explicitly.
+  // }
+  //
+  BuildFile(
+    "name: \"bar.proto\" "
+    "message_type { name: \"Bar\" }");
+
+  BuildFile(
+    "name: \"forward.proto\""
+    "dependency: \"bar.proto\"");
+
+  BuildFileWithErrors(
+    "name: \"foo.proto\" "
+    "dependency: \"forward.proto\" "
+    "message_type {"
+    "  name: \"Foo\""
+    "  field { name:\"foo\" number:1 label:LABEL_OPTIONAL type_name:\"Bar\" }"
+    "}",
+    "foo.proto: Foo.foo: TYPE: \"Bar\" seems to be defined in \"bar.proto\", "
+      "which is not imported by \"foo.proto\".  To use it here, please add the "
+      "necessary import.\n");
+}
+
+TEST_F(ValidationErrorTest, FieldTypeDefinedInPublicDependency) {
+  // Test for public dependencies.
+  //
+  // // bar.proto
+  // message Bar{}
+  //
+  // // forward.proto
+  // import public "bar.proto"
+  //
+  // // foo.proto
+  // import "forward.proto"
+  // message Foo {
+  //   optional Bar foo = 1;  // Correct. "bar.proto" is public imported into
+  //                          // forward.proto, so when "foo.proto" imports
+  //                          // "forward.proto", it imports "bar.proto" too.
+  // }
+  //
+  BuildFile(
+    "name: \"bar.proto\" "
+    "message_type { name: \"Bar\" }");
+
+  BuildFile(
+    "name: \"forward.proto\""
+    "dependency: \"bar.proto\" "
+    "public_dependency: 0");
+
+  BuildFile(
+    "name: \"foo.proto\" "
+    "dependency: \"forward.proto\" "
+    "message_type {"
+    "  name: \"Foo\""
+    "  field { name:\"foo\" number:1 label:LABEL_OPTIONAL type_name:\"Bar\" }"
+    "}");
+}
+
+TEST_F(ValidationErrorTest, FieldTypeDefinedInTransitivePublicDependency) {
+  // Test for public dependencies.
+  //
+  // // bar.proto
+  // message Bar{}
+  //
+  // // forward.proto
+  // import public "bar.proto"
+  //
+  // // forward2.proto
+  // import public "forward.proto"
+  //
+  // // foo.proto
+  // import "forward2.proto"
+  // message Foo {
+  //   optional Bar foo = 1;  // Correct, public imports are transitive.
+  // }
+  //
+  BuildFile(
+    "name: \"bar.proto\" "
+    "message_type { name: \"Bar\" }");
+
+  BuildFile(
+    "name: \"forward.proto\""
+    "dependency: \"bar.proto\" "
+    "public_dependency: 0");
+
+  BuildFile(
+    "name: \"forward2.proto\""
+    "dependency: \"forward.proto\" "
+    "public_dependency: 0");
+
+  BuildFile(
+    "name: \"foo.proto\" "
+    "dependency: \"forward2.proto\" "
+    "message_type {"
+    "  name: \"Foo\""
+    "  field { name:\"foo\" number:1 label:LABEL_OPTIONAL type_name:\"Bar\" }"
+    "}");
+}
+
+TEST_F(ValidationErrorTest,
+       FieldTypeDefinedInPrivateDependencyOfPublicDependency) {
+  // Test for public dependencies.
+  //
+  // // bar.proto
+  // message Bar{}
+  //
+  // // forward.proto
+  // import "bar.proto"
+  //
+  // // forward2.proto
+  // import public "forward.proto"
+  //
+  // // foo.proto
+  // import "forward2.proto"
+  // message Foo {
+  //   optional Bar foo = 1;  // Error, the "bar.proto" is not public imported
+  //                          // into "forward.proto", so will not be imported
+  //                          // into either "forward2.proto" or "foo.proto".
+  // }
+  //
+  BuildFile(
+    "name: \"bar.proto\" "
+    "message_type { name: \"Bar\" }");
+
+  BuildFile(
+    "name: \"forward.proto\""
+    "dependency: \"bar.proto\"");
+
+  BuildFile(
+    "name: \"forward2.proto\""
+    "dependency: \"forward.proto\" "
+    "public_dependency: 0");
+
+  BuildFileWithErrors(
+    "name: \"foo.proto\" "
+    "dependency: \"forward2.proto\" "
+    "message_type {"
+    "  name: \"Foo\""
+    "  field { name:\"foo\" number:1 label:LABEL_OPTIONAL type_name:\"Bar\" }"
+    "}",
+    "foo.proto: Foo.foo: TYPE: \"Bar\" seems to be defined in \"bar.proto\", "
+      "which is not imported by \"foo.proto\".  To use it here, please add the "
+      "necessary import.\n");
+}
+
+
 TEST_F(ValidationErrorTest, SearchMostLocalFirst) {
   // The following should produce an error that Bar.Baz is not defined:
   //   message Bar { message Baz {} }
@@ -3031,7 +3375,8 @@ TEST_F(ValidationErrorTest, InputTypeNotDefined) {
     "  method { name: \"A\" input_type: \"Bar\" output_type: \"Foo\" }"
     "}",
 
-    "foo.proto: TestService.A: INPUT_TYPE: \"Bar\" is not defined.\n");
+    "foo.proto: TestService.A: INPUT_TYPE: \"Bar\" is not defined.\n"
+    );
 }
 
 TEST_F(ValidationErrorTest, InputTypeNotAMessage) {
@@ -3044,7 +3389,8 @@ TEST_F(ValidationErrorTest, InputTypeNotAMessage) {
     "  method { name: \"A\" input_type: \"Bar\" output_type: \"Foo\" }"
     "}",
 
-    "foo.proto: TestService.A: INPUT_TYPE: \"Bar\" is not a message type.\n");
+    "foo.proto: TestService.A: INPUT_TYPE: \"Bar\" is not a message type.\n"
+    );
 }
 
 TEST_F(ValidationErrorTest, OutputTypeNotDefined) {
@@ -3056,7 +3402,8 @@ TEST_F(ValidationErrorTest, OutputTypeNotDefined) {
     "  method { name: \"A\" input_type: \"Foo\" output_type: \"Bar\" }"
     "}",
 
-    "foo.proto: TestService.A: OUTPUT_TYPE: \"Bar\" is not defined.\n");
+    "foo.proto: TestService.A: OUTPUT_TYPE: \"Bar\" is not defined.\n"
+    );
 }
 
 TEST_F(ValidationErrorTest, OutputTypeNotAMessage) {
@@ -3069,9 +3416,11 @@ TEST_F(ValidationErrorTest, OutputTypeNotAMessage) {
     "  method { name: \"A\" input_type: \"Foo\" output_type: \"Bar\" }"
     "}",
 
-    "foo.proto: TestService.A: OUTPUT_TYPE: \"Bar\" is not a message type.\n");
+    "foo.proto: TestService.A: OUTPUT_TYPE: \"Bar\" is not a message type.\n"
+    );
 }
 
+
 TEST_F(ValidationErrorTest, IllegalPackedField) {
   BuildFileWithErrors(
     "name: \"foo.proto\" "
@@ -3592,7 +3941,8 @@ TEST_F(ValidationErrorTest, RollbackAfterError) {
     "  }"
     "}",
 
-    "foo.proto: TestService.Baz: INPUT_TYPE: \"NoSuchType\" is not defined.\n");
+    "foo.proto: TestService.Baz: INPUT_TYPE: \"NoSuchType\" is not defined.\n"
+    );
 
   // Make sure that if we build the same file again with the error fixed,
   // it works.  If the above rollback was incomplete, then some symbols will
@@ -3641,6 +3991,19 @@ TEST_F(ValidationErrorTest, ErrorsReportedToLogError) {
   EXPECT_EQ("  Foo: \"Foo\" is already defined.", errors[1]);
 }
 
+TEST_F(ValidationErrorTest, DisallowEnumAlias) {
+  BuildFileWithErrors(
+    "name: \"foo.proto\" "
+    "enum_type {"
+    "  name: \"Bar\""
+    "  value { name:\"ENUM_A\" number:0 }"
+    "  value { name:\"ENUM_B\" number:0 }"
+    "  options { allow_alias: false }"
+    "}",
+    "foo.proto: Bar: NUMBER: "
+    "\"ENUM_B\" uses the same enum value as \"ENUM_A\"\n");
+}
+
 // ===================================================================
 // DescriptorDatabase
 
@@ -3659,16 +4022,23 @@ class DatabaseBackedPoolTest : public testing::Test {
 
   virtual void SetUp() {
     AddToDatabase(&database_,
-      "name: \"foo.proto\" "
-      "message_type { name:\"Foo\" extension_range { start: 1 end: 100 } } "
-      "enum_type { name:\"TestEnum\" value { name:\"DUMMY\" number:0 } } "
-      "service { name:\"TestService\" } ");
+      "name: 'foo.proto' "
+      "message_type { name:'Foo' extension_range { start: 1 end: 100 } } "
+      "enum_type { name:'TestEnum' value { name:'DUMMY' number:0 } } "
+      "service { name:'TestService' } ");
     AddToDatabase(&database_,
-      "name: \"bar.proto\" "
-      "dependency: \"foo.proto\" "
-      "message_type { name:\"Bar\" } "
-      "extension { name:\"foo_ext\" extendee: \".Foo\" number:5 "
+      "name: 'bar.proto' "
+      "dependency: 'foo.proto' "
+      "message_type { name:'Bar' } "
+      "extension { name:'foo_ext' extendee: '.Foo' number:5 "
       "            label:LABEL_OPTIONAL type:TYPE_INT32 } ");
+    // Baz has an undeclared dependency on Foo.
+    AddToDatabase(&database_,
+      "name: 'baz.proto' "
+      "message_type { "
+      "  name:'Baz' "
+      "  field { name:'foo' number:1 label:LABEL_OPTIONAL type_name:'Foo' } "
+      "}");
   }
 
   // We can't inject a file containing errors into a DescriptorPool, so we
@@ -3907,6 +4277,33 @@ TEST_F(DatabaseBackedPoolTest, ErrorWithErrorCollector) {
     error_collector.text_);
 }
 
+TEST_F(DatabaseBackedPoolTest, UndeclaredDependencyOnUnbuiltType) {
+  // Check that we find and report undeclared dependencies on types that exist
+  // in the descriptor database but that have not not been built yet.
+  MockErrorCollector error_collector;
+  DescriptorPool pool(&database_, &error_collector);
+  EXPECT_TRUE(pool.FindMessageTypeByName("Baz") == NULL);
+  EXPECT_EQ(
+    "baz.proto: Baz.foo: TYPE: \"Foo\" seems to be defined in \"foo.proto\", "
+    "which is not imported by \"baz.proto\".  To use it here, please add "
+    "the necessary import.\n",
+    error_collector.text_);
+}
+
+TEST_F(DatabaseBackedPoolTest, RollbackAfterError) {
+  // Make sure that all traces of bad types are removed from the pool. This used
+  // to be b/4529436, due to the fact that a symbol resolution failure could
+  // potentially cause another file to be recursively built, which would trigger
+  // a checkpoint _past_ possibly invalid symbols.
+  // Baz is defined in the database, but the file is invalid because it is
+  // missing a necessary import.
+  DescriptorPool pool(&database_);
+  EXPECT_TRUE(pool.FindMessageTypeByName("Baz") == NULL);
+  // Make sure that searching again for the file or the type fails.
+  EXPECT_TRUE(pool.FindFileByName("baz.proto") == NULL);
+  EXPECT_TRUE(pool.FindMessageTypeByName("Baz") == NULL);
+}
+
 TEST_F(DatabaseBackedPoolTest, UnittestProto) {
   // Try to load all of unittest.proto from a DescriptorDatabase.  This should
   // thoroughly test all paths through DescriptorBuilder to insure that there
@@ -3963,6 +4360,16 @@ TEST_F(DatabaseBackedPoolTest, DoesntRetryDbUnnecessarily) {
   EXPECT_TRUE(file->FindEnumValueByName("NO_SUCH_VALUE") == NULL);
   EXPECT_TRUE(file->FindServiceByName("NO_SUCH_VALUE") == NULL);
   EXPECT_TRUE(file->FindExtensionByName("no_such_extension") == NULL);
+
+  EXPECT_TRUE(pool.FindFileContainingSymbol("Foo.no.such.field") == NULL);
+  EXPECT_TRUE(pool.FindFileContainingSymbol("Foo.no_such_field") == NULL);
+  EXPECT_TRUE(pool.FindMessageTypeByName("Foo.NoSuchMessageType") == NULL);
+  EXPECT_TRUE(pool.FindFieldByName("Foo.no_such_field") == NULL);
+  EXPECT_TRUE(pool.FindExtensionByName("Foo.no_such_extension") == NULL);
+  EXPECT_TRUE(pool.FindEnumTypeByName("Foo.NoSuchEnumType") == NULL);
+  EXPECT_TRUE(pool.FindEnumValueByName("Foo.NO_SUCH_VALUE") == NULL);
+  EXPECT_TRUE(pool.FindMethodByName("TestService.NoSuchMethod") == NULL);
+
   EXPECT_EQ(0, call_counter.call_count_);
 }
 
@@ -4028,6 +4435,219 @@ TEST_F(DatabaseBackedPoolTest, DoesntFallbackOnWrongType) {
 
 // ===================================================================
 
+class AbortingErrorCollector : public DescriptorPool::ErrorCollector {
+ public:
+  AbortingErrorCollector() {}
+
+  virtual void AddError(
+      const string &filename,
+      const string &element_name,
+      const Message *message,
+      ErrorLocation location,
+      const string &error_message) {
+    GOOGLE_LOG(FATAL) << "AddError() called unexpectedly: " << filename << ": "
+               << error_message;
+  }
+ private:
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(AbortingErrorCollector);
+};
+
+// A source tree containing only one file.
+class SingletonSourceTree : public compiler::SourceTree {
+ public:
+  SingletonSourceTree(const string& filename, const string& contents)
+      : filename_(filename), contents_(contents) {}
+
+  virtual io::ZeroCopyInputStream* Open(const string& filename) {
+    return filename == filename_ ?
+        new io::ArrayInputStream(contents_.data(), contents_.size()) : NULL;
+  }
+
+ private:
+  const string filename_;
+  const string contents_;
+
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(SingletonSourceTree);
+};
+
+const char *const kSourceLocationTestInput =
+  "syntax = \"proto2\";\n"
+  "message A {\n"
+  "  optional int32 a = 1;\n"
+  "  message B {\n"
+  "    required double b = 1;\n"
+  "  }\n"
+  "}\n"
+  "enum Indecision {\n"
+  "  YES   = 1;\n"
+  "  NO    = 2;\n"
+  "  MAYBE = 3;\n"
+  "}\n"
+  "service S {\n"
+  "  rpc Method(A) returns (A.B);\n"
+  // Put an empty line here to make the source location range match.
+  "\n"
+  "}\n";
+
+class SourceLocationTest : public testing::Test {
+ public:
+  SourceLocationTest()
+      : source_tree_("/test/test.proto", kSourceLocationTestInput),
+        db_(&source_tree_),
+        pool_(&db_, &collector_) {}
+
+  static string PrintSourceLocation(const SourceLocation &loc) {
+    return strings::Substitute("$0:$1-$2:$3",
+                               1 + loc.start_line,
+                               1 + loc.start_column,
+                               1 + loc.end_line,
+                               1 + loc.end_column);
+  }
+
+ private:
+  AbortingErrorCollector collector_;
+  SingletonSourceTree source_tree_;
+  compiler::SourceTreeDescriptorDatabase db_;
+
+ protected:
+  DescriptorPool pool_;
+};
+
+// TODO(adonovan): implement support for option fields and for
+// subparts of declarations.
+
+TEST_F(SourceLocationTest, GetSourceLocation) {
+  SourceLocation loc;
+
+  const FileDescriptor *file_desc =
+      GOOGLE_CHECK_NOTNULL(pool_.FindFileByName("/test/test.proto"));
+
+  const Descriptor *a_desc = file_desc->FindMessageTypeByName("A");
+  EXPECT_TRUE(a_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("2:1-7:2", PrintSourceLocation(loc));
+
+  const Descriptor *a_b_desc = a_desc->FindNestedTypeByName("B");
+  EXPECT_TRUE(a_b_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("4:3-6:4", PrintSourceLocation(loc));
+
+  const EnumDescriptor *e_desc = file_desc->FindEnumTypeByName("Indecision");
+  EXPECT_TRUE(e_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("8:1-12:2", PrintSourceLocation(loc));
+
+  const EnumValueDescriptor *yes_desc = e_desc->FindValueByName("YES");
+  EXPECT_TRUE(yes_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("9:3-9:13", PrintSourceLocation(loc));
+
+  const ServiceDescriptor *s_desc = file_desc->FindServiceByName("S");
+  EXPECT_TRUE(s_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("13:1-16:2", PrintSourceLocation(loc));
+
+  const MethodDescriptor *m_desc = s_desc->FindMethodByName("Method");
+  EXPECT_TRUE(m_desc->GetSourceLocation(&loc));
+  EXPECT_EQ("14:3-14:31", PrintSourceLocation(loc));
+
+}
+
+// Missing SourceCodeInfo doesn't cause crash:
+TEST_F(SourceLocationTest, GetSourceLocation_MissingSourceCodeInfo) {
+  SourceLocation loc;
+
+  const FileDescriptor *file_desc =
+      GOOGLE_CHECK_NOTNULL(pool_.FindFileByName("/test/test.proto"));
+
+  FileDescriptorProto proto;
+  file_desc->CopyTo(&proto);  // Note, this discards the SourceCodeInfo.
+  EXPECT_FALSE(proto.has_source_code_info());
+
+  DescriptorPool bad1_pool(&pool_);
+  const FileDescriptor* bad1_file_desc =
+      GOOGLE_CHECK_NOTNULL(bad1_pool.BuildFile(proto));
+  const Descriptor *bad1_a_desc = bad1_file_desc->FindMessageTypeByName("A");
+  EXPECT_FALSE(bad1_a_desc->GetSourceLocation(&loc));
+}
+
+// Corrupt SourceCodeInfo doesn't cause crash:
+TEST_F(SourceLocationTest, GetSourceLocation_BogusSourceCodeInfo) {
+  SourceLocation loc;
+
+  const FileDescriptor *file_desc =
+      GOOGLE_CHECK_NOTNULL(pool_.FindFileByName("/test/test.proto"));
+
+  FileDescriptorProto proto;
+  file_desc->CopyTo(&proto);  // Note, this discards the SourceCodeInfo.
+  EXPECT_FALSE(proto.has_source_code_info());
+  SourceCodeInfo_Location *loc_msg =
+      proto.mutable_source_code_info()->add_location();
+  loc_msg->add_path(1);
+  loc_msg->add_path(2);
+  loc_msg->add_path(3);
+  loc_msg->add_span(4);
+  loc_msg->add_span(5);
+  loc_msg->add_span(6);
+
+  DescriptorPool bad2_pool(&pool_);
+  const FileDescriptor* bad2_file_desc =
+      GOOGLE_CHECK_NOTNULL(bad2_pool.BuildFile(proto));
+  const Descriptor *bad2_a_desc = bad2_file_desc->FindMessageTypeByName("A");
+  EXPECT_FALSE(bad2_a_desc->GetSourceLocation(&loc));
+}
+
+// ===================================================================
+
+const char* const kCopySourceCodeInfoToTestInput =
+  "syntax = \"proto2\";\n"
+  "message Foo {}\n";
+
+// Required since source code information is not preserved by
+// FileDescriptorTest.
+class CopySourceCodeInfoToTest : public testing::Test {
+ public:
+  CopySourceCodeInfoToTest()
+      : source_tree_("/test/test.proto", kCopySourceCodeInfoToTestInput),
+        db_(&source_tree_),
+        pool_(&db_, &collector_) {}
+
+ private:
+  AbortingErrorCollector collector_;
+  SingletonSourceTree source_tree_;
+  compiler::SourceTreeDescriptorDatabase db_;
+
+ protected:
+  DescriptorPool pool_;
+};
+
+TEST_F(CopySourceCodeInfoToTest, CopyTo_DoesNotCopySourceCodeInfo) {
+  const FileDescriptor* file_desc =
+      GOOGLE_CHECK_NOTNULL(pool_.FindFileByName("/test/test.proto"));
+  FileDescriptorProto file_desc_proto;
+  ASSERT_FALSE(file_desc_proto.has_source_code_info());
+
+  file_desc->CopyTo(&file_desc_proto);
+  EXPECT_FALSE(file_desc_proto.has_source_code_info());
+}
+
+TEST_F(CopySourceCodeInfoToTest, CopySourceCodeInfoTo) {
+  const FileDescriptor* file_desc =
+      GOOGLE_CHECK_NOTNULL(pool_.FindFileByName("/test/test.proto"));
+  FileDescriptorProto file_desc_proto;
+  ASSERT_FALSE(file_desc_proto.has_source_code_info());
+
+  file_desc->CopySourceCodeInfoTo(&file_desc_proto);
+  const SourceCodeInfo& info = file_desc_proto.source_code_info();
+  ASSERT_EQ(3, info.location_size());
+  // Get the Foo message location
+  const SourceCodeInfo_Location& foo_location = info.location(1);
+  ASSERT_EQ(2, foo_location.path_size());
+  EXPECT_EQ(FileDescriptorProto::kMessageTypeFieldNumber, foo_location.path(0));
+  EXPECT_EQ(0, foo_location.path(1));      // Foo is the first message defined
+  ASSERT_EQ(3, foo_location.span_size());  // Foo spans one line
+  EXPECT_EQ(1, foo_location.span(0));      // Foo is declared on line 1
+  EXPECT_EQ(0, foo_location.span(1));      // Foo starts at column 0
+  EXPECT_EQ(14, foo_location.span(2));     // Foo ends on column 14
+}
+
+// ===================================================================
+
 
 }  // namespace descriptor_unittest
 }  // namespace protobuf
diff --git a/src/google/protobuf/dynamic_message.cc b/src/google/protobuf/dynamic_message.cc
index c711a2da..e4bebb25 100644
--- a/src/google/protobuf/dynamic_message.cc
+++ b/src/google/protobuf/dynamic_message.cc
@@ -123,7 +123,9 @@ int FieldSpaceUsed(const FieldDescriptor* field) {
       case FD::CPPTYPE_FLOAT  : return sizeof(float   );
       case FD::CPPTYPE_BOOL   : return sizeof(bool    );
       case FD::CPPTYPE_ENUM   : return sizeof(int     );
-      case FD::CPPTYPE_MESSAGE: return sizeof(Message*);
+
+      case FD::CPPTYPE_MESSAGE:
+        return sizeof(Message*);
 
       case FD::CPPTYPE_STRING:
         switch (field->options().ctype()) {
@@ -178,7 +180,17 @@ class DynamicMessage : public Message {
     //   important (the prototype must be deleted *before* the offsets).
     scoped_array<int> offsets;
     scoped_ptr<const GeneratedMessageReflection> reflection;
-    scoped_ptr<const DynamicMessage> prototype;
+    // Don't use a scoped_ptr to hold the prototype: the destructor for
+    // DynamicMessage needs to know whether it is the prototype, and does so by
+    // looking back at this field. This would assume details about the
+    // implementation of scoped_ptr.
+    const DynamicMessage* prototype;
+
+    TypeInfo() : prototype(NULL) {}
+
+    ~TypeInfo() {
+      delete prototype;
+    }
   };
 
   DynamicMessage(const TypeInfo* type_info);
@@ -196,6 +208,14 @@ class DynamicMessage : public Message {
 
   Metadata GetMetadata() const;
 
+  // We actually allocate more memory than sizeof(*this) when this
+  // class's memory is allocated via the global operator new. Thus, we need to
+  // manually call the global operator delete. Calling the destructor is taken
+  // care of for us.
+  static void operator delete(void* ptr) {
+    ::operator delete(ptr);
+  }
+
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DynamicMessage);
 
@@ -368,11 +388,12 @@ DynamicMessage::~DynamicMessage() {
           break;
         }
       }
-    } else if ((field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) &&
-               !is_prototype()) {
-      Message* message = *reinterpret_cast<Message**>(field_ptr);
-      if (message != NULL) {
-        delete message;
+    } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+      if (!is_prototype()) {
+        Message* message = *reinterpret_cast<Message**>(field_ptr);
+        if (message != NULL) {
+          delete message;
+        }
       }
     }
   }
@@ -403,7 +424,7 @@ void DynamicMessage::CrossLinkPrototypes() {
 }
 
 Message* DynamicMessage::New() const {
-  void* new_base = reinterpret_cast<uint8*>(operator new(type_info_->size));
+  void* new_base = operator new(type_info_->size);
   memset(new_base, 0, type_info_->size);
   return new(new_base) DynamicMessage(type_info_);
 }
@@ -465,7 +486,7 @@ const Message* DynamicMessageFactory::GetPrototypeNoLock(
   const DynamicMessage::TypeInfo** target = &prototypes_->map_[type];
   if (*target != NULL) {
     // Already exists.
-    return (*target)->prototype.get();
+    return (*target)->prototype;
   }
 
   DynamicMessage::TypeInfo* type_info = new DynamicMessage::TypeInfo;
@@ -533,13 +554,13 @@ const Message* DynamicMessageFactory::GetPrototypeNoLock(
   void* base = operator new(size);
   memset(base, 0, size);
   DynamicMessage* prototype = new(base) DynamicMessage(type_info);
-  type_info->prototype.reset(prototype);
+  type_info->prototype = prototype;
 
   // Construct the reflection object.
   type_info->reflection.reset(
     new GeneratedMessageReflection(
       type_info->type,
-      type_info->prototype.get(),
+      type_info->prototype,
       type_info->offsets.get(),
       type_info->has_bits_offset,
       type_info->unknown_fields_offset,
diff --git a/src/google/protobuf/dynamic_message.h b/src/google/protobuf/dynamic_message.h
index 81dd2c63..b3d1e5d2 100644
--- a/src/google/protobuf/dynamic_message.h
+++ b/src/google/protobuf/dynamic_message.h
@@ -68,7 +68,7 @@ class DescriptorPool;    // descriptor.h
 class LIBPROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
  public:
   // Construct a DynamicMessageFactory that will search for extensions in
-  // the DescriptorPool in which the exendee is defined.
+  // the DescriptorPool in which the extendee is defined.
   DynamicMessageFactory();
 
   // Construct a DynamicMessageFactory that will search for extensions in
@@ -102,7 +102,7 @@ class LIBPROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
   // object.  The returned object remains property of the factory and will
   // be destroyed when the factory is destroyed.  Also, any objects created
   // by calling the prototype's New() method share some data with the
-  // prototype, so these must be destoyed before the DynamicMessageFactory
+  // prototype, so these must be destroyed before the DynamicMessageFactory
   // is destroyed.
   //
   // The given descriptor must outlive the returned message, and hence must
diff --git a/src/google/protobuf/dynamic_message_unittest.cc b/src/google/protobuf/dynamic_message_unittest.cc
index 41b89ab5..e4615970 100644
--- a/src/google/protobuf/dynamic_message_unittest.cc
+++ b/src/google/protobuf/dynamic_message_unittest.cc
@@ -73,11 +73,15 @@ class DynamicMessageTest : public testing::Test {
     // unittest_import.proto.
     FileDescriptorProto unittest_file;
     FileDescriptorProto unittest_import_file;
+    FileDescriptorProto unittest_import_public_file;
 
     unittest::TestAllTypes::descriptor()->file()->CopyTo(&unittest_file);
     unittest_import::ImportMessage::descriptor()->file()->CopyTo(
       &unittest_import_file);
+    unittest_import::PublicImportMessage::descriptor()->file()->CopyTo(
+      &unittest_import_public_file);
 
+    ASSERT_TRUE(pool_.BuildFile(unittest_import_public_file) != NULL);
     ASSERT_TRUE(pool_.BuildFile(unittest_import_file) != NULL);
     ASSERT_TRUE(pool_.BuildFile(unittest_file) != NULL);
 
diff --git a/src/google/protobuf/extension_set.cc b/src/google/protobuf/extension_set.cc
index 1a6f5dfc..2cbba8f5 100644
--- a/src/google/protobuf/extension_set.cc
+++ b/src/google/protobuf/extension_set.cc
@@ -71,7 +71,7 @@ void DeleteRegistry() {
 
 void InitRegistry() {
   registry_ = new ExtensionRegistry;
-  internal::OnShutdown(&DeleteRegistry);
+  OnShutdown(&DeleteRegistry);
 }
 
 // This function is only called at startup, so there is no need for thread-
@@ -180,6 +180,17 @@ bool ExtensionSet::Has(int number) const {
   return !iter->second.is_cleared;
 }
 
+int ExtensionSet::NumExtensions() const {
+  int result = 0;
+  for (map<int, Extension>::const_iterator iter = extensions_.begin();
+       iter != extensions_.end(); ++iter) {
+    if (!iter->second.is_cleared) {
+      ++result;
+    }
+  }
+  return result;
+}
+
 int ExtensionSet::ExtensionSize(int number) const {
   map<int, Extension>::const_iterator iter = extensions_.find(number);
   if (iter == extensions_.end()) return false;
@@ -293,6 +304,14 @@ PRIMITIVE_ACCESSORS(  BOOL,   bool,   Bool)
 
 #undef PRIMITIVE_ACCESSORS
 
+void* ExtensionSet::MutableRawRepeatedField(int number) {
+  // We assume that all the RepeatedField<>* pointers have the same
+  // size and alignment within the anonymous union in Extension.
+  map<int, Extension>::const_iterator iter = extensions_.find(number);
+  GOOGLE_CHECK(iter != extensions_.end()) << "no extension numbered " << number;
+  return iter->second.repeated_int32_value;
+}
+
 // -------------------------------------------------------------------
 // Enums
 
@@ -422,7 +441,11 @@ const MessageLite& ExtensionSet::GetMessage(
     return default_value;
   } else {
     GOOGLE_DCHECK_TYPE(iter->second, OPTIONAL, MESSAGE);
-    return *iter->second.message_value;
+    if (iter->second.is_lazy) {
+      return iter->second.lazymessage_value->GetMessage(default_value);
+    } else {
+      return *iter->second.message_value;
+    }
   }
 }
 
@@ -439,12 +462,19 @@ MessageLite* ExtensionSet::MutableMessage(int number, FieldType type,
     extension->type = type;
     GOOGLE_DCHECK_EQ(cpp_type(extension->type), WireFormatLite::CPPTYPE_MESSAGE);
     extension->is_repeated = false;
+    extension->is_lazy = false;
     extension->message_value = prototype.New();
+    extension->is_cleared = false;
+    return extension->message_value;
   } else {
     GOOGLE_DCHECK_TYPE(*extension, OPTIONAL, MESSAGE);
+    extension->is_cleared = false;
+    if (extension->is_lazy) {
+      return extension->lazymessage_value->MutableMessage(prototype);
+    } else {
+      return extension->message_value;
+    }
   }
-  extension->is_cleared = false;
-  return extension->message_value;
 }
 
 // Defined in extension_set_heavy.cc.
@@ -452,6 +482,56 @@ MessageLite* ExtensionSet::MutableMessage(int number, FieldType type,
 //                                           const Descriptor* message_type,
 //                                           MessageFactory* factory)
 
+void ExtensionSet::SetAllocatedMessage(int number, FieldType type,
+                                       const FieldDescriptor* descriptor,
+                                       MessageLite* message) {
+  if (message == NULL) {
+    ClearExtension(number);
+    return;
+  }
+  Extension* extension;
+  if (MaybeNewExtension(number, descriptor, &extension)) {
+    extension->type = type;
+    GOOGLE_DCHECK_EQ(cpp_type(extension->type), WireFormatLite::CPPTYPE_MESSAGE);
+    extension->is_repeated = false;
+    extension->is_lazy = false;
+    extension->message_value = message;
+  } else {
+    GOOGLE_DCHECK_TYPE(*extension, OPTIONAL, MESSAGE);
+    if (extension->is_lazy) {
+      extension->lazymessage_value->SetAllocatedMessage(message);
+    } else {
+      delete extension->message_value;
+      extension->message_value = message;
+    }
+  }
+  extension->is_cleared = false;
+}
+
+MessageLite* ExtensionSet::ReleaseMessage(int number,
+                                          const MessageLite& prototype) {
+  map<int, Extension>::iterator iter = extensions_.find(number);
+  if (iter == extensions_.end()) {
+    // Not present.  Return NULL.
+    return NULL;
+  } else {
+    GOOGLE_DCHECK_TYPE(iter->second, OPTIONAL, MESSAGE);
+    MessageLite* ret = NULL;
+    if (iter->second.is_lazy) {
+      ret = iter->second.lazymessage_value->ReleaseMessage(prototype);
+      delete iter->second.lazymessage_value;
+    } else {
+      ret = iter->second.message_value;
+    }
+    extensions_.erase(number);
+    return ret;
+  }
+}
+
+// Defined in extension_set_heavy.cc.
+// MessageLite* ExtensionSet::ReleaseMessage(const FieldDescriptor* descriptor,
+//                                           MessageFactory* factory);
+
 const MessageLite& ExtensionSet::GetRepeatedMessage(
     int number, int index) const {
   map<int, Extension>::const_iterator iter = extensions_.find(number);
@@ -484,7 +564,7 @@ MessageLite* ExtensionSet::AddMessage(int number, FieldType type,
   // RepeatedPtrField<MessageLite> does not know how to Add() since it cannot
   // allocate an abstract object, so we have to be tricky.
   MessageLite* result = extension->repeated_message_value
-      ->AddFromCleared<internal::GenericTypeHandler<MessageLite> >();
+      ->AddFromCleared<GenericTypeHandler<MessageLite> >();
   if (result == NULL) {
     result = prototype.New();
     extension->repeated_message_value->AddAllocated(result);
@@ -540,6 +620,16 @@ void ExtensionSet::RemoveLast(int number) {
   }
 }
 
+MessageLite* ExtensionSet::ReleaseLast(int number) {
+  map<int, Extension>::iterator iter = extensions_.find(number);
+  GOOGLE_CHECK(iter != extensions_.end()) << "Index out-of-bounds (field is empty).";
+
+  Extension* extension = &iter->second;
+  GOOGLE_DCHECK(extension->is_repeated);
+  GOOGLE_DCHECK(cpp_type(extension->type) == WireFormatLite::CPPTYPE_MESSAGE);
+  return extension->repeated_message_value->ReleaseLast();
+}
+
 void ExtensionSet::SwapElements(int number, int index1, int index2) {
   map<int, Extension>::iterator iter = extensions_.find(number);
   GOOGLE_CHECK(iter != extensions_.end()) << "Index out-of-bounds (field is empty).";
@@ -602,9 +692,11 @@ void ExtensionSet::MergeFrom(const ExtensionSet& other) {
       if (is_new) {
         // Extension did not already exist in set.
         extension->type = other_extension.type;
+        extension->is_packed = other_extension.is_packed;
         extension->is_repeated = true;
       } else {
         GOOGLE_DCHECK_EQ(extension->type, other_extension.type);
+        GOOGLE_DCHECK_EQ(extension->is_packed, other_extension.is_packed);
         GOOGLE_DCHECK(extension->is_repeated);
       }
 
@@ -675,12 +767,55 @@ void ExtensionSet::MergeFrom(const ExtensionSet& other) {
                       *other_extension.string_value,
                       other_extension.descriptor);
             break;
-          case WireFormatLite::CPPTYPE_MESSAGE:
-            MutableMessage(iter->first, other_extension.type,
-                           *other_extension.message_value,
-                           other_extension.descriptor)
-              ->CheckTypeAndMergeFrom(*other_extension.message_value);
+          case WireFormatLite::CPPTYPE_MESSAGE: {
+            Extension* extension;
+            bool is_new = MaybeNewExtension(iter->first,
+                                            other_extension.descriptor,
+                                            &extension);
+            if (is_new) {
+              extension->type = other_extension.type;
+              extension->is_packed = other_extension.is_packed;
+              extension->is_repeated = false;
+              if (other_extension.is_lazy) {
+                extension->is_lazy = true;
+                extension->lazymessage_value =
+                    other_extension.lazymessage_value->New();
+                extension->lazymessage_value->MergeFrom(
+                    *other_extension.lazymessage_value);
+              } else {
+                extension->is_lazy = false;
+                extension->message_value =
+                    other_extension.message_value->New();
+                extension->message_value->CheckTypeAndMergeFrom(
+                    *other_extension.message_value);
+              }
+            } else {
+              GOOGLE_DCHECK_EQ(extension->type, other_extension.type);
+              GOOGLE_DCHECK_EQ(extension->is_packed,other_extension.is_packed);
+              GOOGLE_DCHECK(!extension->is_repeated);
+              if (other_extension.is_lazy) {
+                if (extension->is_lazy) {
+                  extension->lazymessage_value->MergeFrom(
+                      *other_extension.lazymessage_value);
+                } else {
+                  extension->message_value->CheckTypeAndMergeFrom(
+                      other_extension.lazymessage_value->GetMessage(
+                          *extension->message_value));
+                }
+              } else {
+                if (extension->is_lazy) {
+                  extension->lazymessage_value->MutableMessage(
+                      *other_extension.message_value)->CheckTypeAndMergeFrom(
+                          *other_extension.message_value);
+                } else {
+                  extension->message_value->CheckTypeAndMergeFrom(
+                      *other_extension.message_value);
+                }
+              }
+            }
+            extension->is_cleared = false;
             break;
+          }
         }
       }
     }
@@ -706,7 +841,11 @@ bool ExtensionSet::IsInitialized() const {
         }
       } else {
         if (!extension.is_cleared) {
-          if (!extension.message_value->IsInitialized()) return false;
+          if (extension.is_lazy) {
+            if (!extension.lazymessage_value->IsInitialized()) return false;
+          } else {
+            if (!extension.message_value->IsInitialized()) return false;
+          }
         }
       }
     }
@@ -715,27 +854,42 @@ bool ExtensionSet::IsInitialized() const {
   return true;
 }
 
-bool ExtensionSet::ParseField(uint32 tag, io::CodedInputStream* input,
-                              ExtensionFinder* extension_finder,
-                              FieldSkipper* field_skipper) {
-  int number = WireFormatLite::GetTagFieldNumber(tag);
+bool ExtensionSet::FindExtensionInfoFromTag(
+    uint32 tag, ExtensionFinder* extension_finder,
+    int* field_number, ExtensionInfo* extension) {
+  *field_number = WireFormatLite::GetTagFieldNumber(tag);
   WireFormatLite::WireType wire_type = WireFormatLite::GetTagWireType(tag);
 
-  ExtensionInfo extension;
   bool is_unknown;
-  if (!extension_finder->Find(number, &extension)) {
+  if (!extension_finder->Find(*field_number, extension)) {
     is_unknown = true;
-  } else if (extension.is_packed) {
+  } else if (extension->is_packed) {
     is_unknown = (wire_type != WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
   } else {
     WireFormatLite::WireType expected_wire_type =
-        WireFormatLite::WireTypeForFieldType(real_type(extension.type));
+        WireFormatLite::WireTypeForFieldType(real_type(extension->type));
     is_unknown = (wire_type != expected_wire_type);
   }
+  return !is_unknown;
+}
+
+bool ExtensionSet::ParseField(uint32 tag, io::CodedInputStream* input,
+                              ExtensionFinder* extension_finder,
+                              FieldSkipper* field_skipper) {
+  int number;
+  ExtensionInfo extension;
+  if (!FindExtensionInfoFromTag(tag, extension_finder, &number, &extension)) {
+    return field_skipper->SkipField(input, tag);
+  } else {
+    return ParseFieldWithExtensionInfo(number, extension, input, field_skipper);
+  }
+}
 
-  if (is_unknown) {
-    field_skipper->SkipField(input, tag);
-  } else if (extension.is_packed) {
+bool ExtensionSet::ParseFieldWithExtensionInfo(
+    int number, const ExtensionInfo& extension,
+    io::CodedInputStream* input,
+    FieldSkipper* field_skipper) {
+  if (extension.is_packed) {
     uint32 size;
     if (!input->ReadVarint32(&size)) return false;
     io::CodedInputStream::Limit limit = input->PushLimit(size);
@@ -852,8 +1006,8 @@ bool ExtensionSet::ParseField(uint32 tag, io::CodedInputStream* input,
 
       case WireFormatLite::TYPE_BYTES:  {
         string* value = extension.is_repeated ?
-          AddString(number, WireFormatLite::TYPE_STRING, extension.descriptor) :
-          MutableString(number, WireFormatLite::TYPE_STRING,
+          AddString(number, WireFormatLite::TYPE_BYTES, extension.descriptor) :
+          MutableString(number, WireFormatLite::TYPE_BYTES,
                         extension.descriptor);
         if (!WireFormatLite::ReadBytes(input, value)) return false;
         break;
@@ -896,120 +1050,11 @@ bool ExtensionSet::ParseField(uint32 tag, io::CodedInputStream* input,
 //                               const MessageLite* containing_type,
 //                               UnknownFieldSet* unknown_fields)
 
-bool ExtensionSet::ParseMessageSet(io::CodedInputStream* input,
-                                   ExtensionFinder* extension_finder,
-                                   FieldSkipper* field_skipper) {
-  while (true) {
-    uint32 tag = input->ReadTag();
-    switch (tag) {
-      case 0:
-        return true;
-      case WireFormatLite::kMessageSetItemStartTag:
-        if (!ParseMessageSetItem(input, extension_finder, field_skipper)) {
-          return false;
-        }
-        break;
-      default:
-        if (!ParseField(tag, input, extension_finder, field_skipper)) {
-          return false;
-        }
-        break;
-    }
-  }
-}
-
-bool ExtensionSet::ParseMessageSet(io::CodedInputStream* input,
-                                   const MessageLite* containing_type) {
-  FieldSkipper skipper;
-  GeneratedExtensionFinder finder(containing_type);
-  return ParseMessageSet(input, &finder, &skipper);
-}
-
 // Defined in extension_set_heavy.cc.
 // bool ExtensionSet::ParseMessageSet(io::CodedInputStream* input,
 //                                    const MessageLite* containing_type,
 //                                    UnknownFieldSet* unknown_fields);
 
-bool ExtensionSet::ParseMessageSetItem(io::CodedInputStream* input,
-                                       ExtensionFinder* extension_finder,
-                                       FieldSkipper* field_skipper) {
-  // TODO(kenton):  It would be nice to share code between this and
-  // WireFormatLite::ParseAndMergeMessageSetItem(), but I think the
-  // differences would be hard to factor out.
-
-  // This method parses a group which should contain two fields:
-  //   required int32 type_id = 2;
-  //   required data message = 3;
-
-  // Once we see a type_id, we'll construct a fake tag for this extension
-  // which is the tag it would have had under the proto2 extensions wire
-  // format.
-  uint32 fake_tag = 0;
-
-  // If we see message data before the type_id, we'll append it to this so
-  // we can parse it later.  This will probably never happen in practice,
-  // as no MessageSet encoder I know of writes the message before the type ID.
-  // But, it's technically valid so we should allow it.
-  // TODO(kenton):  Use a Cord instead?  Do I care?
-  string message_data;
-
-  while (true) {
-    uint32 tag = input->ReadTag();
-    if (tag == 0) return false;
-
-    switch (tag) {
-      case WireFormatLite::kMessageSetTypeIdTag: {
-        uint32 type_id;
-        if (!input->ReadVarint32(&type_id)) return false;
-        fake_tag = WireFormatLite::MakeTag(type_id,
-            WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
-
-        if (!message_data.empty()) {
-          // We saw some message data before the type_id.  Have to parse it
-          // now.
-          io::CodedInputStream sub_input(
-              reinterpret_cast<const uint8*>(message_data.data()),
-              message_data.size());
-          if (!ParseField(fake_tag, &sub_input,
-                          extension_finder, field_skipper)) {
-            return false;
-          }
-          message_data.clear();
-        }
-
-        break;
-      }
-
-      case WireFormatLite::kMessageSetMessageTag: {
-        if (fake_tag == 0) {
-          // We haven't seen a type_id yet.  Append this data to message_data.
-          string temp;
-          uint32 length;
-          if (!input->ReadVarint32(&length)) return false;
-          if (!input->ReadString(&temp, length)) return false;
-          message_data.append(temp);
-        } else {
-          // Already saw type_id, so we can parse this directly.
-          if (!ParseField(fake_tag, input,
-                          extension_finder, field_skipper)) {
-            return false;
-          }
-        }
-
-        break;
-      }
-
-      case WireFormatLite::kMessageSetItemEndTag: {
-        return true;
-      }
-
-      default: {
-        if (!field_skipper->SkipField(input, tag)) return false;
-      }
-    }
-  }
-}
-
 void ExtensionSet::SerializeWithCachedSizes(
     int start_field_number, int end_field_number,
     io::CodedOutputStream* output) const {
@@ -1021,14 +1066,6 @@ void ExtensionSet::SerializeWithCachedSizes(
   }
 }
 
-void ExtensionSet::SerializeMessageSetWithCachedSizes(
-    io::CodedOutputStream* output) const {
-  map<int, Extension>::const_iterator iter;
-  for (iter = extensions_.begin(); iter != extensions_.end(); ++iter) {
-    iter->second.SerializeMessageSetItemWithCachedSizes(iter->first, output);
-  }
-}
-
 int ExtensionSet::ByteSize() const {
   int total_size = 0;
 
@@ -1040,17 +1077,6 @@ int ExtensionSet::ByteSize() const {
   return total_size;
 }
 
-int ExtensionSet::MessageSetByteSize() const {
-  int total_size = 0;
-
-  for (map<int, Extension>::const_iterator iter = extensions_.begin();
-       iter != extensions_.end(); ++iter) {
-    total_size += iter->second.MessageSetItemByteSize(iter->first);
-  }
-
-  return total_size;
-}
-
 // Defined in extension_set_heavy.cc.
 // int ExtensionSet::SpaceUsedExcludingSelf() const
 
@@ -1094,7 +1120,11 @@ void ExtensionSet::Extension::Clear() {
           string_value->clear();
           break;
         case WireFormatLite::CPPTYPE_MESSAGE:
-          message_value->Clear();
+          if (is_lazy) {
+            lazymessage_value->Clear();
+          } else {
+            message_value->Clear();
+          }
           break;
         default:
           // No need to do anything.  Get*() will return the default value
@@ -1206,40 +1236,18 @@ void ExtensionSet::Extension::SerializeFieldWithCachedSizes(
       HANDLE_TYPE(   BYTES,    Bytes,  *string_value);
       HANDLE_TYPE(    ENUM,     Enum,     enum_value);
       HANDLE_TYPE(   GROUP,    Group, *message_value);
-      HANDLE_TYPE( MESSAGE,  Message, *message_value);
 #undef HANDLE_TYPE
+      case WireFormatLite::TYPE_MESSAGE:
+        if (is_lazy) {
+          lazymessage_value->WriteMessage(number, output);
+        } else {
+          WireFormatLite::WriteMessage(number, *message_value, output);
+        }
+        break;
     }
   }
 }
 
-void ExtensionSet::Extension::SerializeMessageSetItemWithCachedSizes(
-    int number,
-    io::CodedOutputStream* output) const {
-  if (type != WireFormatLite::TYPE_MESSAGE || is_repeated) {
-    // Not a valid MessageSet extension, but serialize it the normal way.
-    SerializeFieldWithCachedSizes(number, output);
-    return;
-  }
-
-  if (is_cleared) return;
-
-  // Start group.
-  output->WriteTag(WireFormatLite::kMessageSetItemStartTag);
-
-  // Write type ID.
-  WireFormatLite::WriteUInt32(WireFormatLite::kMessageSetTypeIdNumber,
-                              number,
-                              output);
-  // Write message.
-  WireFormatLite::WriteMessageMaybeToArray(
-      WireFormatLite::kMessageSetMessageNumber,
-      *message_value,
-      output);
-
-  // End group.
-  output->WriteTag(WireFormatLite::kMessageSetItemEndTag);
-}
-
 int ExtensionSet::Extension::ByteSize(int number) const {
   int result = 0;
 
@@ -1353,8 +1361,16 @@ int ExtensionSet::Extension::ByteSize(int number) const {
       HANDLE_TYPE(   BYTES,    Bytes,  *string_value);
       HANDLE_TYPE(    ENUM,     Enum,     enum_value);
       HANDLE_TYPE(   GROUP,    Group, *message_value);
-      HANDLE_TYPE( MESSAGE,  Message, *message_value);
 #undef HANDLE_TYPE
+      case WireFormatLite::TYPE_MESSAGE: {
+        if (is_lazy) {
+          int size = lazymessage_value->ByteSize();
+          result += io::CodedOutputStream::VarintSize32(size) + size;
+        } else {
+          result += WireFormatLite::MessageSize(*message_value);
+        }
+        break;
+      }
 
       // Stuff with fixed size.
 #define HANDLE_TYPE(UPPERCASE, CAMELCASE)                                 \
@@ -1375,29 +1391,6 @@ int ExtensionSet::Extension::ByteSize(int number) const {
   return result;
 }
 
-int ExtensionSet::Extension::MessageSetItemByteSize(int number) const {
-  if (type != WireFormatLite::TYPE_MESSAGE || is_repeated) {
-    // Not a valid MessageSet extension, but compute the byte size for it the
-    // normal way.
-    return ByteSize(number);
-  }
-
-  if (is_cleared) return 0;
-
-  int our_size = WireFormatLite::kMessageSetItemTagsSize;
-
-  // type_id
-  our_size += io::CodedOutputStream::VarintSize32(number);
-
-  // message
-  int message_size = message_value->ByteSize();
-
-  our_size += io::CodedOutputStream::VarintSize32(message_size);
-  our_size += message_size;
-
-  return our_size;
-}
-
 int ExtensionSet::Extension::GetSize() const {
   GOOGLE_DCHECK(is_repeated);
   switch (cpp_type(type)) {
@@ -1448,7 +1441,11 @@ void ExtensionSet::Extension::Free() {
         delete string_value;
         break;
       case WireFormatLite::CPPTYPE_MESSAGE:
-        delete message_value;
+        if (is_lazy) {
+          delete lazymessage_value;
+        } else {
+          delete message_value;
+        }
         break;
       default:
         break;
diff --git a/src/google/protobuf/extension_set.h b/src/google/protobuf/extension_set.h
index ac1ada02..03af7eaf 100644
--- a/src/google/protobuf/extension_set.h
+++ b/src/google/protobuf/extension_set.h
@@ -89,8 +89,8 @@ typedef bool EnumValidityFuncWithArg(const void* arg, int number);
 // Information about a registered extension.
 struct ExtensionInfo {
   inline ExtensionInfo() {}
-  inline ExtensionInfo(FieldType type, bool is_repeated, bool is_packed)
-      : type(type), is_repeated(is_repeated), is_packed(is_packed),
+  inline ExtensionInfo(FieldType type_param, bool isrepeated, bool ispacked)
+      : type(type_param), is_repeated(isrepeated), is_packed(ispacked),
         descriptor(NULL) {}
 
   FieldType type;
@@ -214,6 +214,7 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
 
   bool Has(int number) const;
   int ExtensionSize(int number) const;   // Size of a repeated extension.
+  int NumExtensions() const;  // The number of extensions
   FieldType ExtensionType(int number) const;
   void ClearExtension(int number);
 
@@ -251,10 +252,21 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
                               const MessageLite& prototype, desc);
   MessageLite* MutableMessage(const FieldDescriptor* decsriptor,
                               MessageFactory* factory);
+  // Adds the given message to the ExtensionSet, taking ownership of the
+  // message object. Existing message with the same number will be deleted.
+  // If "message" is NULL, this is equivalent to "ClearExtension(number)".
+  void SetAllocatedMessage(int number, FieldType type,
+                           const FieldDescriptor* descriptor,
+                           MessageLite* message);
+  MessageLite* ReleaseMessage(int number, const MessageLite& prototype);
+  MessageLite* ReleaseMessage(const FieldDescriptor* descriptor,
+                              MessageFactory* factory);
 #undef desc
 
   // repeated fields -------------------------------------------------
 
+  void* MutableRawRepeatedField(int number);
+
   int32  GetRepeatedInt32 (int number, int index) const;
   int64  GetRepeatedInt64 (int number, int index) const;
   uint32 GetRepeatedUInt32(int number, int index) const;
@@ -296,6 +308,7 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
 #undef desc
 
   void RemoveLast(int number);
+  MessageLite* ReleaseLast(int number);
   void SwapElements(int number, int index1, int index2);
 
   // -----------------------------------------------------------------
@@ -312,18 +325,18 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
   void Swap(ExtensionSet* other);
   bool IsInitialized() const;
 
-  // Parses a single extension from the input.  The input should start out
-  // positioned immediately after the tag.  |containing_type| is the default
-  // instance for the containing message; it is used only to look up the
-  // extension by number.  See RegisterExtension(), above.  Unlike the other
-  // methods of ExtensionSet, this only works for generated message types --
-  // it looks up extensions registered using RegisterExtension().
+  // Parses a single extension from the input. The input should start out
+  // positioned immediately after the tag.
   bool ParseField(uint32 tag, io::CodedInputStream* input,
                   ExtensionFinder* extension_finder,
                   FieldSkipper* field_skipper);
 
   // Specific versions for lite or full messages (constructs the appropriate
-  // FieldSkipper automatically).
+  // FieldSkipper automatically).  |containing_type| is the default
+  // instance for the containing message; it is used only to look up the
+  // extension by number.  See RegisterExtension(), above.  Unlike the other
+  // methods of ExtensionSet, this only works for generated message types --
+  // it looks up extensions registered using RegisterExtension().
   bool ParseField(uint32 tag, io::CodedInputStream* input,
                   const MessageLite* containing_type);
   bool ParseField(uint32 tag, io::CodedInputStream* input,
@@ -382,18 +395,49 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
 
  private:
 
+  // Interface of a lazily parsed singular message extension.
+  class LIBPROTOBUF_EXPORT LazyMessageExtension {
+   public:
+    LazyMessageExtension() {}
+    virtual ~LazyMessageExtension() {}
+
+    virtual LazyMessageExtension* New() const = 0;
+    virtual const MessageLite& GetMessage(
+        const MessageLite& prototype) const = 0;
+    virtual MessageLite* MutableMessage(const MessageLite& prototype) = 0;
+    virtual void SetAllocatedMessage(MessageLite *message) = 0;
+    virtual MessageLite* ReleaseMessage(const MessageLite& prototype) = 0;
+
+    virtual bool IsInitialized() const = 0;
+    virtual int ByteSize() const = 0;
+    virtual int SpaceUsed() const = 0;
+
+    virtual void MergeFrom(const LazyMessageExtension& other) = 0;
+    virtual void Clear() = 0;
+
+    virtual bool ReadMessage(const MessageLite& prototype,
+                             io::CodedInputStream* input) = 0;
+    virtual void WriteMessage(int number,
+                              io::CodedOutputStream* output) const = 0;
+    virtual uint8* WriteMessageToArray(int number, uint8* target) const = 0;
+   private:
+    GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(LazyMessageExtension);
+  };
   struct Extension {
+    // The order of these fields packs Extension into 24 bytes when using 8
+    // byte alignment. Consider this when adding or removing fields here.
     union {
-      int32        int32_value;
-      int64        int64_value;
-      uint32       uint32_value;
-      uint64       uint64_value;
-      float        float_value;
-      double       double_value;
-      bool         bool_value;
-      int          enum_value;
-      string*      string_value;
-      MessageLite* message_value;
+      int32                 int32_value;
+      int64                 int64_value;
+      uint32                uint32_value;
+      uint64                uint64_value;
+      float                 float_value;
+      double                double_value;
+      bool                  bool_value;
+      int                   enum_value;
+      string*               string_value;
+      MessageLite*          message_value;
+      LazyMessageExtension* lazymessage_value;
 
       RepeatedField   <int32      >* repeated_int32_value;
       RepeatedField   <int64      >* repeated_int64_value;
@@ -416,21 +460,28 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
     // removing it from the map, we just set is_cleared = true.  This has no
     // meaning for repeated types; for those, the size of the RepeatedField
     // simply becomes zero when cleared.
-    bool is_cleared;
+    bool is_cleared : 4;
+
+    // For singular message types, indicates whether lazy parsing is enabled
+    // for this extension. This field is only valid when type == TYPE_MESSAGE
+    // and !is_repeated because we only support lazy parsing for singular
+    // message types currently. If is_lazy = true, the extension is stored in
+    // lazymessage_value. Otherwise, the extension will be message_value.
+    bool is_lazy : 4;
 
     // For repeated types, this indicates if the [packed=true] option is set.
     bool is_packed;
 
-    // The descriptor for this extension, if one exists and is known.  May be
-    // NULL.  Must not be NULL if the descriptor for the extension does not
-    // live in the same pool as the descriptor for the containing type.
-    const FieldDescriptor* descriptor;
-
     // For packed fields, the size of the packed data is recorded here when
     // ByteSize() is called then used during serialization.
     // TODO(kenton):  Use atomic<int> when C++ supports it.
     mutable int cached_size;
 
+    // The descriptor for this extension, if one exists and is known.  May be
+    // NULL.  Must not be NULL if the descriptor for the extension does not
+    // live in the same pool as the descriptor for the containing type.
+    const FieldDescriptor* descriptor;
+
     // Some helper methods for operations on a single Extension.
     void SerializeFieldWithCachedSizes(
         int number,
@@ -453,6 +504,25 @@ class LIBPROTOBUF_EXPORT ExtensionSet {
   };
 
 
+  // Returns true and fills field_number and extension if extension is found.
+  bool FindExtensionInfoFromTag(uint32 tag, ExtensionFinder* extension_finder,
+                                int* field_number, ExtensionInfo* extension);
+
+  // Parses a single extension from the input. The input should start out
+  // positioned immediately after the wire tag. This method is called in
+  // ParseField() after field number is extracted from the wire tag and
+  // ExtensionInfo is found by the field number.
+  bool ParseFieldWithExtensionInfo(int field_number,
+                                   const ExtensionInfo& extension,
+                                   io::CodedInputStream* input,
+                                   FieldSkipper* field_skipper);
+
+  // Like ParseField(), but this method may parse singular message extensions
+  // lazily depending on the value of FLAGS_eagerly_parse_message_sets.
+  bool ParseFieldMaybeLazily(uint32 tag, io::CodedInputStream* input,
+                             ExtensionFinder* extension_finder,
+                             FieldSkipper* field_skipper);
+
   // Gets the extension with the given number, creating it if it does not
   // already exist.  Returns true if the extension did not already exist.
   bool MaybeNewExtension(int number, const FieldDescriptor* descriptor,
@@ -720,6 +790,15 @@ class MessageTypeTraits {
     return static_cast<Type*>(
       set->MutableMessage(number, field_type, Type::default_instance(), NULL));
   }
+  static inline void SetAllocated(int number, FieldType field_type,
+                                  MutableType message, ExtensionSet* set) {
+    set->SetAllocatedMessage(number, field_type, NULL, message);
+  }
+  static inline MutableType Release(int number, FieldType field_type,
+                                    ExtensionSet* set) {
+    return static_cast<Type*>(set->ReleaseMessage(
+        number, Type::default_instance()));
+  }
 };
 
 template <typename Type>
@@ -787,113 +866,137 @@ class ExtensionIdentifier {
 // causes problems if the class has a nested message or enum type with that
 // name and "_TypeTraits" is technically reserved for the C++ library since
 // it starts with an underscore followed by a capital letter.
+//
+// For similar reason, we use "_field_type" and "_is_packed" as parameter names
+// below, so that "field_type" and "is_packed" can be used as field names.
 #define GOOGLE_PROTOBUF_EXTENSION_ACCESSORS(CLASSNAME)                        \
   /* Has, Size, Clear */                                                      \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline bool HasExtension(                                                   \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) const {     \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) const {   \
     return _extensions_.Has(id.number());                                     \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline void ClearExtension(                                                 \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) {           \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) {         \
     _extensions_.ClearExtension(id.number());                                 \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline int ExtensionSize(                                                   \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) const {     \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) const {   \
     return _extensions_.ExtensionSize(id.number());                           \
   }                                                                           \
                                                                               \
   /* Singular accessors */                                                    \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline typename _proto_TypeTraits::ConstType GetExtension(                  \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) const {     \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) const {   \
     return _proto_TypeTraits::Get(id.number(), _extensions_,                  \
                                   id.default_value());                        \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline typename _proto_TypeTraits::MutableType MutableExtension(            \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) {           \
-    return _proto_TypeTraits::Mutable(id.number(), field_type, &_extensions_);\
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) {         \
+    return _proto_TypeTraits::Mutable(id.number(), _field_type,               \
+                                      &_extensions_);                         \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline void SetExtension(                                                   \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id,             \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
       typename _proto_TypeTraits::ConstType value) {                          \
-    _proto_TypeTraits::Set(id.number(), field_type, value, &_extensions_);    \
+    _proto_TypeTraits::Set(id.number(), _field_type, value, &_extensions_);   \
+  }                                                                           \
+                                                                              \
+  template <typename _proto_TypeTraits,                                       \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
+  inline void SetAllocatedExtension(                                          \
+      const ::google::protobuf::internal::ExtensionIdentifier<                          \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
+      typename _proto_TypeTraits::MutableType value) {                        \
+    _proto_TypeTraits::SetAllocated(id.number(), _field_type,                 \
+                                    value, &_extensions_);                    \
+  }                                                                           \
+  template <typename _proto_TypeTraits,                                       \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
+  inline typename _proto_TypeTraits::MutableType ReleaseExtension(            \
+      const ::google::protobuf::internal::ExtensionIdentifier<                          \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) {         \
+    return _proto_TypeTraits::Release(id.number(), _field_type,               \
+                                      &_extensions_);                         \
   }                                                                           \
                                                                               \
   /* Repeated accessors */                                                    \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline typename _proto_TypeTraits::ConstType GetExtension(                  \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id,             \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
       int index) const {                                                      \
     return _proto_TypeTraits::Get(id.number(), _extensions_, index);          \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline typename _proto_TypeTraits::MutableType MutableExtension(            \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id,             \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
       int index) {                                                            \
     return _proto_TypeTraits::Mutable(id.number(), index, &_extensions_);     \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline void SetExtension(                                                   \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id,             \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
       int index, typename _proto_TypeTraits::ConstType value) {               \
     _proto_TypeTraits::Set(id.number(), index, value, &_extensions_);         \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline typename _proto_TypeTraits::MutableType AddExtension(                \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id) {           \
-    return _proto_TypeTraits::Add(id.number(), field_type, &_extensions_);    \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id) {         \
+    return _proto_TypeTraits::Add(id.number(), _field_type, &_extensions_);   \
   }                                                                           \
                                                                               \
   template <typename _proto_TypeTraits,                                       \
-            ::google::protobuf::internal::FieldType field_type,                         \
-            bool is_packed>                                                   \
+            ::google::protobuf::internal::FieldType _field_type,                        \
+            bool _is_packed>                                                  \
   inline void AddExtension(                                                   \
       const ::google::protobuf::internal::ExtensionIdentifier<                          \
-        CLASSNAME, _proto_TypeTraits, field_type, is_packed>& id,             \
+        CLASSNAME, _proto_TypeTraits, _field_type, _is_packed>& id,           \
       typename _proto_TypeTraits::ConstType value) {                          \
-    _proto_TypeTraits::Add(id.number(), field_type, is_packed,                \
+    _proto_TypeTraits::Add(id.number(), _field_type, _is_packed,              \
                            value, &_extensions_);                             \
   }
 
diff --git a/src/google/protobuf/extension_set_heavy.cc b/src/google/protobuf/extension_set_heavy.cc
index 2721f15d..483d7055 100644
--- a/src/google/protobuf/extension_set_heavy.cc
+++ b/src/google/protobuf/extension_set_heavy.cc
@@ -35,17 +35,20 @@
 // Contains methods defined in extension_set.h which cannot be part of the
 // lite library because they use descriptors or reflection.
 
-#include <google/protobuf/extension_set.h>
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/extension_set.h>
 #include <google/protobuf/message.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/wire_format.h>
 #include <google/protobuf/wire_format_lite_inl.h>
 
 namespace google {
+
 namespace protobuf {
 namespace internal {
 
+
 // Implementation of ExtensionFinder which finds extensions in a given
 // DescriptorPool, using the given MessageFactory to construct sub-objects.
 // This class is implemented in extension_set_heavy.cc.
@@ -103,6 +106,11 @@ inline FieldDescriptor::CppType cpp_type(FieldType type) {
       static_cast<FieldDescriptor::Type>(type));
 }
 
+inline WireFormatLite::FieldType field_type(FieldType type) {
+  GOOGLE_DCHECK(type > 0 && type <= WireFormatLite::MAX_FIELD_TYPE);
+  return static_cast<WireFormatLite::FieldType>(type);
+}
+
 #define GOOGLE_DCHECK_TYPE(EXTENSION, LABEL, CPPTYPE)                            \
   GOOGLE_DCHECK_EQ((EXTENSION).is_repeated ? FieldDescriptor::LABEL_REPEATED     \
                                   : FieldDescriptor::LABEL_OPTIONAL,      \
@@ -118,7 +126,12 @@ const MessageLite& ExtensionSet::GetMessage(int number,
     return *factory->GetPrototype(message_type);
   } else {
     GOOGLE_DCHECK_TYPE(iter->second, OPTIONAL, MESSAGE);
-    return *iter->second.message_value;
+    if (iter->second.is_lazy) {
+      return iter->second.lazymessage_value->GetMessage(
+          *factory->GetPrototype(message_type));
+    } else {
+      return *iter->second.message_value;
+    }
   }
 }
 
@@ -132,13 +145,41 @@ MessageLite* ExtensionSet::MutableMessage(const FieldDescriptor* descriptor,
     extension->is_packed = false;
     const MessageLite* prototype =
         factory->GetPrototype(descriptor->message_type());
-    GOOGLE_CHECK(prototype != NULL);
+    extension->is_lazy = false;
     extension->message_value = prototype->New();
+    extension->is_cleared = false;
+    return extension->message_value;
   } else {
     GOOGLE_DCHECK_TYPE(*extension, OPTIONAL, MESSAGE);
+    extension->is_cleared = false;
+    if (extension->is_lazy) {
+      return extension->lazymessage_value->MutableMessage(
+          *factory->GetPrototype(descriptor->message_type()));
+    } else {
+      return extension->message_value;
+    }
+  }
+}
+
+MessageLite* ExtensionSet::ReleaseMessage(const FieldDescriptor* descriptor,
+                                          MessageFactory* factory) {
+  map<int, Extension>::iterator iter = extensions_.find(descriptor->number());
+  if (iter == extensions_.end()) {
+    // Not present.  Return NULL.
+    return NULL;
+  } else {
+    GOOGLE_DCHECK_TYPE(iter->second, OPTIONAL, MESSAGE);
+    MessageLite* ret = NULL;
+    if (iter->second.is_lazy) {
+      ret = iter->second.lazymessage_value->ReleaseMessage(
+        *factory->GetPrototype(descriptor->message_type()));
+      delete iter->second.lazymessage_value;
+    } else {
+      ret = iter->second.message_value;
+    }
+    extensions_.erase(descriptor->number());
+    return ret;
   }
-  extension->is_cleared = false;
-  return extension->message_value;
 }
 
 MessageLite* ExtensionSet::AddMessage(const FieldDescriptor* descriptor,
@@ -157,7 +198,7 @@ MessageLite* ExtensionSet::AddMessage(const FieldDescriptor* descriptor,
   // RepeatedPtrField<Message> does not know how to Add() since it cannot
   // allocate an abstract object, so we have to be tricky.
   MessageLite* result = extension->repeated_message_value
-      ->AddFromCleared<internal::GenericTypeHandler<MessageLite> >();
+      ->AddFromCleared<GenericTypeHandler<MessageLite> >();
   if (result == NULL) {
     const MessageLite* prototype;
     if (extension->repeated_message_value->size() == 0) {
@@ -286,7 +327,11 @@ int ExtensionSet::Extension::SpaceUsedExcludingSelf() const {
                       StringSpaceUsedExcludingSelf(*string_value);
         break;
       case FieldDescriptor::CPPTYPE_MESSAGE:
-        total_size += down_cast<Message*>(message_value)->SpaceUsed();
+        if (is_lazy) {
+          total_size += lazymessage_value->SpaceUsed();
+        } else {
+          total_size += down_cast<Message*>(message_value)->SpaceUsed();
+        }
         break;
       default:
         // No extra storage costs for primitive types.
@@ -419,8 +464,15 @@ uint8* ExtensionSet::Extension::SerializeFieldWithCachedSizesToArray(
       HANDLE_TYPE(   BYTES,    Bytes,  *string_value);
       HANDLE_TYPE(    ENUM,     Enum,     enum_value);
       HANDLE_TYPE(   GROUP,    Group, *message_value);
-      HANDLE_TYPE( MESSAGE,  Message, *message_value);
 #undef HANDLE_TYPE
+      case FieldDescriptor::TYPE_MESSAGE:
+        if (is_lazy) {
+          target = lazymessage_value->WriteMessageToArray(number, target);
+        } else {
+          target = WireFormatLite::WriteMessageToArray(
+              number, *message_value, target);
+        }
+        break;
     }
   }
   return target;
@@ -444,14 +496,216 @@ uint8* ExtensionSet::Extension::SerializeMessageSetItemWithCachedSizesToArray(
   target = WireFormatLite::WriteUInt32ToArray(
       WireFormatLite::kMessageSetTypeIdNumber, number, target);
   // Write message.
-  target = WireFormatLite::WriteMessageToArray(
-      WireFormatLite::kMessageSetMessageNumber, *message_value, target);
+  if (is_lazy) {
+    target = lazymessage_value->WriteMessageToArray(
+        WireFormatLite::kMessageSetMessageNumber, target);
+  } else {
+    target = WireFormatLite::WriteMessageToArray(
+        WireFormatLite::kMessageSetMessageNumber, *message_value, target);
+  }
   // End group.
   target = io::CodedOutputStream::WriteTagToArray(
       WireFormatLite::kMessageSetItemEndTag, target);
   return target;
 }
 
+
+bool ExtensionSet::ParseFieldMaybeLazily(
+    uint32 tag, io::CodedInputStream* input,
+    ExtensionFinder* extension_finder,
+    FieldSkipper* field_skipper) {
+  return ParseField(tag, input, extension_finder, field_skipper);
+}
+
+bool ExtensionSet::ParseMessageSet(io::CodedInputStream* input,
+                                   ExtensionFinder* extension_finder,
+                                   FieldSkipper* field_skipper) {
+  while (true) {
+    uint32 tag = input->ReadTag();
+    switch (tag) {
+      case 0:
+        return true;
+      case WireFormatLite::kMessageSetItemStartTag:
+        if (!ParseMessageSetItem(input, extension_finder, field_skipper)) {
+          return false;
+        }
+        break;
+      default:
+        if (!ParseField(tag, input, extension_finder, field_skipper)) {
+          return false;
+        }
+        break;
+    }
+  }
+}
+
+bool ExtensionSet::ParseMessageSet(io::CodedInputStream* input,
+                                   const MessageLite* containing_type) {
+  FieldSkipper skipper;
+  GeneratedExtensionFinder finder(containing_type);
+  return ParseMessageSet(input, &finder, &skipper);
+}
+
+bool ExtensionSet::ParseMessageSetItem(io::CodedInputStream* input,
+                                       ExtensionFinder* extension_finder,
+                                       FieldSkipper* field_skipper) {
+  // TODO(kenton):  It would be nice to share code between this and
+  // WireFormatLite::ParseAndMergeMessageSetItem(), but I think the
+  // differences would be hard to factor out.
+
+  // This method parses a group which should contain two fields:
+  //   required int32 type_id = 2;
+  //   required data message = 3;
+
+  // Once we see a type_id, we'll construct a fake tag for this extension
+  // which is the tag it would have had under the proto2 extensions wire
+  // format.
+  uint32 fake_tag = 0;
+
+  // If we see message data before the type_id, we'll append it to this so
+  // we can parse it later.
+  string message_data;
+
+  while (true) {
+    uint32 tag = input->ReadTag();
+    if (tag == 0) return false;
+
+    switch (tag) {
+      case WireFormatLite::kMessageSetTypeIdTag: {
+        uint32 type_id;
+        if (!input->ReadVarint32(&type_id)) return false;
+        fake_tag = WireFormatLite::MakeTag(type_id,
+            WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+
+        if (!message_data.empty()) {
+          // We saw some message data before the type_id.  Have to parse it
+          // now.
+          io::CodedInputStream sub_input(
+              reinterpret_cast<const uint8*>(message_data.data()),
+              message_data.size());
+          if (!ParseFieldMaybeLazily(fake_tag, &sub_input,
+                                     extension_finder, field_skipper)) {
+            return false;
+          }
+          message_data.clear();
+        }
+
+        break;
+      }
+
+      case WireFormatLite::kMessageSetMessageTag: {
+        if (fake_tag == 0) {
+          // We haven't seen a type_id yet.  Append this data to message_data.
+          string temp;
+          uint32 length;
+          if (!input->ReadVarint32(&length)) return false;
+          if (!input->ReadString(&temp, length)) return false;
+          io::StringOutputStream output_stream(&message_data);
+          io::CodedOutputStream coded_output(&output_stream);
+          coded_output.WriteVarint32(length);
+          coded_output.WriteString(temp);
+        } else {
+          // Already saw type_id, so we can parse this directly.
+          if (!ParseFieldMaybeLazily(fake_tag, input,
+                                     extension_finder, field_skipper)) {
+            return false;
+          }
+        }
+
+        break;
+      }
+
+      case WireFormatLite::kMessageSetItemEndTag: {
+        return true;
+      }
+
+      default: {
+        if (!field_skipper->SkipField(input, tag)) return false;
+      }
+    }
+  }
+}
+
+void ExtensionSet::Extension::SerializeMessageSetItemWithCachedSizes(
+    int number,
+    io::CodedOutputStream* output) const {
+  if (type != WireFormatLite::TYPE_MESSAGE || is_repeated) {
+    // Not a valid MessageSet extension, but serialize it the normal way.
+    SerializeFieldWithCachedSizes(number, output);
+    return;
+  }
+
+  if (is_cleared) return;
+
+  // Start group.
+  output->WriteTag(WireFormatLite::kMessageSetItemStartTag);
+
+  // Write type ID.
+  WireFormatLite::WriteUInt32(WireFormatLite::kMessageSetTypeIdNumber,
+                              number,
+                              output);
+  // Write message.
+  if (is_lazy) {
+    lazymessage_value->WriteMessage(
+        WireFormatLite::kMessageSetMessageNumber, output);
+  } else {
+    WireFormatLite::WriteMessageMaybeToArray(
+        WireFormatLite::kMessageSetMessageNumber,
+        *message_value,
+        output);
+  }
+
+  // End group.
+  output->WriteTag(WireFormatLite::kMessageSetItemEndTag);
+}
+
+int ExtensionSet::Extension::MessageSetItemByteSize(int number) const {
+  if (type != WireFormatLite::TYPE_MESSAGE || is_repeated) {
+    // Not a valid MessageSet extension, but compute the byte size for it the
+    // normal way.
+    return ByteSize(number);
+  }
+
+  if (is_cleared) return 0;
+
+  int our_size = WireFormatLite::kMessageSetItemTagsSize;
+
+  // type_id
+  our_size += io::CodedOutputStream::VarintSize32(number);
+
+  // message
+  int message_size = 0;
+  if (is_lazy) {
+    message_size = lazymessage_value->ByteSize();
+  } else {
+    message_size = message_value->ByteSize();
+  }
+
+  our_size += io::CodedOutputStream::VarintSize32(message_size);
+  our_size += message_size;
+
+  return our_size;
+}
+
+void ExtensionSet::SerializeMessageSetWithCachedSizes(
+    io::CodedOutputStream* output) const {
+  map<int, Extension>::const_iterator iter;
+  for (iter = extensions_.begin(); iter != extensions_.end(); ++iter) {
+    iter->second.SerializeMessageSetItemWithCachedSizes(iter->first, output);
+  }
+}
+
+int ExtensionSet::MessageSetByteSize() const {
+  int total_size = 0;
+
+  for (map<int, Extension>::const_iterator iter = extensions_.begin();
+       iter != extensions_.end(); ++iter) {
+    total_size += iter->second.MessageSetItemByteSize(iter->first);
+  }
+
+  return total_size;
+}
+
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/extension_set_unittest.cc b/src/google/protobuf/extension_set_unittest.cc
index 000f846c..1e7c5a5e 100644
--- a/src/google/protobuf/extension_set_unittest.cc
+++ b/src/google/protobuf/extension_set_unittest.cc
@@ -34,6 +34,7 @@
 
 #include <google/protobuf/extension_set.h>
 #include <google/protobuf/unittest.pb.h>
+#include <google/protobuf/unittest_mset.pb.h>
 #include <google/protobuf/test_util.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
@@ -46,9 +47,10 @@
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
+
 namespace protobuf {
 namespace internal {
 namespace {
@@ -140,23 +142,98 @@ TEST(ExtensionSetTest, ClearOneField) {
   TestUtil::ExpectAllExtensionsSet(message);
 }
 
+TEST(ExtensionSetTest, SetAllocatedExtensin) {
+  unittest::TestAllExtensions message;
+  EXPECT_FALSE(message.HasExtension(
+      unittest::optional_foreign_message_extension));
+  // Add a extension using SetAllocatedExtension
+  unittest::ForeignMessage* foreign_message = new unittest::ForeignMessage();
+  message.SetAllocatedExtension(unittest::optional_foreign_message_extension,
+                                foreign_message);
+  EXPECT_TRUE(message.HasExtension(
+      unittest::optional_foreign_message_extension));
+  EXPECT_EQ(foreign_message,
+            message.MutableExtension(
+                unittest::optional_foreign_message_extension));
+  EXPECT_EQ(foreign_message,
+            &message.GetExtension(
+                unittest::optional_foreign_message_extension));
+
+  // SetAllocatedExtension should delete the previously existing extension.
+  // (We reply on unittest to check memory leaks for this case)
+  message.SetAllocatedExtension(unittest::optional_foreign_message_extension,
+                                 new unittest::ForeignMessage());
+
+  // SetAllocatedExtension with a NULL parameter is equivalent to ClearExtenion.
+  message.SetAllocatedExtension(unittest::optional_foreign_message_extension,
+                                 NULL);
+  EXPECT_FALSE(message.HasExtension(
+      unittest::optional_foreign_message_extension));
+}
+
+TEST(ExtensionSetTest, ReleaseExtension) {
+  unittest::TestMessageSet message;
+  EXPECT_FALSE(message.HasExtension(
+      unittest::TestMessageSetExtension1::message_set_extension));
+  // Add a extension using SetAllocatedExtension
+  unittest::TestMessageSetExtension1* extension =
+      new unittest::TestMessageSetExtension1();
+  message.SetAllocatedExtension(
+      unittest::TestMessageSetExtension1::message_set_extension,
+      extension);
+  EXPECT_TRUE(message.HasExtension(
+      unittest::TestMessageSetExtension1::message_set_extension));
+  // Release the extension using ReleaseExtension
+  unittest::TestMessageSetExtension1* released_extension =
+      message.ReleaseExtension(
+        unittest::TestMessageSetExtension1::message_set_extension);
+  EXPECT_EQ(extension, released_extension);
+  EXPECT_FALSE(message.HasExtension(
+      unittest::TestMessageSetExtension1::message_set_extension));
+  // ReleaseExtension will return the underlying object even after
+  // ClearExtension is called.
+  message.SetAllocatedExtension(
+      unittest::TestMessageSetExtension1::message_set_extension,
+      extension);
+  message.ClearExtension(
+      unittest::TestMessageSetExtension1::message_set_extension);
+  released_extension = message.ReleaseExtension(
+        unittest::TestMessageSetExtension1::message_set_extension);
+  EXPECT_TRUE(released_extension != NULL);
+  delete released_extension;
+}
+
+
 TEST(ExtensionSetTest, CopyFrom) {
   unittest::TestAllExtensions message1, message2;
-  string data;
 
   TestUtil::SetAllExtensions(&message1);
   message2.CopyFrom(message1);
   TestUtil::ExpectAllExtensionsSet(message2);
+  message2.CopyFrom(message1);  // exercise copy when fields already exist
+  TestUtil::ExpectAllExtensionsSet(message2);
+}
+
+TEST(ExtensioSetTest, CopyFromPacked) {
+  unittest::TestPackedExtensions message1, message2;
+
+  TestUtil::SetPackedExtensions(&message1);
+  message2.CopyFrom(message1);
+  TestUtil::ExpectPackedExtensionsSet(message2);
+  message2.CopyFrom(message1);  // exercise copy when fields already exist
+  TestUtil::ExpectPackedExtensionsSet(message2);
 }
 
 TEST(ExtensionSetTest, CopyFromUpcasted) {
   unittest::TestAllExtensions message1, message2;
-  string data;
   const Message& upcasted_message = message1;
 
   TestUtil::SetAllExtensions(&message1);
   message2.CopyFrom(upcasted_message);
   TestUtil::ExpectAllExtensionsSet(message2);
+  // exercise copy when fields already exist
+  message2.CopyFrom(upcasted_message);
+  TestUtil::ExpectAllExtensionsSet(message2);
 }
 
 TEST(ExtensionSetTest, SwapWithEmpty) {
@@ -418,7 +495,8 @@ TEST(ExtensionSetTest, SpaceUsedExcludingSelf) {
     for (int i = 0; i < 16; ++i) {                                             \
       message.AddExtension(unittest::repeated_##type##_extension, value);      \
     }                                                                          \
-    int expected_size = sizeof(cpptype) * 16 + empty_repeated_field_size;      \
+    int expected_size = sizeof(cpptype) * (16 -                                \
+        kMinRepeatedFieldAllocationSize) + empty_repeated_field_size;          \
     EXPECT_EQ(expected_size, message.SpaceUsed()) << #type;                    \
   } while (0)
 
@@ -450,7 +528,8 @@ TEST(ExtensionSetTest, SpaceUsedExcludingSelf) {
     for (int i = 0; i < 16; ++i) {
       message.AddExtension(unittest::repeated_string_extension, value);
     }
-    min_expected_size += (sizeof(value) + value.size()) * 16;
+    min_expected_size += (sizeof(value) + value.size()) *
+        (16 - kMinRepeatedFieldAllocationSize);
     EXPECT_LE(min_expected_size, message.SpaceUsed());
   }
   // Repeated messages
@@ -465,7 +544,8 @@ TEST(ExtensionSetTest, SpaceUsedExcludingSelf) {
       message.AddExtension(unittest::repeated_foreign_message_extension)->
           CopyFrom(prototype);
     }
-    min_expected_size += 16 * prototype.SpaceUsed();
+    min_expected_size +=
+        (16 - kMinRepeatedFieldAllocationSize) * prototype.SpaceUsed();
     EXPECT_LE(min_expected_size, message.SpaceUsed());
   }
 }
diff --git a/src/google/protobuf/generated_enum_reflection.h b/src/google/protobuf/generated_enum_reflection.h
new file mode 100644
index 00000000..a09a540b
--- /dev/null
+++ b/src/google/protobuf/generated_enum_reflection.h
@@ -0,0 +1,85 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: jasonh@google.com (Jason Hsueh)
+//
+// This header is logically internal, but is made public because it is used
+// from protocol-compiler-generated code, which may reside in other components.
+// It provides reflection support for generated enums, and is included in
+// generated .pb.h files and should have minimal dependencies. The methods are
+// implemented in generated_message_reflection.cc.
+
+#ifndef GOOGLE_PROTOBUF_GENERATED_ENUM_REFLECTION_H__
+#define GOOGLE_PROTOBUF_GENERATED_ENUM_REFLECTION_H__
+
+#include <string>
+
+namespace google {
+namespace protobuf {
+  class EnumDescriptor;
+}  // namespace protobuf
+
+namespace protobuf {
+
+// Returns the EnumDescriptor for enum type E, which must be a
+// proto-declared enum type.  Code generated by the protocol compiler
+// will include specializations of this template for each enum type declared.
+template <typename E>
+const EnumDescriptor* GetEnumDescriptor();
+
+namespace internal {
+
+// Helper for EnumType_Parse functions: try to parse the string 'name' as an
+// enum name of the given type, returning true and filling in value on success,
+// or returning false and leaving value unchanged on failure.
+LIBPROTOBUF_EXPORT bool ParseNamedEnum(const EnumDescriptor* descriptor,
+                    const string& name,
+                    int* value);
+
+template<typename EnumType>
+bool ParseNamedEnum(const EnumDescriptor* descriptor,
+                    const string& name,
+                    EnumType* value) {
+  int tmp;
+  if (!ParseNamedEnum(descriptor, name, &tmp)) return false;
+  *value = static_cast<EnumType>(tmp);
+  return true;
+}
+
+// Just a wrapper around printing the name of a value. The main point of this
+// function is not to be inlined, so that you can do this without including
+// descriptor.h.
+LIBPROTOBUF_EXPORT const string& NameOfEnum(const EnumDescriptor* descriptor, int value);
+
+}  // namespace internal
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_GENERATED_ENUM_REFLECTION_H__
diff --git a/src/google/protobuf/generated_message_reflection.cc b/src/google/protobuf/generated_message_reflection.cc
index a0dd75c6..f4d0851d 100644
--- a/src/google/protobuf/generated_message_reflection.cc
+++ b/src/google/protobuf/generated_message_reflection.cc
@@ -33,9 +33,9 @@
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
 #include <algorithm>
+#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/generated_message_reflection.h>
 #include <google/protobuf/descriptor.h>
-#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/extension_set.h>
 #include <google/protobuf/generated_message_util.h>
@@ -321,7 +321,7 @@ void GeneratedMessageReflection::Swap(
        "descriptor.";
   GOOGLE_CHECK_EQ(message2->GetReflection(), this)
     << "Second argument to Swap() (of type \""
-    << message1->GetDescriptor()->full_name()
+    << message2->GetDescriptor()->full_name()
     << "\") is not compatible with this reflection object (which is for type \""
     << descriptor_->full_name()
     << "\").  Note that the exact same class is required; not just the same "
@@ -380,8 +380,11 @@ void GeneratedMessageReflection::Swap(
           SWAP_VALUES(DOUBLE, double);
           SWAP_VALUES(BOOL  , bool  );
           SWAP_VALUES(ENUM  , int   );
-          SWAP_VALUES(MESSAGE, Message*);
 #undef SWAP_VALUES
+        case FieldDescriptor::CPPTYPE_MESSAGE:
+          std::swap(*MutableRaw<Message*>(message1, field),
+                    *MutableRaw<Message*>(message2, field));
+          break;
 
         case FieldDescriptor::CPPTYPE_STRING:
           switch (field->options().ctype()) {
@@ -588,6 +591,20 @@ void GeneratedMessageReflection::RemoveLast(
   }
 }
 
+Message* GeneratedMessageReflection::ReleaseLast(
+    Message* message,
+    const FieldDescriptor* field) const {
+  USAGE_CHECK_ALL(ReleaseLast, REPEATED, MESSAGE);
+
+  if (field->is_extension()) {
+    return static_cast<Message*>(
+        MutableExtensionSet(message)->ReleaseLast(field->number()));
+  } else {
+    return MutableRaw<RepeatedPtrFieldBase>(message, field)
+        ->ReleaseLast<GenericTypeHandler<Message> >();
+  }
+}
+
 void GeneratedMessageReflection::SwapElements(
     Message* message,
     const FieldDescriptor* field,
@@ -889,7 +906,9 @@ const EnumValueDescriptor* GeneratedMessageReflection::GetEnum(
   }
   const EnumValueDescriptor* result =
     field->enum_type()->FindValueByNumber(value);
-  GOOGLE_CHECK(result != NULL);
+  GOOGLE_CHECK(result != NULL) << "Value " << value << " is not valid for field "
+                        << field->full_name() << " of type "
+                        << field->enum_type()->full_name() << ".";
   return result;
 }
 
@@ -919,7 +938,9 @@ const EnumValueDescriptor* GeneratedMessageReflection::GetRepeatedEnum(
   }
   const EnumValueDescriptor* result =
     field->enum_type()->FindValueByNumber(value);
-  GOOGLE_CHECK(result != NULL);
+  GOOGLE_CHECK(result != NULL) << "Value " << value << " is not valid for field "
+                        << field->full_name() << " of type "
+                        << field->enum_type()->full_name() << ".";
   return result;
 }
 
@@ -960,13 +981,15 @@ const Message& GeneratedMessageReflection::GetMessage(
     MessageFactory* factory) const {
   USAGE_CHECK_ALL(GetMessage, SINGULAR, MESSAGE);
 
+  if (factory == NULL) factory = message_factory_;
+
   if (field->is_extension()) {
     return static_cast<const Message&>(
         GetExtensionSet(message).GetMessage(
-          field->number(), field->message_type(),
-          factory == NULL ? message_factory_ : factory));
+          field->number(), field->message_type(), factory));
   } else {
-    const Message* result = GetRaw<const Message*>(message, field);
+    const Message* result;
+    result = GetRaw<const Message*>(message, field);
     if (result == NULL) {
       result = DefaultRaw<const Message*>(field);
     }
@@ -979,17 +1002,40 @@ Message* GeneratedMessageReflection::MutableMessage(
     MessageFactory* factory) const {
   USAGE_CHECK_ALL(MutableMessage, SINGULAR, MESSAGE);
 
+  if (factory == NULL) factory = message_factory_;
+
   if (field->is_extension()) {
     return static_cast<Message*>(
-        MutableExtensionSet(message)->MutableMessage(field,
-          factory == NULL ? message_factory_ : factory));
+        MutableExtensionSet(message)->MutableMessage(field, factory));
   } else {
-    Message** result = MutableField<Message*>(message, field);
-    if (*result == NULL) {
+    Message* result;
+    Message** result_holder = MutableField<Message*>(message, field);
+    if (*result_holder == NULL) {
       const Message* default_message = DefaultRaw<const Message*>(field);
-      *result = default_message->New();
+      *result_holder = default_message->New();
     }
-    return *result;
+    result = *result_holder;
+    return result;
+  }
+}
+
+Message* GeneratedMessageReflection::ReleaseMessage(
+    Message* message,
+    const FieldDescriptor* field,
+    MessageFactory* factory) const {
+  USAGE_CHECK_ALL(ReleaseMessage, SINGULAR, MESSAGE);
+
+  if (factory == NULL) factory = message_factory_;
+
+  if (field->is_extension()) {
+    return static_cast<Message*>(
+        MutableExtensionSet(message)->ReleaseMessage(field, factory));
+  } else {
+    ClearBit(message, field);
+    Message** result = MutableRaw<Message*>(message, field);
+    Message* ret = *result;
+    *result = NULL;
+    return ret;
   }
 }
 
@@ -1034,7 +1080,7 @@ Message* GeneratedMessageReflection::AddMessage(
     // We can't use AddField<Message>() because RepeatedPtrFieldBase doesn't
     // know how to allocate one.
     RepeatedPtrFieldBase* repeated =
-      MutableRaw<RepeatedPtrFieldBase>(message, field);
+        MutableRaw<RepeatedPtrFieldBase>(message, field);
     Message* result = repeated->AddFromCleared<GenericTypeHandler<Message> >();
     if (result == NULL) {
       // We must allocate a new object.
@@ -1051,7 +1097,26 @@ Message* GeneratedMessageReflection::AddMessage(
   }
 }
 
-// -------------------------------------------------------------------
+void* GeneratedMessageReflection::MutableRawRepeatedField(
+    Message* message, const FieldDescriptor* field,
+    FieldDescriptor::CppType cpptype,
+    int ctype, const Descriptor* desc) const {
+  USAGE_CHECK_REPEATED("MutableRawRepeatedField");
+  if (field->cpp_type() != cpptype)
+    ReportReflectionUsageTypeError(descriptor_,
+        field, "MutableRawRepeatedField", cpptype);
+  if (ctype >= 0)
+    GOOGLE_CHECK_EQ(field->options().ctype(), ctype) << "subtype mismatch";
+  if (desc != NULL)
+    GOOGLE_CHECK_EQ(field->message_type(), desc) << "wrong submessage type";
+  if (field->is_extension())
+    return MutableExtensionSet(message)->MutableRawRepeatedField(
+        field->number());
+  else
+    return reinterpret_cast<uint8*>(message) + offsets_[field->index()];
+}
+
+// -----------------------------------------------------------------------------
 
 const FieldDescriptor* GeneratedMessageReflection::FindKnownExtensionByName(
     const string& name) const {
diff --git a/src/google/protobuf/generated_message_reflection.h b/src/google/protobuf/generated_message_reflection.h
index b545fa1a..e6670aea 100644
--- a/src/google/protobuf/generated_message_reflection.h
+++ b/src/google/protobuf/generated_message_reflection.h
@@ -40,17 +40,23 @@
 
 #include <string>
 #include <vector>
+#include <google/protobuf/stubs/common.h>
+// TODO(jasonh): Remove this once the compiler change to directly include this
+// is released to components.
+#include <google/protobuf/generated_enum_reflection.h>
 #include <google/protobuf/message.h>
 #include <google/protobuf/unknown_field_set.h>
 
 
 namespace google {
+namespace upb {
+namespace proto2_bridge_opensource {
+class FieldAccessor;
+}  // namespace protobuf_bridge_google3
+}  // namespace upb
+
 namespace protobuf {
   class DescriptorPool;
-  // Generated code needs these to have been forward-declared.  Easier to do it
-  // here than to print them inside every .pb.h file.
-  class FileDescriptor;
-  class EnumDescriptor;
 }
 
 namespace protobuf {
@@ -141,6 +147,7 @@ class LIBPROTOBUF_EXPORT GeneratedMessageReflection : public Reflection {
   int FieldSize(const Message& message, const FieldDescriptor* field) const;
   void ClearField(Message* message, const FieldDescriptor* field) const;
   void RemoveLast(Message* message, const FieldDescriptor* field) const;
+  Message* ReleaseLast(Message* message, const FieldDescriptor* field) const;
   void Swap(Message* message1, Message* message2) const;
   void SwapElements(Message* message, const FieldDescriptor* field,
             int index1, int index2) const;
@@ -193,6 +200,8 @@ class LIBPROTOBUF_EXPORT GeneratedMessageReflection : public Reflection {
                  const EnumValueDescriptor* value) const;
   Message* MutableMessage(Message* message, const FieldDescriptor* field,
                           MessageFactory* factory = NULL) const;
+  Message* ReleaseMessage(Message* message, const FieldDescriptor* field,
+                          MessageFactory* factory = NULL) const;
 
   int32  GetRepeatedInt32 (const Message& message,
                            const FieldDescriptor* field, int index) const;
@@ -270,9 +279,18 @@ class LIBPROTOBUF_EXPORT GeneratedMessageReflection : public Reflection {
   const FieldDescriptor* FindKnownExtensionByName(const string& name) const;
   const FieldDescriptor* FindKnownExtensionByNumber(int number) const;
 
+ protected:
+  virtual void* MutableRawRepeatedField(
+      Message* message, const FieldDescriptor* field, FieldDescriptor::CppType,
+      int ctype, const Descriptor* desc) const;
+
  private:
   friend class GeneratedMessage;
 
+  // To parse directly into a proto2 generated class, FieldAccessor needs
+  // access to member offsets and hasbits.
+  friend class LIBPROTOBUF_EXPORT upb::proto2_bridge_opensource::FieldAccessor;
+
   const Descriptor* descriptor_;
   const Message* default_instance_;
   const int* offsets_;
@@ -293,7 +311,6 @@ class LIBPROTOBUF_EXPORT GeneratedMessageReflection : public Reflection {
                           const FieldDescriptor* field) const;
   template <typename Type>
   inline const Type& DefaultRaw(const FieldDescriptor* field) const;
-  inline const Message* GetMessagePrototype(const FieldDescriptor* field) const;
 
   inline const uint32* GetHasBits(const Message& message) const;
   inline uint32* MutableHasBits(Message* message) const;
@@ -395,28 +412,6 @@ inline To dynamic_cast_if_available(From from) {
 #endif
 }
 
-// Helper for EnumType_Parse functions: try to parse the string 'name' as an
-// enum name of the given type, returning true and filling in value on success,
-// or returning false and leaving value unchanged on failure.
-LIBPROTOBUF_EXPORT bool ParseNamedEnum(const EnumDescriptor* descriptor,
-                    const string& name,
-                    int* value);
-
-template<typename EnumType>
-bool ParseNamedEnum(const EnumDescriptor* descriptor,
-                    const string& name,
-                    EnumType* value) {
-  int tmp;
-  if (!ParseNamedEnum(descriptor, name, &tmp)) return false;
-  *value = static_cast<EnumType>(tmp);
-  return true;
-}
-
-// Just a wrapper around printing the name of a value. The main point of this
-// function is not to be inlined, so that you can do this without including
-// descriptor.h.
-LIBPROTOBUF_EXPORT const string& NameOfEnum(const EnumDescriptor* descriptor, int value);
-
 }  // namespace internal
 }  // namespace protobuf
 
diff --git a/src/google/protobuf/generated_message_reflection_unittest.cc b/src/google/protobuf/generated_message_reflection_unittest.cc
index a03bcdb7..f60e430d 100644
--- a/src/google/protobuf/generated_message_reflection_unittest.cc
+++ b/src/google/protobuf/generated_message_reflection_unittest.cc
@@ -225,11 +225,59 @@ TEST(GeneratedMessageReflectionTest, RemoveLastExtensions) {
     unittest::TestAllExtensions::descriptor());
 
   TestUtil::SetAllExtensions(&message);
+
   reflection_tester.RemoveLastRepeatedsViaReflection(&message);
 
   TestUtil::ExpectLastRepeatedExtensionsRemoved(message);
 }
 
+TEST(GeneratedMessageReflectionTest, ReleaseLast) {
+  unittest::TestAllTypes message;
+  const Descriptor* descriptor = message.GetDescriptor();
+  TestUtil::ReflectionTester reflection_tester(descriptor);
+
+  TestUtil::SetAllFields(&message);
+
+  reflection_tester.ReleaseLastRepeatedsViaReflection(&message, false);
+
+  TestUtil::ExpectLastRepeatedsReleased(message);
+
+  // Now test that we actually release the right message.
+  message.Clear();
+  TestUtil::SetAllFields(&message);
+  ASSERT_EQ(2, message.repeated_foreign_message_size());
+  const protobuf_unittest::ForeignMessage* expected =
+      message.mutable_repeated_foreign_message(1);
+  scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
+      &message, descriptor->FindFieldByName("repeated_foreign_message")));
+  EXPECT_EQ(expected, released.get());
+}
+
+TEST(GeneratedMessageReflectionTest, ReleaseLastExtensions) {
+  unittest::TestAllExtensions message;
+  const Descriptor* descriptor = message.GetDescriptor();
+  TestUtil::ReflectionTester reflection_tester(descriptor);
+
+  TestUtil::SetAllExtensions(&message);
+
+  reflection_tester.ReleaseLastRepeatedsViaReflection(&message, true);
+
+  TestUtil::ExpectLastRepeatedExtensionsReleased(message);
+
+  // Now test that we actually release the right message.
+  message.Clear();
+  TestUtil::SetAllExtensions(&message);
+  ASSERT_EQ(2, message.ExtensionSize(
+      unittest::repeated_foreign_message_extension));
+  const protobuf_unittest::ForeignMessage* expected = message.MutableExtension(
+      unittest::repeated_foreign_message_extension, 1);
+  scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
+      &message, descriptor->file()->FindExtensionByName(
+          "repeated_foreign_message_extension")));
+  EXPECT_EQ(expected, released.get());
+
+}
+
 TEST(GeneratedMessageReflectionTest, SwapRepeatedElements) {
   unittest::TestAllTypes message;
   TestUtil::ReflectionTester reflection_tester(
@@ -327,6 +375,58 @@ TEST(GeneratedMessageReflectionTest, FindKnownExtensionByName) {
               FindKnownExtensionByName(extension1->full_name()) == NULL);
 }
 
+TEST(GeneratedMessageReflectionTest, ReleaseMessageTest) {
+  unittest::TestAllTypes message;
+  TestUtil::ReflectionTester reflection_tester(
+    unittest::TestAllTypes::descriptor());
+
+  // When nothing is set, we expect all released messages to be NULL.
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::IS_NULL);
+
+  // After fields are set we should get non-NULL releases.
+  reflection_tester.SetAllFieldsViaReflection(&message);
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::NOT_NULL);
+
+  // After Clear() we may or may not get a message from ReleaseMessage().
+  // This is implementation specific.
+  reflection_tester.SetAllFieldsViaReflection(&message);
+  message.Clear();
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::CAN_BE_NULL);
+
+  // Test a different code path for setting after releasing.
+  TestUtil::SetAllFields(&message);
+  TestUtil::ExpectAllFieldsSet(message);
+}
+
+TEST(GeneratedMessageReflectionTest, ReleaseExtensionMessageTest) {
+  unittest::TestAllExtensions message;
+  TestUtil::ReflectionTester reflection_tester(
+    unittest::TestAllExtensions::descriptor());
+
+  // When nothing is set, we expect all released messages to be NULL.
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::IS_NULL);
+
+  // After fields are set we should get non-NULL releases.
+  reflection_tester.SetAllFieldsViaReflection(&message);
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::NOT_NULL);
+
+  // After Clear() we may or may not get a message from ReleaseMessage().
+  // This is implementation specific.
+  reflection_tester.SetAllFieldsViaReflection(&message);
+  message.Clear();
+  reflection_tester.ExpectMessagesReleasedViaReflection(
+      &message, TestUtil::ReflectionTester::CAN_BE_NULL);
+
+  // Test a different code path for setting after releasing.
+  TestUtil::SetAllExtensions(&message);
+  TestUtil::ExpectAllExtensionsSet(message);
+}
+
 #ifdef GTEST_HAS_DEATH_TEST
 
 TEST(GeneratedMessageReflectionTest, UsageErrors) {
diff --git a/src/google/protobuf/generated_message_util.cc b/src/google/protobuf/generated_message_util.cc
index 76e547bb..ac321501 100644
--- a/src/google/protobuf/generated_message_util.cc
+++ b/src/google/protobuf/generated_message_util.cc
@@ -49,7 +49,6 @@ double NaN() {
 
 const ::std::string kEmptyString;
 
-
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/generated_message_util.h b/src/google/protobuf/generated_message_util.h
index 77ae1064..b2fb8f0b 100644
--- a/src/google/protobuf/generated_message_util.h
+++ b/src/google/protobuf/generated_message_util.h
@@ -41,16 +41,8 @@
 #include <string>
 
 #include <google/protobuf/stubs/common.h>
-
-
 namespace google {
 namespace protobuf {
-  namespace io {
-    class CodedInputStream;      // coded_stream.h
-  }
-}
-
-namespace protobuf {
 namespace internal {
 
 // Annotation for the compiler to emit a deprecation message if a field marked
@@ -60,11 +52,7 @@ namespace internal {
 // For internal use in the pb.cc files, deprecation warnings are suppressed
 // there.
 #undef DEPRECATED_PROTOBUF_FIELD
-#if !defined(INTERNAL_SUPPRESS_PROTOBUF_FIELD_DEPRECATION)
-#  define PROTOBUF_DEPRECATED GOOGLE_ATTRIBUTE_DEPRECATED
-#else
-#  define PROTOBUF_DEPRECATED
-#endif
+#define PROTOBUF_DEPRECATED
 
 
 // Constants for special floating point values.
@@ -74,6 +62,13 @@ LIBPROTOBUF_EXPORT double NaN();
 // Constant used for empty default strings.
 LIBPROTOBUF_EXPORT extern const ::std::string kEmptyString;
 
+// Defined in generated_message_reflection.cc -- not actually part of the lite
+// library.
+//
+// TODO(jasonh): The various callers get this declaration from a variety of
+// places: probably in most cases repeated_field.h. Clean these up so they all
+// get the declaration from this file.
+LIBPROTOBUF_EXPORT int StringSpaceUsedExcludingSelf(const string& str);
 
 }  // namespace internal
 }  // namespace protobuf
diff --git a/src/google/protobuf/io/coded_stream.cc b/src/google/protobuf/io/coded_stream.cc
index 402a3ad3..36add8c3 100644
--- a/src/google/protobuf/io/coded_stream.cc
+++ b/src/google/protobuf/io/coded_stream.cc
@@ -43,7 +43,7 @@
 #include <limits.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 
 namespace google {
@@ -69,6 +69,19 @@ inline bool NextNonEmpty(ZeroCopyInputStream* input,
 
 // CodedInputStream ==================================================
 
+CodedInputStream::~CodedInputStream() {
+  if (input_ != NULL) {
+    BackUpInputToCurrentPosition();
+  }
+
+  if (total_bytes_warning_threshold_ == -2) {
+    GOOGLE_LOG(WARNING) << "The total number of bytes read was " << total_bytes_read_;
+  }
+}
+
+// Static.
+int CodedInputStream::default_recursion_limit_ = 100;
+
 
 void CodedInputStream::BackUpInputToCurrentPosition() {
   int backup_bytes = BufferSize() + buffer_size_after_limit_ + overflow_bytes_;
@@ -98,8 +111,7 @@ inline void CodedInputStream::RecomputeBufferLimits() {
 
 CodedInputStream::Limit CodedInputStream::PushLimit(int byte_limit) {
   // Current position relative to the beginning of the stream.
-  int current_position = total_bytes_read_ -
-      (BufferSize() + buffer_size_after_limit_);
+  int current_position = CurrentPosition();
 
   Limit old_limit = current_limit_;
 
@@ -133,10 +145,9 @@ void CodedInputStream::PopLimit(Limit limit) {
   legitimate_message_end_ = false;
 }
 
-int CodedInputStream::BytesUntilLimit() {
+int CodedInputStream::BytesUntilLimit() const {
   if (current_limit_ == INT_MAX) return -1;
-  int current_position = total_bytes_read_ -
-      (BufferSize() + buffer_size_after_limit_);
+  int current_position = CurrentPosition();
 
   return current_limit_ - current_position;
 }
@@ -145,10 +156,14 @@ void CodedInputStream::SetTotalBytesLimit(
     int total_bytes_limit, int warning_threshold) {
   // Make sure the limit isn't already past, since this could confuse other
   // code.
-  int current_position = total_bytes_read_ -
-      (BufferSize() + buffer_size_after_limit_);
+  int current_position = CurrentPosition();
   total_bytes_limit_ = max(current_position, total_bytes_limit);
-  total_bytes_warning_threshold_ = warning_threshold;
+  if (warning_threshold >= 0) {
+    total_bytes_warning_threshold_ = warning_threshold;
+  } else {
+    // warning_threshold is negative
+    total_bytes_warning_threshold_ = -1;
+  }
   RecomputeBufferLimits();
 }
 
@@ -368,16 +383,17 @@ uint32 CodedInputStream::ReadTagSlow() {
 
   // For the slow path, just do a 64-bit read. Try to optimize for one-byte tags
   // again, since we have now refreshed the buffer.
-  uint64 result;
+  uint64 result = 0;
   if (!ReadVarint64(&result)) return 0;
   return static_cast<uint32>(result);
 }
 
 uint32 CodedInputStream::ReadTagFallback() {
-  if (BufferSize() >= kMaxVarintBytes ||
+  const int buf_size = BufferSize();
+  if (buf_size >= kMaxVarintBytes ||
       // Optimization:  If the varint ends at exactly the end of the buffer,
       // we can detect that and still use the fast path.
-      (buffer_end_ > buffer_ && !(buffer_end_[-1] & 0x80))) {
+      (buf_size > 0 && !(buffer_end_[-1] & 0x80))) {
     uint32 tag;
     const uint8* end = ReadVarint32FromArray(buffer_, &tag);
     if (end == NULL) {
@@ -388,7 +404,9 @@ uint32 CodedInputStream::ReadTagFallback() {
   } else {
     // We are commonly at a limit when attempting to read tags. Try to quickly
     // detect this case without making another function call.
-    if (buffer_ == buffer_end_ && buffer_size_after_limit_ > 0 &&
+    if ((buf_size == 0) &&
+        ((buffer_size_after_limit_ > 0) ||
+         (total_bytes_read_ == current_limit_)) &&
         // Make sure that the limit we hit is not total_bytes_limit_, since
         // in that case we still need to call Refresh() so that it prints an
         // error.
@@ -492,8 +510,8 @@ bool CodedInputStream::Refresh() {
                       "CodedInputStream::SetTotalBytesLimit() in "
                       "google/protobuf/io/coded_stream.h.";
 
-    // Don't warn again for this stream.
-    total_bytes_warning_threshold_ = -1;
+    // Don't warn again for this stream, and print total size at the end.
+    total_bytes_warning_threshold_ = -2;
   }
 
   const void* void_buffer;
diff --git a/src/google/protobuf/io/coded_stream.h b/src/google/protobuf/io/coded_stream.h
index 97ac5079..66cbee00 100644
--- a/src/google/protobuf/io/coded_stream.h
+++ b/src/google/protobuf/io/coded_stream.h
@@ -170,6 +170,9 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   // successfully and the stream's byte limit.
   ~CodedInputStream();
 
+  // Return true if this CodedInputStream reads from a flat array instead of
+  // a ZeroCopyInputStream.
+  inline bool IsFlat() const;
 
   // Skips a number of bytes.  Returns false if an underlying read error
   // occurs.
@@ -311,7 +314,10 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
 
   // Returns the number of bytes left until the nearest limit on the
   // stack is hit, or -1 if no limits are in place.
-  int BytesUntilLimit();
+  int BytesUntilLimit() const;
+
+  // Returns current position relative to the beginning of the input stream.
+  int CurrentPosition() const;
 
   // Total Bytes Limit -----------------------------------------------
   // To prevent malicious users from sending excessively large messages
@@ -327,8 +333,9 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   // cause integer overflows is 512MB.  The default limit is 64MB.  Apps
   // should set shorter limits if possible.  If warning_threshold is not -1,
   // a warning will be printed to stderr after warning_threshold bytes are
-  // read.  An error will always be printed to stderr if the limit is
-  // reached.
+  // read.  For backwards compatibility all negative values get squached to -1,
+  // as other negative values might have special internal meanings.
+  // An error will always be printed to stderr if the limit is reached.
   //
   // This is unrelated to PushLimit()/PopLimit().
   //
@@ -355,9 +362,10 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   // messages and groups.  CodedInputStream keeps track of this because it
   // is the only object that is passed down the stack during parsing.
 
-  // Sets the maximum recursion depth.  The default is 64.
+  // Sets the maximum recursion depth.  The default is 100.
   void SetRecursionLimit(int limit);
 
+
   // Increments the current recursion depth.  Returns true if the depth is
   // under the limit, false if it has gone over.
   bool IncrementRecursionDepth();
@@ -433,7 +441,8 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   //
   // Note that this feature is ignored when parsing "lite" messages as they do
   // not have descriptors.
-  void SetExtensionRegistry(DescriptorPool* pool, MessageFactory* factory);
+  void SetExtensionRegistry(const DescriptorPool* pool,
+                            MessageFactory* factory);
 
   // Get the DescriptorPool set via SetExtensionRegistry(), or NULL if no pool
   // has been provided.
@@ -482,6 +491,11 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   // Maximum number of bytes to read, period.  This is unrelated to
   // current_limit_.  Set using SetTotalBytesLimit().
   int total_bytes_limit_;
+
+  // If positive/0: Limit for bytes read after which a warning due to size
+  // should be logged.
+  // If -1: Printing of warning disabled. Can be set by client.
+  // If -2: Internal: Limit has been reached, print full size when destructing.
   int total_bytes_warning_threshold_;
 
   // Current recursion depth, controlled by IncrementRecursionDepth() and
@@ -539,7 +553,8 @@ class LIBPROTOBUF_EXPORT CodedInputStream {
   static const int kDefaultTotalBytesLimit = 64 << 20;  // 64MB
 
   static const int kDefaultTotalBytesWarningThreshold = 32 << 20;  // 32MB
-  static const int kDefaultRecursionLimit = 64;
+
+  static int default_recursion_limit_;  // 100 by default.
 };
 
 // Class which encodes and writes binary data which is composed of varint-
@@ -891,7 +906,9 @@ inline bool CodedInputStream::ExpectAtEnd() {
   // If we are at a limit we know no more bytes can be read.  Otherwise, it's
   // hard to say without calling Refresh(), and we'd rather not do that.
 
-  if (buffer_ == buffer_end_ && buffer_size_after_limit_ != 0) {
+  if (buffer_ == buffer_end_ &&
+      ((buffer_size_after_limit_ != 0) ||
+       (total_bytes_read_ == current_limit_))) {
     last_tag_ = 0;                   // Pretend we called ReadTag()...
     legitimate_message_end_ = true;  // ... and it hit EOF.
     return true;
@@ -900,6 +917,10 @@ inline bool CodedInputStream::ExpectAtEnd() {
   }
 }
 
+inline int CodedInputStream::CurrentPosition() const {
+  return total_bytes_read_ - (BufferSize() + buffer_size_after_limit_);
+}
+
 inline uint8* CodedOutputStream::GetDirectBufferForNBytesAndAdvance(int size) {
   if (buffer_size_ < size) {
     return NULL;
@@ -1039,7 +1060,7 @@ inline void CodedInputStream::DecrementRecursionDepth() {
   if (recursion_depth_ > 0) --recursion_depth_;
 }
 
-inline void CodedInputStream::SetExtensionRegistry(DescriptorPool* pool,
+inline void CodedInputStream::SetExtensionRegistry(const DescriptorPool* pool,
                                                    MessageFactory* factory) {
   extension_pool_ = pool;
   extension_factory_ = factory;
@@ -1071,7 +1092,7 @@ inline CodedInputStream::CodedInputStream(ZeroCopyInputStream* input)
     total_bytes_limit_(kDefaultTotalBytesLimit),
     total_bytes_warning_threshold_(kDefaultTotalBytesWarningThreshold),
     recursion_depth_(0),
-    recursion_limit_(kDefaultRecursionLimit),
+    recursion_limit_(default_recursion_limit_),
     extension_pool_(NULL),
     extension_factory_(NULL) {
   // Eagerly Refresh() so buffer space is immediately available.
@@ -1092,17 +1113,15 @@ inline CodedInputStream::CodedInputStream(const uint8* buffer, int size)
     total_bytes_limit_(kDefaultTotalBytesLimit),
     total_bytes_warning_threshold_(kDefaultTotalBytesWarningThreshold),
     recursion_depth_(0),
-    recursion_limit_(kDefaultRecursionLimit),
+    recursion_limit_(default_recursion_limit_),
     extension_pool_(NULL),
     extension_factory_(NULL) {
   // Note that setting current_limit_ == size is important to prevent some
   // code paths from trying to access input_ and segfaulting.
 }
 
-inline CodedInputStream::~CodedInputStream() {
-  if (input_ != NULL) {
-    BackUpInputToCurrentPosition();
-  }
+inline bool CodedInputStream::IsFlat() const {
+  return input_ == NULL;
 }
 
 }  // namespace io
diff --git a/src/google/protobuf/io/coded_stream_inl.h b/src/google/protobuf/io/coded_stream_inl.h
index e9799d47..94495fb8 100644
--- a/src/google/protobuf/io/coded_stream_inl.h
+++ b/src/google/protobuf/io/coded_stream_inl.h
@@ -38,7 +38,7 @@
 
 #include <google/protobuf/io/coded_stream.h>
 #include <string>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/io/coded_stream_unittest.cc b/src/google/protobuf/io/coded_stream_unittest.cc
index ff268ab9..2daab194 100644
--- a/src/google/protobuf/io/coded_stream_unittest.cc
+++ b/src/google/protobuf/io/coded_stream_unittest.cc
@@ -44,7 +44,6 @@
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
-#include <google/protobuf/stubs/strutil.h>
 
 
 // This declares an unsigned long long integer literal in a portable way.
@@ -125,6 +124,13 @@ namespace {
 
 class CodedStreamTest : public testing::Test {
  protected:
+  // Helper method used by tests for bytes warning. See implementation comment
+  // for further information.
+  static void SetupTotalBytesLimitWarningTest(
+      int total_bytes_limit, int warning_threshold,
+      vector<string>* out_errors, vector<string>* out_warnings);
+
+  // Buffer used during most of the tests. This assumes tests run sequentially.
   static const int kBufferSize = 1024 * 64;
   static uint8 buffer_[kBufferSize];
 };
@@ -1022,6 +1028,59 @@ TEST_F(CodedStreamTest, TotalBytesLimitNotValidMessageEnd) {
   EXPECT_FALSE(coded_input.ConsumedEntireMessage());
 }
 
+// This method is used by the tests below.
+// It constructs a CodedInputStream with the given limits and tries to read 2KiB
+// of data from it. Then it returns the logged errors and warnings in the given
+// vectors.
+void CodedStreamTest::SetupTotalBytesLimitWarningTest(
+    int total_bytes_limit, int warning_threshold,
+    vector<string>* out_errors, vector<string>* out_warnings) {
+  ArrayInputStream raw_input(buffer_, sizeof(buffer_), 128);
+
+  ScopedMemoryLog scoped_log;
+  {
+    CodedInputStream input(&raw_input);
+    input.SetTotalBytesLimit(total_bytes_limit, warning_threshold);
+    string str;
+    EXPECT_TRUE(input.ReadString(&str, 2048));
+  }
+
+  *out_errors = scoped_log.GetMessages(ERROR);
+  *out_warnings = scoped_log.GetMessages(WARNING);
+}
+
+TEST_F(CodedStreamTest, TotalBytesLimitWarning) {
+  vector<string> errors;
+  vector<string> warnings;
+  SetupTotalBytesLimitWarningTest(10240, 1024, &errors, &warnings);
+
+  EXPECT_EQ(0, errors.size());
+
+  ASSERT_EQ(2, warnings.size());
+  EXPECT_PRED_FORMAT2(testing::IsSubstring,
+    "Reading dangerously large protocol message.  If the message turns out to "
+    "be larger than 10240 bytes, parsing will be halted for security reasons.",
+    warnings[0]);
+  EXPECT_PRED_FORMAT2(testing::IsSubstring,
+    "The total number of bytes read was 2048",
+    warnings[1]);
+}
+
+TEST_F(CodedStreamTest, TotalBytesLimitWarningDisabled) {
+  vector<string> errors;
+  vector<string> warnings;
+
+  // Test with -1
+  SetupTotalBytesLimitWarningTest(10240, -1, &errors, &warnings);
+  EXPECT_EQ(0, errors.size());
+  EXPECT_EQ(0, warnings.size());
+
+  // Test again with -2, expecting the same result
+  SetupTotalBytesLimitWarningTest(10240, -2, &errors, &warnings);
+  EXPECT_EQ(0, errors.size());
+  EXPECT_EQ(0, warnings.size());
+}
+
 
 TEST_F(CodedStreamTest, RecursionLimit) {
   ArrayInputStream input(buffer_, sizeof(buffer_));
@@ -1060,6 +1119,7 @@ TEST_F(CodedStreamTest, RecursionLimit) {
   EXPECT_FALSE(coded_input.IncrementRecursionDepth());     // 7
 }
 
+
 class ReallyBigInputStream : public ZeroCopyInputStream {
  public:
   ReallyBigInputStream() : backup_amount_(0), buffer_count_(0) {}
diff --git a/src/google/protobuf/io/gzip_stream.cc b/src/google/protobuf/io/gzip_stream.cc
index 0f1ff872..fe1f3319 100644
--- a/src/google/protobuf/io/gzip_stream.cc
+++ b/src/google/protobuf/io/gzip_stream.cc
@@ -199,16 +199,6 @@ GzipOutputStream::GzipOutputStream(ZeroCopyOutputStream* sub_stream,
   Init(sub_stream, options);
 }
 
-GzipOutputStream::GzipOutputStream(
-    ZeroCopyOutputStream* sub_stream, Format format, int buffer_size) {
-  Options options;
-  options.format = format;
-  if (buffer_size != -1) {
-    options.buffer_size = buffer_size;
-  }
-  Init(sub_stream, options);
-}
-
 void GzipOutputStream::Init(ZeroCopyOutputStream* sub_stream,
                             const Options& options) {
   sub_stream_ = sub_stream;
@@ -309,10 +299,11 @@ int64 GzipOutputStream::ByteCount() const {
 }
 
 bool GzipOutputStream::Flush() {
-  do {
-    zerror_ = Deflate(Z_FULL_FLUSH);
-  } while (zerror_ == Z_OK);
-  return zerror_ == Z_OK;
+  zerror_ = Deflate(Z_FULL_FLUSH);
+  // Return true if the flush succeeded or if it was a no-op.
+  return  (zerror_ == Z_OK) ||
+      (zerror_ == Z_BUF_ERROR && zcontext_.avail_in == 0 &&
+       zcontext_.avail_out != 0);
 }
 
 bool GzipOutputStream::Close() {
diff --git a/src/google/protobuf/io/gzip_stream.h b/src/google/protobuf/io/gzip_stream.h
index 65dbc5b5..7ee24bc3 100644
--- a/src/google/protobuf/io/gzip_stream.h
+++ b/src/google/protobuf/io/gzip_stream.h
@@ -45,6 +45,7 @@
 
 #include <zlib.h>
 
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 
 namespace google {
@@ -144,12 +145,6 @@ class LIBPROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream {
       ZeroCopyOutputStream* sub_stream,
       const Options& options);
 
-  // DEPRECATED:  Use one of the above constructors instead.
-  GzipOutputStream(
-      ZeroCopyOutputStream* sub_stream,
-      Format format,
-      int buffer_size = -1) GOOGLE_ATTRIBUTE_DEPRECATED;
-
   virtual ~GzipOutputStream();
 
   // Return last error message or NULL if no error.
@@ -165,6 +160,13 @@ class LIBPROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream {
   // necessary.
   // Compression may be less efficient stopping and starting around flushes.
   // Returns true if no error.
+  //
+  // Please ensure that block size is > 6. Here is an excerpt from the zlib
+  // doc that explains why:
+  //
+  // In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out
+  // is greater than six to avoid repeated flush markers due to
+  // avail_out == 0 on return.
   bool Flush();
 
   // Writes out all data and closes the gzip stream.
diff --git a/src/google/protobuf/io/printer.cc b/src/google/protobuf/io/printer.cc
index 9ab90dee..d2bf3f54 100644
--- a/src/google/protobuf/io/printer.cc
+++ b/src/google/protobuf/io/printer.cc
@@ -35,7 +35,6 @@
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/strutil.h>
 
 namespace google {
 namespace protobuf {
@@ -51,8 +50,8 @@ Printer::Printer(ZeroCopyOutputStream* output, char variable_delimiter)
 }
 
 Printer::~Printer() {
-  // Only BackUp() if we're sure we've successfully called Next() at least once.
-  if (buffer_size_ > 0) {
+  // Only BackUp() if we have called Next() at least once and never failed.
+  if (buffer_size_ > 0 && !failed_) {
     output_->BackUp(buffer_size_);
   }
 }
@@ -169,7 +168,7 @@ void Printer::WriteRaw(const char* data, int size) {
   if (failed_) return;
   if (size == 0) return;
 
-  if (at_start_of_line_) {
+  if (at_start_of_line_ && (size > 0) && (data[0] != '\n')) {
     // Insert an indent.
     at_start_of_line_ = false;
     WriteRaw(indent_.data(), indent_.size());
diff --git a/src/google/protobuf/io/printer_unittest.cc b/src/google/protobuf/io/printer_unittest.cc
index 580a53da..399395c8 100644
--- a/src/google/protobuf/io/printer_unittest.cc
+++ b/src/google/protobuf/io/printer_unittest.cc
@@ -233,7 +233,31 @@ TEST(Printer, Death) {
 }
 #endif  // GTEST_HAS_DEATH_TEST
 
-TEST(Printer, WriteFailure) {
+TEST(Printer, WriteFailurePartial) {
+  char buffer[17];
+
+  ArrayOutputStream output(buffer, sizeof(buffer));
+  Printer printer(&output, '$');
+
+  // Print 16 bytes to almost fill the buffer (should not fail).
+  printer.Print("0123456789abcdef");
+  EXPECT_FALSE(printer.failed());
+
+  // Try to print 2 chars. Only one fits.
+  printer.Print("<>");
+  EXPECT_TRUE(printer.failed());
+
+  // Anything else should fail too.
+  printer.Print(" ");
+  EXPECT_TRUE(printer.failed());
+  printer.Print("blah");
+  EXPECT_TRUE(printer.failed());
+
+  // Buffer should contain the first 17 bytes written.
+  EXPECT_EQ("0123456789abcdef<", string(buffer, sizeof(buffer)));
+}
+
+TEST(Printer, WriteFailureExact) {
   char buffer[16];
 
   ArrayOutputStream output(buffer, sizeof(buffer));
diff --git a/src/google/protobuf/io/tokenizer.cc b/src/google/protobuf/io/tokenizer.cc
index 513831d5..a022b71d 100644
--- a/src/google/protobuf/io/tokenizer.cc
+++ b/src/google/protobuf/io/tokenizer.cc
@@ -89,8 +89,11 @@
 // exactly pretty.
 
 #include <google/protobuf/io/tokenizer.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -118,6 +121,8 @@ namespace {
 
 CHARACTER_CLASS(Whitespace, c == ' ' || c == '\n' || c == '\t' ||
                             c == '\r' || c == '\v' || c == '\f');
+CHARACTER_CLASS(WhitespaceNoNewline, c == ' ' || c == '\t' ||
+                                     c == '\r' || c == '\v' || c == '\f');
 
 CHARACTER_CLASS(Unprintable, c < ' ' && c > '\0');
 
@@ -187,7 +192,8 @@ Tokenizer::Tokenizer(ZeroCopyInputStream* input,
     read_error_(false),
     line_(0),
     column_(0),
-    token_start_(-1),
+    record_target_(NULL),
+    record_start_(-1),
     allow_f_after_float_(false),
     comment_style_(CPP_COMMENT_STYLE) {
 
@@ -238,9 +244,9 @@ void Tokenizer::Refresh() {
   }
 
   // If we're in a token, append the rest of the buffer to it.
-  if (token_start_ >= 0 && token_start_ < buffer_size_) {
-    current_.text.append(buffer_ + token_start_, buffer_size_ - token_start_);
-    token_start_ = 0;
+  if (record_target_ != NULL && record_start_ < buffer_size_) {
+    record_target_->append(buffer_ + record_start_, buffer_size_ - record_start_);
+    record_start_ = 0;
   }
 
   const void* data = NULL;
@@ -261,23 +267,33 @@ void Tokenizer::Refresh() {
   current_char_ = buffer_[0];
 }
 
+inline void Tokenizer::RecordTo(string* target) {
+  record_target_ = target;
+  record_start_ = buffer_pos_;
+}
+
+inline void Tokenizer::StopRecording() {
+  // Note:  The if() is necessary because some STL implementations crash when
+  //   you call string::append(NULL, 0), presumably because they are trying to
+  //   be helpful by detecting the NULL pointer, even though there's nothing
+  //   wrong with reading zero bytes from NULL.
+  if (buffer_pos_ != record_start_) {
+    record_target_->append(buffer_ + record_start_, buffer_pos_ - record_start_);
+  }
+  record_target_ = NULL;
+  record_start_ = -1;
+}
+
 inline void Tokenizer::StartToken() {
-  token_start_ = buffer_pos_;
   current_.type = TYPE_START;    // Just for the sake of initializing it.
   current_.text.clear();
   current_.line = line_;
   current_.column = column_;
+  RecordTo(&current_.text);
 }
 
 inline void Tokenizer::EndToken() {
-  // Note:  The if() is necessary because some STL implementations crash when
-  //   you call string::append(NULL, 0), presumably because they are trying to
-  //   be helpful by detecting the NULL pointer, even though there's nothing
-  //   wrong with reading zero bytes from NULL.
-  if (buffer_pos_ != token_start_) {
-    current_.text.append(buffer_ + token_start_, buffer_pos_ - token_start_);
-  }
-  token_start_ = -1;
+  StopRecording();
   current_.end_column = column_;
 }
 
@@ -353,6 +369,27 @@ void Tokenizer::ConsumeString(char delimiter) {
             AddError("Expected hex digits for escape sequence.");
           }
           // Possibly followed by another hex digit, but again we don't care.
+        } else if (TryConsume('u')) {
+          if (!TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>()) {
+            AddError("Expected four hex digits for \\u escape sequence.");
+          }
+        } else if (TryConsume('U')) {
+          // We expect 8 hex digits; but only the range up to 0x10ffff is
+          // legal.
+          if (!TryConsume('0') ||
+              !TryConsume('0') ||
+              !(TryConsume('0') || TryConsume('1')) ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>() ||
+              !TryConsumeOne<HexDigit>()) {
+            AddError("Expected eight hex digits up to 10ffff for \\U escape "
+                     "sequence");
+          }
         } else {
           AddError("Invalid escape sequence in string literal.");
         }
@@ -426,26 +463,51 @@ Tokenizer::TokenType Tokenizer::ConsumeNumber(bool started_with_zero,
   return is_float ? TYPE_FLOAT : TYPE_INTEGER;
 }
 
-void Tokenizer::ConsumeLineComment() {
+void Tokenizer::ConsumeLineComment(string* content) {
+  if (content != NULL) RecordTo(content);
+
   while (current_char_ != '\0' && current_char_ != '\n') {
     NextChar();
   }
   TryConsume('\n');
+
+  if (content != NULL) StopRecording();
 }
 
-void Tokenizer::ConsumeBlockComment() {
+void Tokenizer::ConsumeBlockComment(string* content) {
   int start_line = line_;
   int start_column = column_ - 2;
 
+  if (content != NULL) RecordTo(content);
+
   while (true) {
     while (current_char_ != '\0' &&
            current_char_ != '*' &&
-           current_char_ != '/') {
+           current_char_ != '/' &&
+           current_char_ != '\n') {
       NextChar();
     }
 
-    if (TryConsume('*') && TryConsume('/')) {
+    if (TryConsume('\n')) {
+      if (content != NULL) StopRecording();
+
+      // Consume leading whitespace and asterisk;
+      ConsumeZeroOrMore<WhitespaceNoNewline>();
+      if (TryConsume('*')) {
+        if (TryConsume('/')) {
+          // End of comment.
+          break;
+        }
+      }
+
+      if (content != NULL) RecordTo(content);
+    } else if (TryConsume('*') && TryConsume('/')) {
       // End of comment.
+      if (content != NULL) {
+        StopRecording();
+        // Strip trailing "*/".
+        content->erase(content->size() - 2);
+      }
       break;
     } else if (TryConsume('/') && current_char_ == '*') {
       // Note:  We didn't consume the '*' because if there is a '/' after it
@@ -456,42 +518,59 @@ void Tokenizer::ConsumeBlockComment() {
       AddError("End-of-file inside block comment.");
       error_collector_->AddError(
         start_line, start_column, "  Comment started here.");
+      if (content != NULL) StopRecording();
       break;
     }
   }
 }
 
+Tokenizer::NextCommentStatus Tokenizer::TryConsumeCommentStart() {
+  if (comment_style_ == CPP_COMMENT_STYLE && TryConsume('/')) {
+    if (TryConsume('/')) {
+      return LINE_COMMENT;
+    } else if (TryConsume('*')) {
+      return BLOCK_COMMENT;
+    } else {
+      // Oops, it was just a slash.  Return it.
+      current_.type = TYPE_SYMBOL;
+      current_.text = "/";
+      current_.line = line_;
+      current_.column = column_ - 1;
+      current_.end_column = column_;
+      return SLASH_NOT_COMMENT;
+    }
+  } else if (comment_style_ == SH_COMMENT_STYLE && TryConsume('#')) {
+    return LINE_COMMENT;
+  } else {
+    return NO_COMMENT;
+  }
+}
+
 // -------------------------------------------------------------------
 
 bool Tokenizer::Next() {
   previous_ = current_;
 
-  // Did we skip any characters after the last token?
-  bool skipped_stuff = false;
-
   while (!read_error_) {
-    if (TryConsumeOne<Whitespace>()) {
-      ConsumeZeroOrMore<Whitespace>();
-
-    } else if (comment_style_ == CPP_COMMENT_STYLE && TryConsume('/')) {
-      // Starting a comment?
-      if (TryConsume('/')) {
-        ConsumeLineComment();
-      } else if (TryConsume('*')) {
-        ConsumeBlockComment();
-      } else {
-        // Oops, it was just a slash.  Return it.
-        current_.type = TYPE_SYMBOL;
-        current_.text = "/";
-        current_.line = line_;
-        current_.column = column_ - 1;
+    ConsumeZeroOrMore<Whitespace>();
+
+    switch (TryConsumeCommentStart()) {
+      case LINE_COMMENT:
+        ConsumeLineComment(NULL);
+        continue;
+      case BLOCK_COMMENT:
+        ConsumeBlockComment(NULL);
+        continue;
+      case SLASH_NOT_COMMENT:
         return true;
-      }
+      case NO_COMMENT:
+        break;
+    }
 
-    } else if (comment_style_ == SH_COMMENT_STYLE && TryConsume('#')) {
-      ConsumeLineComment();
+    // Check for EOF before continuing.
+    if (read_error_) break;
 
-    } else if (LookingAt<Unprintable>() || current_char_ == '\0') {
+    if (LookingAt<Unprintable>() || current_char_ == '\0') {
       AddError("Invalid control characters encountered in text.");
       NextChar();
       // Skip more unprintable characters, too.  But, remember that '\0' is
@@ -519,7 +598,9 @@ bool Tokenizer::Next() {
 
         if (TryConsumeOne<Digit>()) {
           // It's a floating-point number.
-          if (previous_.type == TYPE_IDENTIFIER && !skipped_stuff) {
+          if (previous_.type == TYPE_IDENTIFIER &&
+              current_.line == previous_.line &&
+              current_.column == previous_.end_column) {
             // We don't accept syntax like "blah.123".
             error_collector_->AddError(line_, column_ - 2,
               "Need space between identifier and decimal point.");
@@ -544,8 +625,6 @@ bool Tokenizer::Next() {
       EndToken();
       return true;
     }
-
-    skipped_stuff = true;
   }
 
   // EOF
@@ -557,6 +636,195 @@ bool Tokenizer::Next() {
   return false;
 }
 
+namespace {
+
+// Helper class for collecting comments and putting them in the right places.
+//
+// This basically just buffers the most recent comment until it can be decided
+// exactly where that comment should be placed.  When Flush() is called, the
+// current comment goes into either prev_trailing_comments or detached_comments.
+// When the CommentCollector is destroyed, the last buffered comment goes into
+// next_leading_comments.
+class CommentCollector {
+ public:
+  CommentCollector(string* prev_trailing_comments,
+                   vector<string>* detached_comments,
+                   string* next_leading_comments)
+      : prev_trailing_comments_(prev_trailing_comments),
+        detached_comments_(detached_comments),
+        next_leading_comments_(next_leading_comments),
+        has_comment_(false),
+        is_line_comment_(false),
+        can_attach_to_prev_(true) {
+    if (prev_trailing_comments != NULL) prev_trailing_comments->clear();
+    if (detached_comments != NULL) detached_comments->clear();
+    if (next_leading_comments != NULL) next_leading_comments->clear();
+  }
+
+  ~CommentCollector() {
+    // Whatever is in the buffer is a leading comment.
+    if (next_leading_comments_ != NULL && has_comment_) {
+      comment_buffer_.swap(*next_leading_comments_);
+    }
+  }
+
+  // About to read a line comment.  Get the comment buffer pointer in order to
+  // read into it.
+  string* GetBufferForLineComment() {
+    // We want to combine with previous line comments, but not block comments.
+    if (has_comment_ && !is_line_comment_) {
+      Flush();
+    }
+    has_comment_ = true;
+    is_line_comment_ = true;
+    return &comment_buffer_;
+  }
+
+  // About to read a block comment.  Get the comment buffer pointer in order to
+  // read into it.
+  string* GetBufferForBlockComment() {
+    if (has_comment_) {
+      Flush();
+    }
+    has_comment_ = true;
+    is_line_comment_ = false;
+    return &comment_buffer_;
+  }
+
+  void ClearBuffer() {
+    comment_buffer_.clear();
+    has_comment_ = false;
+  }
+
+  // Called once we know that the comment buffer is complete and is *not*
+  // connected to the next token.
+  void Flush() {
+    if (has_comment_) {
+      if (can_attach_to_prev_) {
+        if (prev_trailing_comments_ != NULL) {
+          prev_trailing_comments_->append(comment_buffer_);
+        }
+        can_attach_to_prev_ = false;
+      } else {
+        if (detached_comments_ != NULL) {
+          detached_comments_->push_back(comment_buffer_);
+        }
+      }
+      ClearBuffer();
+    }
+  }
+
+  void DetachFromPrev() {
+    can_attach_to_prev_ = false;
+  }
+
+ private:
+  string* prev_trailing_comments_;
+  vector<string>* detached_comments_;
+  string* next_leading_comments_;
+
+  string comment_buffer_;
+
+  // True if any comments were read into comment_buffer_.  This can be true even
+  // if comment_buffer_ is empty, namely if the comment was "/**/".
+  bool has_comment_;
+
+  // Is the comment in the comment buffer a line comment?
+  bool is_line_comment_;
+
+  // Is it still possible that we could be reading a comment attached to the
+  // previous token?
+  bool can_attach_to_prev_;
+};
+
+} // namespace
+
+bool Tokenizer::NextWithComments(string* prev_trailing_comments,
+                                 vector<string>* detached_comments,
+                                 string* next_leading_comments) {
+  CommentCollector collector(prev_trailing_comments, detached_comments,
+                             next_leading_comments);
+
+  if (current_.type == TYPE_START) {
+    collector.DetachFromPrev();
+  } else {
+    // A comment appearing on the same line must be attached to the previous
+    // declaration.
+    ConsumeZeroOrMore<WhitespaceNoNewline>();
+    switch (TryConsumeCommentStart()) {
+      case LINE_COMMENT:
+        ConsumeLineComment(collector.GetBufferForLineComment());
+
+        // Don't allow comments on subsequent lines to be attached to a trailing
+        // comment.
+        collector.Flush();
+        break;
+      case BLOCK_COMMENT:
+        ConsumeBlockComment(collector.GetBufferForBlockComment());
+
+        ConsumeZeroOrMore<WhitespaceNoNewline>();
+        if (!TryConsume('\n')) {
+          // Oops, the next token is on the same line.  If we recorded a comment
+          // we really have no idea which token it should be attached to.
+          collector.ClearBuffer();
+          return Next();
+        }
+
+        // Don't allow comments on subsequent lines to be attached to a trailing
+        // comment.
+        collector.Flush();
+        break;
+      case SLASH_NOT_COMMENT:
+        return true;
+      case NO_COMMENT:
+        if (!TryConsume('\n')) {
+          // The next token is on the same line.  There are no comments.
+          return Next();
+        }
+        break;
+    }
+  }
+
+  // OK, we are now on the line *after* the previous token.
+  while (true) {
+    ConsumeZeroOrMore<WhitespaceNoNewline>();
+
+    switch (TryConsumeCommentStart()) {
+      case LINE_COMMENT:
+        ConsumeLineComment(collector.GetBufferForLineComment());
+        break;
+      case BLOCK_COMMENT:
+        ConsumeBlockComment(collector.GetBufferForBlockComment());
+
+        // Consume the rest of the line so that we don't interpret it as a
+        // blank line the next time around the loop.
+        ConsumeZeroOrMore<WhitespaceNoNewline>();
+        TryConsume('\n');
+        break;
+      case SLASH_NOT_COMMENT:
+        return true;
+      case NO_COMMENT:
+        if (TryConsume('\n')) {
+          // Completely blank line.
+          collector.Flush();
+          collector.DetachFromPrev();
+        } else {
+          bool result = Next();
+          if (!result ||
+              current_.text == "}" ||
+              current_.text == "]" ||
+              current_.text == ")") {
+            // It looks like we're at the end of a scope.  In this case it
+            // makes no sense to attach a comment to the following token.
+            collector.Flush();
+          }
+          return result;
+        }
+        break;
+    }
+  }
+}
+
 // -------------------------------------------------------------------
 // Token-parsing helpers.  Remember that these don't need to report
 // errors since any errors should already have been reported while
@@ -626,17 +894,138 @@ double Tokenizer::ParseFloat(const string& text) {
   return result;
 }
 
+// Helper to append a Unicode code point to a string as UTF8, without bringing
+// in any external dependencies.
+static void AppendUTF8(uint32 code_point, string* output) {
+  uint32 tmp = 0;
+  int len = 0;
+  if (code_point <= 0x7f) {
+    tmp = code_point;
+    len = 1;
+  } else if (code_point <= 0x07ff) {
+    tmp = 0x0000c080 |
+        ((code_point & 0x07c0) << 2) |
+        (code_point & 0x003f);
+    len = 2;
+  } else if (code_point <= 0xffff) {
+    tmp = 0x00e08080 |
+        ((code_point & 0xf000) << 4) |
+        ((code_point & 0x0fc0) << 2) |
+        (code_point & 0x003f);
+    len = 3;
+  } else if (code_point <= 0x1fffff) {
+    tmp = 0xf0808080 |
+        ((code_point & 0x1c0000) << 6) |
+        ((code_point & 0x03f000) << 4) |
+        ((code_point & 0x000fc0) << 2) |
+        (code_point & 0x003f);
+    len = 4;
+  } else {
+    // UTF-16 is only defined for code points up to 0x10FFFF, and UTF-8 is
+    // normally only defined up to there as well.
+    StringAppendF(output, "\\U%08x", code_point);
+    return;
+  }
+  tmp = ghtonl(tmp);
+  output->append(reinterpret_cast<const char*>(&tmp) + sizeof(tmp) - len, len);
+}
+
+// Try to read <len> hex digits from ptr, and stuff the numeric result into
+// *result. Returns true if that many digits were successfully consumed.
+static bool ReadHexDigits(const char* ptr, int len, uint32* result) {
+  *result = 0;
+  if (len == 0) return false;
+  for (const char* end = ptr + len; ptr < end; ++ptr) {
+    if (*ptr == '\0') return false;
+    *result = (*result << 4) + DigitValue(*ptr);
+  }
+  return true;
+}
+
+// Handling UTF-16 surrogate pairs. UTF-16 encodes code points in the range
+// 0x10000...0x10ffff as a pair of numbers, a head surrogate followed by a trail
+// surrogate. These numbers are in a reserved range of Unicode code points, so
+// if we encounter such a pair we know how to parse it and convert it into a
+// single code point.
+static const uint32 kMinHeadSurrogate = 0xd800;
+static const uint32 kMaxHeadSurrogate = 0xdc00;
+static const uint32 kMinTrailSurrogate = 0xdc00;
+static const uint32 kMaxTrailSurrogate = 0xe000;
+
+static inline bool IsHeadSurrogate(uint32 code_point) {
+  return (code_point >= kMinHeadSurrogate) && (code_point < kMaxHeadSurrogate);
+}
+
+static inline bool IsTrailSurrogate(uint32 code_point) {
+  return (code_point >= kMinTrailSurrogate) &&
+      (code_point < kMaxTrailSurrogate);
+}
+
+// Combine a head and trail surrogate into a single Unicode code point.
+static uint32 AssembleUTF16(uint32 head_surrogate, uint32 trail_surrogate) {
+  GOOGLE_DCHECK(IsHeadSurrogate(head_surrogate));
+  GOOGLE_DCHECK(IsTrailSurrogate(trail_surrogate));
+  return 0x10000 + (((head_surrogate - kMinHeadSurrogate) << 10) |
+      (trail_surrogate - kMinTrailSurrogate));
+}
+
+// Convert the escape sequence parameter to a number of expected hex digits.
+static inline int UnicodeLength(char key) {
+  if (key == 'u') return 4;
+  if (key == 'U') return 8;
+  return 0;
+}
+
+// Given a pointer to the 'u' or 'U' starting a Unicode escape sequence, attempt
+// to parse that sequence. On success, returns a pointer to the first char
+// beyond that sequence, and fills in *code_point. On failure, returns ptr
+// itself.
+static const char* FetchUnicodePoint(const char* ptr, uint32* code_point) {
+  const char* p = ptr;
+  // Fetch the code point.
+  const int len = UnicodeLength(*p++);
+  if (!ReadHexDigits(p, len, code_point))
+    return ptr;
+  p += len;
+
+  // Check if the code point we read is a "head surrogate." If so, then we
+  // expect it to be immediately followed by another code point which is a valid
+  // "trail surrogate," and together they form a UTF-16 pair which decodes into
+  // a single Unicode point. Trail surrogates may only use \u, not \U.
+  if (IsHeadSurrogate(*code_point) && *p == '\\' && *(p + 1) == 'u') {
+    uint32 trail_surrogate;
+    if (ReadHexDigits(p + 2, 4, &trail_surrogate) &&
+        IsTrailSurrogate(trail_surrogate)) {
+      *code_point = AssembleUTF16(*code_point, trail_surrogate);
+      p += 6;
+    }
+    // If this failed, then we just emit the head surrogate as a code point.
+    // It's bogus, but so is the string.
+  }
+
+  return p;
+}
+
+// The text string must begin and end with single or double quote
+// characters.
 void Tokenizer::ParseStringAppend(const string& text, string* output) {
-  // Reminder:  text[0] is always the quote character.  (If text is
-  //   empty, it's invalid, so we'll just return.)
-  if (text.empty()) {
+  // Reminder: text[0] is always a quote character.  (If text is
+  // empty, it's invalid, so we'll just return).
+  const size_t text_size = text.size();
+  if (text_size == 0) {
     GOOGLE_LOG(DFATAL)
       << " Tokenizer::ParseStringAppend() passed text that could not"
          " have been tokenized as a string: " << CEscape(text);
     return;
   }
 
-  output->reserve(output->size() + text.size());
+  // Reserve room for new string. The branch is necessary because if
+  // there is already space available the reserve() call might
+  // downsize the output.
+  const size_t new_len = text_size + output->size();
+  if (new_len > output->capacity()) {
+    output->reserve(new_len);
+  }
 
   // Loop through the string copying characters to "output" and
   // interpreting escape sequences.  Note that any invalid escape
@@ -674,19 +1063,27 @@ void Tokenizer::ParseStringAppend(const string& text, string* output) {
         }
         output->push_back(static_cast<char>(code));
 
+      } else if (*ptr == 'u' || *ptr == 'U') {
+        uint32 unicode;
+        const char* end = FetchUnicodePoint(ptr, &unicode);
+        if (end == ptr) {
+          // Failure: Just dump out what we saw, don't try to parse it.
+          output->push_back(*ptr);
+        } else {
+          AppendUTF8(unicode, output);
+          ptr = end - 1;  // Because we're about to ++ptr.
+        }
       } else {
         // Some other escape code.
         output->push_back(TranslateEscape(*ptr));
       }
 
-    } else if (*ptr == text[0]) {
-      // Ignore quote matching the starting quote.
+    } else if (*ptr == text[0] && ptr[1] == '\0') {
+      // Ignore final quote matching the starting quote.
     } else {
       output->push_back(*ptr);
     }
   }
-
-  return;
 }
 
 }  // namespace io
diff --git a/src/google/protobuf/io/tokenizer.h b/src/google/protobuf/io/tokenizer.h
index 8f759abb..d85b82f9 100644
--- a/src/google/protobuf/io/tokenizer.h
+++ b/src/google/protobuf/io/tokenizer.h
@@ -38,6 +38,7 @@
 #define GOOGLE_PROTOBUF_IO_TOKENIZER_H__
 
 #include <string>
+#include <vector>
 #include <google/protobuf/stubs/common.h>
 
 namespace google {
@@ -137,6 +138,53 @@ class LIBPROTOBUF_EXPORT Tokenizer {
   // reached.
   bool Next();
 
+  // Like Next(), but also collects comments which appear between the previous
+  // and next tokens.
+  //
+  // Comments which appear to be attached to the previous token are stored
+  // in *prev_tailing_comments.  Comments which appear to be attached to the
+  // next token are stored in *next_leading_comments.  Comments appearing in
+  // between which do not appear to be attached to either will be added to
+  // detached_comments.  Any of these parameters can be NULL to simply discard
+  // the comments.
+  //
+  // A series of line comments appearing on consecutive lines, with no other
+  // tokens appearing on those lines, will be treated as a single comment.
+  //
+  // Only the comment content is returned; comment markers (e.g. //) are
+  // stripped out.  For block comments, leading whitespace and an asterisk will
+  // be stripped from the beginning of each line other than the first.  Newlines
+  // are included in the output.
+  //
+  // Examples:
+  //
+  //   optional int32 foo = 1;  // Comment attached to foo.
+  //   // Comment attached to bar.
+  //   optional int32 bar = 2;
+  //
+  //   optional string baz = 3;
+  //   // Comment attached to baz.
+  //   // Another line attached to baz.
+  //
+  //   // Comment attached to qux.
+  //   //
+  //   // Another line attached to qux.
+  //   optional double qux = 4;
+  //
+  //   // Detached comment.  This is not attached to qux or corge
+  //   // because there are blank lines separating it from both.
+  //
+  //   optional string corge = 5;
+  //   /* Block comment attached
+  //    * to corge.  Leading asterisks
+  //    * will be removed. */
+  //   /* Block comment attached to
+  //    * grault. */
+  //   optional int32 grault = 6;
+  bool NextWithComments(string* prev_trailing_comments,
+                        vector<string>* detached_comments,
+                        string* next_leading_comments);
+
   // Parse helpers ---------------------------------------------------
 
   // Parses a TYPE_FLOAT token.  This never fails, so long as the text actually
@@ -200,11 +248,12 @@ class LIBPROTOBUF_EXPORT Tokenizer {
   int line_;
   int column_;
 
-  // Position in buffer_ where StartToken() was called.  If the token
-  // started in the previous buffer, this is zero, and current_.text already
-  // contains the part of the token from the previous buffer.  If not
-  // currently parsing a token, this is -1.
-  int token_start_;
+  // String to which text should be appended as we advance through it.
+  // Call RecordTo(&str) to start recording and StopRecording() to stop.
+  // E.g. StartToken() calls RecordTo(&current_.text).  record_start_ is the
+  // position within the current buffer where recording started.
+  string* record_target_;
+  int record_start_;
 
   // Options.
   bool allow_f_after_float_;
@@ -223,6 +272,9 @@ class LIBPROTOBUF_EXPORT Tokenizer {
   // Read a new buffer from the input.
   void Refresh();
 
+  inline void RecordTo(string* target);
+  inline void StopRecording();
+
   // Called when the current character is the first character of a new
   // token (not including whitespace or comments).
   inline void StartToken();
@@ -255,9 +307,28 @@ class LIBPROTOBUF_EXPORT Tokenizer {
   TokenType ConsumeNumber(bool started_with_zero, bool started_with_dot);
 
   // Consume the rest of a line.
-  void ConsumeLineComment();
+  void ConsumeLineComment(string* content);
   // Consume until "*/".
-  void ConsumeBlockComment();
+  void ConsumeBlockComment(string* content);
+
+  enum NextCommentStatus {
+    // Started a line comment.
+    LINE_COMMENT,
+
+    // Started a block comment.
+    BLOCK_COMMENT,
+
+    // Consumed a slash, then realized it wasn't a comment.  current_ has
+    // been filled in with a slash token.  The caller should return it.
+    SLASH_NOT_COMMENT,
+
+    // We do not appear to be starting a comment here.
+    NO_COMMENT
+  };
+
+  // If we're at the start of a new comment, consume it and return what kind
+  // of comment it is.
+  NextCommentStatus TryConsumeCommentStart();
 
   // -----------------------------------------------------------------
   // These helper methods make the parsing code more readable.  The
diff --git a/src/google/protobuf/io/tokenizer_unittest.cc b/src/google/protobuf/io/tokenizer_unittest.cc
index 106d080f..8de43939 100644
--- a/src/google/protobuf/io/tokenizer_unittest.cc
+++ b/src/google/protobuf/io/tokenizer_unittest.cc
@@ -32,9 +32,10 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include <vector>
-#include <math.h>
 #include <limits.h>
+#include <math.h>
+
+#include <vector>
 
 #include <google/protobuf/io/tokenizer.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
@@ -514,6 +515,217 @@ TEST_1D(TokenizerTest, ShCommentStyle, kBlockSizes) {
 
 // -------------------------------------------------------------------
 
+// In each case, the input is expected to have two tokens named "prev" and
+// "next" with comments in between.
+struct DocCommentCase {
+  string input;
+
+  const char* prev_trailing_comments;
+  const char* detached_comments[10];
+  const char* next_leading_comments;
+};
+
+inline ostream& operator<<(ostream& out,
+                           const DocCommentCase& test_case) {
+  return out << CEscape(test_case.input);
+}
+
+DocCommentCase kDocCommentCases[] = {
+  {
+    "prev next",
+
+    "",
+    {},
+    ""
+      },
+
+        {
+      "prev /* ignored */ next",
+
+      "",
+      {},
+      ""
+        },
+
+          {
+        "prev // trailing comment\n"
+            "next",
+
+            " trailing comment\n",
+            {},
+            ""
+          },
+
+            {
+          "prev\n"
+              "// leading comment\n"
+              "// line 2\n"
+              "next",
+
+              "",
+              {},
+              " leading comment\n"
+              " line 2\n"
+            },
+
+              {
+            "prev\n"
+                "// trailing comment\n"
+                "// line 2\n"
+                "\n"
+                "next",
+
+                " trailing comment\n"
+                " line 2\n",
+                {},
+                ""
+              },
+
+                {
+              "prev // trailing comment\n"
+                  "// leading comment\n"
+                  "// line 2\n"
+                  "next",
+
+                  " trailing comment\n",
+                  {},
+                  " leading comment\n"
+                  " line 2\n"
+                },
+
+                  {
+                "prev /* trailing block comment */\n"
+                    "/* leading block comment\n"
+                    " * line 2\n"
+                    " * line 3 */"
+                    "next",
+
+                    " trailing block comment ",
+                    {},
+                    " leading block comment\n"
+                    " line 2\n"
+                    " line 3 "
+                  },
+
+                    {
+                  "prev\n"
+                      "/* trailing block comment\n"
+                      " * line 2\n"
+                      " * line 3\n"
+                      " */\n"
+                      "/* leading block comment\n"
+                      " * line 2\n"
+                      " * line 3 */"
+                      "next",
+
+                      " trailing block comment\n"
+                      " line 2\n"
+                      " line 3\n",
+                      {},
+                      " leading block comment\n"
+                      " line 2\n"
+                      " line 3 "
+                    },
+
+                      {
+                    "prev\n"
+                        "// trailing comment\n"
+                        "\n"
+                        "// detached comment\n"
+                        "// line 2\n"
+                        "\n"
+                        "// second detached comment\n"
+                        "/* third detached comment\n"
+                        " * line 2 */\n"
+                        "// leading comment\n"
+                        "next",
+
+                        " trailing comment\n",
+                        {
+                      " detached comment\n"
+                          " line 2\n",
+                          " second detached comment\n",
+                          " third detached comment\n"
+                          " line 2 "
+                        },
+                          " leading comment\n"
+                        },
+
+                          {
+                        "prev /**/\n"
+                            "\n"
+                            "// detached comment\n"
+                            "\n"
+                            "// leading comment\n"
+                            "next",
+
+                            "",
+                            {
+                          " detached comment\n"
+                            },
+                              " leading comment\n"
+                            },
+
+                              {
+                            "prev /**/\n"
+                                "// leading comment\n"
+                                "next",
+
+                                "",
+                                {},
+                                " leading comment\n"
+                              },
+                              };
+
+TEST_2D(TokenizerTest, DocComments, kDocCommentCases, kBlockSizes) {
+  // Set up the tokenizer.
+  TestInputStream input(kDocCommentCases_case.input.data(),
+                        kDocCommentCases_case.input.size(),
+                        kBlockSizes_case);
+  TestErrorCollector error_collector;
+  Tokenizer tokenizer(&input, &error_collector);
+
+  // Set up a second tokenizer where we'll pass all NULLs to NextWithComments().
+  TestInputStream input2(kDocCommentCases_case.input.data(),
+                        kDocCommentCases_case.input.size(),
+                        kBlockSizes_case);
+  Tokenizer tokenizer2(&input2, &error_collector);
+
+  tokenizer.Next();
+  tokenizer2.Next();
+
+  EXPECT_EQ("prev", tokenizer.current().text);
+  EXPECT_EQ("prev", tokenizer2.current().text);
+
+  string prev_trailing_comments;
+  vector<string> detached_comments;
+  string next_leading_comments;
+  tokenizer.NextWithComments(&prev_trailing_comments, &detached_comments,
+                             &next_leading_comments);
+  tokenizer2.NextWithComments(NULL, NULL, NULL);
+  EXPECT_EQ("next", tokenizer.current().text);
+  EXPECT_EQ("next", tokenizer2.current().text);
+
+  EXPECT_EQ(kDocCommentCases_case.prev_trailing_comments,
+            prev_trailing_comments);
+
+  for (int i = 0; i < detached_comments.size(); i++) {
+    ASSERT_LT(i, GOOGLE_ARRAYSIZE(kDocCommentCases));
+    ASSERT_TRUE(kDocCommentCases_case.detached_comments[i] != NULL);
+    EXPECT_EQ(kDocCommentCases_case.detached_comments[i],
+              detached_comments[i]);
+  }
+
+  // Verify that we matched all the detached comments.
+  EXPECT_EQ(NULL,
+      kDocCommentCases_case.detached_comments[detached_comments.size()]);
+
+  EXPECT_EQ(kDocCommentCases_case.next_leading_comments,
+            next_leading_comments);
+}
+
+// -------------------------------------------------------------------
+
 // Test parse helpers.  It's not really worth setting up a full data-driven
 // test here.
 TEST_F(TokenizerTest, ParseInteger) {
@@ -614,6 +826,22 @@ TEST_F(TokenizerTest, ParseString) {
   Tokenizer::ParseString("'\\", &output);
   EXPECT_EQ("\\", output);
 
+  // Experiment with Unicode escapes. Here are one-, two- and three-byte Unicode
+  // characters.
+  Tokenizer::ParseString("'\\u0024\\u00a2\\u20ac\\U00024b62XX'", &output);
+  EXPECT_EQ("$¢€𤭢XX", output);
+  // Same thing encoded using UTF16.
+  Tokenizer::ParseString("'\\u0024\\u00a2\\u20ac\\ud852\\udf62XX'", &output);
+  EXPECT_EQ("$¢€𤭢XX", output);
+  // Here's some broken UTF16; there's a head surrogate with no tail surrogate.
+  // We just output this as if it were UTF8; it's not a defined code point, but
+  // it has a defined encoding.
+  Tokenizer::ParseString("'\\ud852XX'", &output);
+  EXPECT_EQ("\xed\xa1\x92XX", output);
+  // Malformed escape: Demons may fly out of the nose.
+  Tokenizer::ParseString("\\u0", &output);
+  EXPECT_EQ("u0", output);
+
   // Test invalid strings that will never be tokenized as strings.
 #ifdef GTEST_HAS_DEATH_TEST  // death tests do not work on Windows yet
   EXPECT_DEBUG_DEATH(Tokenizer::ParseString("", &output),
@@ -658,6 +886,12 @@ ErrorCase kErrorCases[] = {
     "0:4: String literals cannot cross line boundaries.\n" },
   { "'bar\nfoo", true,
     "0:4: String literals cannot cross line boundaries.\n" },
+  { "'\\u01' foo", true,
+    "0:5: Expected four hex digits for \\u escape sequence.\n" },
+  { "'\\u01' foo", true,
+    "0:5: Expected four hex digits for \\u escape sequence.\n" },
+  { "'\\uXYZ' foo", true,
+    "0:3: Expected four hex digits for \\u escape sequence.\n" },
 
   // Integer errors.
   { "123foo", true,
@@ -734,7 +968,7 @@ TEST_2D(TokenizerTest, Errors, kErrorCases, kBlockSizes) {
   }
 
   // Check that the errors match what was expected.
-  EXPECT_EQ(error_collector.text_, kErrorCases_case.errors);
+  EXPECT_EQ(kErrorCases_case.errors, error_collector.text_);
 
   // If the error was recoverable, make sure we saw "foo" after it.
   if (kErrorCases_case.recoverable) {
@@ -760,6 +994,7 @@ TEST_1D(TokenizerTest, BackUpOnDestruction, kBlockSizes) {
   EXPECT_EQ(strlen("foo"), input.ByteCount());
 }
 
+
 }  // namespace
 }  // namespace io
 }  // namespace protobuf
diff --git a/src/google/protobuf/io/zero_copy_stream_impl.cc b/src/google/protobuf/io/zero_copy_stream_impl.cc
index 1384c746..9fcbb622 100644
--- a/src/google/protobuf/io/zero_copy_stream_impl.cc
+++ b/src/google/protobuf/io/zero_copy_stream_impl.cc
@@ -46,7 +46,8 @@
 
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
+
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/io/zero_copy_stream_impl_lite.cc b/src/google/protobuf/io/zero_copy_stream_impl_lite.cc
index e8012510..f552e1f8 100644
--- a/src/google/protobuf/io/zero_copy_stream_impl_lite.cc
+++ b/src/google/protobuf/io/zero_copy_stream_impl_lite.cc
@@ -32,9 +32,9 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/io/zero_copy_stream_unittest.cc b/src/google/protobuf/io/zero_copy_stream_unittest.cc
index 5196d905..6f155df7 100644
--- a/src/google/protobuf/io/zero_copy_stream_unittest.cc
+++ b/src/google/protobuf/io/zero_copy_stream_unittest.cc
@@ -370,6 +370,100 @@ TEST_F(IoTest, GzipIo) {
   delete [] buffer;
 }
 
+TEST_F(IoTest, GzipIoWithFlush) {
+  const int kBufferSize = 2*1024;
+  uint8* buffer = new uint8[kBufferSize];
+  // We start with i = 4 as we want a block size > 6. With block size <= 6
+  // Flush() fills up the entire 2K buffer with flush markers and the test
+  // fails. See documentation for Flush() for more detail.
+  for (int i = 4; i < kBlockSizeCount; i++) {
+    for (int j = 0; j < kBlockSizeCount; j++) {
+      for (int z = 0; z < kBlockSizeCount; z++) {
+        int gzip_buffer_size = kBlockSizes[z];
+        int size;
+        {
+          ArrayOutputStream output(buffer, kBufferSize, kBlockSizes[i]);
+          GzipOutputStream::Options options;
+          options.format = GzipOutputStream::GZIP;
+          if (gzip_buffer_size != -1) {
+            options.buffer_size = gzip_buffer_size;
+          }
+          GzipOutputStream gzout(&output, options);
+          WriteStuff(&gzout);
+          EXPECT_TRUE(gzout.Flush());
+          gzout.Close();
+          size = output.ByteCount();
+        }
+        {
+          ArrayInputStream input(buffer, size, kBlockSizes[j]);
+          GzipInputStream gzin(
+              &input, GzipInputStream::GZIP, gzip_buffer_size);
+          ReadStuff(&gzin);
+        }
+      }
+    }
+  }
+  delete [] buffer;
+}
+
+TEST_F(IoTest, GzipIoContiguousFlushes) {
+  const int kBufferSize = 2*1024;
+  uint8* buffer = new uint8[kBufferSize];
+
+  int block_size = kBlockSizes[4];
+  int gzip_buffer_size = block_size;
+  int size;
+
+  ArrayOutputStream output(buffer, kBufferSize, block_size);
+  GzipOutputStream::Options options;
+  options.format = GzipOutputStream::GZIP;
+  if (gzip_buffer_size != -1) {
+    options.buffer_size = gzip_buffer_size;
+  }
+  GzipOutputStream gzout(&output, options);
+  WriteStuff(&gzout);
+  EXPECT_TRUE(gzout.Flush());
+  EXPECT_TRUE(gzout.Flush());
+  gzout.Close();
+  size = output.ByteCount();
+
+  ArrayInputStream input(buffer, size, block_size);
+  GzipInputStream gzin(
+      &input, GzipInputStream::GZIP, gzip_buffer_size);
+  ReadStuff(&gzin);
+
+  delete [] buffer;
+}
+
+TEST_F(IoTest, GzipIoReadAfterFlush) {
+  const int kBufferSize = 2*1024;
+  uint8* buffer = new uint8[kBufferSize];
+
+  int block_size = kBlockSizes[4];
+  int gzip_buffer_size = block_size;
+  int size;
+  ArrayOutputStream output(buffer, kBufferSize, block_size);
+  GzipOutputStream::Options options;
+  options.format = GzipOutputStream::GZIP;
+  if (gzip_buffer_size != -1) {
+    options.buffer_size = gzip_buffer_size;
+  }
+
+  GzipOutputStream gzout(&output, options);
+  WriteStuff(&gzout);
+  EXPECT_TRUE(gzout.Flush());
+  size = output.ByteCount();
+
+  ArrayInputStream input(buffer, size, block_size);
+  GzipInputStream gzin(
+      &input, GzipInputStream::GZIP, gzip_buffer_size);
+  ReadStuff(&gzin);
+
+  gzout.Close();
+
+  delete [] buffer;
+}
+
 TEST_F(IoTest, ZlibIo) {
   const int kBufferSize = 2*1024;
   uint8* buffer = new uint8[kBufferSize];
diff --git a/src/google/protobuf/lite_unittest.cc b/src/google/protobuf/lite_unittest.cc
index ffeec3c4..7a0a57b7 100644
--- a/src/google/protobuf/lite_unittest.cc
+++ b/src/google/protobuf/lite_unittest.cc
@@ -33,11 +33,32 @@
 #include <string>
 #include <iostream>
 
-#include <google/protobuf/test_util_lite.h>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/test_util_lite.h>
+#include <google/protobuf/unittest_lite.pb.h>
 
 using namespace std;
 
+namespace {
+// Helper methods to test parsing merge behavior.
+void ExpectMessageMerged(const google::protobuf::unittest::TestAllTypesLite& message) {
+  GOOGLE_CHECK(message.optional_int32() == 3);
+  GOOGLE_CHECK(message.optional_int64() == 2);
+  GOOGLE_CHECK(message.optional_string() == "hello");
+}
+
+void AssignParsingMergeMessages(
+    google::protobuf::unittest::TestAllTypesLite* msg1,
+    google::protobuf::unittest::TestAllTypesLite* msg2,
+    google::protobuf::unittest::TestAllTypesLite* msg3) {
+  msg1->set_optional_int32(1);
+  msg2->set_optional_int64(2);
+  msg3->set_optional_int32(3);
+  msg3->set_optional_string("hello");
+}
+
+}  // namespace
+
 int main(int argc, char* argv[]) {
   string data, packed_data;
 
@@ -107,6 +128,58 @@ int main(int argc, char* argv[]) {
     google::protobuf::TestUtilLite::ExpectPackedExtensionsClear(message);
   }
 
+  {
+    // Test that if an optional or required message/group field appears multiple
+    // times in the input, they need to be merged.
+    google::protobuf::unittest::TestParsingMergeLite::RepeatedFieldsGenerator generator;
+    google::protobuf::unittest::TestAllTypesLite* msg1;
+    google::protobuf::unittest::TestAllTypesLite* msg2;
+    google::protobuf::unittest::TestAllTypesLite* msg3;
+
+#define ASSIGN_REPEATED_FIELD(FIELD)                \
+  msg1 = generator.add_##FIELD();                   \
+  msg2 = generator.add_##FIELD();                   \
+  msg3 = generator.add_##FIELD();                   \
+  AssignParsingMergeMessages(msg1, msg2, msg3)
+
+    ASSIGN_REPEATED_FIELD(field1);
+    ASSIGN_REPEATED_FIELD(field2);
+    ASSIGN_REPEATED_FIELD(field3);
+    ASSIGN_REPEATED_FIELD(ext1);
+    ASSIGN_REPEATED_FIELD(ext2);
+
+#undef ASSIGN_REPEATED_FIELD
+#define ASSIGN_REPEATED_GROUP(FIELD)                \
+  msg1 = generator.add_##FIELD()->mutable_field1(); \
+  msg2 = generator.add_##FIELD()->mutable_field1(); \
+  msg3 = generator.add_##FIELD()->mutable_field1(); \
+  AssignParsingMergeMessages(msg1, msg2, msg3)
+
+    ASSIGN_REPEATED_GROUP(group1);
+    ASSIGN_REPEATED_GROUP(group2);
+
+#undef ASSIGN_REPEATED_GROUP
+
+    string buffer;
+    generator.SerializeToString(&buffer);
+    google::protobuf::unittest::TestParsingMergeLite parsing_merge;
+    parsing_merge.ParseFromString(buffer);
+
+    // Required and optional fields should be merged.
+    ExpectMessageMerged(parsing_merge.required_all_types());
+    ExpectMessageMerged(parsing_merge.optional_all_types());
+    ExpectMessageMerged(
+        parsing_merge.optionalgroup().optional_group_all_types());
+    ExpectMessageMerged(parsing_merge.GetExtension(
+        google::protobuf::unittest::TestParsingMergeLite::optional_ext));
+
+    // Repeated fields should not be merged.
+    GOOGLE_CHECK(parsing_merge.repeated_all_types_size() == 3);
+    GOOGLE_CHECK(parsing_merge.repeatedgroup_size() == 3);
+    GOOGLE_CHECK(parsing_merge.ExtensionSize(
+        google::protobuf::unittest::TestParsingMergeLite::repeated_ext) == 3);
+  }
+
   cout << "PASS" << endl;
   return 0;
 }
diff --git a/src/google/protobuf/message.cc b/src/google/protobuf/message.cc
index 91e6878e..6119d26a 100644
--- a/src/google/protobuf/message.cc
+++ b/src/google/protobuf/message.cc
@@ -43,11 +43,12 @@
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/generated_message_util.h>
 #include <google/protobuf/reflection_ops.h>
 #include <google/protobuf/wire_format.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/map-util.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -181,9 +182,46 @@ bool Message::SerializePartialToOstream(ostream* output) const {
 }
 
 
+// =============================================================================
+// Reflection and associated Template Specializations
+
 Reflection::~Reflection() {}
 
-// ===================================================================
+#define HANDLE_TYPE(TYPE, CPPTYPE, CTYPE)                             \
+template<>                                                            \
+const RepeatedField<TYPE>& Reflection::GetRepeatedField<TYPE>(        \
+    const Message& message, const FieldDescriptor* field) const {     \
+  return *static_cast<RepeatedField<TYPE>* >(                         \
+      MutableRawRepeatedField(const_cast<Message*>(&message),         \
+                          field, CPPTYPE, CTYPE, NULL));              \
+}                                                                     \
+                                                                      \
+template<>                                                            \
+RepeatedField<TYPE>* Reflection::MutableRepeatedField<TYPE>(          \
+    Message* message, const FieldDescriptor* field) const {           \
+  return static_cast<RepeatedField<TYPE>* >(                          \
+      MutableRawRepeatedField(message, field, CPPTYPE, CTYPE, NULL)); \
+}
+
+HANDLE_TYPE(int32,  FieldDescriptor::CPPTYPE_INT32,  -1);
+HANDLE_TYPE(int64,  FieldDescriptor::CPPTYPE_INT64,  -1);
+HANDLE_TYPE(uint32, FieldDescriptor::CPPTYPE_UINT32, -1);
+HANDLE_TYPE(uint64, FieldDescriptor::CPPTYPE_UINT64, -1);
+HANDLE_TYPE(float,  FieldDescriptor::CPPTYPE_FLOAT,  -1);
+HANDLE_TYPE(double, FieldDescriptor::CPPTYPE_DOUBLE, -1);
+HANDLE_TYPE(bool,   FieldDescriptor::CPPTYPE_BOOL,   -1);
+
+
+#undef HANDLE_TYPE
+
+void* Reflection::MutableRawRepeatedString(
+    Message* message, const FieldDescriptor* field, bool is_string) const {
+  return MutableRawRepeatedField(message, field,
+      FieldDescriptor::CPPTYPE_STRING, FieldOptions::STRING, NULL);
+}
+
+
+// =============================================================================
 // MessageFactory
 
 MessageFactory::~MessageFactory() {}
@@ -257,6 +295,7 @@ void GeneratedMessageFactory::RegisterType(const Descriptor* descriptor,
   }
 }
 
+
 const Message* GeneratedMessageFactory::GetPrototype(const Descriptor* type) {
   {
     ReaderMutexLock lock(&mutex_);
diff --git a/src/google/protobuf/message.h b/src/google/protobuf/message.h
index 4bbc6418..77faa9a7 100644
--- a/src/google/protobuf/message.h
+++ b/src/google/protobuf/message.h
@@ -79,18 +79,19 @@
 //     // Same as the last block, but do it dynamically via the Message
 //     // reflection interface.
 //     Message* foo = new Foo;
-//     Descriptor* descriptor = foo->GetDescriptor();
+//     const Descriptor* descriptor = foo->GetDescriptor();
 //
 //     // Get the descriptors for the fields we're interested in and verify
 //     // their types.
-//     FieldDescriptor* text_field = descriptor->FindFieldByName("text");
+//     const FieldDescriptor* text_field = descriptor->FindFieldByName("text");
 //     assert(text_field != NULL);
 //     assert(text_field->type() == FieldDescriptor::TYPE_STRING);
-//     assert(text_field->label() == FieldDescriptor::TYPE_OPTIONAL);
-//     FieldDescriptor* numbers_field = descriptor->FindFieldByName("numbers");
+//     assert(text_field->label() == FieldDescriptor::LABEL_OPTIONAL);
+//     const FieldDescriptor* numbers_field = descriptor->
+//                                            FindFieldByName("numbers");
 //     assert(numbers_field != NULL);
 //     assert(numbers_field->type() == FieldDescriptor::TYPE_INT32);
-//     assert(numbers_field->label() == FieldDescriptor::TYPE_REPEATED);
+//     assert(numbers_field->label() == FieldDescriptor::LABEL_REPEATED);
 //
 //     // Parse the message.
 //     foo->ParseFromString(data);
@@ -122,6 +123,7 @@
 #include <google/protobuf/message_lite.h>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/descriptor.h>
 
 
 namespace google {
@@ -133,17 +135,20 @@ class Reflection;
 class MessageFactory;
 
 // Defined in other files.
-class Descriptor;            // descriptor.h
-class FieldDescriptor;       // descriptor.h
-class EnumDescriptor;        // descriptor.h
-class EnumValueDescriptor;   // descriptor.h
+class UnknownFieldSet;         // unknown_field_set.h
 namespace io {
   class ZeroCopyInputStream;   // zero_copy_stream.h
   class ZeroCopyOutputStream;  // zero_copy_stream.h
   class CodedInputStream;      // coded_stream.h
   class CodedOutputStream;     // coded_stream.h
 }
-class UnknownFieldSet;       // unknown_field_set.h
+
+
+template<typename T>
+class RepeatedField;     // repeated_field.h
+
+template<typename T>
+class RepeatedPtrField;  // repeated_field.h
 
 // A container to hold message metadata.
 struct Metadata {
@@ -151,12 +156,6 @@ struct Metadata {
   const Reflection* reflection;
 };
 
-// Returns the EnumDescriptor for enum type E, which must be a
-// proto-declared enum type.  Code generated by the protocol compiler
-// will include specializations of this template for each enum type declared.
-template <typename E>
-const EnumDescriptor* GetEnumDescriptor();
-
 // Abstract interface for protocol messages.
 //
 // See also MessageLite, which contains most every-day operations.  Message
@@ -360,7 +359,6 @@ class LIBPROTOBUF_EXPORT Message : public MessageLite {
 //   write fields from a Reflection without paying attention to the type.
 class LIBPROTOBUF_EXPORT Reflection {
  public:
-  // TODO(kenton):  Remove parameter.
   inline Reflection() {}
   virtual ~Reflection();
 
@@ -390,7 +388,7 @@ class LIBPROTOBUF_EXPORT Reflection {
   virtual void ClearField(Message* message,
                           const FieldDescriptor* field) const = 0;
 
-  // Remove the last element of a repeated field.
+  // Removes the last element of a repeated field.
   // We don't provide a way to remove any element other than the last
   // because it invites inefficient use, such as O(n^2) filtering loops
   // that should have been O(n).  If you want to remove an element other
@@ -399,6 +397,10 @@ class LIBPROTOBUF_EXPORT Reflection {
   // call RemoveLast().
   virtual void RemoveLast(Message* message,
                           const FieldDescriptor* field) const = 0;
+  // Removes the last element of a repeated message field, and returns the
+  // pointer to the caller.  Caller takes ownership of the returned pointer.
+  virtual Message* ReleaseLast(Message* message,
+                               const FieldDescriptor* field) const = 0;
 
   // Swap the complete contents of two messages.
   virtual void Swap(Message* message1, Message* message2) const = 0;
@@ -500,6 +502,16 @@ class LIBPROTOBUF_EXPORT Reflection {
   virtual Message* MutableMessage(Message* message,
                                   const FieldDescriptor* field,
                                   MessageFactory* factory = NULL) const = 0;
+  // Releases the message specified by 'field' and returns the pointer,
+  // ReleaseMessage() will return the message the message object if it exists.
+  // Otherwise, it may or may not return NULL.  In any case, if the return value
+  // is non-NULL, the caller takes ownership of the pointer.
+  // If the field existed (HasField() is true), then the returned pointer will
+  // be the same as the pointer returned by MutableMessage().
+  // This function has the same effect as ClearField().
+  virtual Message* ReleaseMessage(Message* message,
+                                  const FieldDescriptor* field,
+                                  MessageFactory* factory = NULL) const = 0;
 
 
   // Repeated field getters ------------------------------------------
@@ -607,7 +619,39 @@ class LIBPROTOBUF_EXPORT Reflection {
                               MessageFactory* factory = NULL) const = 0;
 
 
-  // Extensions ------------------------------------------------------
+  // Repeated field accessors  -------------------------------------------------
+  // The methods above, e.g. GetRepeatedInt32(msg, fd, index), provide singular
+  // access to the data in a RepeatedField.  The methods below provide aggregate
+  // access by exposing the RepeatedField object itself with the Message.
+  // Applying these templates to inappropriate types will lead to an undefined
+  // reference at link time (e.g. GetRepeatedField<***double>), or possibly a
+  // template matching error at compile time (e.g. GetRepeatedPtrField<File>).
+  //
+  // Usage example: my_doubs = refl->GetRepeatedField<double>(msg, fd);
+
+  // for T = Cord and all protobuf scalar types except enums.
+  template<typename T>
+  const RepeatedField<T>& GetRepeatedField(
+      const Message&, const FieldDescriptor*) const;
+
+  // for T = Cord and all protobuf scalar types except enums.
+  template<typename T>
+  RepeatedField<T>* MutableRepeatedField(
+      Message*, const FieldDescriptor*) const;
+
+  // for T = string, google::protobuf::internal::StringPieceField
+  //         google::protobuf::Message & descendants.
+  template<typename T>
+  const RepeatedPtrField<T>& GetRepeatedPtrField(
+      const Message&, const FieldDescriptor*) const;
+
+  // for T = string, google::protobuf::internal::StringPieceField
+  //         google::protobuf::Message & descendants.
+  template<typename T>
+  RepeatedPtrField<T>* MutableRepeatedPtrField(
+      Message*, const FieldDescriptor*) const;
+
+  // Extensions ----------------------------------------------------------------
 
   // Try to find an extension of this message type by fully-qualified field
   // name.  Returns NULL if no extension is known for this name or number.
@@ -619,7 +663,26 @@ class LIBPROTOBUF_EXPORT Reflection {
   virtual const FieldDescriptor* FindKnownExtensionByNumber(
       int number) const = 0;
 
+  // ---------------------------------------------------------------------------
+
+ protected:
+  // Obtain a pointer to a Repeated Field Structure and do some type checking:
+  //   on field->cpp_type(),
+  //   on field->field_option().ctype() (if ctype >= 0)
+  //   of field->message_type() (if message_type != NULL).
+  // We use 1 routine rather than 4 (const vs mutable) x (scalar vs pointer).
+  virtual void* MutableRawRepeatedField(
+      Message* message, const FieldDescriptor* field, FieldDescriptor::CppType,
+      int ctype, const Descriptor* message_type) const = 0;
+
  private:
+  // Special version for specialized implementations of string.  We can't call
+  // MutableRawRepeatedField directly here because we don't have access to
+  // FieldOptions::* which are defined in descriptor.pb.h.  Including that
+  // file here is not possible because it would cause a circular include cycle.
+  void* MutableRawRepeatedString(
+      Message* message, const FieldDescriptor* field, bool is_string) const;
+
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Reflection);
 };
 
@@ -682,10 +745,71 @@ class LIBPROTOBUF_EXPORT MessageFactory {
   static void InternalRegisterGeneratedMessage(const Descriptor* descriptor,
                                                const Message* prototype);
 
+
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageFactory);
 };
 
+// =============================================================================
+// Implementation details for {Get,Mutable}RawRepeatedPtrField.  We provide
+// specializations for <string>, <StringPieceField> and <Message> and handle
+// everything else with the default template which will match any type having
+// a method with signature "static const google::protobuf::Descriptor* descriptor()".
+// Such a type presumably is a descendant of google::protobuf::Message.
+
+template<>
+inline const RepeatedPtrField<string>& Reflection::GetRepeatedPtrField<string>(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<RepeatedPtrField<string>* >(
+      MutableRawRepeatedString(const_cast<Message*>(&message), field, true));
+}
+
+template<>
+inline RepeatedPtrField<string>* Reflection::MutableRepeatedPtrField<string>(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<string>* >(
+      MutableRawRepeatedString(message, field, true));
+}
+
+
+// -----
+
+template<>
+inline const RepeatedPtrField<Message>& Reflection::GetRepeatedPtrField(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<RepeatedPtrField<Message>* >(
+      MutableRawRepeatedField(const_cast<Message*>(&message), field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          NULL));
+}
+
+template<>
+inline RepeatedPtrField<Message>* Reflection::MutableRepeatedPtrField(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<Message>* >(
+      MutableRawRepeatedField(message, field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          NULL));
+}
+
+template<typename PB>
+inline const RepeatedPtrField<PB>& Reflection::GetRepeatedPtrField(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<RepeatedPtrField<PB>* >(
+      MutableRawRepeatedField(const_cast<Message*>(&message), field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          PB::default_instance().GetDescriptor()));
+}
+
+template<typename PB>
+inline RepeatedPtrField<PB>* Reflection::MutableRepeatedPtrField(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<PB>* >(
+      MutableRawRepeatedField(message, field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          PB::default_instance().GetDescriptor()));
+}
+
 }  // namespace protobuf
 
 }  // namespace google
diff --git a/src/google/protobuf/message_lite.cc b/src/google/protobuf/message_lite.cc
index 7c8f37dc..49dbe6e0 100644
--- a/src/google/protobuf/message_lite.cc
+++ b/src/google/protobuf/message_lite.cc
@@ -37,8 +37,8 @@
 #include <string>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/io/coded_stream.h>
-#include <google/protobuf/io/zero_copy_stream_impl.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/message_lite.h b/src/google/protobuf/message_lite.h
index ebf4ba3c..1ec3068c 100644
--- a/src/google/protobuf/message_lite.h
+++ b/src/google/protobuf/message_lite.h
@@ -40,11 +40,17 @@
 #define GOOGLE_PROTOBUF_MESSAGE_LITE_H__
 
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/io/coded_stream.h>
 
 namespace google {
 namespace protobuf {
 
+namespace io {
+  class CodedInputStream;
+  class CodedOutputStream;
+  class ZeroCopyInputStream;
+  class ZeroCopyOutputStream;
+}
+
 // Interface to light weight protocol messages.
 //
 // This interface is implemented by all protocol message objects.  Non-lite
@@ -158,6 +164,7 @@ class LIBPROTOBUF_EXPORT MessageLite {
   // followed by IsInitialized().
   virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0;
 
+
   // Serialization ---------------------------------------------------
   // Methods for serializing in protocol buffer format.  Most of these
   // are just simple wrappers around ByteSize() and SerializeWithCachedSizes().
diff --git a/src/google/protobuf/message_unittest.cc b/src/google/protobuf/message_unittest.cc
index 33b9e77c..8aaeabb4 100644
--- a/src/google/protobuf/message_unittest.cc
+++ b/src/google/protobuf/message_unittest.cc
@@ -257,6 +257,78 @@ TEST(MessageTest, ParseFailsOnInvalidMessageEnd) {
   EXPECT_FALSE(message.ParseFromArray("\014", 1));
 }
 
+namespace {
+
+void ExpectMessageMerged(const unittest::TestAllTypes& message) {
+  EXPECT_EQ(3, message.optional_int32());
+  EXPECT_EQ(2, message.optional_int64());
+  EXPECT_EQ("hello", message.optional_string());
+}
+
+void AssignParsingMergeMessages(
+    unittest::TestAllTypes* msg1,
+    unittest::TestAllTypes* msg2,
+    unittest::TestAllTypes* msg3) {
+  msg1->set_optional_int32(1);
+  msg2->set_optional_int64(2);
+  msg3->set_optional_int32(3);
+  msg3->set_optional_string("hello");
+}
+
+}  // namespace
+
+// Test that if an optional or required message/group field appears multiple
+// times in the input, they need to be merged.
+TEST(MessageTest, ParsingMerge) {
+  unittest::TestParsingMerge::RepeatedFieldsGenerator generator;
+  unittest::TestAllTypes* msg1;
+  unittest::TestAllTypes* msg2;
+  unittest::TestAllTypes* msg3;
+
+#define ASSIGN_REPEATED_FIELD(FIELD)                \
+  msg1 = generator.add_##FIELD();                   \
+  msg2 = generator.add_##FIELD();                   \
+  msg3 = generator.add_##FIELD();                   \
+  AssignParsingMergeMessages(msg1, msg2, msg3)
+
+  ASSIGN_REPEATED_FIELD(field1);
+  ASSIGN_REPEATED_FIELD(field2);
+  ASSIGN_REPEATED_FIELD(field3);
+  ASSIGN_REPEATED_FIELD(ext1);
+  ASSIGN_REPEATED_FIELD(ext2);
+
+#undef ASSIGN_REPEATED_FIELD
+#define ASSIGN_REPEATED_GROUP(FIELD)                \
+  msg1 = generator.add_##FIELD()->mutable_field1(); \
+  msg2 = generator.add_##FIELD()->mutable_field1(); \
+  msg3 = generator.add_##FIELD()->mutable_field1(); \
+  AssignParsingMergeMessages(msg1, msg2, msg3)
+
+  ASSIGN_REPEATED_GROUP(group1);
+  ASSIGN_REPEATED_GROUP(group2);
+
+#undef ASSIGN_REPEATED_GROUP
+
+  string buffer;
+  generator.SerializeToString(&buffer);
+  unittest::TestParsingMerge parsing_merge;
+  parsing_merge.ParseFromString(buffer);
+
+  // Required and optional fields should be merged.
+  ExpectMessageMerged(parsing_merge.required_all_types());
+  ExpectMessageMerged(parsing_merge.optional_all_types());
+  ExpectMessageMerged(
+      parsing_merge.optionalgroup().optional_group_all_types());
+  ExpectMessageMerged(
+      parsing_merge.GetExtension(unittest::TestParsingMerge::optional_ext));
+
+  // Repeated fields should not be merged.
+  EXPECT_EQ(3, parsing_merge.repeated_all_types_size());
+  EXPECT_EQ(3, parsing_merge.repeatedgroup_size());
+  EXPECT_EQ(3, parsing_merge.ExtensionSize(
+      unittest::TestParsingMerge::repeated_ext));
+}
+
 TEST(MessageFactoryTest, GeneratedFactoryLookup) {
   EXPECT_EQ(
     MessageFactory::generated_factory()->GetPrototype(
@@ -277,5 +349,6 @@ TEST(MessageFactoryTest, GeneratedFactoryUnknownType) {
     MessageFactory::generated_factory()->GetPrototype(descriptor) == NULL);
 }
 
+
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/reflection_ops.cc b/src/google/protobuf/reflection_ops.cc
index 897c0d7c..f00997c6 100644
--- a/src/google/protobuf/reflection_ops.cc
+++ b/src/google/protobuf/reflection_ops.cc
@@ -32,8 +32,12 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
+#include <string>
+#include <vector>
+
 #include <google/protobuf/reflection_ops.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/unknown_field_set.h>
 #include <google/protobuf/stubs/strutil.h>
 
@@ -151,11 +155,12 @@ bool ReflectionOps::IsInitialized(const Message& message) {
   for (int i = 0; i < fields.size(); i++) {
     const FieldDescriptor* field = fields[i];
     if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+
       if (field->is_repeated()) {
         int size = reflection->FieldSize(message, field);
 
-        for (int i = 0; i < size; i++) {
-          if (!reflection->GetRepeatedMessage(message, field, i)
+        for (int j = 0; j < size; j++) {
+          if (!reflection->GetRepeatedMessage(message, field, j)
                           .IsInitialized()) {
             return false;
           }
@@ -183,8 +188,8 @@ void ReflectionOps::DiscardUnknownFields(Message* message) {
     if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       if (field->is_repeated()) {
         int size = reflection->FieldSize(*message, field);
-        for (int i = 0; i < size; i++) {
-          reflection->MutableRepeatedMessage(message, field, i)
+        for (int j = 0; j < size; j++) {
+          reflection->MutableRepeatedMessage(message, field, j)
                     ->DiscardUnknownFields();
         }
       } else {
@@ -240,11 +245,11 @@ void ReflectionOps::FindInitializationErrors(
       if (field->is_repeated()) {
         int size = reflection->FieldSize(message, field);
 
-        for (int i = 0; i < size; i++) {
+        for (int j = 0; j < size; j++) {
           const Message& sub_message =
-            reflection->GetRepeatedMessage(message, field, i);
+            reflection->GetRepeatedMessage(message, field, j);
           FindInitializationErrors(sub_message,
-                                   SubMessagePrefix(prefix, field, i),
+                                   SubMessagePrefix(prefix, field, j),
                                    errors);
         }
       } else {
diff --git a/src/google/protobuf/reflection_ops.h b/src/google/protobuf/reflection_ops.h
index 355a0a5d..60165c2a 100644
--- a/src/google/protobuf/reflection_ops.h
+++ b/src/google/protobuf/reflection_ops.h
@@ -38,6 +38,7 @@
 #ifndef GOOGLE_PROTOBUF_REFLECTION_OPS_H__
 #define GOOGLE_PROTOBUF_REFLECTION_OPS_H__
 
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/message.h>
 
 namespace google {
diff --git a/src/google/protobuf/repeated_field.cc b/src/google/protobuf/repeated_field.cc
index 09377742..87ce28c8 100644
--- a/src/google/protobuf/repeated_field.cc
+++ b/src/google/protobuf/repeated_field.cc
@@ -46,7 +46,8 @@ void RepeatedPtrFieldBase::Reserve(int new_size) {
   if (total_size_ >= new_size) return;
 
   void** old_elements = elements_;
-  total_size_ = max(total_size_ * 2, new_size);
+  total_size_ = max(kMinRepeatedFieldAllocationSize,
+                    max(total_size_ * 2, new_size));
   elements_ = new void*[total_size_];
   memcpy(elements_, old_elements, allocated_size_ * sizeof(elements_[0]));
   if (old_elements != initial_space_) {
@@ -55,6 +56,7 @@ void RepeatedPtrFieldBase::Reserve(int new_size) {
 }
 
 void RepeatedPtrFieldBase::Swap(RepeatedPtrFieldBase* other) {
+  if (this == other) return;
   void** swap_elements       = elements_;
   int    swap_current_size   = current_size_;
   int    swap_allocated_size = allocated_size_;
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h
index aed4ce9f..f0032e7d 100644
--- a/src/google/protobuf/repeated_field.h
+++ b/src/google/protobuf/repeated_field.h
@@ -46,24 +46,35 @@
 #ifndef GOOGLE_PROTOBUF_REPEATED_FIELD_H__
 #define GOOGLE_PROTOBUF_REPEATED_FIELD_H__
 
+#include <algorithm>
 #include <string>
 #include <iterator>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/type_traits.h>
+#include <google/protobuf/generated_message_util.h>
 #include <google/protobuf/message_lite.h>
 
 namespace google {
 
+namespace upb {
+namespace proto2_bridge_opensource {
+class FieldAccessor;
+}  // namespace protobuf_bridge_opensource
+}  // namespace upb
+
 namespace protobuf {
 
 class Message;
 
 namespace internal {
 
-// We need this (from generated_message_reflection.cc).
-LIBPROTOBUF_EXPORT int StringSpaceUsedExcludingSelf(const string& str);
+static const int kMinRepeatedFieldAllocationSize = 4;
 
+// A utility function for logging that doesn't need any template types.
+void LogIndexOutOfBounds(int index, int size);
 }  // namespace internal
 
+
 // RepeatedField is used to represent repeated fields of a primitive type (in
 // other words, everything except strings and nested Messages).  Most users will
 // not ever use a RepeatedField directly; they will use the get-by-index,
@@ -73,6 +84,8 @@ class RepeatedField {
  public:
   RepeatedField();
   RepeatedField(const RepeatedField& other);
+  template <typename Iter>
+  RepeatedField(Iter begin, const Iter& end);
   ~RepeatedField();
 
   RepeatedField& operator=(const RepeatedField& other);
@@ -85,12 +98,14 @@ class RepeatedField {
   void Add(const Element& value);
   Element* Add();
   // Remove the last element in the array.
-  // We don't provide a way to remove any element other than the last
-  // because it invites inefficient use, such as O(n^2) filtering loops
-  // that should have been O(n).  If you want to remove an element other
-  // than the last, the best way to do it is to re-arrange the elements
-  // so that the one you want removed is at the end, then call RemoveLast().
   void RemoveLast();
+
+  // Extract elements with indices in "[start .. start+num-1]".
+  // Copy them into "elements[0 .. num-1]" if "elements" is not NULL.
+  // Caution: implementation also moves elements with indices [start+num ..].
+  // Calling this routine inside a loop can cause quadratic behavior.
+  void ExtractSubrange(int start, int num, Element* elements);
+
   void Clear();
   void MergeFrom(const RepeatedField& other);
   void CopyFrom(const RepeatedField& other);
@@ -121,25 +136,49 @@ class RepeatedField {
   typedef Element* iterator;
   typedef const Element* const_iterator;
   typedef Element value_type;
+  typedef value_type& reference;
+  typedef const value_type& const_reference;
+  typedef value_type* pointer;
+  typedef const value_type* const_pointer;
+  typedef int size_type;
+  typedef ptrdiff_t difference_type;
 
   iterator begin();
   const_iterator begin() const;
   iterator end();
   const_iterator end() const;
 
+  // Reverse iterator support
+  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+  typedef std::reverse_iterator<iterator> reverse_iterator;
+  reverse_iterator rbegin() {
+    return reverse_iterator(end());
+  }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(end());
+  }
+  reverse_iterator rend() {
+    return reverse_iterator(begin());
+  }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(begin());
+  }
+
   // Returns the number of bytes used by the repeated field, excluding
   // sizeof(*this)
   int SpaceUsedExcludingSelf() const;
 
  private:
-  static const int kInitialSize = 4;
+  static const int kInitialSize = 0;
+
+  // This cannot be the last attribute defined if kInitialSize is 0 or
+  // the checks elements_ != initial_space_ to delete are not valid.
+  Element  initial_space_[kInitialSize];
 
   Element* elements_;
   int      current_size_;
   int      total_size_;
 
-  Element  initial_space_[kInitialSize];
-
   // Move the contents of |from| into |to|, possibly clobbering |from| in the
   // process.  For primitive types this is just a memcpy(), but it could be
   // specialized for non-primitive types to, say, swap each element instead.
@@ -151,7 +190,21 @@ class RepeatedField {
 
 namespace internal {
 template <typename It> class RepeatedPtrIterator;
-template <typename It> class RepeatedPtrOverPtrsIterator;
+template <typename It, typename VoidPtr> class RepeatedPtrOverPtrsIterator;
+}  // namespace internal
+
+namespace internal {
+
+// This is a helper template to copy an array of elements effeciently when they
+// have a trivial copy constructor, and correctly otherwise. This really
+// shouldn't be necessary, but our compiler doesn't optimize std::copy very
+// effectively.
+template <typename Element,
+          bool HasTrivialCopy = has_trivial_copy<Element>::value>
+struct ElementCopier {
+  void operator()(Element to[], const Element from[], int array_size);
+};
+
 }  // namespace internal
 
 namespace internal {
@@ -186,6 +239,10 @@ class LIBPROTOBUF_EXPORT RepeatedPtrFieldBase {
   // use of AddFromCleared(), which is not part of the public interface.
   friend class ExtensionSet;
 
+  // To parse directly into a proto2 generated class, the upb FieldAccessor
+  // needs to be able to modify a RepeatedPtrFieldBase directly.
+  friend class LIBPROTOBUF_EXPORT upb::proto2_bridge_opensource::FieldAccessor;
+
   RepeatedPtrFieldBase();
 
   // Must be called from destructor.
@@ -209,6 +266,14 @@ class LIBPROTOBUF_EXPORT RepeatedPtrFieldBase {
   template <typename TypeHandler>
   void CopyFrom(const RepeatedPtrFieldBase& other);
 
+  void CloseGap(int start, int num) {
+    // Close up a gap of "num" elements starting at offset "start".
+    for (int i = start + num; i < allocated_size_; ++i)
+      elements_[i - num] = elements_[i];
+    current_size_ -= num;
+    allocated_size_ -= num;
+  }
+
   void Reserve(int new_size);
 
   int Capacity() const;
@@ -250,15 +315,17 @@ class LIBPROTOBUF_EXPORT RepeatedPtrFieldBase {
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(RepeatedPtrFieldBase);
 
-  static const int kInitialSize = 4;
+  static const int kInitialSize = 0;
+
+  // This cannot be the last attribute defined if kInitialSize is 0 or
+  // the checks elements_ != initial_space_ to delete are not valid.
+  void*  initial_space_[kInitialSize];
 
   void** elements_;
   int    current_size_;
   int    allocated_size_;
   int    total_size_;
 
-  void*  initial_space_[kInitialSize];
-
   template <typename TypeHandler>
   static inline typename TypeHandler::Type* cast(void* element) {
     return reinterpret_cast<typename TypeHandler::Type*>(element);
@@ -280,6 +347,7 @@ class GenericTypeHandler {
     to->MergeFrom(from);
   }
   static int SpaceUsed(const GenericType& value) { return value.SpaceUsed(); }
+  static const Type& default_instance() { return Type::default_instance(); }
 };
 
 template <>
@@ -288,6 +356,25 @@ inline void GenericTypeHandler<MessageLite>::Merge(
   to->CheckTypeAndMergeFrom(from);
 }
 
+template <>
+inline const MessageLite& GenericTypeHandler<MessageLite>::default_instance() {
+  // Yes, the behavior of the code is undefined, but this function is only
+  // called when we're already deep into the world of undefined, because the
+  // caller called Get(index) out of bounds.
+  MessageLite* null = NULL;
+  return *null;
+}
+
+template <>
+inline const Message& GenericTypeHandler<Message>::default_instance() {
+  // Yes, the behavior of the code is undefined, but this function is only
+  // called when we're already deep into the world of undefined, because the
+  // caller called Get(index) out of bounds.
+  Message* null = NULL;
+  return *null;
+}
+
+
 // HACK:  If a class is declared as DLL-exported in MSVC, it insists on
 //   generating copies of all its methods -- even inline ones -- to include
 //   in the DLL.  But SpaceUsed() calls StringSpaceUsedExcludingSelf() which
@@ -303,6 +390,9 @@ class LIBPROTOBUF_EXPORT StringTypeHandlerBase {
   static void Delete(string* value);
   static void Clear(string* value) { value->clear(); }
   static void Merge(const string& from, string* to) { *to = from; }
+  static const Type& default_instance() {
+    return ::google::protobuf::internal::kEmptyString;
+  }
 };
 
 class StringTypeHandler : public StringTypeHandlerBase {
@@ -322,6 +412,8 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase {
  public:
   RepeatedPtrField();
   RepeatedPtrField(const RepeatedPtrField& other);
+  template <typename Iter>
+  RepeatedPtrField(Iter begin, const Iter& end);
   ~RepeatedPtrField();
 
   RepeatedPtrField& operator=(const RepeatedPtrField& other);
@@ -331,7 +423,16 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase {
   const Element& Get(int index) const;
   Element* Mutable(int index);
   Element* Add();
-  void RemoveLast();  // Remove the last element in the array.
+
+  // Remove the last element in the array.
+  // Ownership of the element is retained by the array.
+  void RemoveLast();
+
+  // Delete elements with indices in the range [start .. start+num-1].
+  // Caution: implementation moves all elements with indices [start+num .. ].
+  // Calling this routine inside a loop can cause quadratic behavior.
+  void DeleteSubrange(int start, int num);
+
   void Clear();
   void MergeFrom(const RepeatedPtrField& other);
   void CopyFrom(const RepeatedPtrField& other);
@@ -358,42 +459,78 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase {
   typedef internal::RepeatedPtrIterator<Element> iterator;
   typedef internal::RepeatedPtrIterator<const Element> const_iterator;
   typedef Element value_type;
+  typedef value_type& reference;
+  typedef const value_type& const_reference;
+  typedef value_type* pointer;
+  typedef const value_type* const_pointer;
+  typedef int size_type;
+  typedef ptrdiff_t difference_type;
 
   iterator begin();
   const_iterator begin() const;
   iterator end();
   const_iterator end() const;
 
+  // Reverse iterator support
+  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+  typedef std::reverse_iterator<iterator> reverse_iterator;
+  reverse_iterator rbegin() {
+    return reverse_iterator(end());
+  }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(end());
+  }
+  reverse_iterator rend() {
+    return reverse_iterator(begin());
+  }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(begin());
+  }
+
   // Custom STL-like iterator that iterates over and returns the underlying
   // pointers to Element rather than Element itself.
-  typedef internal::RepeatedPtrOverPtrsIterator<Element> pointer_iterator;
+  typedef internal::RepeatedPtrOverPtrsIterator<Element, void*>
+  pointer_iterator;
+  typedef internal::RepeatedPtrOverPtrsIterator<const Element, const void*>
+  const_pointer_iterator;
   pointer_iterator pointer_begin();
+  const_pointer_iterator pointer_begin() const;
   pointer_iterator pointer_end();
+  const_pointer_iterator pointer_end() const;
 
   // Returns (an estimate of) the number of bytes used by the repeated field,
   // excluding sizeof(*this).
   int SpaceUsedExcludingSelf() const;
 
   // Advanced memory management --------------------------------------
-  // When hardcore memory management becomes necessary -- as it often
+  // When hardcore memory management becomes necessary -- as it sometimes
   // does here at Google -- the following methods may be useful.
 
   // Add an already-allocated object, passing ownership to the
   // RepeatedPtrField.
   void AddAllocated(Element* value);
-  // Remove the last element and return it, passing ownership to the
-  // caller.
+  // Remove the last element and return it, passing ownership to the caller.
   // Requires:  size() > 0
   Element* ReleaseLast();
 
+  // Extract elements with indices in the range "[start .. start+num-1]".
+  // The caller assumes ownership of the extracted elements and is responsible
+  // for deleting them when they are no longer needed.
+  // If "elements" is non-NULL, then pointers to the extracted elements
+  // are stored in "elements[0 .. num-1]" for the convenience of the caller.
+  // If "elements" is NULL, then the caller must use some other mechanism
+  // to perform any further operations (like deletion) on these elements.
+  // Caution: implementation also moves elements with indices [start+num ..].
+  // Calling this routine inside a loop can cause quadratic behavior.
+  void ExtractSubrange(int start, int num, Element** elements);
+
   // When elements are removed by calls to RemoveLast() or Clear(), they
   // are not actually freed.  Instead, they are cleared and kept so that
   // they can be reused later.  This can save lots of CPU time when
   // repeatedly reusing a protocol message for similar purposes.
   //
-  // Really, extremely hardcore programs may actually want to manipulate
-  // these objects to better-optimize memory management.  These methods
-  // allow that.
+  // Hardcore programs may choose to manipulate these cleared objects
+  // to better optimize memory management using the following routines.
 
   // Get the number of cleared objects that are currently being kept
   // around for reuse.
@@ -434,6 +571,17 @@ inline RepeatedField<Element>::RepeatedField(const RepeatedField& other)
 }
 
 template <typename Element>
+template <typename Iter>
+inline RepeatedField<Element>::RepeatedField(Iter begin, const Iter& end)
+  : elements_(initial_space_),
+    current_size_(0),
+    total_size_(kInitialSize) {
+  for (; begin != end; ++begin) {
+    Add(*begin);
+  }
+}
+
+template <typename Element>
 RepeatedField<Element>::~RepeatedField() {
   if (elements_ != initial_space_) {
     delete [] elements_;
@@ -443,7 +591,8 @@ RepeatedField<Element>::~RepeatedField() {
 template <typename Element>
 inline RepeatedField<Element>&
 RepeatedField<Element>::operator=(const RepeatedField& other) {
-  CopyFrom(other);
+  if (this != &other)
+    CopyFrom(other);
   return *this;
 }
 
@@ -506,6 +655,27 @@ inline void RepeatedField<Element>::RemoveLast() {
 }
 
 template <typename Element>
+void RepeatedField<Element>::ExtractSubrange(
+    int start, int num, Element* elements) {
+  GOOGLE_DCHECK_GE(start, 0);
+  GOOGLE_DCHECK_GE(num, 0);
+  GOOGLE_DCHECK_LE(start + num, this->size());
+
+  // Save the values of the removed elements if requested.
+  if (elements != NULL) {
+    for (int i = 0; i < num; ++i)
+      elements[i] = this->Get(i + start);
+  }
+
+  // Slide remaining elements down to fill the gap.
+  if (num > 0) {
+    for (int i = start + num; i < this->size(); ++i)
+      this->Set(i - num, this->Get(i));
+    this->Truncate(this->size() - num);
+  }
+}
+
+template <typename Element>
 inline void RepeatedField<Element>::Clear() {
   current_size_ = 0;
 }
@@ -536,6 +706,7 @@ inline const Element* RepeatedField<Element>::data() const {
 
 template <typename Element>
 void RepeatedField<Element>::Swap(RepeatedField* other) {
+  if (this == other) return;
   Element* swap_elements     = elements_;
   int      swap_current_size = current_size_;
   int      swap_total_size   = total_size_;
@@ -593,14 +764,15 @@ inline int RepeatedField<Element>::SpaceUsedExcludingSelf() const {
   return (elements_ != initial_space_) ? total_size_ * sizeof(elements_[0]) : 0;
 }
 
-// Avoid inlining of Reserve(): new, memcpy, and delete[] lead to a significant
+// Avoid inlining of Reserve(): new, copy, and delete[] lead to a significant
 // amount of code bloat.
 template <typename Element>
 void RepeatedField<Element>::Reserve(int new_size) {
   if (total_size_ >= new_size) return;
 
   Element* old_elements = elements_;
-  total_size_ = max(total_size_ * 2, new_size);
+  total_size_ = max(google::protobuf::internal::kMinRepeatedFieldAllocationSize,
+                    max(total_size_ * 2, new_size));
   elements_ = new Element[total_size_];
   MoveArray(elements_, old_elements, current_size_);
   if (old_elements != initial_space_) {
@@ -617,15 +789,32 @@ inline void RepeatedField<Element>::Truncate(int new_size) {
 template <typename Element>
 inline void RepeatedField<Element>::MoveArray(
     Element to[], Element from[], int array_size) {
-  memcpy(to, from, array_size * sizeof(Element));
+  CopyArray(to, from, array_size);
 }
 
 template <typename Element>
 inline void RepeatedField<Element>::CopyArray(
     Element to[], const Element from[], int array_size) {
-  memcpy(to, from, array_size * sizeof(Element));
+  internal::ElementCopier<Element>()(to, from, array_size);
 }
 
+namespace internal {
+
+template <typename Element, bool HasTrivialCopy>
+void ElementCopier<Element, HasTrivialCopy>::operator()(
+    Element to[], const Element from[], int array_size) {
+  std::copy(from, from + array_size, to);
+}
+
+template <typename Element>
+struct ElementCopier<Element, true> {
+  void operator()(Element to[], const Element from[], int array_size) {
+    memcpy(to, from, array_size * sizeof(Element));
+  }
+};
+
+}  // namespace internal
+
 
 // -------------------------------------------------------------------
 
@@ -652,7 +841,6 @@ inline int RepeatedPtrFieldBase::size() const {
   return current_size_;
 }
 
-
 template <typename TypeHandler>
 inline const typename TypeHandler::Type&
 RepeatedPtrFieldBase::Get(int index) const {
@@ -660,6 +848,7 @@ RepeatedPtrFieldBase::Get(int index) const {
   return *cast<TypeHandler>(elements_[index]);
 }
 
+
 template <typename TypeHandler>
 inline typename TypeHandler::Type*
 RepeatedPtrFieldBase::Mutable(int index) {
@@ -798,7 +987,6 @@ inline typename TypeHandler::Type* RepeatedPtrFieldBase::ReleaseLast() {
   return result;
 }
 
-
 inline int RepeatedPtrFieldBase::ClearedCount() const {
   return allocated_size_ - current_size_;
 }
@@ -822,11 +1010,13 @@ inline typename TypeHandler::Type* RepeatedPtrFieldBase::ReleaseCleared() {
 
 template <typename Element>
 class RepeatedPtrField<Element>::TypeHandler
-    : public internal::GenericTypeHandler<Element> {};
+    : public internal::GenericTypeHandler<Element> {
+};
 
 template <>
 class RepeatedPtrField<string>::TypeHandler
-    : public internal::StringTypeHandler {};
+    : public internal::StringTypeHandler {
+};
 
 
 template <typename Element>
@@ -839,6 +1029,15 @@ inline RepeatedPtrField<Element>::RepeatedPtrField(
 }
 
 template <typename Element>
+template <typename Iter>
+inline RepeatedPtrField<Element>::RepeatedPtrField(
+    Iter begin, const Iter& end) {
+  for (; begin != end; ++begin) {
+    *Add() = *begin;
+  }
+}
+
+template <typename Element>
 RepeatedPtrField<Element>::~RepeatedPtrField() {
   Destroy<TypeHandler>();
 }
@@ -846,7 +1045,8 @@ RepeatedPtrField<Element>::~RepeatedPtrField() {
 template <typename Element>
 inline RepeatedPtrField<Element>& RepeatedPtrField<Element>::operator=(
     const RepeatedPtrField& other) {
-  CopyFrom(other);
+  if (this != &other)
+    CopyFrom(other);
   return *this;
 }
 
@@ -860,6 +1060,7 @@ inline const Element& RepeatedPtrField<Element>::Get(int index) const {
   return RepeatedPtrFieldBase::Get<TypeHandler>(index);
 }
 
+
 template <typename Element>
 inline Element* RepeatedPtrField<Element>::Mutable(int index) {
   return RepeatedPtrFieldBase::Mutable<TypeHandler>(index);
@@ -876,6 +1077,33 @@ inline void RepeatedPtrField<Element>::RemoveLast() {
 }
 
 template <typename Element>
+inline void RepeatedPtrField<Element>::DeleteSubrange(int start, int num) {
+  GOOGLE_DCHECK_GE(start, 0);
+  GOOGLE_DCHECK_GE(num, 0);
+  GOOGLE_DCHECK_LE(start + num, size());
+  for (int i = 0; i < num; ++i)
+    delete RepeatedPtrFieldBase::Mutable<TypeHandler>(start + i);
+  ExtractSubrange(start, num, NULL);
+}
+
+template <typename Element>
+inline void RepeatedPtrField<Element>::ExtractSubrange(
+    int start, int num, Element** elements) {
+  GOOGLE_DCHECK_GE(start, 0);
+  GOOGLE_DCHECK_GE(num, 0);
+  GOOGLE_DCHECK_LE(start + num, size());
+
+  if (num > 0) {
+    // Save the values of the removed elements if requested.
+    if (elements != NULL) {
+      for (int i = 0; i < num; ++i)
+        elements[i] = RepeatedPtrFieldBase::Mutable<TypeHandler>(i + start);
+    }
+    CloseGap(start, num);
+  }
+}
+
+template <typename Element>
 inline void RepeatedPtrField<Element>::Clear() {
   RepeatedPtrFieldBase::Clear<TypeHandler>();
 }
@@ -961,7 +1189,7 @@ namespace internal {
 // refer to this class directly; use RepeatedPtrField<T>::iterator instead.
 //
 // The iterator for RepeatedPtrField<T>, RepeatedPtrIterator<T>, is
-// very similar to iterator_ptr<T**> in util/gtl/iterator_adaptors-inl.h,
+// very similar to iterator_ptr<T**> in util/gtl/iterator_adaptors.h,
 // but adds random-access operators and is modified to wrap a void** base
 // iterator (since RepeatedPtrField stores its array as a void* array and
 // casting void** to T** would violate C++ aliasing rules).
@@ -1057,11 +1285,14 @@ class RepeatedPtrIterator
 // rather than the objects themselves as RepeatedPtrIterator does.
 // Consider using this when working with stl algorithms that change
 // the array.
-template<typename Element>
+// The VoidPtr template parameter holds the type-agnostic pointer value
+// referenced by the iterator.  It should either be "void *" for a mutable
+// iterator, or "const void *" for a constant iterator.
+template<typename Element, typename VoidPtr>
 class RepeatedPtrOverPtrsIterator
     : public std::iterator<std::random_access_iterator_tag, Element*> {
  public:
-  typedef RepeatedPtrOverPtrsIterator<Element> iterator;
+  typedef RepeatedPtrOverPtrsIterator<Element, VoidPtr> iterator;
   typedef std::iterator<
           std::random_access_iterator_tag, Element*> superclass;
 
@@ -1072,7 +1303,7 @@ class RepeatedPtrOverPtrsIterator
   typedef typename superclass::difference_type difference_type;
 
   RepeatedPtrOverPtrsIterator() : it_(NULL) {}
-  explicit RepeatedPtrOverPtrsIterator(void** it) : it_(it) {}
+  explicit RepeatedPtrOverPtrsIterator(VoidPtr* it) : it_(it) {}
 
   // dereferenceable
   reference operator*() const { return *reinterpret_cast<Element**>(it_); }
@@ -1127,10 +1358,9 @@ class RepeatedPtrOverPtrsIterator
   friend class RepeatedPtrIterator;
 
   // The internal iterator.
-  void** it_;
+  VoidPtr* it_;
 };
 
-
 }  // namespace internal
 
 template <typename Element>
@@ -1160,10 +1390,21 @@ RepeatedPtrField<Element>::pointer_begin() {
   return pointer_iterator(raw_mutable_data());
 }
 template <typename Element>
+inline typename RepeatedPtrField<Element>::const_pointer_iterator
+RepeatedPtrField<Element>::pointer_begin() const {
+  return const_pointer_iterator(const_cast<const void**>(raw_mutable_data()));
+}
+template <typename Element>
 inline typename RepeatedPtrField<Element>::pointer_iterator
 RepeatedPtrField<Element>::pointer_end() {
   return pointer_iterator(raw_mutable_data() + size());
 }
+template <typename Element>
+inline typename RepeatedPtrField<Element>::const_pointer_iterator
+RepeatedPtrField<Element>::pointer_end() const {
+  return const_pointer_iterator(
+      const_cast<const void**>(raw_mutable_data() + size()));
+}
 
 
 // Iterators and helper functions that follow the spirit of the STL
@@ -1173,7 +1414,7 @@ RepeatedPtrField<Element>::pointer_end() {
 //   std::copy(some_sequence.begin(), some_sequence.end(),
 //             google::protobuf::RepeatedFieldBackInserter(proto.mutable_sequence()));
 //
-// Ported by johannes from util/gtl/proto-array-iterators-inl.h
+// Ported by johannes from util/gtl/proto-array-iterators.h
 
 namespace internal {
 // A back inserter for RepeatedField objects.
@@ -1194,7 +1435,7 @@ template<typename T> class RepeatedFieldBackInsertIterator
   RepeatedFieldBackInsertIterator<T>& operator++() {
     return *this;
   }
-  RepeatedFieldBackInsertIterator<T>& operator++(int ignores_parameter) {
+  RepeatedFieldBackInsertIterator<T>& operator++(int /* unused */) {
     return *this;
   }
 
@@ -1225,7 +1466,7 @@ template<typename T> class RepeatedPtrFieldBackInsertIterator
   RepeatedPtrFieldBackInsertIterator<T>& operator++() {
     return *this;
   }
-  RepeatedPtrFieldBackInsertIterator<T>& operator++(int ignores_parameter) {
+  RepeatedPtrFieldBackInsertIterator<T>& operator++(int /* unused */) {
     return *this;
   }
 
@@ -1254,7 +1495,7 @@ template<typename T> class AllocatedRepeatedPtrFieldBackInsertIterator
     return *this;
   }
   AllocatedRepeatedPtrFieldBackInsertIterator<T>& operator++(
-      int ignores_parameter) {
+      int /* unused */) {
     return *this;
   }
 
@@ -1264,16 +1505,22 @@ template<typename T> class AllocatedRepeatedPtrFieldBackInsertIterator
 }  // namespace internal
 
 // Provides a back insert iterator for RepeatedField instances,
-// similar to std::back_inserter(). Note the identically named
-// function for RepeatedPtrField instances.
+// similar to std::back_inserter().
 template<typename T> internal::RepeatedFieldBackInsertIterator<T>
 RepeatedFieldBackInserter(RepeatedField<T>* const mutable_field) {
   return internal::RepeatedFieldBackInsertIterator<T>(mutable_field);
 }
 
 // Provides a back insert iterator for RepeatedPtrField instances,
-// similar to std::back_inserter(). Note the identically named
-// function for RepeatedField instances.
+// similar to std::back_inserter().
+template<typename T> internal::RepeatedPtrFieldBackInsertIterator<T>
+RepeatedPtrFieldBackInserter(RepeatedPtrField<T>* const mutable_field) {
+  return internal::RepeatedPtrFieldBackInsertIterator<T>(mutable_field);
+}
+
+// Special back insert iterator for RepeatedPtrField instances, just in
+// case someone wants to write generic template code that can access both
+// RepeatedFields and RepeatedPtrFields using a common name.
 template<typename T> internal::RepeatedPtrFieldBackInsertIterator<T>
 RepeatedFieldBackInserter(RepeatedPtrField<T>* const mutable_field) {
   return internal::RepeatedPtrFieldBackInsertIterator<T>(mutable_field);
diff --git a/src/google/protobuf/repeated_field_reflection_unittest.cc b/src/google/protobuf/repeated_field_reflection_unittest.cc
new file mode 100644
index 00000000..5fcfb007
--- /dev/null
+++ b/src/google/protobuf/repeated_field_reflection_unittest.cc
@@ -0,0 +1,193 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: tgs@google.com (Tom Szymanski)
+//
+// Test reflection methods for aggregate access to Repeated[Ptr]Fields.
+// This test proto2 methods on a proto2 layout.
+
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/stringprintf.h>
+#include <google/protobuf/unittest.pb.h>
+#include <google/protobuf/test_util.h>
+#include <gtest/gtest.h>
+
+namespace google {
+namespace protobuf {
+
+using unittest::ForeignMessage;
+using unittest::TestAllTypes;
+using unittest::TestAllExtensions;
+
+namespace {
+
+static int Func(int i, int j) {
+  return i * j;
+}
+
+static string StrFunc(int i, int j) {
+  string str;
+  SStringPrintf(&str, "%d", Func(i, 4));
+  return str;
+}
+
+
+TEST(RepeatedFieldReflectionTest, RegularFields) {
+  TestAllTypes message;
+  const Reflection* refl = message.GetReflection();
+  const Descriptor* desc = message.GetDescriptor();
+
+  for (int i = 0; i < 10; ++i) {
+    message.add_repeated_int32(Func(i, 1));
+    message.add_repeated_double(Func(i, 2));
+    message.add_repeated_string(StrFunc(i, 5));
+    message.add_repeated_foreign_message()->set_c(Func(i, 6));
+  }
+
+  // Get FieldDescriptors for all the fields of interest.
+  const FieldDescriptor* fd_repeated_int32 =
+      desc->FindFieldByName("repeated_int32");
+  const FieldDescriptor* fd_repeated_double =
+      desc->FindFieldByName("repeated_double");
+  const FieldDescriptor* fd_repeated_string =
+      desc->FindFieldByName("repeated_string");
+  const FieldDescriptor* fd_repeated_foreign_message =
+      desc->FindFieldByName("repeated_foreign_message");
+
+  // Get RepeatedField objects for all fields of interest.
+  const RepeatedField<int32>& rf_int32 =
+      refl->GetRepeatedField<int32>(message, fd_repeated_int32);
+  const RepeatedField<double>& rf_double =
+      refl->GetRepeatedField<double>(message, fd_repeated_double);
+
+  // Get mutable RepeatedField objects for all fields of interest.
+  RepeatedField<int32>* mrf_int32 =
+      refl->MutableRepeatedField<int32>(&message, fd_repeated_int32);
+  RepeatedField<double>* mrf_double =
+      refl->MutableRepeatedField<double>(&message, fd_repeated_double);
+
+  // Get RepeatedPtrField objects for all fields of interest.
+  const RepeatedPtrField<string>& rpf_string =
+      refl->GetRepeatedPtrField<string>(message, fd_repeated_string);
+  const RepeatedPtrField<ForeignMessage>& rpf_foreign_message =
+      refl->GetRepeatedPtrField<ForeignMessage>(
+          message, fd_repeated_foreign_message);
+  const RepeatedPtrField<Message>& rpf_message =
+      refl->GetRepeatedPtrField<Message>(
+          message, fd_repeated_foreign_message);
+
+  // Get mutable RepeatedPtrField objects for all fields of interest.
+  RepeatedPtrField<string>* mrpf_string =
+      refl->MutableRepeatedPtrField<string>(&message, fd_repeated_string);
+  RepeatedPtrField<ForeignMessage>* mrpf_foreign_message =
+      refl->MutableRepeatedPtrField<ForeignMessage>(
+          &message, fd_repeated_foreign_message);
+  RepeatedPtrField<Message>* mrpf_message =
+      refl->MutableRepeatedPtrField<Message>(
+          &message, fd_repeated_foreign_message);
+
+  // Make sure we can do get and sets through the Repeated[Ptr]Field objects.
+  for (int i = 0; i < 10; ++i) {
+    // Check gets through const objects.
+    EXPECT_EQ(rf_int32.Get(i), Func(i, 1));
+    EXPECT_EQ(rf_double.Get(i), Func(i, 2));
+    EXPECT_EQ(rpf_string.Get(i), StrFunc(i, 5));
+    EXPECT_EQ(rpf_foreign_message.Get(i).c(), Func(i, 6));
+    EXPECT_EQ(down_cast<const ForeignMessage&>(rpf_message.Get(i)).c(),
+              Func(i, 6));
+
+    // Check gets through mutable objects.
+    EXPECT_EQ(mrf_int32->Get(i), Func(i, 1));
+    EXPECT_EQ(mrf_double->Get(i), Func(i, 2));
+    EXPECT_EQ(mrpf_string->Get(i), StrFunc(i, 5));
+    EXPECT_EQ(mrpf_foreign_message->Get(i).c(), Func(i, 6));
+    EXPECT_EQ(down_cast<const ForeignMessage&>(mrpf_message->Get(i)).c(),
+              Func(i, 6));
+
+    // Check sets through mutable objects.
+    mrf_int32->Set(i, Func(i, -1));
+    mrf_double->Set(i, Func(i, -2));
+    mrpf_string->Mutable(i)->assign(StrFunc(i, -5));
+    mrpf_foreign_message->Mutable(i)->set_c(Func(i, -6));
+    EXPECT_EQ(message.repeated_int32(i), Func(i, -1));
+    EXPECT_EQ(message.repeated_double(i), Func(i, -2));
+    EXPECT_EQ(message.repeated_string(i), StrFunc(i, -5));
+    EXPECT_EQ(message.repeated_foreign_message(i).c(), Func(i, -6));
+    down_cast<ForeignMessage*>(mrpf_message->Mutable(i))->set_c(Func(i, 7));
+    EXPECT_EQ(message.repeated_foreign_message(i).c(), Func(i, 7));
+  }
+
+  // Make sure types are checked correctly at runtime.
+  const FieldDescriptor* fd_optional_int32 =
+      desc->FindFieldByName("optional_int32");
+  EXPECT_DEATH(refl->GetRepeatedField<int32>(
+      message, fd_optional_int32), "requires a repeated field");
+  EXPECT_DEATH(refl->GetRepeatedField<double>(
+      message, fd_repeated_int32), "not the right type");
+  EXPECT_DEATH(refl->GetRepeatedPtrField<TestAllTypes>(
+      message, fd_repeated_foreign_message), "wrong submessage type");
+}
+
+
+
+
+TEST(RepeatedFieldReflectionTest, ExtensionFields) {
+  TestAllExtensions extended_message;
+  const Reflection* refl = extended_message.GetReflection();
+  const Descriptor* desc = extended_message.GetDescriptor();
+
+  for (int i = 0; i < 10; ++i) {
+    extended_message.AddExtension(
+        unittest::repeated_int64_extension, Func(i, 1));
+  }
+
+  const FieldDescriptor* fd_repeated_int64_extension =
+      desc->file()->FindExtensionByName("repeated_int64_extension");
+  GOOGLE_CHECK(fd_repeated_int64_extension != NULL);
+
+  const RepeatedField<int64>& rf_int64_extension =
+      refl->GetRepeatedField<int64>(extended_message,
+                                    fd_repeated_int64_extension);
+
+  RepeatedField<int64>* mrf_int64_extension =
+      refl->MutableRepeatedField<int64>(&extended_message,
+                                        fd_repeated_int64_extension);
+
+  for (int i = 0; i < 10; ++i) {
+    EXPECT_EQ(Func(i, 1), rf_int64_extension.Get(i));
+    mrf_int64_extension->Set(i, Func(i, -1));
+    EXPECT_EQ(Func(i, -1),
+        extended_message.GetExtension(unittest::repeated_int64_extension, i));
+  }
+}
+
+}  // namespace
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/repeated_field_unittest.cc b/src/google/protobuf/repeated_field_unittest.cc
index e7e1e99b..99d5842d 100644
--- a/src/google/protobuf/repeated_field_unittest.cc
+++ b/src/google/protobuf/repeated_field_unittest.cc
@@ -36,6 +36,7 @@
 //   other proto2 unittests.
 
 #include <algorithm>
+#include <limits>
 #include <list>
 #include <vector>
 
@@ -46,7 +47,7 @@
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 using protobuf_unittest::TestAllTypes;
@@ -54,8 +55,7 @@ using protobuf_unittest::TestAllTypes;
 namespace protobuf {
 namespace {
 
-// Test operations on a RepeatedField which is small enough that it does
-// not allocate a separate array for storage.
+// Test operations on a small RepeatedField.
 TEST(RepeatedField, Small) {
   RepeatedField<int> field;
 
@@ -77,7 +77,6 @@ TEST(RepeatedField, Small) {
   EXPECT_EQ(field.size(), 2);
   EXPECT_EQ(field.Get(0), 5);
   EXPECT_EQ(field.Get(1), 23);
-  EXPECT_EQ(field.SpaceUsedExcludingSelf(), 0);
 
   field.RemoveLast();
 
@@ -87,9 +86,11 @@ TEST(RepeatedField, Small) {
   field.Clear();
 
   EXPECT_EQ(field.size(), 0);
-  EXPECT_EQ(field.SpaceUsedExcludingSelf(), 0);
+  int expected_usage = 4 * sizeof(int);
+  EXPECT_EQ(field.SpaceUsedExcludingSelf(), expected_usage);
 }
 
+
 // Test operations on a RepeatedField which is large enough to allocate a
 // separate array.
 TEST(RepeatedField, Large) {
@@ -213,10 +214,8 @@ TEST(RepeatedField, ReserveLessThanExisting) {
 
 TEST(RepeatedField, MergeFrom) {
   RepeatedField<int> source, destination;
-
   source.Add(4);
   source.Add(5);
-
   destination.Add(1);
   destination.Add(2);
   destination.Add(3);
@@ -224,7 +223,6 @@ TEST(RepeatedField, MergeFrom) {
   destination.MergeFrom(source);
 
   ASSERT_EQ(5, destination.size());
-
   EXPECT_EQ(1, destination.Get(0));
   EXPECT_EQ(2, destination.Get(1));
   EXPECT_EQ(3, destination.Get(2));
@@ -234,10 +232,8 @@ TEST(RepeatedField, MergeFrom) {
 
 TEST(RepeatedField, CopyFrom) {
   RepeatedField<int> source, destination;
-
   source.Add(4);
   source.Add(5);
-
   destination.Add(1);
   destination.Add(2);
   destination.Add(3);
@@ -245,7 +241,6 @@ TEST(RepeatedField, CopyFrom) {
   destination.CopyFrom(source);
 
   ASSERT_EQ(2, destination.size());
-
   EXPECT_EQ(4, destination.Get(0));
   EXPECT_EQ(5, destination.Get(1));
 }
@@ -262,12 +257,26 @@ TEST(RepeatedField, CopyConstruct) {
   EXPECT_EQ(2, destination.Get(1));
 }
 
+TEST(RepeatedField, IteratorConstruct) {
+  vector<int> values;
+  values.push_back(1);
+  values.push_back(2);
+
+  RepeatedField<int> field(values.begin(), values.end());
+  ASSERT_EQ(values.size(), field.size());
+  EXPECT_EQ(values[0], field.Get(0));
+  EXPECT_EQ(values[1], field.Get(1));
+
+  RepeatedField<int> other(field.begin(), field.end());
+  ASSERT_EQ(values.size(), other.size());
+  EXPECT_EQ(values[0], other.Get(0));
+  EXPECT_EQ(values[1], other.Get(1));
+}
+
 TEST(RepeatedField, CopyAssign) {
   RepeatedField<int> source, destination;
-
   source.Add(4);
   source.Add(5);
-
   destination.Add(1);
   destination.Add(2);
   destination.Add(3);
@@ -275,11 +284,24 @@ TEST(RepeatedField, CopyAssign) {
   destination = source;
 
   ASSERT_EQ(2, destination.size());
-
   EXPECT_EQ(4, destination.Get(0));
   EXPECT_EQ(5, destination.Get(1));
 }
 
+TEST(RepeatedField, SelfAssign) {
+  // Verify that assignment to self does not destroy data.
+  RepeatedField<int> source, *p;
+  p = &source;
+  source.Add(7);
+  source.Add(8);
+
+  *p = source;
+
+  ASSERT_EQ(2, source.size());
+  EXPECT_EQ(7, source.Get(0));
+  EXPECT_EQ(8, source.Get(1));
+}
+
 TEST(RepeatedField, MutableDataIsMutable) {
   RepeatedField<int> field;
   field.Add(1);
@@ -315,6 +337,41 @@ TEST(RepeatedField, Truncate) {
 }
 
 
+TEST(RepeatedField, ExtractSubrange) {
+  // Exhaustively test every subrange in arrays of all sizes from 0 through 9.
+  for (int sz = 0; sz < 10; ++sz) {
+    for (int num = 0; num <= sz; ++num) {
+      for (int start = 0; start < sz - num; ++start) {
+        // Create RepeatedField with sz elements having values 0 through sz-1.
+        RepeatedField<int32> field;
+        for (int i = 0; i < sz; ++i)
+          field.Add(i);
+        EXPECT_EQ(field.size(), sz);
+
+        // Create a catcher array and call ExtractSubrange.
+        int32 catcher[10];
+        for (int i = 0; i < 10; ++i)
+          catcher[i] = -1;
+        field.ExtractSubrange(start, num, catcher);
+
+        // Does the resulting array have the right size?
+        EXPECT_EQ(field.size(), sz - num);
+
+        // Were the removed elements extracted into the catcher array?
+        for (int i = 0; i < num; ++i)
+          EXPECT_EQ(catcher[i], start + i);
+        EXPECT_EQ(catcher[num], -1);
+
+        // Does the resulting array contain the right values?
+        for (int i = 0; i < start; ++i)
+          EXPECT_EQ(field.Get(i), i);
+        for (int i = start; i < field.size(); ++i)
+          EXPECT_EQ(field.Get(i), i + num);
+      }
+    }
+  }
+}
+
 // ===================================================================
 // RepeatedPtrField tests.  These pretty much just mirror the RepeatedField
 // tests above.
@@ -351,6 +408,7 @@ TEST(RepeatedPtrField, Small) {
   EXPECT_EQ(field.size(), 0);
 }
 
+
 TEST(RepeatedPtrField, Large) {
   RepeatedPtrField<string> field;
 
@@ -565,10 +623,8 @@ TEST(RepeatedPtrField, AddAlocated) {
 
 TEST(RepeatedPtrField, MergeFrom) {
   RepeatedPtrField<string> source, destination;
-
   source.Add()->assign("4");
   source.Add()->assign("5");
-
   destination.Add()->assign("1");
   destination.Add()->assign("2");
   destination.Add()->assign("3");
@@ -576,7 +632,6 @@ TEST(RepeatedPtrField, MergeFrom) {
   destination.MergeFrom(source);
 
   ASSERT_EQ(5, destination.size());
-
   EXPECT_EQ("1", destination.Get(0));
   EXPECT_EQ("2", destination.Get(1));
   EXPECT_EQ("3", destination.Get(2));
@@ -586,10 +641,8 @@ TEST(RepeatedPtrField, MergeFrom) {
 
 TEST(RepeatedPtrField, CopyFrom) {
   RepeatedPtrField<string> source, destination;
-
   source.Add()->assign("4");
   source.Add()->assign("5");
-
   destination.Add()->assign("1");
   destination.Add()->assign("2");
   destination.Add()->assign("3");
@@ -597,14 +650,12 @@ TEST(RepeatedPtrField, CopyFrom) {
   destination.CopyFrom(source);
 
   ASSERT_EQ(2, destination.size());
-
   EXPECT_EQ("4", destination.Get(0));
   EXPECT_EQ("5", destination.Get(1));
 }
 
 TEST(RepeatedPtrField, CopyConstruct) {
   RepeatedPtrField<string> source;
-
   source.Add()->assign("1");
   source.Add()->assign("2");
 
@@ -615,12 +666,45 @@ TEST(RepeatedPtrField, CopyConstruct) {
   EXPECT_EQ("2", destination.Get(1));
 }
 
+TEST(RepeatedPtrField, IteratorConstruct_String) {
+  vector<string> values;
+  values.push_back("1");
+  values.push_back("2");
+
+  RepeatedPtrField<string> field(values.begin(), values.end());
+  ASSERT_EQ(values.size(), field.size());
+  EXPECT_EQ(values[0], field.Get(0));
+  EXPECT_EQ(values[1], field.Get(1));
+
+  RepeatedPtrField<string> other(field.begin(), field.end());
+  ASSERT_EQ(values.size(), other.size());
+  EXPECT_EQ(values[0], other.Get(0));
+  EXPECT_EQ(values[1], other.Get(1));
+}
+
+TEST(RepeatedPtrField, IteratorConstruct_Proto) {
+  typedef TestAllTypes::NestedMessage Nested;
+  vector<Nested> values;
+  values.push_back(Nested());
+  values.back().set_bb(1);
+  values.push_back(Nested());
+  values.back().set_bb(2);
+
+  RepeatedPtrField<Nested> field(values.begin(), values.end());
+  ASSERT_EQ(values.size(), field.size());
+  EXPECT_EQ(values[0].bb(), field.Get(0).bb());
+  EXPECT_EQ(values[1].bb(), field.Get(1).bb());
+
+  RepeatedPtrField<Nested> other(field.begin(), field.end());
+  ASSERT_EQ(values.size(), other.size());
+  EXPECT_EQ(values[0].bb(), other.Get(0).bb());
+  EXPECT_EQ(values[1].bb(), other.Get(1).bb());
+}
+
 TEST(RepeatedPtrField, CopyAssign) {
   RepeatedPtrField<string> source, destination;
-
   source.Add()->assign("4");
   source.Add()->assign("5");
-
   destination.Add()->assign("1");
   destination.Add()->assign("2");
   destination.Add()->assign("3");
@@ -628,11 +712,24 @@ TEST(RepeatedPtrField, CopyAssign) {
   destination = source;
 
   ASSERT_EQ(2, destination.size());
-
   EXPECT_EQ("4", destination.Get(0));
   EXPECT_EQ("5", destination.Get(1));
 }
 
+TEST(RepeatedPtrField, SelfAssign) {
+  // Verify that assignment to self does not destroy data.
+  RepeatedPtrField<string> source, *p;
+  p = &source;
+  source.Add()->assign("7");
+  source.Add()->assign("8");
+
+  *p = source;
+
+  ASSERT_EQ(2, source.size());
+  EXPECT_EQ("7", source.Get(0));
+  EXPECT_EQ("8", source.Get(1));
+}
+
 TEST(RepeatedPtrField, MutableDataIsMutable) {
   RepeatedPtrField<string> field;
   *field.Add() = "1";
@@ -644,6 +741,77 @@ TEST(RepeatedPtrField, MutableDataIsMutable) {
   EXPECT_EQ("2", field.Get(0));
 }
 
+TEST(RepeatedPtrField, ExtractSubrange) {
+  // Exhaustively test every subrange in arrays of all sizes from 0 through 9
+  // with 0 through 3 cleared elements at the end.
+  for (int sz = 0; sz < 10; ++sz) {
+    for (int num = 0; num <= sz; ++num) {
+      for (int start = 0; start < sz - num; ++start) {
+        for (int extra = 0; extra < 4; ++extra) {
+          vector<string*> subject;
+
+          // Create an array with "sz" elements and "extra" cleared elements.
+          RepeatedPtrField<string> field;
+          for (int i = 0; i < sz + extra; ++i) {
+            subject.push_back(new string());
+            field.AddAllocated(subject[i]);
+          }
+          EXPECT_EQ(field.size(), sz + extra);
+          for (int i = 0; i < extra; ++i)
+            field.RemoveLast();
+          EXPECT_EQ(field.size(), sz);
+          EXPECT_EQ(field.ClearedCount(), extra);
+
+          // Create a catcher array and call ExtractSubrange.
+          string* catcher[10];
+          for (int i = 0; i < 10; ++i)
+            catcher[i] = NULL;
+          field.ExtractSubrange(start, num, catcher);
+
+          // Does the resulting array have the right size?
+          EXPECT_EQ(field.size(), sz - num);
+
+          // Were the removed elements extracted into the catcher array?
+          for (int i = 0; i < num; ++i)
+            EXPECT_EQ(catcher[i], subject[start + i]);
+          EXPECT_EQ(NULL, catcher[num]);
+
+          // Does the resulting array contain the right values?
+          for (int i = 0; i < start; ++i)
+            EXPECT_EQ(field.Mutable(i), subject[i]);
+          for (int i = start; i < field.size(); ++i)
+            EXPECT_EQ(field.Mutable(i), subject[i + num]);
+
+          // Reinstate the cleared elements.
+          EXPECT_EQ(field.ClearedCount(), extra);
+          for (int i = 0; i < extra; ++i)
+            field.Add();
+          EXPECT_EQ(field.ClearedCount(), 0);
+          EXPECT_EQ(field.size(), sz - num + extra);
+
+          // Make sure the extra elements are all there (in some order).
+          for (int i = sz; i < sz + extra; ++i) {
+            int count = 0;
+            for (int j = sz; j < sz + extra; ++j) {
+              if (field.Mutable(j - num) == subject[i])
+                count += 1;
+            }
+            EXPECT_EQ(count, 1);
+          }
+
+          // Release the caught elements.
+          for (int i = 0; i < num; ++i)
+            delete catcher[i];
+        }
+      }
+    }
+  }
+}
+
+TEST(RepeatedPtrField, DeleteSubrange) {
+  // DeleteSubrange is a trivial extension of ExtendSubrange.
+}
+
 // ===================================================================
 
 // Iterator tests stolen from net/proto/proto-array_unittest.
@@ -738,6 +906,30 @@ TEST_F(RepeatedPtrFieldIteratorTest, ConstIteration) {
   EXPECT_EQ("baz", *(--const_proto_array.end()));
 }
 
+TEST_F(RepeatedPtrFieldIteratorTest, MutableReverseIteration) {
+  RepeatedPtrField<string>::reverse_iterator iter = proto_array_.rbegin();
+  EXPECT_EQ("baz", *iter);
+  ++iter;
+  EXPECT_EQ("bar", *(iter++));
+  EXPECT_EQ("foo", *iter);
+  ++iter;
+  EXPECT_TRUE(proto_array_.rend() == iter);
+  EXPECT_EQ("foo", *(--proto_array_.rend()));
+}
+
+TEST_F(RepeatedPtrFieldIteratorTest, ConstReverseIteration) {
+  const RepeatedPtrField<string>& const_proto_array = proto_array_;
+  RepeatedPtrField<string>::const_reverse_iterator iter
+      = const_proto_array.rbegin();
+  EXPECT_EQ("baz", *iter);
+  ++iter;
+  EXPECT_EQ("bar", *(iter++));
+  EXPECT_EQ("foo", *iter);
+  ++iter;
+  EXPECT_TRUE(const_proto_array.rend() == iter);
+  EXPECT_EQ("foo", *(--const_proto_array.rend()));
+}
+
 TEST_F(RepeatedPtrFieldIteratorTest, RandomAccess) {
   RepeatedPtrField<string>::iterator iter = proto_array_.begin();
   RepeatedPtrField<string>::iterator iter2 = iter;
@@ -805,9 +997,11 @@ class RepeatedPtrFieldPtrsIteratorTest : public testing::Test {
     proto_array_.Add()->assign("foo");
     proto_array_.Add()->assign("bar");
     proto_array_.Add()->assign("baz");
+    const_proto_array_ = &proto_array_;
   }
 
   RepeatedPtrField<string> proto_array_;
+  const RepeatedPtrField<string>* const_proto_array_;
 };
 
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, ConvertiblePtr) {
@@ -815,6 +1009,11 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, ConvertiblePtr) {
       proto_array_.pointer_begin();
 }
 
+TEST_F(RepeatedPtrFieldPtrsIteratorTest, ConvertibleConstPtr) {
+  RepeatedPtrField<string>::const_pointer_iterator iter =
+      const_proto_array_->pointer_begin();
+}
+
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, MutablePtrIteration) {
   RepeatedPtrField<string>::pointer_iterator iter =
       proto_array_.pointer_begin();
@@ -827,6 +1026,18 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, MutablePtrIteration) {
   EXPECT_EQ("baz", **(--proto_array_.pointer_end()));
 }
 
+TEST_F(RepeatedPtrFieldPtrsIteratorTest, MutableConstPtrIteration) {
+  RepeatedPtrField<string>::const_pointer_iterator iter =
+      const_proto_array_->pointer_begin();
+  EXPECT_EQ("foo", **iter);
+  ++iter;
+  EXPECT_EQ("bar", **(iter++));
+  EXPECT_EQ("baz", **iter);
+  ++iter;
+  EXPECT_TRUE(const_proto_array_->pointer_end() == iter);
+  EXPECT_EQ("baz", **(--const_proto_array_->pointer_end()));
+}
+
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, RandomPtrAccess) {
   RepeatedPtrField<string>::pointer_iterator iter =
       proto_array_.pointer_begin();
@@ -840,6 +1051,19 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, RandomPtrAccess) {
   EXPECT_EQ(3, proto_array_.end() - proto_array_.begin());
 }
 
+TEST_F(RepeatedPtrFieldPtrsIteratorTest, RandomConstPtrAccess) {
+  RepeatedPtrField<string>::const_pointer_iterator iter =
+      const_proto_array_->pointer_begin();
+  RepeatedPtrField<string>::const_pointer_iterator iter2 = iter;
+  ++iter2;
+  ++iter2;
+  EXPECT_TRUE(iter + 2 == iter2);
+  EXPECT_TRUE(iter == iter2 - 2);
+  EXPECT_EQ("baz", *iter[2]);
+  EXPECT_EQ("baz", **(iter + 2));
+  EXPECT_EQ(3, const_proto_array_->end() - const_proto_array_->begin());
+}
+
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, ComparablePtr) {
   RepeatedPtrField<string>::pointer_iterator iter =
       proto_array_.pointer_begin();
@@ -854,6 +1078,20 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, ComparablePtr) {
   EXPECT_TRUE(iter >= iter);
 }
 
+TEST_F(RepeatedPtrFieldPtrsIteratorTest, ComparableConstPtr) {
+  RepeatedPtrField<string>::const_pointer_iterator iter =
+      const_proto_array_->pointer_begin();
+  RepeatedPtrField<string>::const_pointer_iterator iter2 = iter + 1;
+  EXPECT_TRUE(iter == iter);
+  EXPECT_TRUE(iter != iter2);
+  EXPECT_TRUE(iter < iter2);
+  EXPECT_TRUE(iter <= iter2);
+  EXPECT_TRUE(iter <= iter);
+  EXPECT_TRUE(iter2 > iter);
+  EXPECT_TRUE(iter2 >= iter);
+  EXPECT_TRUE(iter >= iter);
+}
+
 // Uninitialized iterator does not point to any of the RepeatedPtrOverPtrs.
 // Dereferencing an uninitialized iterator crashes the process.
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, UninitializedPtrIterator) {
@@ -865,6 +1103,14 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, UninitializedPtrIterator) {
   EXPECT_TRUE(iter != proto_array_.pointer_end());
 }
 
+TEST_F(RepeatedPtrFieldPtrsIteratorTest, UninitializedConstPtrIterator) {
+  RepeatedPtrField<string>::const_pointer_iterator iter;
+  EXPECT_TRUE(iter != const_proto_array_->pointer_begin());
+  EXPECT_TRUE(iter != const_proto_array_->pointer_begin() + 1);
+  EXPECT_TRUE(iter != const_proto_array_->pointer_begin() + 2);
+  EXPECT_TRUE(iter != const_proto_array_->pointer_begin() + 3);
+  EXPECT_TRUE(iter != const_proto_array_->pointer_end());
+}
 
 // This comparison functor is required by the tests for RepeatedPtrOverPtrs.
 // They operate on strings and need to compare strings as strings in
@@ -889,17 +1135,33 @@ TEST_F(RepeatedPtrFieldPtrsIteratorTest, PtrSTLAlgorithms_lower_bound) {
   proto_array_.Add()->assign("x");
   proto_array_.Add()->assign("y");
 
-  RepeatedPtrField<string>::pointer_iterator iter =
-      proto_array_.pointer_begin();
-  string v = "f";
-  RepeatedPtrField<string>::pointer_iterator it =
-      lower_bound(proto_array_.pointer_begin(), proto_array_.pointer_end(),
-                  &v, StringLessThan());
+  {
+    RepeatedPtrField<string>::pointer_iterator iter =
+        proto_array_.pointer_begin();
+    string v = "f";
+    RepeatedPtrField<string>::pointer_iterator it =
+        lower_bound(proto_array_.pointer_begin(), proto_array_.pointer_end(),
+                    &v, StringLessThan());
 
-  GOOGLE_CHECK(*it != NULL);
+    GOOGLE_CHECK(*it != NULL);
 
-  EXPECT_EQ(**it, "n");
-  EXPECT_TRUE(it == proto_array_.pointer_begin() + 3);
+    EXPECT_EQ(**it, "n");
+    EXPECT_TRUE(it == proto_array_.pointer_begin() + 3);
+  }
+  {
+    RepeatedPtrField<string>::const_pointer_iterator iter =
+        const_proto_array_->pointer_begin();
+    string v = "f";
+    RepeatedPtrField<string>::const_pointer_iterator it =
+        lower_bound(const_proto_array_->pointer_begin(),
+                    const_proto_array_->pointer_end(),
+                    &v, StringLessThan());
+
+    GOOGLE_CHECK(*it != NULL);
+
+    EXPECT_EQ(**it, "n");
+    EXPECT_TRUE(it == const_proto_array_->pointer_begin() + 3);
+  }
 }
 
 TEST_F(RepeatedPtrFieldPtrsIteratorTest, PtrMutation) {
@@ -1025,13 +1287,24 @@ TEST_F(RepeatedFieldInsertionIteratorsTest, Halves) {
 
 TEST_F(RepeatedFieldInsertionIteratorsTest, Words) {
   ASSERT_EQ(words.size(), protobuffer.repeated_string_size());
-  EXPECT_EQ(words.at(0), protobuffer.repeated_string(0));
-  EXPECT_EQ(words.at(1), protobuffer.repeated_string(1));
-  EXPECT_EQ(words.at(2), protobuffer.repeated_string(2));
-  EXPECT_EQ(words.at(3), protobuffer.repeated_string(3));
-  EXPECT_EQ(words.at(4), protobuffer.repeated_string(4));
-  EXPECT_EQ(words.at(5), protobuffer.repeated_string(5));
-  EXPECT_EQ(words.at(6), protobuffer.repeated_string(6));
+  for (int i = 0; i < words.size(); ++i)
+    EXPECT_EQ(words.at(i), protobuffer.repeated_string(i));
+}
+
+TEST_F(RepeatedFieldInsertionIteratorsTest, Words2) {
+  words.clear();
+  words.push_back("sing");
+  words.push_back("a");
+  words.push_back("song");
+  words.push_back("of");
+  words.push_back("six");
+  words.push_back("pence");
+  protobuffer.mutable_repeated_string()->Clear();
+  std::copy(words.begin(), words.end(), RepeatedPtrFieldBackInserter(
+      protobuffer.mutable_repeated_string()));
+  ASSERT_EQ(words.size(), protobuffer.repeated_string_size());
+  for (int i = 0; i < words.size(); ++i)
+    EXPECT_EQ(words.at(i), protobuffer.repeated_string(i));
 }
 
 TEST_F(RepeatedFieldInsertionIteratorsTest, Nesteds) {
diff --git a/src/google/protobuf/stubs/common.cc b/src/google/protobuf/stubs/common.cc
index 7b15be44..16d78528 100644
--- a/src/google/protobuf/stubs/common.cc
+++ b/src/google/protobuf/stubs/common.cc
@@ -320,6 +320,24 @@ void Mutex::AssertHeld() {
 #endif
 
 // ===================================================================
+// emulates google3/util/endian/endian.h
+//
+// TODO(xiaofeng): PROTOBUF_LITTLE_ENDIAN is unfortunately defined in
+// google/protobuf/io/coded_stream.h and therefore can not be used here.
+// Maybe move that macro definition here in the furture.
+uint32 ghtonl(uint32 x) {
+  union {
+    uint32 result;
+    uint8 result_array[4];
+  };
+  result_array[0] = static_cast<uint8>(x >> 24);
+  result_array[1] = static_cast<uint8>((x >> 16) & 0xFF);
+  result_array[2] = static_cast<uint8>((x >> 8) & 0xFF);
+  result_array[3] = static_cast<uint8>(x & 0xFF);
+  return result;
+}
+
+// ===================================================================
 // Shutdown support.
 
 namespace internal {
diff --git a/src/google/protobuf/stubs/common.h b/src/google/protobuf/stubs/common.h
index 7f5fd4d2..07ae5307 100644
--- a/src/google/protobuf/stubs/common.h
+++ b/src/google/protobuf/stubs/common.h
@@ -341,6 +341,12 @@ inline To down_cast(From* f) {                   // so we only accept pointers
   return static_cast<To>(f);
 }
 
+// Simplified down_cast for reference type.
+template<typename To, typename From>
+inline To down_cast(From& f) {
+  return static_cast<To>(f);
+}
+
 }  // namespace internal
 
 // We made these internal so that they would show up as such in the docs,
@@ -686,6 +692,7 @@ class LIBPROTOBUF_EXPORT LogFinisher {
 #undef GOOGLE_CHECK_LE
 #undef GOOGLE_CHECK_GT
 #undef GOOGLE_CHECK_GE
+#undef GOOGLE_CHECK_NOTNULL
 
 #undef GOOGLE_DLOG
 #undef GOOGLE_DCHECK
@@ -712,6 +719,18 @@ class LIBPROTOBUF_EXPORT LogFinisher {
 #define GOOGLE_CHECK_GT(A, B) GOOGLE_CHECK((A) >  (B))
 #define GOOGLE_CHECK_GE(A, B) GOOGLE_CHECK((A) >= (B))
 
+namespace internal {
+template<typename T>
+T* CheckNotNull(const char *file, int line, const char *name, T* val) {
+  if (val == NULL) {
+    GOOGLE_LOG(FATAL) << name;
+  }
+  return val;
+}
+}  // namespace internal
+#define GOOGLE_CHECK_NOTNULL(A) \
+  internal::CheckNotNull(__FILE__, __LINE__, "'" #A "' must not be NULL", (A))
+
 #ifdef NDEBUG
 
 #define GOOGLE_DLOG GOOGLE_LOG_IF(INFO, false)
@@ -1136,20 +1155,10 @@ using internal::WriterMutexLock;
 using internal::MutexLockMaybe;
 
 // ===================================================================
-// from google3/base/type_traits.h
+// from google3/util/utf8/public/unilib.h
 
 namespace internal {
 
-// Specified by TR1 [4.7.4] Pointer modifications.
-template<typename T> struct remove_pointer { typedef T type; };
-template<typename T> struct remove_pointer<T*> { typedef T type; };
-template<typename T> struct remove_pointer<T* const> { typedef T type; };
-template<typename T> struct remove_pointer<T* volatile> { typedef T type; };
-template<typename T> struct remove_pointer<T* const volatile> {
-  typedef T type; };
-
-// ===================================================================
-
 // Checks if the buffer contains structurally-valid UTF-8.  Implemented in
 // structurally_valid.cc.
 LIBPROTOBUF_EXPORT bool IsStructurallyValidUTF8(const char* buf, int len);
@@ -1157,6 +1166,10 @@ LIBPROTOBUF_EXPORT bool IsStructurallyValidUTF8(const char* buf, int len);
 }  // namespace internal
 
 // ===================================================================
+// from google3/util/endian/endian.h
+LIBPROTOBUF_EXPORT uint32 ghtonl(uint32 x);
+
+// ===================================================================
 // Shutdown support.
 
 // Shut down the entire protocol buffers library, deleting all static-duration
diff --git a/src/google/protobuf/stubs/hash.h b/src/google/protobuf/stubs/hash.h
index 822d6050..f7d10712 100644
--- a/src/google/protobuf/stubs/hash.h
+++ b/src/google/protobuf/stubs/hash.h
@@ -90,12 +90,16 @@ template <typename Key, typename Data,
           typename HashFcn = hash<Key>,
           typename EqualKey = int >
 class hash_map : public std::map<Key, Data, HashFcn> {
+ public:
+  hash_map(int = 0) {}
 };
 
 template <typename Key,
           typename HashFcn = hash<Key>,
           typename EqualKey = int >
 class hash_set : public std::set<Key, HashFcn> {
+ public:
+  hash_set(int = 0) {}
 };
 
 #elif defined(_MSC_VER) && !defined(_STLPORT_VERSION)
@@ -123,6 +127,8 @@ template <typename Key, typename Data,
           typename EqualKey = int >
 class hash_map : public HASH_NAMESPACE::hash_map<
     Key, Data, HashFcn> {
+ public:
+  hash_map(int = 0) {}
 };
 
 template <typename Key,
@@ -130,6 +136,8 @@ template <typename Key,
           typename EqualKey = int >
 class hash_set : public HASH_NAMESPACE::hash_set<
     Key, HashFcn> {
+ public:
+  hash_set(int = 0) {}
 };
 
 #else
@@ -163,6 +171,8 @@ template <typename Key, typename Data,
           typename EqualKey = std::equal_to<Key> >
 class hash_map : public HASH_NAMESPACE::HASH_MAP_CLASS<
     Key, Data, HashFcn, EqualKey> {
+ public:
+  hash_map(int = 0) {}
 };
 
 template <typename Key,
@@ -170,6 +180,8 @@ template <typename Key,
           typename EqualKey = std::equal_to<Key> >
 class hash_set : public HASH_NAMESPACE::HASH_SET_CLASS<
     Key, HashFcn, EqualKey> {
+ public:
+  hash_set(int = 0) {}
 };
 
 #endif
diff --git a/src/google/protobuf/stubs/map-util.h b/src/google/protobuf/stubs/map-util.h
index f5c9d6b6..775848b9 100644
--- a/src/google/protobuf/stubs/map-util.h
+++ b/src/google/protobuf/stubs/map-util.h
@@ -68,6 +68,30 @@ FindOrNull(const Collection& collection,
   return &it->second;
 }
 
+// Perform a lookup in a map or hash_map, assuming that the key exists.
+// Crash if it does not.
+//
+// This is intended as a replacement for operator[] as an rvalue (for reading)
+// when the key is guaranteed to exist.
+//
+// operator[] is discouraged for several reasons:
+//  * It has a side-effect of inserting missing keys
+//  * It is not thread-safe (even when it is not inserting, it can still
+//      choose to resize the underlying storage)
+//  * It invalidates iterators (when it chooses to resize)
+//  * It default constructs a value object even if it doesn't need to
+//
+// This version assumes the key is printable, and includes it in the fatal log
+// message.
+template <class Collection>
+const typename Collection::value_type::second_type&
+FindOrDie(const Collection& collection,
+          const typename Collection::value_type::first_type& key) {
+  typename Collection::const_iterator it = collection.find(key);
+  GOOGLE_CHECK(it != collection.end()) << "Map key not found: " << key;
+  return it->second;
+}
+
 // Perform a lookup in a map or hash_map whose values are pointers.
 // If the key is present a const pointer to the associated value is returned,
 // otherwise a NULL pointer is returned.
diff --git a/src/google/protobuf/stubs/stl_util.h b/src/google/protobuf/stubs/stl_util.h
new file mode 100644
index 00000000..9021dada
--- /dev/null
+++ b/src/google/protobuf/stubs/stl_util.h
@@ -0,0 +1,121 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// from google3/util/gtl/stl_util.h
+
+#ifndef GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
+#define GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
+
+#include <google/protobuf/stubs/common.h>
+
+namespace google {
+namespace protobuf {
+
+// STLDeleteContainerPointers()
+//  For a range within a container of pointers, calls delete
+//  (non-array version) on these pointers.
+// NOTE: for these three functions, we could just implement a DeleteObject
+// functor and then call for_each() on the range and functor, but this
+// requires us to pull in all of algorithm.h, which seems expensive.
+// For hash_[multi]set, it is important that this deletes behind the iterator
+// because the hash_set may call the hash function on the iterator when it is
+// advanced, which could result in the hash function trying to deference a
+// stale pointer.
+template <class ForwardIterator>
+void STLDeleteContainerPointers(ForwardIterator begin,
+                                ForwardIterator end) {
+  while (begin != end) {
+    ForwardIterator temp = begin;
+    ++begin;
+    delete *temp;
+  }
+}
+
+// Inside Google, this function implements a horrible, disgusting hack in which
+// we reach into the string's private implementation and resize it without
+// initializing the new bytes.  In some cases doing this can significantly
+// improve performance.  However, since it's totally non-portable it has no
+// place in open source code.  Feel free to fill this function in with your
+// own disgusting hack if you want the perf boost.
+inline void STLStringResizeUninitialized(string* s, size_t new_size) {
+  s->resize(new_size);
+}
+
+// Return a mutable char* pointing to a string's internal buffer,
+// which may not be null-terminated. Writing through this pointer will
+// modify the string.
+//
+// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
+// next call to a string method that invalidates iterators.
+//
+// As of 2006-04, there is no standard-blessed way of getting a
+// mutable reference to a string's internal buffer. However, issue 530
+// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
+// proposes this as the method. According to Matt Austern, this should
+// already work on all current implementations.
+inline char* string_as_array(string* str) {
+  // DO NOT USE const_cast<char*>(str->data())! See the unittest for why.
+  return str->empty() ? NULL : &*str->begin();
+}
+
+// STLDeleteElements() deletes all the elements in an STL container and clears
+// the container.  This function is suitable for use with a vector, set,
+// hash_set, or any other STL container which defines sensible begin(), end(),
+// and clear() methods.
+//
+// If container is NULL, this function is a no-op.
+//
+// As an alternative to calling STLDeleteElements() directly, consider
+// ElementDeleter (defined below), which ensures that your container's elements
+// are deleted when the ElementDeleter goes out of scope.
+template <class T>
+void STLDeleteElements(T *container) {
+  if (!container) return;
+  STLDeleteContainerPointers(container->begin(), container->end());
+  container->clear();
+}
+
+// Given an STL container consisting of (key, value) pairs, STLDeleteValues
+// deletes all the "value" components and clears the container.  Does nothing
+// in the case it's given a NULL pointer.
+
+template <class T>
+void STLDeleteValues(T *v) {
+  if (!v) return;
+  for (typename T::iterator i = v->begin(); i != v->end(); ++i) {
+    delete i->second;
+  }
+  v->clear();
+}
+
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
diff --git a/src/google/protobuf/stubs/stringprintf.cc b/src/google/protobuf/stubs/stringprintf.cc
new file mode 100644
index 00000000..d66a497a
--- /dev/null
+++ b/src/google/protobuf/stubs/stringprintf.cc
@@ -0,0 +1,170 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2012 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// from google3/base/stringprintf.cc
+
+#include <google/protobuf/stubs/stringprintf.h>
+
+#include <errno.h>
+#include <stdarg.h> // For va_list and related operations
+#include <stdio.h> // MSVC requires this for _vsnprintf
+#include <vector>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/testing/googletest.h>
+
+namespace google {
+namespace protobuf {
+
+#ifdef _MSC_VER
+enum { IS_COMPILER_MSVC = 1 };
+#else
+enum { IS_COMPILER_MSVC = 0 };
+#endif
+
+void StringAppendV(string* dst, const char* format, va_list ap) {
+  // First try with a small fixed size buffer
+  static const int kSpaceLength = 1024;
+  char space[kSpaceLength];
+
+  // It's possible for methods that use a va_list to invalidate
+  // the data in it upon use.  The fix is to make a copy
+  // of the structure before using it and use that copy instead.
+  va_list backup_ap;
+  va_copy(backup_ap, ap);
+  int result = vsnprintf(space, kSpaceLength, format, backup_ap);
+  va_end(backup_ap);
+
+  if (result < kSpaceLength) {
+    if (result >= 0) {
+      // Normal case -- everything fit.
+      dst->append(space, result);
+      return;
+    }
+
+    if (IS_COMPILER_MSVC) {
+      // Error or MSVC running out of space.  MSVC 8.0 and higher
+      // can be asked about space needed with the special idiom below:
+      va_copy(backup_ap, ap);
+      result = vsnprintf(NULL, 0, format, backup_ap);
+      va_end(backup_ap);
+    }
+
+    if (result < 0) {
+      // Just an error.
+      return;
+    }
+  }
+
+  // Increase the buffer size to the size requested by vsnprintf,
+  // plus one for the closing \0.
+  int length = result+1;
+  char* buf = new char[length];
+
+  // Restore the va_list before we use it again
+  va_copy(backup_ap, ap);
+  result = vsnprintf(buf, length, format, backup_ap);
+  va_end(backup_ap);
+
+  if (result >= 0 && result < length) {
+    // It fit
+    dst->append(buf, result);
+  }
+  delete[] buf;
+}
+
+
+string StringPrintf(const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  string result;
+  StringAppendV(&result, format, ap);
+  va_end(ap);
+  return result;
+}
+
+const string& SStringPrintf(string* dst, const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  dst->clear();
+  StringAppendV(dst, format, ap);
+  va_end(ap);
+  return *dst;
+}
+
+void StringAppendF(string* dst, const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  StringAppendV(dst, format, ap);
+  va_end(ap);
+}
+
+// Max arguments supported by StringPrintVector
+const int kStringPrintfVectorMaxArgs = 32;
+
+// An empty block of zero for filler arguments.  This is const so that if
+// printf tries to write to it (via %n) then the program gets a SIGSEGV
+// and we can fix the problem or protect against an attack.
+static const char string_printf_empty_block[256] = { '\0' };
+
+string StringPrintfVector(const char* format, const vector<string>& v) {
+  GOOGLE_CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)
+      << "StringPrintfVector currently only supports up to "
+      << kStringPrintfVectorMaxArgs << " arguments. "
+      << "Feel free to add support for more if you need it.";
+
+  // Add filler arguments so that bogus format+args have a harder time
+  // crashing the program, corrupting the program (%n),
+  // or displaying random chunks of memory to users.
+
+  const char* cstr[kStringPrintfVectorMaxArgs];
+  for (int i = 0; i < v.size(); ++i) {
+    cstr[i] = v[i].c_str();
+  }
+  for (int i = v.size(); i < GOOGLE_ARRAYSIZE(cstr); ++i) {
+    cstr[i] = &string_printf_empty_block[0];
+  }
+
+  // I do not know any way to pass kStringPrintfVectorMaxArgs arguments,
+  // or any way to build a va_list by hand, or any API for printf
+  // that accepts an array of arguments.  The best I can do is stick
+  // this COMPILE_ASSERT right next to the actual statement.
+
+  GOOGLE_COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);
+  return StringPrintf(format,
+                      cstr[0], cstr[1], cstr[2], cstr[3], cstr[4],
+                      cstr[5], cstr[6], cstr[7], cstr[8], cstr[9],
+                      cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],
+                      cstr[15], cstr[16], cstr[17], cstr[18], cstr[19],
+                      cstr[20], cstr[21], cstr[22], cstr[23], cstr[24],
+                      cstr[25], cstr[26], cstr[27], cstr[28], cstr[29],
+                      cstr[30], cstr[31]);
+}
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/stubs/stringprintf.h b/src/google/protobuf/stubs/stringprintf.h
new file mode 100644
index 00000000..573f30f3
--- /dev/null
+++ b/src/google/protobuf/stubs/stringprintf.h
@@ -0,0 +1,76 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2012 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// from google3/base/stringprintf.h
+//
+// Printf variants that place their output in a C++ string.
+//
+// Usage:
+//      string result = StringPrintf("%d %s\n", 10, "hello");
+//      SStringPrintf(&result, "%d %s\n", 10, "hello");
+//      StringAppendF(&result, "%d %s\n", 20, "there");
+
+#ifndef GOOGLE_PROTOBUF_STUBS_STRINGPRINTF_H
+#define GOOGLE_PROTOBUF_STUBS_STRINGPRINTF_H
+
+#include <stdarg.h>
+#include <string>
+#include <vector>
+
+#include <google/protobuf/stubs/common.h>
+
+namespace google {
+namespace protobuf {
+
+// Return a C++ string
+extern string StringPrintf(const char* format, ...);
+
+// Store result into a supplied string and return it
+extern const string& SStringPrintf(string* dst, const char* format, ...);
+
+// Append result to a supplied string
+extern void StringAppendF(string* dst, const char* format, ...);
+
+// Lower-level routine that takes a va_list and appends to a specified
+// string.  All other routines are just convenience wrappers around it.
+extern void StringAppendV(string* dst, const char* format, va_list ap);
+
+// The max arguments supported by StringPrintfVector
+extern const int kStringPrintfVectorMaxArgs;
+
+// You can use this version when all your arguments are strings, but
+// you don't know how many arguments you'll have at compile time.
+// StringPrintfVector will LOG(FATAL) if v.size() > kStringPrintfVectorMaxArgs
+extern string StringPrintfVector(const char* format, const vector<string>& v);
+
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_STUBS_STRINGPRINTF_H
diff --git a/src/google/protobuf/stubs/stringprintf_unittest.cc b/src/google/protobuf/stubs/stringprintf_unittest.cc
new file mode 100644
index 00000000..5cf7fffc
--- /dev/null
+++ b/src/google/protobuf/stubs/stringprintf_unittest.cc
@@ -0,0 +1,152 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2012 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// from google3/base/stringprintf_unittest.cc
+
+#include <google/protobuf/stubs/stringprintf.h>
+
+#include <cerrno>
+#include <string>
+
+#include <google/protobuf/testing/googletest.h>
+#include <gtest/gtest.h>
+
+namespace google {
+namespace protobuf {
+namespace {
+
+TEST(StringPrintfTest, Empty) {
+#if 0
+  // gcc 2.95.3, gcc 4.1.0, and gcc 4.2.2 all warn about this:
+  // warning: zero-length printf format string.
+  // so we do not allow them in google3.
+  EXPECT_EQ("", StringPrintf(""));
+#endif
+  EXPECT_EQ("", StringPrintf("%s", string().c_str()));
+  EXPECT_EQ("", StringPrintf("%s", ""));
+}
+
+TEST(StringPrintfTest, Misc) {
+// MSVC does not support $ format specifier.
+#if !defined(COMPILER_MSVC)
+  EXPECT_EQ("123hello w", StringPrintf("%3$d%2$s %1$c", 'w', "hello", 123));
+#endif  // !COMPILER_MSVC
+}
+
+TEST(StringAppendFTest, Empty) {
+  string value("Hello");
+  const char* empty = "";
+  StringAppendF(&value, "%s", empty);
+  EXPECT_EQ("Hello", value);
+}
+
+TEST(StringAppendFTest, EmptyString) {
+  string value("Hello");
+  StringAppendF(&value, "%s", "");
+  EXPECT_EQ("Hello", value);
+}
+
+TEST(StringAppendFTest, String) {
+  string value("Hello");
+  StringAppendF(&value, " %s", "World");
+  EXPECT_EQ("Hello World", value);
+}
+
+TEST(StringAppendFTest, Int) {
+  string value("Hello");
+  StringAppendF(&value, " %d", 123);
+  EXPECT_EQ("Hello 123", value);
+}
+
+TEST(StringPrintfTest, Multibyte) {
+  // If we are in multibyte mode and feed invalid multibyte sequence,
+  // StringPrintf should return an empty string instead of running
+  // out of memory while trying to determine destination buffer size.
+  // see b/4194543.
+
+  char* old_locale = setlocale(LC_CTYPE, NULL);
+  // Push locale with multibyte mode
+  setlocale(LC_CTYPE, "en_US.utf8");
+
+  const char kInvalidCodePoint[] = "\375\067s";
+  string value = StringPrintf("%.*s", 3, kInvalidCodePoint);
+
+  // In some versions of glibc (e.g. eglibc-2.11.1, aka GRTEv2), snprintf
+  // returns error given an invalid codepoint. Other versions
+  // (e.g. eglibc-2.15, aka pre-GRTEv3) emit the codepoint verbatim.
+  // We test that the output is one of the above.
+  EXPECT_TRUE(value.empty() || value == kInvalidCodePoint);
+
+  // Repeat with longer string, to make sure that the dynamically
+  // allocated path in StringAppendV is handled correctly.
+  int n = 2048;
+  char* buf = new char[n+1];
+  memset(buf, ' ', n-3);
+  memcpy(buf + n - 3, kInvalidCodePoint, 4);
+  value =  StringPrintf("%.*s", n, buf);
+  // See GRTEv2 vs. GRTEv3 comment above.
+  EXPECT_TRUE(value.empty() || value == buf);
+  delete[] buf;
+
+  setlocale(LC_CTYPE, old_locale);
+}
+
+TEST(StringPrintfTest, NoMultibyte) {
+  // No multibyte handling, but the string contains funny chars.
+  char* old_locale = setlocale(LC_CTYPE, NULL);
+  setlocale(LC_CTYPE, "POSIX");
+  string value = StringPrintf("%.*s", 3, "\375\067s");
+  setlocale(LC_CTYPE, old_locale);
+  EXPECT_EQ("\375\067s", value);
+}
+
+TEST(StringPrintfTest, DontOverwriteErrno) {
+  // Check that errno isn't overwritten unless we're printing
+  // something significantly larger than what people are normally
+  // printing in their badly written PLOG() statements.
+  errno = ECHILD;
+  string value = StringPrintf("Hello, %s!", "World");
+  EXPECT_EQ(ECHILD, errno);
+}
+
+TEST(StringPrintfTest, LargeBuf) {
+  // Check that the large buffer is handled correctly.
+  int n = 2048;
+  char* buf = new char[n+1];
+  memset(buf, ' ', n);
+  buf[n] = 0;
+  string value = StringPrintf("%s", buf);
+  EXPECT_EQ(buf, value);
+  delete[] buf;
+}
+
+}  // anonymous namespace
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/stubs/strutil.cc b/src/google/protobuf/stubs/strutil.cc
index ee07ce75..917b3e9f 100644
--- a/src/google/protobuf/stubs/strutil.cc
+++ b/src/google/protobuf/stubs/strutil.cc
@@ -189,6 +189,44 @@ void SplitStringUsing(const string& full,
   SplitStringToIteratorUsing(full, delim, it);
 }
 
+// Split a string using a character delimiter. Append the components
+// to 'result'.  If there are consecutive delimiters, this function
+// will return corresponding empty strings. The string is split into
+// at most the specified number of pieces greedily. This means that the
+// last piece may possibly be split further. To split into as many pieces
+// as possible, specify 0 as the number of pieces.
+//
+// If "full" is the empty string, yields an empty string as the only value.
+//
+// If "pieces" is negative for some reason, it returns the whole string
+// ----------------------------------------------------------------------
+template <typename StringType, typename ITR>
+static inline
+void SplitStringToIteratorAllowEmpty(const StringType& full,
+                                     const char* delim,
+                                     int pieces,
+                                     ITR& result) {
+  string::size_type begin_index, end_index;
+  begin_index = 0;
+
+  for (int i = 0; (i < pieces-1) || (pieces == 0); i++) {
+    end_index = full.find_first_of(delim, begin_index);
+    if (end_index == string::npos) {
+      *result++ = full.substr(begin_index);
+      return;
+    }
+    *result++ = full.substr(begin_index, (end_index - begin_index));
+    begin_index = end_index + 1;
+  }
+  *result++ = full.substr(begin_index);
+}
+
+void SplitStringAllowEmpty(const string& full, const char* delim,
+                           vector<string>* result) {
+  back_insert_iterator<vector<string> > it(*result);
+  SplitStringToIteratorAllowEmpty(full, delim, 0, it);
+}
+
 // ----------------------------------------------------------------------
 // JoinStrings()
 //    This merges a vector of string components with delim inserted
diff --git a/src/google/protobuf/stubs/strutil.h b/src/google/protobuf/stubs/strutil.h
index 4a79c224..a401c63a 100644
--- a/src/google/protobuf/stubs/strutil.h
+++ b/src/google/protobuf/stubs/strutil.h
@@ -168,6 +168,18 @@ LIBPROTOBUF_EXPORT string StringReplace(const string& s, const string& oldsub,
 LIBPROTOBUF_EXPORT void SplitStringUsing(const string& full, const char* delim,
                                          vector<string>* res);
 
+// Split a string using one or more byte delimiters, presented
+// as a nul-terminated c string. Append the components to 'result'.
+// If there are consecutive delimiters, this function will return
+// corresponding empty strings.  If you want to drop the empty
+// strings, try SplitStringUsing().
+//
+// If "full" is the empty string, yields an empty string as the only value.
+// ----------------------------------------------------------------------
+LIBPROTOBUF_EXPORT void SplitStringAllowEmpty(const string& full,
+                                              const char* delim,
+                                              vector<string>* result);
+
 // ----------------------------------------------------------------------
 // JoinStrings()
 //    These methods concatenate a vector of strings into a C++ string, using
@@ -453,5 +465,3 @@ LIBPROTOBUF_EXPORT double NoLocaleStrtod(const char* text, char** endptr);
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_STUBS_STRUTIL_H__
-
-
diff --git a/src/google/protobuf/stubs/substitute.cc b/src/google/protobuf/stubs/substitute.cc
index b542aaa4..259245b3 100644
--- a/src/google/protobuf/stubs/substitute.cc
+++ b/src/google/protobuf/stubs/substitute.cc
@@ -32,7 +32,7 @@
 
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/stubs/strutil.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/stubs/template_util.h b/src/google/protobuf/stubs/template_util.h
new file mode 100644
index 00000000..4f30ffa3
--- /dev/null
+++ b/src/google/protobuf/stubs/template_util.h
@@ -0,0 +1,138 @@
+// Copyright 2005 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ----
+// Author: lar@google.com (Laramie Leavitt)
+//
+// Template metaprogramming utility functions.
+//
+// This code is compiled directly on many platforms, including client
+// platforms like Windows, Mac, and embedded systems.  Before making
+// any changes here, make sure that you're not breaking any platforms.
+//
+//
+// The names choosen here reflect those used in tr1 and the boost::mpl
+// library, there are similar operations used in the Loki library as
+// well.  I prefer the boost names for 2 reasons:
+// 1.  I think that portions of the Boost libraries are more likely to
+// be included in the c++ standard.
+// 2.  It is not impossible that some of the boost libraries will be
+// included in our own build in the future.
+// Both of these outcomes means that we may be able to directly replace
+// some of these with boost equivalents.
+//
+#ifndef GOOGLE_PROTOBUF_TEMPLATE_UTIL_H_
+#define GOOGLE_PROTOBUF_TEMPLATE_UTIL_H_
+
+namespace google {
+namespace protobuf {
+namespace internal {
+
+// Types small_ and big_ are guaranteed such that sizeof(small_) <
+// sizeof(big_)
+typedef char small_;
+
+struct big_ {
+  char dummy[2];
+};
+
+// Identity metafunction.
+template <class T>
+struct identity_ {
+  typedef T type;
+};
+
+// integral_constant, defined in tr1, is a wrapper for an integer
+// value. We don't really need this generality; we could get away
+// with hardcoding the integer type to bool. We use the fully
+// general integer_constant for compatibility with tr1.
+
+template<class T, T v>
+struct integral_constant {
+  static const T value = v;
+  typedef T value_type;
+  typedef integral_constant<T, v> type;
+};
+
+template <class T, T v> const T integral_constant<T, v>::value;
+
+
+// Abbreviations: true_type and false_type are structs that represent boolean
+// true and false values. Also define the boost::mpl versions of those names,
+// true_ and false_.
+typedef integral_constant<bool, true>  true_type;
+typedef integral_constant<bool, false> false_type;
+typedef true_type  true_;
+typedef false_type false_;
+
+// if_ is a templatized conditional statement.
+// if_<cond, A, B> is a compile time evaluation of cond.
+// if_<>::type contains A if cond is true, B otherwise.
+template<bool cond, typename A, typename B>
+struct if_{
+  typedef A type;
+};
+
+template<typename A, typename B>
+struct if_<false, A, B> {
+  typedef B type;
+};
+
+
+// type_equals_ is a template type comparator, similar to Loki IsSameType.
+// type_equals_<A, B>::value is true iff "A" is the same type as "B".
+//
+// New code should prefer base::is_same, defined in base/type_traits.h.
+// It is functionally identical, but is_same is the standard spelling.
+template<typename A, typename B>
+struct type_equals_ : public false_ {
+};
+
+template<typename A>
+struct type_equals_<A, A> : public true_ {
+};
+
+// and_ is a template && operator.
+// and_<A, B>::value evaluates "A::value && B::value".
+template<typename A, typename B>
+struct and_ : public integral_constant<bool, (A::value && B::value)> {
+};
+
+// or_ is a template || operator.
+// or_<A, B>::value evaluates "A::value || B::value".
+template<typename A, typename B>
+struct or_ : public integral_constant<bool, (A::value || B::value)> {
+};
+
+
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_TEMPLATE_UTIL_H_
diff --git a/src/google/protobuf/stubs/template_util_unittest.cc b/src/google/protobuf/stubs/template_util_unittest.cc
new file mode 100644
index 00000000..b1745e2b
--- /dev/null
+++ b/src/google/protobuf/stubs/template_util_unittest.cc
@@ -0,0 +1,130 @@
+// Copyright 2005 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ----
+// Author: lar@google.com (Laramie Leavitt)
+//
+// These tests are really compile time tests.
+// If you try to step through this in a debugger
+// you will not see any evaluations, merely that
+// value is assigned true or false sequentially.
+
+#include <google/protobuf/stubs/template_util.h>
+
+#include <google/protobuf/testing/googletest.h>
+#include <gtest/gtest.h>
+
+namespace GOOGLE_NAMESPACE = google::protobuf::internal;
+
+namespace google {
+namespace protobuf {
+namespace internal {
+namespace {
+
+TEST(TemplateUtilTest, TestSize) {
+  EXPECT_GT(sizeof(GOOGLE_NAMESPACE::big_), sizeof(GOOGLE_NAMESPACE::small_));
+}
+
+TEST(TemplateUtilTest, TestIntegralConstants) {
+  // test the built-in types.
+  EXPECT_TRUE(true_type::value);
+  EXPECT_FALSE(false_type::value);
+
+  typedef integral_constant<int, 1> one_type;
+  EXPECT_EQ(1, one_type::value);
+}
+
+TEST(TemplateUtilTest, TestTemplateIf) {
+  typedef if_<true, true_type, false_type>::type if_true;
+  EXPECT_TRUE(if_true::value);
+
+  typedef if_<false, true_type, false_type>::type if_false;
+  EXPECT_FALSE(if_false::value);
+}
+
+TEST(TemplateUtilTest, TestTemplateTypeEquals) {
+  // Check that the TemplateTypeEquals works correctly.
+  bool value = false;
+
+  // Test the same type is true.
+  value = type_equals_<int, int>::value;
+  EXPECT_TRUE(value);
+
+  // Test different types are false.
+  value = type_equals_<float, int>::value;
+  EXPECT_FALSE(value);
+
+  // Test type aliasing.
+  typedef const int foo;
+  value = type_equals_<const foo, const int>::value;
+  EXPECT_TRUE(value);
+}
+
+TEST(TemplateUtilTest, TestTemplateAndOr) {
+  // Check that the TemplateTypeEquals works correctly.
+  bool value = false;
+
+  // Yes && Yes == true.
+  value = and_<true_, true_>::value;
+  EXPECT_TRUE(value);
+  // Yes && No == false.
+  value = and_<true_, false_>::value;
+  EXPECT_FALSE(value);
+  // No && Yes == false.
+  value = and_<false_, true_>::value;
+  EXPECT_FALSE(value);
+  // No && No == false.
+  value = and_<false_, false_>::value;
+  EXPECT_FALSE(value);
+
+  // Yes || Yes == true.
+  value = or_<true_, true_>::value;
+  EXPECT_TRUE(value);
+  // Yes || No == true.
+  value = or_<true_, false_>::value;
+  EXPECT_TRUE(value);
+  // No || Yes == true.
+  value = or_<false_, true_>::value;
+  EXPECT_TRUE(value);
+  // No || No == false.
+  value = or_<false_, false_>::value;
+  EXPECT_FALSE(value);
+}
+
+TEST(TemplateUtilTest, TestIdentity) {
+  EXPECT_TRUE(
+      (type_equals_<GOOGLE_NAMESPACE::identity_<int>::type, int>::value));
+  EXPECT_TRUE(
+      (type_equals_<GOOGLE_NAMESPACE::identity_<void>::type, void>::value));
+}
+
+}  // anonymous namespace
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/stubs/type_traits.h b/src/google/protobuf/stubs/type_traits.h
new file mode 100644
index 00000000..997f35d4
--- /dev/null
+++ b/src/google/protobuf/stubs/type_traits.h
@@ -0,0 +1,346 @@
+// Copyright (c) 2006, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ----
+// Author: Matt Austern
+//
+// This code is compiled directly on many platforms, including client
+// platforms like Windows, Mac, and embedded systems.  Before making
+// any changes here, make sure that you're not breaking any platforms.
+//
+// Define a small subset of tr1 type traits. The traits we define are:
+//   is_integral
+//   is_floating_point
+//   is_pointer
+//   is_enum
+//   is_reference
+//   is_pod
+//   has_trivial_constructor
+//   has_trivial_copy
+//   has_trivial_assign
+//   has_trivial_destructor
+//   remove_const
+//   remove_volatile
+//   remove_cv
+//   remove_reference
+//   add_reference
+//   remove_pointer
+//   is_same
+//   is_convertible
+// We can add more type traits as required.
+
+#ifndef GOOGLE_PROTOBUF_TYPE_TRAITS_H_
+#define GOOGLE_PROTOBUF_TYPE_TRAITS_H_
+
+#include <utility>                  // For pair
+
+#include <google/protobuf/stubs/template_util.h>  // For true_type and false_type
+
+namespace google {
+namespace protobuf {
+namespace internal {
+
+template <class T> struct is_integral;
+template <class T> struct is_floating_point;
+template <class T> struct is_pointer;
+// MSVC can't compile this correctly, and neither can gcc 3.3.5 (at least)
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+// is_enum uses is_convertible, which is not available on MSVC.
+template <class T> struct is_enum;
+#endif
+template <class T> struct is_reference;
+template <class T> struct is_pod;
+template <class T> struct has_trivial_constructor;
+template <class T> struct has_trivial_copy;
+template <class T> struct has_trivial_assign;
+template <class T> struct has_trivial_destructor;
+template <class T> struct remove_const;
+template <class T> struct remove_volatile;
+template <class T> struct remove_cv;
+template <class T> struct remove_reference;
+template <class T> struct add_reference;
+template <class T> struct remove_pointer;
+template <class T, class U> struct is_same;
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+template <class From, class To> struct is_convertible;
+#endif
+
+// is_integral is false except for the built-in integer types. A
+// cv-qualified type is integral if and only if the underlying type is.
+template <class T> struct is_integral : false_type { };
+template<> struct is_integral<bool> : true_type { };
+template<> struct is_integral<char> : true_type { };
+template<> struct is_integral<unsigned char> : true_type { };
+template<> struct is_integral<signed char> : true_type { };
+#if defined(_MSC_VER)
+// wchar_t is not by default a distinct type from unsigned short in
+// Microsoft C.
+// See http://msdn2.microsoft.com/en-us/library/dh8che7s(VS.80).aspx
+template<> struct is_integral<__wchar_t> : true_type { };
+#else
+template<> struct is_integral<wchar_t> : true_type { };
+#endif
+template<> struct is_integral<short> : true_type { };
+template<> struct is_integral<unsigned short> : true_type { };
+template<> struct is_integral<int> : true_type { };
+template<> struct is_integral<unsigned int> : true_type { };
+template<> struct is_integral<long> : true_type { };
+template<> struct is_integral<unsigned long> : true_type { };
+#ifdef HAVE_LONG_LONG
+template<> struct is_integral<long long> : true_type { };
+template<> struct is_integral<unsigned long long> : true_type { };
+#endif
+template <class T> struct is_integral<const T> : is_integral<T> { };
+template <class T> struct is_integral<volatile T> : is_integral<T> { };
+template <class T> struct is_integral<const volatile T> : is_integral<T> { };
+
+// is_floating_point is false except for the built-in floating-point types.
+// A cv-qualified type is integral if and only if the underlying type is.
+template <class T> struct is_floating_point : false_type { };
+template<> struct is_floating_point<float> : true_type { };
+template<> struct is_floating_point<double> : true_type { };
+template<> struct is_floating_point<long double> : true_type { };
+template <class T> struct is_floating_point<const T>
+    : is_floating_point<T> { };
+template <class T> struct is_floating_point<volatile T>
+    : is_floating_point<T> { };
+template <class T> struct is_floating_point<const volatile T>
+    : is_floating_point<T> { };
+
+// is_pointer is false except for pointer types. A cv-qualified type (e.g.
+// "int* const", as opposed to "int const*") is cv-qualified if and only if
+// the underlying type is.
+template <class T> struct is_pointer : false_type { };
+template <class T> struct is_pointer<T*> : true_type { };
+template <class T> struct is_pointer<const T> : is_pointer<T> { };
+template <class T> struct is_pointer<volatile T> : is_pointer<T> { };
+template <class T> struct is_pointer<const volatile T> : is_pointer<T> { };
+
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+
+namespace internal {
+
+template <class T> struct is_class_or_union {
+  template <class U> static small_ tester(void (U::*)());
+  template <class U> static big_ tester(...);
+  static const bool value = sizeof(tester<T>(0)) == sizeof(small_);
+};
+
+// is_convertible chokes if the first argument is an array. That's why
+// we use add_reference here.
+template <bool NotUnum, class T> struct is_enum_impl
+    : is_convertible<typename add_reference<T>::type, int> { };
+
+template <class T> struct is_enum_impl<true, T> : false_type { };
+
+}  // namespace internal
+
+// Specified by TR1 [4.5.1] primary type categories.
+
+// Implementation note:
+//
+// Each type is either void, integral, floating point, array, pointer,
+// reference, member object pointer, member function pointer, enum,
+// union or class. Out of these, only integral, floating point, reference,
+// class and enum types are potentially convertible to int. Therefore,
+// if a type is not a reference, integral, floating point or class and
+// is convertible to int, it's a enum. Adding cv-qualification to a type
+// does not change whether it's an enum.
+//
+// Is-convertible-to-int check is done only if all other checks pass,
+// because it can't be used with some types (e.g. void or classes with
+// inaccessible conversion operators).
+template <class T> struct is_enum
+    : internal::is_enum_impl<
+          is_same<T, void>::value ||
+              is_integral<T>::value ||
+              is_floating_point<T>::value ||
+              is_reference<T>::value ||
+              internal::is_class_or_union<T>::value,
+          T> { };
+
+template <class T> struct is_enum<const T> : is_enum<T> { };
+template <class T> struct is_enum<volatile T> : is_enum<T> { };
+template <class T> struct is_enum<const volatile T> : is_enum<T> { };
+
+#endif
+
+// is_reference is false except for reference types.
+template<typename T> struct is_reference : false_type {};
+template<typename T> struct is_reference<T&> : true_type {};
+
+
+// We can't get is_pod right without compiler help, so fail conservatively.
+// We will assume it's false except for arithmetic types, enumerations,
+// pointers and cv-qualified versions thereof. Note that std::pair<T,U>
+// is not a POD even if T and U are PODs.
+template <class T> struct is_pod
+ : integral_constant<bool, (is_integral<T>::value ||
+                            is_floating_point<T>::value ||
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+                            // is_enum is not available on MSVC.
+                            is_enum<T>::value ||
+#endif
+                            is_pointer<T>::value)> { };
+template <class T> struct is_pod<const T> : is_pod<T> { };
+template <class T> struct is_pod<volatile T> : is_pod<T> { };
+template <class T> struct is_pod<const volatile T> : is_pod<T> { };
+
+
+// We can't get has_trivial_constructor right without compiler help, so
+// fail conservatively. We will assume it's false except for: (1) types
+// for which is_pod is true. (2) std::pair of types with trivial
+// constructors. (3) array of a type with a trivial constructor.
+// (4) const versions thereof.
+template <class T> struct has_trivial_constructor : is_pod<T> { };
+template <class T, class U> struct has_trivial_constructor<std::pair<T, U> >
+  : integral_constant<bool,
+                      (has_trivial_constructor<T>::value &&
+                       has_trivial_constructor<U>::value)> { };
+template <class A, int N> struct has_trivial_constructor<A[N]>
+  : has_trivial_constructor<A> { };
+template <class T> struct has_trivial_constructor<const T>
+  : has_trivial_constructor<T> { };
+
+// We can't get has_trivial_copy right without compiler help, so fail
+// conservatively. We will assume it's false except for: (1) types
+// for which is_pod is true. (2) std::pair of types with trivial copy
+// constructors. (3) array of a type with a trivial copy constructor.
+// (4) const versions thereof.
+template <class T> struct has_trivial_copy : is_pod<T> { };
+template <class T, class U> struct has_trivial_copy<std::pair<T, U> >
+  : integral_constant<bool,
+                      (has_trivial_copy<T>::value &&
+                       has_trivial_copy<U>::value)> { };
+template <class A, int N> struct has_trivial_copy<A[N]>
+  : has_trivial_copy<A> { };
+template <class T> struct has_trivial_copy<const T> : has_trivial_copy<T> { };
+
+// We can't get has_trivial_assign right without compiler help, so fail
+// conservatively. We will assume it's false except for: (1) types
+// for which is_pod is true. (2) std::pair of types with trivial copy
+// constructors. (3) array of a type with a trivial assign constructor.
+template <class T> struct has_trivial_assign : is_pod<T> { };
+template <class T, class U> struct has_trivial_assign<std::pair<T, U> >
+  : integral_constant<bool,
+                      (has_trivial_assign<T>::value &&
+                       has_trivial_assign<U>::value)> { };
+template <class A, int N> struct has_trivial_assign<A[N]>
+  : has_trivial_assign<A> { };
+
+// We can't get has_trivial_destructor right without compiler help, so
+// fail conservatively. We will assume it's false except for: (1) types
+// for which is_pod is true. (2) std::pair of types with trivial
+// destructors. (3) array of a type with a trivial destructor.
+// (4) const versions thereof.
+template <class T> struct has_trivial_destructor : is_pod<T> { };
+template <class T, class U> struct has_trivial_destructor<std::pair<T, U> >
+  : integral_constant<bool,
+                      (has_trivial_destructor<T>::value &&
+                       has_trivial_destructor<U>::value)> { };
+template <class A, int N> struct has_trivial_destructor<A[N]>
+  : has_trivial_destructor<A> { };
+template <class T> struct has_trivial_destructor<const T>
+  : has_trivial_destructor<T> { };
+
+// Specified by TR1 [4.7.1]
+template<typename T> struct remove_const { typedef T type; };
+template<typename T> struct remove_const<T const> { typedef T type; };
+template<typename T> struct remove_volatile { typedef T type; };
+template<typename T> struct remove_volatile<T volatile> { typedef T type; };
+template<typename T> struct remove_cv {
+  typedef typename remove_const<typename remove_volatile<T>::type>::type type;
+};
+
+
+// Specified by TR1 [4.7.2] Reference modifications.
+template<typename T> struct remove_reference { typedef T type; };
+template<typename T> struct remove_reference<T&> { typedef T type; };
+
+template <typename T> struct add_reference { typedef T& type; };
+template <typename T> struct add_reference<T&> { typedef T& type; };
+
+// Specified by TR1 [4.7.4] Pointer modifications.
+template<typename T> struct remove_pointer { typedef T type; };
+template<typename T> struct remove_pointer<T*> { typedef T type; };
+template<typename T> struct remove_pointer<T* const> { typedef T type; };
+template<typename T> struct remove_pointer<T* volatile> { typedef T type; };
+template<typename T> struct remove_pointer<T* const volatile> {
+  typedef T type; };
+
+// Specified by TR1 [4.6] Relationships between types
+template<typename T, typename U> struct is_same : public false_type { };
+template<typename T> struct is_same<T, T> : public true_type { };
+
+// Specified by TR1 [4.6] Relationships between types
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+namespace internal {
+
+// This class is an implementation detail for is_convertible, and you
+// don't need to know how it works to use is_convertible. For those
+// who care: we declare two different functions, one whose argument is
+// of type To and one with a variadic argument list. We give them
+// return types of different size, so we can use sizeof to trick the
+// compiler into telling us which function it would have chosen if we
+// had called it with an argument of type From.  See Alexandrescu's
+// _Modern C++ Design_ for more details on this sort of trick.
+
+template <typename From, typename To>
+struct ConvertHelper {
+  static small_ Test(To);
+  static big_ Test(...);
+  static From Create();
+};
+}  // namespace internal
+
+// Inherits from true_type if From is convertible to To, false_type otherwise.
+template <typename From, typename To>
+struct is_convertible
+    : integral_constant<bool,
+                        sizeof(internal::ConvertHelper<From, To>::Test(
+                                  internal::ConvertHelper<From, To>::Create()))
+                        == sizeof(small_)> {
+};
+#endif
+
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+// Right now these macros are no-ops, and mostly just document the fact
+// these types are PODs, for human use.  They may be made more contentful
+// later.  The typedef is just to make it legal to put a semicolon after
+// these macros.
+#define DECLARE_POD(TypeName) typedef int Dummy_Type_For_DECLARE_POD
+#define DECLARE_NESTED_POD(TypeName) DECLARE_POD(TypeName)
+#define PROPAGATE_POD_FROM_TEMPLATE_ARGUMENT(TemplateName)             \
+    typedef int Dummy_Type_For_PROPAGATE_POD_FROM_TEMPLATE_ARGUMENT
+#define ENFORCE_POD(TypeName) typedef int Dummy_Type_For_ENFORCE_POD
+
+#endif  // GOOGLE_PROTOBUF_TYPE_TRAITS_H_
diff --git a/src/google/protobuf/stubs/type_traits_unittest.cc b/src/google/protobuf/stubs/type_traits_unittest.cc
new file mode 100644
index 00000000..00e5a476
--- /dev/null
+++ b/src/google/protobuf/stubs/type_traits_unittest.cc
@@ -0,0 +1,647 @@
+// Copyright (c) 2006, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ----
+// Author: Matt Austern
+
+#include <google/protobuf/stubs/type_traits.h>
+
+#include <stdlib.h>   // for exit()
+#include <stdio.h>
+#include <string>
+#include <vector>
+
+#include <google/protobuf/testing/googletest.h>
+#include <gtest/gtest.h>
+
+typedef int int32;
+typedef long int64;
+
+using std::string;
+using std::vector;
+using std::pair;
+
+using google::protobuf::internal::add_reference;
+using google::protobuf::internal::has_trivial_assign;
+using google::protobuf::internal::has_trivial_constructor;
+using google::protobuf::internal::has_trivial_copy;
+using google::protobuf::internal::has_trivial_destructor;
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+using google::protobuf::internal::is_convertible;
+using google::protobuf::internal::is_enum;
+#endif
+using google::protobuf::internal::is_floating_point;
+using google::protobuf::internal::is_integral;
+using google::protobuf::internal::is_pointer;
+using google::protobuf::internal::is_pod;
+using google::protobuf::internal::is_reference;
+using google::protobuf::internal::is_same;
+using google::protobuf::internal::remove_const;
+using google::protobuf::internal::remove_cv;
+using google::protobuf::internal::remove_pointer;
+using google::protobuf::internal::remove_reference;
+using google::protobuf::internal::remove_volatile;
+
+
+// This assertion produces errors like "error: invalid use of
+// incomplete type 'struct <unnamed>::AssertTypesEq<const int, int>'"
+// when it fails.
+template<typename T, typename U> struct AssertTypesEq;
+template<typename T> struct AssertTypesEq<T, T> {};
+#define COMPILE_ASSERT_TYPES_EQ(T, U) static_cast<void>(AssertTypesEq<T, U>())
+
+// A user-defined POD type.
+struct A {
+  int n_;
+};
+
+// A user-defined non-POD type with a trivial copy constructor.
+class B {
+ public:
+  explicit B(int n) : n_(n) { }
+ private:
+  int n_;
+};
+
+// Another user-defined non-POD type with a trivial copy constructor.
+// We will explicitly declare C to have a trivial copy constructor
+// by specializing has_trivial_copy.
+class C {
+ public:
+  explicit C(int n) : n_(n) { }
+ private:
+  int n_;
+};
+
+namespace google {
+namespace protobuf {
+namespace internal {
+template<> struct has_trivial_copy<C> : true_type { };
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+// Another user-defined non-POD type with a trivial assignment operator.
+// We will explicitly declare C to have a trivial assignment operator
+// by specializing has_trivial_assign.
+class D {
+ public:
+  explicit D(int n) : n_(n) { }
+ private:
+  int n_;
+};
+
+namespace google {
+namespace protobuf {
+namespace internal {
+template<> struct has_trivial_assign<D> : true_type { };
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+// Another user-defined non-POD type with a trivial constructor.
+// We will explicitly declare E to have a trivial constructor
+// by specializing has_trivial_constructor.
+class E {
+ public:
+  int n_;
+};
+
+namespace google {
+namespace protobuf {
+namespace internal {
+template<> struct has_trivial_constructor<E> : true_type { };
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+// Another user-defined non-POD type with a trivial destructor.
+// We will explicitly declare E to have a trivial destructor
+// by specializing has_trivial_destructor.
+class F {
+ public:
+  explicit F(int n) : n_(n) { }
+ private:
+  int n_;
+};
+
+namespace google {
+namespace protobuf {
+namespace internal {
+template<> struct has_trivial_destructor<F> : true_type { };
+}  // namespace internal
+}  // namespace protobuf
+}  // namespace google
+
+enum G {};
+
+union H {};
+
+class I {
+ public:
+  operator int() const;
+};
+
+class J {
+ private:
+  operator int() const;
+};
+
+namespace google {
+namespace protobuf {
+namespace {
+
+// A base class and a derived class that inherits from it, used for
+// testing conversion type traits.
+class Base {
+ public:
+  virtual ~Base() { }
+};
+
+class Derived : public Base {
+};
+
+TEST(TypeTraitsTest, TestIsInteger) {
+  // Verify that is_integral is true for all integer types.
+  EXPECT_TRUE(is_integral<bool>::value);
+  EXPECT_TRUE(is_integral<char>::value);
+  EXPECT_TRUE(is_integral<unsigned char>::value);
+  EXPECT_TRUE(is_integral<signed char>::value);
+  EXPECT_TRUE(is_integral<wchar_t>::value);
+  EXPECT_TRUE(is_integral<int>::value);
+  EXPECT_TRUE(is_integral<unsigned int>::value);
+  EXPECT_TRUE(is_integral<short>::value);
+  EXPECT_TRUE(is_integral<unsigned short>::value);
+  EXPECT_TRUE(is_integral<long>::value);
+  EXPECT_TRUE(is_integral<unsigned long>::value);
+
+  // Verify that is_integral is false for a few non-integer types.
+  EXPECT_FALSE(is_integral<void>::value);
+  EXPECT_FALSE(is_integral<float>::value);
+  EXPECT_FALSE(is_integral<string>::value);
+  EXPECT_FALSE(is_integral<int*>::value);
+  EXPECT_FALSE(is_integral<A>::value);
+  EXPECT_FALSE((is_integral<pair<int, int> >::value));
+
+  // Verify that cv-qualified integral types are still integral, and
+  // cv-qualified non-integral types are still non-integral.
+  EXPECT_TRUE(is_integral<const char>::value);
+  EXPECT_TRUE(is_integral<volatile bool>::value);
+  EXPECT_TRUE(is_integral<const volatile unsigned int>::value);
+  EXPECT_FALSE(is_integral<const float>::value);
+  EXPECT_FALSE(is_integral<int* volatile>::value);
+  EXPECT_FALSE(is_integral<const volatile string>::value);
+}
+
+TEST(TypeTraitsTest, TestIsFloating) {
+  // Verify that is_floating_point is true for all floating-point types.
+  EXPECT_TRUE(is_floating_point<float>::value);
+  EXPECT_TRUE(is_floating_point<double>::value);
+  EXPECT_TRUE(is_floating_point<long double>::value);
+
+  // Verify that is_floating_point is false for a few non-float types.
+  EXPECT_FALSE(is_floating_point<void>::value);
+  EXPECT_FALSE(is_floating_point<long>::value);
+  EXPECT_FALSE(is_floating_point<string>::value);
+  EXPECT_FALSE(is_floating_point<float*>::value);
+  EXPECT_FALSE(is_floating_point<A>::value);
+  EXPECT_FALSE((is_floating_point<pair<int, int> >::value));
+
+  // Verify that cv-qualified floating point types are still floating, and
+  // cv-qualified non-floating types are still non-floating.
+  EXPECT_TRUE(is_floating_point<const float>::value);
+  EXPECT_TRUE(is_floating_point<volatile double>::value);
+  EXPECT_TRUE(is_floating_point<const volatile long double>::value);
+  EXPECT_FALSE(is_floating_point<const int>::value);
+  EXPECT_FALSE(is_floating_point<volatile string>::value);
+  EXPECT_FALSE(is_floating_point<const volatile char>::value);
+}
+
+TEST(TypeTraitsTest, TestIsPointer) {
+  // Verify that is_pointer is true for some pointer types.
+  EXPECT_TRUE(is_pointer<int*>::value);
+  EXPECT_TRUE(is_pointer<void*>::value);
+  EXPECT_TRUE(is_pointer<string*>::value);
+  EXPECT_TRUE(is_pointer<const void*>::value);
+  EXPECT_TRUE(is_pointer<volatile float* const*>::value);
+
+  // Verify that is_pointer is false for some non-pointer types.
+  EXPECT_FALSE(is_pointer<void>::value);
+  EXPECT_FALSE(is_pointer<float&>::value);
+  EXPECT_FALSE(is_pointer<long>::value);
+  EXPECT_FALSE(is_pointer<vector<int*> >::value);
+  EXPECT_FALSE(is_pointer<int[5]>::value);
+
+  // A function pointer is a pointer, but a function type, or a function
+  // reference type, is not.
+  EXPECT_TRUE(is_pointer<int (*)(int x)>::value);
+  EXPECT_FALSE(is_pointer<void(char x)>::value);
+  EXPECT_FALSE(is_pointer<double (&)(string x)>::value);
+
+  // Verify that is_pointer<T> is true for some cv-qualified pointer types,
+  // and false for some cv-qualified non-pointer types.
+  EXPECT_TRUE(is_pointer<int* const>::value);
+  EXPECT_TRUE(is_pointer<const void* volatile>::value);
+  EXPECT_TRUE(is_pointer<char** const volatile>::value);
+  EXPECT_FALSE(is_pointer<const int>::value);
+  EXPECT_FALSE(is_pointer<volatile vector<int*> >::value);
+  EXPECT_FALSE(is_pointer<const volatile double>::value);
+}
+
+TEST(TypeTraitsTest, TestIsEnum) {
+// is_enum isn't supported on MSVC or gcc 3.x
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+  // Verify that is_enum is true for enum types.
+  EXPECT_TRUE(is_enum<G>::value);
+  EXPECT_TRUE(is_enum<const G>::value);
+  EXPECT_TRUE(is_enum<volatile G>::value);
+  EXPECT_TRUE(is_enum<const volatile G>::value);
+
+  // Verify that is_enum is false for a few non-enum types.
+  EXPECT_FALSE(is_enum<void>::value);
+  EXPECT_FALSE(is_enum<G&>::value);
+  EXPECT_FALSE(is_enum<G[1]>::value);
+  EXPECT_FALSE(is_enum<const G[1]>::value);
+  EXPECT_FALSE(is_enum<G[]>::value);
+  EXPECT_FALSE(is_enum<int>::value);
+  EXPECT_FALSE(is_enum<float>::value);
+  EXPECT_FALSE(is_enum<A>::value);
+  EXPECT_FALSE(is_enum<A*>::value);
+  EXPECT_FALSE(is_enum<const A>::value);
+  EXPECT_FALSE(is_enum<H>::value);
+  EXPECT_FALSE(is_enum<I>::value);
+  EXPECT_FALSE(is_enum<J>::value);
+  EXPECT_FALSE(is_enum<void()>::value);
+  EXPECT_FALSE(is_enum<void(*)()>::value);
+  EXPECT_FALSE(is_enum<int A::*>::value);
+  EXPECT_FALSE(is_enum<void (A::*)()>::value);
+#endif
+}
+
+TEST(TypeTraitsTest, TestIsReference) {
+  // Verifies that is_reference is true for all reference types.
+  typedef float& RefFloat;
+  EXPECT_TRUE(is_reference<float&>::value);
+  EXPECT_TRUE(is_reference<const int&>::value);
+  EXPECT_TRUE(is_reference<const int*&>::value);
+  EXPECT_TRUE(is_reference<int (&)(bool)>::value);
+  EXPECT_TRUE(is_reference<RefFloat>::value);
+  EXPECT_TRUE(is_reference<const RefFloat>::value);
+  EXPECT_TRUE(is_reference<volatile RefFloat>::value);
+  EXPECT_TRUE(is_reference<const volatile RefFloat>::value);
+
+
+  // Verifies that is_reference is false for all non-reference types.
+  EXPECT_FALSE(is_reference<float>::value);
+  EXPECT_FALSE(is_reference<const float>::value);
+  EXPECT_FALSE(is_reference<volatile float>::value);
+  EXPECT_FALSE(is_reference<const volatile float>::value);
+  EXPECT_FALSE(is_reference<const int*>::value);
+  EXPECT_FALSE(is_reference<int()>::value);
+  EXPECT_FALSE(is_reference<void(*)(const char&)>::value);
+}
+
+TEST(TypeTraitsTest, TestAddReference) {
+  COMPILE_ASSERT_TYPES_EQ(int&, add_reference<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(const int&, add_reference<const int>::type);
+  COMPILE_ASSERT_TYPES_EQ(volatile int&,
+                          add_reference<volatile int>::type);
+  COMPILE_ASSERT_TYPES_EQ(const volatile int&,
+                          add_reference<const volatile int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int&, add_reference<int&>::type);
+  COMPILE_ASSERT_TYPES_EQ(const int&, add_reference<const int&>::type);
+  COMPILE_ASSERT_TYPES_EQ(volatile int&,
+                          add_reference<volatile int&>::type);
+  COMPILE_ASSERT_TYPES_EQ(const volatile int&,
+                          add_reference<const volatile int&>::type);
+}
+
+TEST(TypeTraitsTest, TestIsPod) {
+  // Verify that arithmetic types and pointers are marked as PODs.
+  EXPECT_TRUE(is_pod<bool>::value);
+  EXPECT_TRUE(is_pod<char>::value);
+  EXPECT_TRUE(is_pod<unsigned char>::value);
+  EXPECT_TRUE(is_pod<signed char>::value);
+  EXPECT_TRUE(is_pod<wchar_t>::value);
+  EXPECT_TRUE(is_pod<int>::value);
+  EXPECT_TRUE(is_pod<unsigned int>::value);
+  EXPECT_TRUE(is_pod<short>::value);
+  EXPECT_TRUE(is_pod<unsigned short>::value);
+  EXPECT_TRUE(is_pod<long>::value);
+  EXPECT_TRUE(is_pod<unsigned long>::value);
+  EXPECT_TRUE(is_pod<float>::value);
+  EXPECT_TRUE(is_pod<double>::value);
+  EXPECT_TRUE(is_pod<long double>::value);
+  EXPECT_TRUE(is_pod<string*>::value);
+  EXPECT_TRUE(is_pod<A*>::value);
+  EXPECT_TRUE(is_pod<const B*>::value);
+  EXPECT_TRUE(is_pod<C**>::value);
+  EXPECT_TRUE(is_pod<const int>::value);
+  EXPECT_TRUE(is_pod<char* volatile>::value);
+  EXPECT_TRUE(is_pod<const volatile double>::value);
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+  EXPECT_TRUE(is_pod<G>::value);
+  EXPECT_TRUE(is_pod<const G>::value);
+  EXPECT_TRUE(is_pod<volatile G>::value);
+  EXPECT_TRUE(is_pod<const volatile G>::value);
+#endif
+
+  // Verify that some non-POD types are not marked as PODs.
+  EXPECT_FALSE(is_pod<void>::value);
+  EXPECT_FALSE(is_pod<string>::value);
+  EXPECT_FALSE((is_pod<pair<int, int> >::value));
+  EXPECT_FALSE(is_pod<A>::value);
+  EXPECT_FALSE(is_pod<B>::value);
+  EXPECT_FALSE(is_pod<C>::value);
+  EXPECT_FALSE(is_pod<const string>::value);
+  EXPECT_FALSE(is_pod<volatile A>::value);
+  EXPECT_FALSE(is_pod<const volatile B>::value);
+}
+
+TEST(TypeTraitsTest, TestHasTrivialConstructor) {
+  // Verify that arithmetic types and pointers have trivial constructors.
+  EXPECT_TRUE(has_trivial_constructor<bool>::value);
+  EXPECT_TRUE(has_trivial_constructor<char>::value);
+  EXPECT_TRUE(has_trivial_constructor<unsigned char>::value);
+  EXPECT_TRUE(has_trivial_constructor<signed char>::value);
+  EXPECT_TRUE(has_trivial_constructor<wchar_t>::value);
+  EXPECT_TRUE(has_trivial_constructor<int>::value);
+  EXPECT_TRUE(has_trivial_constructor<unsigned int>::value);
+  EXPECT_TRUE(has_trivial_constructor<short>::value);
+  EXPECT_TRUE(has_trivial_constructor<unsigned short>::value);
+  EXPECT_TRUE(has_trivial_constructor<long>::value);
+  EXPECT_TRUE(has_trivial_constructor<unsigned long>::value);
+  EXPECT_TRUE(has_trivial_constructor<float>::value);
+  EXPECT_TRUE(has_trivial_constructor<double>::value);
+  EXPECT_TRUE(has_trivial_constructor<long double>::value);
+  EXPECT_TRUE(has_trivial_constructor<string*>::value);
+  EXPECT_TRUE(has_trivial_constructor<A*>::value);
+  EXPECT_TRUE(has_trivial_constructor<const B*>::value);
+  EXPECT_TRUE(has_trivial_constructor<C**>::value);
+
+  // Verify that pairs and arrays of such types have trivial
+  // constructors.
+  typedef int int10[10];
+  EXPECT_TRUE((has_trivial_constructor<pair<int, char*> >::value));
+  EXPECT_TRUE(has_trivial_constructor<int10>::value);
+
+  // Verify that pairs of types without trivial constructors
+  // are not marked as trivial.
+  EXPECT_FALSE((has_trivial_constructor<pair<int, string> >::value));
+  EXPECT_FALSE((has_trivial_constructor<pair<string, int> >::value));
+
+  // Verify that types without trivial constructors are
+  // correctly marked as such.
+  EXPECT_FALSE(has_trivial_constructor<string>::value);
+  EXPECT_FALSE(has_trivial_constructor<vector<int> >::value);
+
+  // Verify that E, which we have declared to have a trivial
+  // constructor, is correctly marked as such.
+  EXPECT_TRUE(has_trivial_constructor<E>::value);
+}
+
+TEST(TypeTraitsTest, TestHasTrivialCopy) {
+  // Verify that arithmetic types and pointers have trivial copy
+  // constructors.
+  EXPECT_TRUE(has_trivial_copy<bool>::value);
+  EXPECT_TRUE(has_trivial_copy<char>::value);
+  EXPECT_TRUE(has_trivial_copy<unsigned char>::value);
+  EXPECT_TRUE(has_trivial_copy<signed char>::value);
+  EXPECT_TRUE(has_trivial_copy<wchar_t>::value);
+  EXPECT_TRUE(has_trivial_copy<int>::value);
+  EXPECT_TRUE(has_trivial_copy<unsigned int>::value);
+  EXPECT_TRUE(has_trivial_copy<short>::value);
+  EXPECT_TRUE(has_trivial_copy<unsigned short>::value);
+  EXPECT_TRUE(has_trivial_copy<long>::value);
+  EXPECT_TRUE(has_trivial_copy<unsigned long>::value);
+  EXPECT_TRUE(has_trivial_copy<float>::value);
+  EXPECT_TRUE(has_trivial_copy<double>::value);
+  EXPECT_TRUE(has_trivial_copy<long double>::value);
+  EXPECT_TRUE(has_trivial_copy<string*>::value);
+  EXPECT_TRUE(has_trivial_copy<A*>::value);
+  EXPECT_TRUE(has_trivial_copy<const B*>::value);
+  EXPECT_TRUE(has_trivial_copy<C**>::value);
+
+  // Verify that pairs and arrays of such types have trivial
+  // copy constructors.
+  typedef int int10[10];
+  EXPECT_TRUE((has_trivial_copy<pair<int, char*> >::value));
+  EXPECT_TRUE(has_trivial_copy<int10>::value);
+
+  // Verify that pairs of types without trivial copy constructors
+  // are not marked as trivial.
+  EXPECT_FALSE((has_trivial_copy<pair<int, string> >::value));
+  EXPECT_FALSE((has_trivial_copy<pair<string, int> >::value));
+
+  // Verify that types without trivial copy constructors are
+  // correctly marked as such.
+  EXPECT_FALSE(has_trivial_copy<string>::value);
+  EXPECT_FALSE(has_trivial_copy<vector<int> >::value);
+
+  // Verify that C, which we have declared to have a trivial
+  // copy constructor, is correctly marked as such.
+  EXPECT_TRUE(has_trivial_copy<C>::value);
+}
+
+TEST(TypeTraitsTest, TestHasTrivialAssign) {
+  // Verify that arithmetic types and pointers have trivial assignment
+  // operators.
+  EXPECT_TRUE(has_trivial_assign<bool>::value);
+  EXPECT_TRUE(has_trivial_assign<char>::value);
+  EXPECT_TRUE(has_trivial_assign<unsigned char>::value);
+  EXPECT_TRUE(has_trivial_assign<signed char>::value);
+  EXPECT_TRUE(has_trivial_assign<wchar_t>::value);
+  EXPECT_TRUE(has_trivial_assign<int>::value);
+  EXPECT_TRUE(has_trivial_assign<unsigned int>::value);
+  EXPECT_TRUE(has_trivial_assign<short>::value);
+  EXPECT_TRUE(has_trivial_assign<unsigned short>::value);
+  EXPECT_TRUE(has_trivial_assign<long>::value);
+  EXPECT_TRUE(has_trivial_assign<unsigned long>::value);
+  EXPECT_TRUE(has_trivial_assign<float>::value);
+  EXPECT_TRUE(has_trivial_assign<double>::value);
+  EXPECT_TRUE(has_trivial_assign<long double>::value);
+  EXPECT_TRUE(has_trivial_assign<string*>::value);
+  EXPECT_TRUE(has_trivial_assign<A*>::value);
+  EXPECT_TRUE(has_trivial_assign<const B*>::value);
+  EXPECT_TRUE(has_trivial_assign<C**>::value);
+
+  // Verify that pairs and arrays of such types have trivial
+  // assignment operators.
+  typedef int int10[10];
+  EXPECT_TRUE((has_trivial_assign<pair<int, char*> >::value));
+  EXPECT_TRUE(has_trivial_assign<int10>::value);
+
+  // Verify that pairs of types without trivial assignment operators
+  // are not marked as trivial.
+  EXPECT_FALSE((has_trivial_assign<pair<int, string> >::value));
+  EXPECT_FALSE((has_trivial_assign<pair<string, int> >::value));
+
+  // Verify that types without trivial assignment operators are
+  // correctly marked as such.
+  EXPECT_FALSE(has_trivial_assign<string>::value);
+  EXPECT_FALSE(has_trivial_assign<vector<int> >::value);
+
+  // Verify that D, which we have declared to have a trivial
+  // assignment operator, is correctly marked as such.
+  EXPECT_TRUE(has_trivial_assign<D>::value);
+}
+
+TEST(TypeTraitsTest, TestHasTrivialDestructor) {
+  // Verify that arithmetic types and pointers have trivial destructors.
+  EXPECT_TRUE(has_trivial_destructor<bool>::value);
+  EXPECT_TRUE(has_trivial_destructor<char>::value);
+  EXPECT_TRUE(has_trivial_destructor<unsigned char>::value);
+  EXPECT_TRUE(has_trivial_destructor<signed char>::value);
+  EXPECT_TRUE(has_trivial_destructor<wchar_t>::value);
+  EXPECT_TRUE(has_trivial_destructor<int>::value);
+  EXPECT_TRUE(has_trivial_destructor<unsigned int>::value);
+  EXPECT_TRUE(has_trivial_destructor<short>::value);
+  EXPECT_TRUE(has_trivial_destructor<unsigned short>::value);
+  EXPECT_TRUE(has_trivial_destructor<long>::value);
+  EXPECT_TRUE(has_trivial_destructor<unsigned long>::value);
+  EXPECT_TRUE(has_trivial_destructor<float>::value);
+  EXPECT_TRUE(has_trivial_destructor<double>::value);
+  EXPECT_TRUE(has_trivial_destructor<long double>::value);
+  EXPECT_TRUE(has_trivial_destructor<string*>::value);
+  EXPECT_TRUE(has_trivial_destructor<A*>::value);
+  EXPECT_TRUE(has_trivial_destructor<const B*>::value);
+  EXPECT_TRUE(has_trivial_destructor<C**>::value);
+
+  // Verify that pairs and arrays of such types have trivial
+  // destructors.
+  typedef int int10[10];
+  EXPECT_TRUE((has_trivial_destructor<pair<int, char*> >::value));
+  EXPECT_TRUE(has_trivial_destructor<int10>::value);
+
+  // Verify that pairs of types without trivial destructors
+  // are not marked as trivial.
+  EXPECT_FALSE((has_trivial_destructor<pair<int, string> >::value));
+  EXPECT_FALSE((has_trivial_destructor<pair<string, int> >::value));
+
+  // Verify that types without trivial destructors are
+  // correctly marked as such.
+  EXPECT_FALSE(has_trivial_destructor<string>::value);
+  EXPECT_FALSE(has_trivial_destructor<vector<int> >::value);
+
+  // Verify that F, which we have declared to have a trivial
+  // destructor, is correctly marked as such.
+  EXPECT_TRUE(has_trivial_destructor<F>::value);
+}
+
+// Tests remove_pointer.
+TEST(TypeTraitsTest, TestRemovePointer) {
+  COMPILE_ASSERT_TYPES_EQ(int, remove_pointer<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_pointer<int*>::type);
+  COMPILE_ASSERT_TYPES_EQ(const int, remove_pointer<const int*>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_pointer<int* const>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_pointer<int* volatile>::type);
+}
+
+TEST(TypeTraitsTest, TestRemoveConst) {
+  COMPILE_ASSERT_TYPES_EQ(int, remove_const<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_const<const int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int *, remove_const<int * const>::type);
+  // TR1 examples.
+  COMPILE_ASSERT_TYPES_EQ(const int *, remove_const<const int *>::type);
+  COMPILE_ASSERT_TYPES_EQ(volatile int,
+                          remove_const<const volatile int>::type);
+}
+
+TEST(TypeTraitsTest, TestRemoveVolatile) {
+  COMPILE_ASSERT_TYPES_EQ(int, remove_volatile<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_volatile<volatile int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int *, remove_volatile<int * volatile>::type);
+  // TR1 examples.
+  COMPILE_ASSERT_TYPES_EQ(volatile int *,
+                          remove_volatile<volatile int *>::type);
+  COMPILE_ASSERT_TYPES_EQ(const int,
+                          remove_volatile<const volatile int>::type);
+}
+
+TEST(TypeTraitsTest, TestRemoveCV) {
+  COMPILE_ASSERT_TYPES_EQ(int, remove_cv<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_cv<volatile int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_cv<const int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int *, remove_cv<int * const volatile>::type);
+  // TR1 examples.
+  COMPILE_ASSERT_TYPES_EQ(const volatile int *,
+                          remove_cv<const volatile int *>::type);
+  COMPILE_ASSERT_TYPES_EQ(int,
+                          remove_cv<const volatile int>::type);
+}
+
+TEST(TypeTraitsTest, TestRemoveReference) {
+  COMPILE_ASSERT_TYPES_EQ(int, remove_reference<int>::type);
+  COMPILE_ASSERT_TYPES_EQ(int, remove_reference<int&>::type);
+  COMPILE_ASSERT_TYPES_EQ(const int, remove_reference<const int&>::type);
+  COMPILE_ASSERT_TYPES_EQ(int*, remove_reference<int * &>::type);
+}
+
+TEST(TypeTraitsTest, TestIsSame) {
+  EXPECT_TRUE((is_same<int32, int32>::value));
+  EXPECT_FALSE((is_same<int32, int64>::value));
+  EXPECT_FALSE((is_same<int64, int32>::value));
+  EXPECT_FALSE((is_same<int, const int>::value));
+
+  EXPECT_TRUE((is_same<void, void>::value));
+  EXPECT_FALSE((is_same<void, int>::value));
+  EXPECT_FALSE((is_same<int, void>::value));
+
+  EXPECT_TRUE((is_same<int*, int*>::value));
+  EXPECT_TRUE((is_same<void*, void*>::value));
+  EXPECT_FALSE((is_same<int*, void*>::value));
+  EXPECT_FALSE((is_same<void*, int*>::value));
+  EXPECT_FALSE((is_same<void*, const void*>::value));
+  EXPECT_FALSE((is_same<void*, void* const>::value));
+
+  EXPECT_TRUE((is_same<Base*, Base*>::value));
+  EXPECT_TRUE((is_same<Derived*, Derived*>::value));
+  EXPECT_FALSE((is_same<Base*, Derived*>::value));
+  EXPECT_FALSE((is_same<Derived*, Base*>::value));
+}
+
+TEST(TypeTraitsTest, TestConvertible) {
+#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ <= 3)
+  EXPECT_TRUE((is_convertible<int, int>::value));
+  EXPECT_TRUE((is_convertible<int, long>::value));
+  EXPECT_TRUE((is_convertible<long, int>::value));
+
+  EXPECT_TRUE((is_convertible<int*, void*>::value));
+  EXPECT_FALSE((is_convertible<void*, int*>::value));
+
+  EXPECT_TRUE((is_convertible<Derived*, Base*>::value));
+  EXPECT_FALSE((is_convertible<Base*, Derived*>::value));
+  EXPECT_TRUE((is_convertible<Derived*, const Base*>::value));
+  EXPECT_FALSE((is_convertible<const Derived*, Base*>::value));
+#endif
+}
+
+}  // anonymous namespace
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/test_util.cc b/src/google/protobuf/test_util.cc
index af8b3909..841f4b30 100644
--- a/src/google/protobuf/test_util.cc
+++ b/src/google/protobuf/test_util.cc
@@ -50,6 +50,13 @@ namespace google {
 namespace protobuf {
 
 void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
+  SetOptionalFields(message);
+  AddRepeatedFields1(message);
+  AddRepeatedFields2(message);
+  SetDefaultFields(message);
+}
+
+void TestUtil::SetOptionalFields(unittest::TestAllTypes* message) {
   message->set_optional_int32   (101);
   message->set_optional_int64   (102);
   message->set_optional_uint32  (103);
@@ -66,10 +73,12 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
   message->set_optional_string  ("115");
   message->set_optional_bytes   ("116");
 
-  message->mutable_optionalgroup           ()->set_a(117);
-  message->mutable_optional_nested_message ()->set_bb(118);
-  message->mutable_optional_foreign_message()->set_c(119);
-  message->mutable_optional_import_message ()->set_d(120);
+  message->mutable_optionalgroup                 ()->set_a(117);
+  message->mutable_optional_nested_message       ()->set_bb(118);
+  message->mutable_optional_foreign_message      ()->set_c(119);
+  message->mutable_optional_import_message       ()->set_d(120);
+  message->mutable_optional_public_import_message()->set_e(126);
+  message->mutable_optional_lazy_message         ()->set_bb(127);
 
   message->set_optional_nested_enum (unittest::TestAllTypes::BAZ);
   message->set_optional_foreign_enum(unittest::FOREIGN_BAZ      );
@@ -87,9 +96,11 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
     message->GetDescriptor()->FindFieldByName("optional_cord"),
     "125");
 #endif  // !PROTOBUF_TEST_NO_DESCRIPTORS
+}
 
-  // -----------------------------------------------------------------
+// -------------------------------------------------------------------
 
+void TestUtil::AddRepeatedFields1(unittest::TestAllTypes* message) {
   message->add_repeated_int32   (201);
   message->add_repeated_int64   (202);
   message->add_repeated_uint32  (203);
@@ -110,6 +121,7 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
   message->add_repeated_nested_message ()->set_bb(218);
   message->add_repeated_foreign_message()->set_c(219);
   message->add_repeated_import_message ()->set_d(220);
+  message->add_repeated_lazy_message   ()->set_bb(227);
 
   message->add_repeated_nested_enum (unittest::TestAllTypes::BAR);
   message->add_repeated_foreign_enum(unittest::FOREIGN_BAR      );
@@ -125,7 +137,9 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
     message->GetDescriptor()->FindFieldByName("repeated_cord"),
     "225");
 #endif  // !PROTOBUF_TEST_NO_DESCRIPTORS
+}
 
+void TestUtil::AddRepeatedFields2(unittest::TestAllTypes* message) {
   // Add a second one of each field.
   message->add_repeated_int32   (301);
   message->add_repeated_int64   (302);
@@ -147,6 +161,7 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
   message->add_repeated_nested_message ()->set_bb(318);
   message->add_repeated_foreign_message()->set_c(319);
   message->add_repeated_import_message ()->set_d(320);
+  message->add_repeated_lazy_message   ()->set_bb(327);
 
   message->add_repeated_nested_enum (unittest::TestAllTypes::BAZ);
   message->add_repeated_foreign_enum(unittest::FOREIGN_BAZ      );
@@ -162,9 +177,11 @@ void TestUtil::SetAllFields(unittest::TestAllTypes* message) {
     message->GetDescriptor()->FindFieldByName("repeated_cord"),
     "325");
 #endif  // !PROTOBUF_TEST_NO_DESCRIPTORS
+}
 
-  // -----------------------------------------------------------------
+// -------------------------------------------------------------------
 
+void TestUtil::SetDefaultFields(unittest::TestAllTypes* message) {
   message->set_default_int32   (401);
   message->set_default_int64   (402);
   message->set_default_uint32  (403);
@@ -220,6 +237,7 @@ void TestUtil::ModifyRepeatedFields(unittest::TestAllTypes* message) {
   message->mutable_repeated_nested_message (1)->set_bb(518);
   message->mutable_repeated_foreign_message(1)->set_c(519);
   message->mutable_repeated_import_message (1)->set_d(520);
+  message->mutable_repeated_lazy_message   (1)->set_bb(527);
 
   message->set_repeated_nested_enum (1, unittest::TestAllTypes::FOO);
   message->set_repeated_foreign_enum(1, unittest::FOREIGN_FOO      );
@@ -256,15 +274,19 @@ void TestUtil::ExpectAllFieldsSet(const unittest::TestAllTypes& message) {
   EXPECT_TRUE(message.has_optional_string  ());
   EXPECT_TRUE(message.has_optional_bytes   ());
 
-  EXPECT_TRUE(message.has_optionalgroup           ());
-  EXPECT_TRUE(message.has_optional_nested_message ());
-  EXPECT_TRUE(message.has_optional_foreign_message());
-  EXPECT_TRUE(message.has_optional_import_message ());
+  EXPECT_TRUE(message.has_optionalgroup                 ());
+  EXPECT_TRUE(message.has_optional_nested_message       ());
+  EXPECT_TRUE(message.has_optional_foreign_message      ());
+  EXPECT_TRUE(message.has_optional_import_message       ());
+  EXPECT_TRUE(message.has_optional_public_import_message());
+  EXPECT_TRUE(message.has_optional_lazy_message         ());
 
-  EXPECT_TRUE(message.optionalgroup           ().has_a());
-  EXPECT_TRUE(message.optional_nested_message ().has_bb());
-  EXPECT_TRUE(message.optional_foreign_message().has_c());
-  EXPECT_TRUE(message.optional_import_message ().has_d());
+  EXPECT_TRUE(message.optionalgroup                 ().has_a());
+  EXPECT_TRUE(message.optional_nested_message       ().has_bb());
+  EXPECT_TRUE(message.optional_foreign_message      ().has_c());
+  EXPECT_TRUE(message.optional_import_message       ().has_d());
+  EXPECT_TRUE(message.optional_public_import_message().has_e());
+  EXPECT_TRUE(message.optional_lazy_message         ().has_bb());
 
   EXPECT_TRUE(message.has_optional_nested_enum ());
   EXPECT_TRUE(message.has_optional_foreign_enum());
@@ -291,10 +313,12 @@ void TestUtil::ExpectAllFieldsSet(const unittest::TestAllTypes& message) {
   EXPECT_EQ("115", message.optional_string  ());
   EXPECT_EQ("116", message.optional_bytes   ());
 
-  EXPECT_EQ(117, message.optionalgroup           ().a());
-  EXPECT_EQ(118, message.optional_nested_message ().bb());
-  EXPECT_EQ(119, message.optional_foreign_message().c());
-  EXPECT_EQ(120, message.optional_import_message ().d());
+  EXPECT_EQ(117, message.optionalgroup                  ().a());
+  EXPECT_EQ(118, message.optional_nested_message        ().bb());
+  EXPECT_EQ(119, message.optional_foreign_message       ().c());
+  EXPECT_EQ(120, message.optional_import_message        ().d());
+  EXPECT_EQ(126, message.optional_public_import_message ().e());
+  EXPECT_EQ(127, message.optional_lazy_message          ().bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAZ, message.optional_nested_enum ());
   EXPECT_EQ(unittest::FOREIGN_BAZ      , message.optional_foreign_enum());
@@ -323,6 +347,7 @@ void TestUtil::ExpectAllFieldsSet(const unittest::TestAllTypes& message) {
   ASSERT_EQ(2, message.repeated_nested_message_size ());
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   ASSERT_EQ(2, message.repeated_import_message_size ());
+  ASSERT_EQ(2, message.repeated_lazy_message_size   ());
   ASSERT_EQ(2, message.repeated_nested_enum_size    ());
   ASSERT_EQ(2, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(2, message.repeated_import_enum_size    ());
@@ -352,6 +377,7 @@ void TestUtil::ExpectAllFieldsSet(const unittest::TestAllTypes& message) {
   EXPECT_EQ(218, message.repeated_nested_message (0).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(0).c());
   EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(227, message.repeated_lazy_message   (0).bb());
 
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.repeated_nested_enum (0));
@@ -378,6 +404,7 @@ void TestUtil::ExpectAllFieldsSet(const unittest::TestAllTypes& message) {
   EXPECT_EQ(318, message.repeated_nested_message (1).bb());
   EXPECT_EQ(319, message.repeated_foreign_message(1).c());
   EXPECT_EQ(320, message.repeated_import_message (1).d());
+  EXPECT_EQ(327, message.repeated_lazy_message   (1).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAZ, message.repeated_nested_enum (1));
   EXPECT_EQ(unittest::FOREIGN_BAZ      , message.repeated_foreign_enum(1));
@@ -449,10 +476,12 @@ void TestUtil::ExpectClear(const unittest::TestAllTypes& message) {
   EXPECT_FALSE(message.has_optional_string  ());
   EXPECT_FALSE(message.has_optional_bytes   ());
 
-  EXPECT_FALSE(message.has_optionalgroup           ());
-  EXPECT_FALSE(message.has_optional_nested_message ());
-  EXPECT_FALSE(message.has_optional_foreign_message());
-  EXPECT_FALSE(message.has_optional_import_message ());
+  EXPECT_FALSE(message.has_optionalgroup                 ());
+  EXPECT_FALSE(message.has_optional_nested_message       ());
+  EXPECT_FALSE(message.has_optional_foreign_message      ());
+  EXPECT_FALSE(message.has_optional_import_message       ());
+  EXPECT_FALSE(message.has_optional_public_import_message());
+  EXPECT_FALSE(message.has_optional_lazy_message         ());
 
   EXPECT_FALSE(message.has_optional_nested_enum ());
   EXPECT_FALSE(message.has_optional_foreign_enum());
@@ -479,15 +508,19 @@ void TestUtil::ExpectClear(const unittest::TestAllTypes& message) {
   EXPECT_EQ(""   , message.optional_bytes   ());
 
   // Embedded messages should also be clear.
-  EXPECT_FALSE(message.optionalgroup           ().has_a());
-  EXPECT_FALSE(message.optional_nested_message ().has_bb());
-  EXPECT_FALSE(message.optional_foreign_message().has_c());
-  EXPECT_FALSE(message.optional_import_message ().has_d());
-
-  EXPECT_EQ(0, message.optionalgroup           ().a());
-  EXPECT_EQ(0, message.optional_nested_message ().bb());
-  EXPECT_EQ(0, message.optional_foreign_message().c());
-  EXPECT_EQ(0, message.optional_import_message ().d());
+  EXPECT_FALSE(message.optionalgroup                 ().has_a());
+  EXPECT_FALSE(message.optional_nested_message       ().has_bb());
+  EXPECT_FALSE(message.optional_foreign_message      ().has_c());
+  EXPECT_FALSE(message.optional_import_message       ().has_d());
+  EXPECT_FALSE(message.optional_public_import_message().has_e());
+  EXPECT_FALSE(message.optional_lazy_message         ().has_bb());
+
+  EXPECT_EQ(0, message.optionalgroup                 ().a());
+  EXPECT_EQ(0, message.optional_nested_message       ().bb());
+  EXPECT_EQ(0, message.optional_foreign_message      ().c());
+  EXPECT_EQ(0, message.optional_import_message       ().d());
+  EXPECT_EQ(0, message.optional_public_import_message().e());
+  EXPECT_EQ(0, message.optional_lazy_message         ().bb());
 
   // Enums without defaults are set to the first value in the enum.
   EXPECT_EQ(unittest::TestAllTypes::FOO, message.optional_nested_enum ());
@@ -516,6 +549,7 @@ void TestUtil::ExpectClear(const unittest::TestAllTypes& message) {
   EXPECT_EQ(0, message.repeated_nested_message_size ());
   EXPECT_EQ(0, message.repeated_foreign_message_size());
   EXPECT_EQ(0, message.repeated_import_message_size ());
+  EXPECT_EQ(0, message.repeated_lazy_message_size   ());
   EXPECT_EQ(0, message.repeated_nested_enum_size    ());
   EXPECT_EQ(0, message.repeated_foreign_enum_size   ());
   EXPECT_EQ(0, message.repeated_import_enum_size    ());
@@ -595,6 +629,7 @@ void TestUtil::ExpectRepeatedFieldsModified(
   ASSERT_EQ(2, message.repeated_nested_message_size ());
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   ASSERT_EQ(2, message.repeated_import_message_size ());
+  ASSERT_EQ(2, message.repeated_lazy_message_size   ());
   ASSERT_EQ(2, message.repeated_nested_enum_size    ());
   ASSERT_EQ(2, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(2, message.repeated_import_enum_size    ());
@@ -624,6 +659,7 @@ void TestUtil::ExpectRepeatedFieldsModified(
   EXPECT_EQ(218, message.repeated_nested_message (0).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(0).c());
   EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(227, message.repeated_lazy_message   (0).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.repeated_nested_enum (0));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.repeated_foreign_enum(0));
@@ -651,6 +687,7 @@ void TestUtil::ExpectRepeatedFieldsModified(
   EXPECT_EQ(518, message.repeated_nested_message (1).bb());
   EXPECT_EQ(519, message.repeated_foreign_message(1).c());
   EXPECT_EQ(520, message.repeated_import_message (1).d());
+  EXPECT_EQ(527, message.repeated_lazy_message   (1).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::FOO, message.repeated_nested_enum (1));
   EXPECT_EQ(unittest::FOREIGN_FOO      , message.repeated_foreign_enum(1));
@@ -953,6 +990,9 @@ void TestUtil::SetAllExtensions(unittest::TestAllExtensions* message) {
   message->SetExtension(unittest::optional_string_piece_extension, "124");
   message->SetExtension(unittest::optional_cord_extension, "125");
 
+  message->MutableExtension(unittest::optional_public_import_message_extension)->set_e(126);
+  message->MutableExtension(unittest::optional_lazy_message_extension)->set_bb(127);
+
   // -----------------------------------------------------------------
 
   message->AddExtension(unittest::repeated_int32_extension   , 201);
@@ -975,6 +1015,7 @@ void TestUtil::SetAllExtensions(unittest::TestAllExtensions* message) {
   message->AddExtension(unittest::repeated_nested_message_extension )->set_bb(218);
   message->AddExtension(unittest::repeated_foreign_message_extension)->set_c(219);
   message->AddExtension(unittest::repeated_import_message_extension )->set_d(220);
+  message->AddExtension(unittest::repeated_lazy_message_extension   )->set_bb(227);
 
   message->AddExtension(unittest::repeated_nested_enum_extension , unittest::TestAllTypes::BAR);
   message->AddExtension(unittest::repeated_foreign_enum_extension, unittest::FOREIGN_BAR      );
@@ -1004,6 +1045,7 @@ void TestUtil::SetAllExtensions(unittest::TestAllExtensions* message) {
   message->AddExtension(unittest::repeated_nested_message_extension )->set_bb(318);
   message->AddExtension(unittest::repeated_foreign_message_extension)->set_c(319);
   message->AddExtension(unittest::repeated_import_message_extension )->set_d(320);
+  message->AddExtension(unittest::repeated_lazy_message_extension   )->set_bb(327);
 
   message->AddExtension(unittest::repeated_nested_enum_extension , unittest::TestAllTypes::BAZ);
   message->AddExtension(unittest::repeated_foreign_enum_extension, unittest::FOREIGN_BAZ      );
@@ -1073,6 +1115,7 @@ void TestUtil::ModifyRepeatedExtensions(unittest::TestAllExtensions* message) {
   message->MutableExtension(unittest::repeated_nested_message_extension , 1)->set_bb(518);
   message->MutableExtension(unittest::repeated_foreign_message_extension, 1)->set_c(519);
   message->MutableExtension(unittest::repeated_import_message_extension , 1)->set_d(520);
+  message->MutableExtension(unittest::repeated_lazy_message_extension   , 1)->set_bb(527);
 
   message->SetExtension(unittest::repeated_nested_enum_extension , 1, unittest::TestAllTypes::FOO);
   message->SetExtension(unittest::repeated_foreign_enum_extension, 1, unittest::FOREIGN_FOO      );
@@ -1102,15 +1145,19 @@ void TestUtil::ExpectAllExtensionsSet(
   EXPECT_TRUE(message.HasExtension(unittest::optional_string_extension  ));
   EXPECT_TRUE(message.HasExtension(unittest::optional_bytes_extension   ));
 
-  EXPECT_TRUE(message.HasExtension(unittest::optionalgroup_extension           ));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_nested_message_extension ));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_message_extension));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_import_message_extension ));
+  EXPECT_TRUE(message.HasExtension(unittest::optionalgroup_extension                 ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_nested_message_extension       ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_message_extension      ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_import_message_extension       ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_public_import_message_extension));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_lazy_message_extension         ));
 
-  EXPECT_TRUE(message.GetExtension(unittest::optionalgroup_extension           ).has_a());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_nested_message_extension ).has_bb());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_foreign_message_extension).has_c());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_import_message_extension ).has_d());
+  EXPECT_TRUE(message.GetExtension(unittest::optionalgroup_extension                 ).has_a());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_nested_message_extension       ).has_bb());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_foreign_message_extension      ).has_c());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_import_message_extension       ).has_d());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_public_import_message_extension).has_e());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_lazy_message_extension         ).has_bb());
 
   EXPECT_TRUE(message.HasExtension(unittest::optional_nested_enum_extension ));
   EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_enum_extension));
@@ -1146,6 +1193,8 @@ void TestUtil::ExpectAllExtensionsSet(
 
   EXPECT_EQ("124", message.GetExtension(unittest::optional_string_piece_extension));
   EXPECT_EQ("125", message.GetExtension(unittest::optional_cord_extension));
+  EXPECT_EQ(126, message.GetExtension(unittest::optional_public_import_message_extension ).e());
+  EXPECT_EQ(127, message.GetExtension(unittest::optional_lazy_message_extension).bb());
 
   // -----------------------------------------------------------------
 
@@ -1169,6 +1218,7 @@ void TestUtil::ExpectAllExtensionsSet(
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_message_extension ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_message_extension));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_enum_extension    ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_enum_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_enum_extension    ));
@@ -1196,6 +1246,7 @@ void TestUtil::ExpectAllExtensionsSet(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension , 0).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension, 0).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.GetExtension(unittest::repeated_nested_enum_extension , 0));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension, 0));
@@ -1224,6 +1275,7 @@ void TestUtil::ExpectAllExtensionsSet(
   EXPECT_EQ(318, message.GetExtension(unittest::repeated_nested_message_extension , 1).bb());
   EXPECT_EQ(319, message.GetExtension(unittest::repeated_foreign_message_extension, 1).c());
   EXPECT_EQ(320, message.GetExtension(unittest::repeated_import_message_extension , 1).d());
+  EXPECT_EQ(327, message.GetExtension(unittest::repeated_lazy_message_extension   , 1).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAZ, message.GetExtension(unittest::repeated_nested_enum_extension , 1));
   EXPECT_EQ(unittest::FOREIGN_BAZ      , message.GetExtension(unittest::repeated_foreign_enum_extension, 1));
@@ -1307,10 +1359,12 @@ void TestUtil::ExpectExtensionsClear(
   EXPECT_FALSE(message.HasExtension(unittest::optional_string_extension  ));
   EXPECT_FALSE(message.HasExtension(unittest::optional_bytes_extension   ));
 
-  EXPECT_FALSE(message.HasExtension(unittest::optionalgroup_extension           ));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_nested_message_extension ));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_message_extension));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_import_message_extension ));
+  EXPECT_FALSE(message.HasExtension(unittest::optionalgroup_extension                 ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_nested_message_extension       ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_message_extension      ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_import_message_extension       ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_public_import_message_extension));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_lazy_message_extension         ));
 
   EXPECT_FALSE(message.HasExtension(unittest::optional_nested_enum_extension ));
   EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_enum_extension));
@@ -1337,15 +1391,19 @@ void TestUtil::ExpectExtensionsClear(
   EXPECT_EQ(""   , message.GetExtension(unittest::optional_bytes_extension   ));
 
   // Embedded messages should also be clear.
-  EXPECT_FALSE(message.GetExtension(unittest::optionalgroup_extension           ).has_a());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_nested_message_extension ).has_bb());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_foreign_message_extension).has_c());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_import_message_extension ).has_d());
-
-  EXPECT_EQ(0, message.GetExtension(unittest::optionalgroup_extension           ).a());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_nested_message_extension ).bb());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_foreign_message_extension).c());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_import_message_extension ).d());
+  EXPECT_FALSE(message.GetExtension(unittest::optionalgroup_extension                 ).has_a());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_nested_message_extension       ).has_bb());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_foreign_message_extension      ).has_c());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_import_message_extension       ).has_d());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_public_import_message_extension).has_e());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_lazy_message_extension         ).has_bb());
+
+  EXPECT_EQ(0, message.GetExtension(unittest::optionalgroup_extension                 ).a());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_nested_message_extension       ).bb());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_foreign_message_extension      ).c());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_import_message_extension       ).d());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_public_import_message_extension).e());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_lazy_message_extension         ).bb());
 
   // Enums without defaults are set to the first value in the enum.
   EXPECT_EQ(unittest::TestAllTypes::FOO, message.GetExtension(unittest::optional_nested_enum_extension ));
@@ -1376,6 +1434,7 @@ void TestUtil::ExpectExtensionsClear(
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_nested_message_extension ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_foreign_message_extension));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_nested_enum_extension    ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_foreign_enum_extension   ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_import_enum_extension    ));
@@ -1459,6 +1518,7 @@ void TestUtil::ExpectRepeatedExtensionsModified(
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_message_extension ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_message_extension));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_enum_extension    ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_enum_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_enum_extension    ));
@@ -1486,6 +1546,7 @@ void TestUtil::ExpectRepeatedExtensionsModified(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension , 0).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension, 0).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.GetExtension(unittest::repeated_nested_enum_extension , 0));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension, 0));
@@ -1515,6 +1576,7 @@ void TestUtil::ExpectRepeatedExtensionsModified(
   EXPECT_EQ(518, message.GetExtension(unittest::repeated_nested_message_extension , 1).bb());
   EXPECT_EQ(519, message.GetExtension(unittest::repeated_foreign_message_extension, 1).c());
   EXPECT_EQ(520, message.GetExtension(unittest::repeated_import_message_extension , 1).d());
+  EXPECT_EQ(527, message.GetExtension(unittest::repeated_lazy_message_extension   , 1).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::FOO, message.GetExtension(unittest::repeated_nested_enum_extension , 1));
   EXPECT_EQ(unittest::FOREIGN_FOO      , message.GetExtension(unittest::repeated_foreign_enum_extension, 1));
@@ -1750,6 +1812,7 @@ void TestUtil::ExpectLastRepeatedsRemoved(
   ASSERT_EQ(1, message.repeated_nested_message_size ());
   ASSERT_EQ(1, message.repeated_foreign_message_size());
   ASSERT_EQ(1, message.repeated_import_message_size ());
+  ASSERT_EQ(1, message.repeated_import_message_size ());
   ASSERT_EQ(1, message.repeated_nested_enum_size    ());
   ASSERT_EQ(1, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(1, message.repeated_import_enum_size    ());
@@ -1780,6 +1843,7 @@ void TestUtil::ExpectLastRepeatedsRemoved(
   EXPECT_EQ(218, message.repeated_nested_message (0).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(0).c());
   EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(220, message.repeated_import_message (0).d());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.repeated_nested_enum (0));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.repeated_foreign_enum(0));
@@ -1810,6 +1874,7 @@ void TestUtil::ExpectLastRepeatedExtensionsRemoved(
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_nested_message_extension ));
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_foreign_message_extension));
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_nested_enum_extension    ));
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_foreign_enum_extension   ));
   ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_import_enum_extension    ));
@@ -1838,6 +1903,7 @@ void TestUtil::ExpectLastRepeatedExtensionsRemoved(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension , 0).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension, 0).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.GetExtension(unittest::repeated_nested_enum_extension , 0));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension, 0));
@@ -1847,6 +1913,36 @@ void TestUtil::ExpectLastRepeatedExtensionsRemoved(
   EXPECT_EQ("225", message.GetExtension(unittest::repeated_cord_extension, 0));
 }
 
+void TestUtil::ExpectLastRepeatedsReleased(
+    const unittest::TestAllTypes& message) {
+  ASSERT_EQ(1, message.repeatedgroup_size           ());
+  ASSERT_EQ(1, message.repeated_nested_message_size ());
+  ASSERT_EQ(1, message.repeated_foreign_message_size());
+  ASSERT_EQ(1, message.repeated_import_message_size ());
+  ASSERT_EQ(1, message.repeated_import_message_size ());
+
+  EXPECT_EQ(217, message.repeatedgroup           (0).a());
+  EXPECT_EQ(218, message.repeated_nested_message (0).bb());
+  EXPECT_EQ(219, message.repeated_foreign_message(0).c());
+  EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(220, message.repeated_import_message (0).d());
+}
+
+void TestUtil::ExpectLastRepeatedExtensionsReleased(
+    const unittest::TestAllExtensions& message) {
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeatedgroup_extension           ));
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_nested_message_extension ));
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_foreign_message_extension));
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  ASSERT_EQ(1, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
+
+  EXPECT_EQ(217, message.GetExtension(unittest::repeatedgroup_extension           , 0).a());
+  EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension , 0).bb());
+  EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension, 0).c());
+  EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension   , 0).bb());
+}
+
 void TestUtil::ExpectRepeatedsSwapped(
     const unittest::TestAllTypes& message) {
   ASSERT_EQ(2, message.repeated_int32_size   ());
@@ -1869,6 +1965,7 @@ void TestUtil::ExpectRepeatedsSwapped(
   ASSERT_EQ(2, message.repeated_nested_message_size ());
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   ASSERT_EQ(2, message.repeated_import_message_size ());
+  ASSERT_EQ(2, message.repeated_import_message_size ());
   ASSERT_EQ(2, message.repeated_nested_enum_size    ());
   ASSERT_EQ(2, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(2, message.repeated_import_enum_size    ());
@@ -1899,6 +1996,7 @@ void TestUtil::ExpectRepeatedsSwapped(
   EXPECT_EQ(218, message.repeated_nested_message (1).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(1).c());
   EXPECT_EQ(220, message.repeated_import_message (1).d());
+  EXPECT_EQ(220, message.repeated_import_message (1).d());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.repeated_nested_enum (1));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.repeated_foreign_enum(1));
@@ -1924,6 +2022,7 @@ void TestUtil::ExpectRepeatedsSwapped(
   EXPECT_EQ(318, message.repeated_nested_message (0).bb());
   EXPECT_EQ(319, message.repeated_foreign_message(0).c());
   EXPECT_EQ(320, message.repeated_import_message (0).d());
+  EXPECT_EQ(320, message.repeated_import_message (0).d());
 
   EXPECT_EQ(unittest::TestAllTypes::BAZ, message.repeated_nested_enum (0));
   EXPECT_EQ(unittest::FOREIGN_BAZ      , message.repeated_foreign_enum(0));
@@ -1953,6 +2052,7 @@ void TestUtil::ExpectRepeatedExtensionsSwapped(
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_message_extension ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_message_extension));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_message_extension ));
+  ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_lazy_message_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_enum_extension    ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_enum_extension   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_enum_extension    ));
@@ -1980,6 +2080,7 @@ void TestUtil::ExpectRepeatedExtensionsSwapped(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension , 1).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension, 1).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension , 1).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension   , 1).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAR, message.GetExtension(unittest::repeated_nested_enum_extension , 1));
   EXPECT_EQ(unittest::FOREIGN_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension, 1));
@@ -2008,6 +2109,7 @@ void TestUtil::ExpectRepeatedExtensionsSwapped(
   EXPECT_EQ(318, message.GetExtension(unittest::repeated_nested_message_extension , 0).bb());
   EXPECT_EQ(319, message.GetExtension(unittest::repeated_foreign_message_extension, 0).c());
   EXPECT_EQ(320, message.GetExtension(unittest::repeated_import_message_extension , 0).d());
+  EXPECT_EQ(327, message.GetExtension(unittest::repeated_lazy_message_extension   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypes::BAZ, message.GetExtension(unittest::repeated_nested_enum_extension , 0));
   EXPECT_EQ(unittest::FOREIGN_BAZ      , message.GetExtension(unittest::repeated_foreign_enum_extension, 0));
@@ -2031,6 +2133,8 @@ TestUtil::ReflectionTester::ReflectionTester(
     pool->FindFieldByName("protobuf_unittest.ForeignMessage.c");
   import_d_ =
     pool->FindFieldByName("protobuf_unittest_import.ImportMessage.d");
+  import_e_ =
+    pool->FindFieldByName("protobuf_unittest_import.PublicImportMessage.e");
   nested_foo_ =
     pool->FindEnumValueByName("protobuf_unittest.TestAllTypes.FOO");
   nested_bar_ =
@@ -2067,6 +2171,7 @@ TestUtil::ReflectionTester::ReflectionTester(
   EXPECT_TRUE(nested_b_         != NULL);
   EXPECT_TRUE(foreign_c_        != NULL);
   EXPECT_TRUE(import_d_         != NULL);
+  EXPECT_TRUE(import_e_         != NULL);
   EXPECT_TRUE(nested_foo_       != NULL);
   EXPECT_TRUE(nested_bar_       != NULL);
   EXPECT_TRUE(nested_baz_       != NULL);
@@ -2129,6 +2234,12 @@ void TestUtil::ReflectionTester::SetAllFieldsViaReflection(Message* message) {
   reflection->SetString(message, F("optional_string_piece"), "124");
   reflection->SetString(message, F("optional_cord"), "125");
 
+  sub_message = reflection->MutableMessage(message, F("optional_public_import_message"));
+  sub_message->GetReflection()->SetInt32(sub_message, import_e_, 126);
+
+  sub_message = reflection->MutableMessage(message, F("optional_lazy_message"));
+  sub_message->GetReflection()->SetInt32(sub_message, nested_b_, 127);
+
   // -----------------------------------------------------------------
 
   reflection->AddInt32 (message, F("repeated_int32"   ), 201);
@@ -2155,6 +2266,8 @@ void TestUtil::ReflectionTester::SetAllFieldsViaReflection(Message* message) {
   sub_message->GetReflection()->SetInt32(sub_message, foreign_c_, 219);
   sub_message = reflection->AddMessage(message, F("repeated_import_message"));
   sub_message->GetReflection()->SetInt32(sub_message, import_d_, 220);
+  sub_message = reflection->AddMessage(message, F("repeated_lazy_message"));
+  sub_message->GetReflection()->SetInt32(sub_message, nested_b_, 227);
 
   reflection->AddEnum(message, F("repeated_nested_enum" ),  nested_bar_);
   reflection->AddEnum(message, F("repeated_foreign_enum"), foreign_bar_);
@@ -2188,6 +2301,8 @@ void TestUtil::ReflectionTester::SetAllFieldsViaReflection(Message* message) {
   sub_message->GetReflection()->SetInt32(sub_message, foreign_c_, 319);
   sub_message = reflection->AddMessage(message, F("repeated_import_message"));
   sub_message->GetReflection()->SetInt32(sub_message, import_d_, 320);
+  sub_message = reflection->AddMessage(message, F("repeated_lazy_message"));
+  sub_message->GetReflection()->SetInt32(sub_message, nested_b_, 327);
 
   reflection->AddEnum(message, F("repeated_nested_enum" ),  nested_baz_);
   reflection->AddEnum(message, F("repeated_foreign_enum"), foreign_baz_);
@@ -2289,10 +2404,12 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection1(
   EXPECT_TRUE(reflection->HasField(message, F("optional_string"  )));
   EXPECT_TRUE(reflection->HasField(message, F("optional_bytes"   )));
 
-  EXPECT_TRUE(reflection->HasField(message, F("optionalgroup"           )));
-  EXPECT_TRUE(reflection->HasField(message, F("optional_nested_message" )));
-  EXPECT_TRUE(reflection->HasField(message, F("optional_foreign_message")));
-  EXPECT_TRUE(reflection->HasField(message, F("optional_import_message" )));
+  EXPECT_TRUE(reflection->HasField(message, F("optionalgroup"                 )));
+  EXPECT_TRUE(reflection->HasField(message, F("optional_nested_message"       )));
+  EXPECT_TRUE(reflection->HasField(message, F("optional_foreign_message"      )));
+  EXPECT_TRUE(reflection->HasField(message, F("optional_import_message"       )));
+  EXPECT_TRUE(reflection->HasField(message, F("optional_public_import_message")));
+  EXPECT_TRUE(reflection->HasField(message, F("optional_lazy_message"         )));
 
   sub_message = &reflection->GetMessage(message, F("optionalgroup"));
   EXPECT_TRUE(sub_message->GetReflection()->HasField(*sub_message, group_a_));
@@ -2302,6 +2419,10 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection1(
   EXPECT_TRUE(sub_message->GetReflection()->HasField(*sub_message, foreign_c_));
   sub_message = &reflection->GetMessage(message, F("optional_import_message"));
   EXPECT_TRUE(sub_message->GetReflection()->HasField(*sub_message, import_d_));
+  sub_message = &reflection->GetMessage(message, F("optional_public_import_message"));
+  EXPECT_TRUE(sub_message->GetReflection()->HasField(*sub_message, import_e_));
+  sub_message = &reflection->GetMessage(message, F("optional_lazy_message"));
+  EXPECT_TRUE(sub_message->GetReflection()->HasField(*sub_message, nested_b_));
 
   EXPECT_TRUE(reflection->HasField(message, F("optional_nested_enum" )));
   EXPECT_TRUE(reflection->HasField(message, F("optional_foreign_enum")));
@@ -2337,6 +2458,10 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection1(
   EXPECT_EQ(119, sub_message->GetReflection()->GetInt32(*sub_message, foreign_c_));
   sub_message = &reflection->GetMessage(message, F("optional_import_message"));
   EXPECT_EQ(120, sub_message->GetReflection()->GetInt32(*sub_message, import_d_));
+  sub_message = &reflection->GetMessage(message, F("optional_public_import_message"));
+  EXPECT_EQ(126, sub_message->GetReflection()->GetInt32(*sub_message, import_e_));
+  sub_message = &reflection->GetMessage(message, F("optional_lazy_message"));
+  EXPECT_EQ(127, sub_message->GetReflection()->GetInt32(*sub_message, nested_b_));
 
   EXPECT_EQ( nested_baz_, reflection->GetEnum(message, F("optional_nested_enum" )));
   EXPECT_EQ(foreign_baz_, reflection->GetEnum(message, F("optional_foreign_enum")));
@@ -2347,6 +2472,7 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection1(
 
   EXPECT_EQ("125", reflection->GetString(message, F("optional_cord")));
   EXPECT_EQ("125", reflection->GetStringReference(message, F("optional_cord"), &scratch));
+
 }
 
 void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection2(
@@ -2377,6 +2503,7 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection2(
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_nested_message" )));
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_foreign_message")));
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_import_message" )));
+  ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_lazy_message"   )));
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_nested_enum"    )));
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_foreign_enum"   )));
   ASSERT_EQ(2, reflection->FieldSize(message, F("repeated_import_enum"    )));
@@ -2411,6 +2538,8 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection2(
   EXPECT_EQ(219, sub_message->GetReflection()->GetInt32(*sub_message, foreign_c_));
   sub_message = &reflection->GetRepeatedMessage(message, F("repeated_import_message"), 0);
   EXPECT_EQ(220, sub_message->GetReflection()->GetInt32(*sub_message, import_d_));
+  sub_message = &reflection->GetRepeatedMessage(message, F("repeated_lazy_message"), 0);
+  EXPECT_EQ(227, sub_message->GetReflection()->GetInt32(*sub_message, nested_b_));
 
   EXPECT_EQ( nested_bar_, reflection->GetRepeatedEnum(message, F("repeated_nested_enum" ),0));
   EXPECT_EQ(foreign_bar_, reflection->GetRepeatedEnum(message, F("repeated_foreign_enum"),0));
@@ -2453,6 +2582,8 @@ void TestUtil::ReflectionTester::ExpectAllFieldsSetViaReflection2(
   EXPECT_EQ(319, sub_message->GetReflection()->GetInt32(*sub_message, foreign_c_));
   sub_message = &reflection->GetRepeatedMessage(message, F("repeated_import_message"), 1);
   EXPECT_EQ(320, sub_message->GetReflection()->GetInt32(*sub_message, import_d_));
+  sub_message = &reflection->GetRepeatedMessage(message, F("repeated_lazy_message"), 1);
+  EXPECT_EQ(327, sub_message->GetReflection()->GetInt32(*sub_message, nested_b_));
 
   EXPECT_EQ( nested_baz_, reflection->GetRepeatedEnum(message, F("repeated_nested_enum" ),1));
   EXPECT_EQ(foreign_baz_, reflection->GetRepeatedEnum(message, F("repeated_foreign_enum"),1));
@@ -2609,6 +2740,8 @@ void TestUtil::ReflectionTester::ExpectClearViaReflection(
   EXPECT_FALSE(reflection->HasField(message, F("optional_nested_message" )));
   EXPECT_FALSE(reflection->HasField(message, F("optional_foreign_message")));
   EXPECT_FALSE(reflection->HasField(message, F("optional_import_message" )));
+  EXPECT_FALSE(reflection->HasField(message, F("optional_public_import_message")));
+  EXPECT_FALSE(reflection->HasField(message, F("optional_lazy_message")));
 
   EXPECT_FALSE(reflection->HasField(message, F("optional_nested_enum" )));
   EXPECT_FALSE(reflection->HasField(message, F("optional_foreign_enum")));
@@ -2650,6 +2783,12 @@ void TestUtil::ReflectionTester::ExpectClearViaReflection(
   sub_message = &reflection->GetMessage(message, F("optional_import_message"));
   EXPECT_FALSE(sub_message->GetReflection()->HasField(*sub_message, import_d_));
   EXPECT_EQ(0, sub_message->GetReflection()->GetInt32(*sub_message, import_d_));
+  sub_message = &reflection->GetMessage(message, F("optional_public_import_message"));
+  EXPECT_FALSE(sub_message->GetReflection()->HasField(*sub_message, import_e_));
+  EXPECT_EQ(0, sub_message->GetReflection()->GetInt32(*sub_message, import_e_));
+  sub_message = &reflection->GetMessage(message, F("optional_lazy_message"));
+  EXPECT_FALSE(sub_message->GetReflection()->HasField(*sub_message, nested_b_));
+  EXPECT_EQ(0, sub_message->GetReflection()->GetInt32(*sub_message, nested_b_));
 
   // Enums without defaults are set to the first value in the enum.
   EXPECT_EQ( nested_foo_, reflection->GetEnum(message, F("optional_nested_enum" )));
@@ -2683,6 +2822,7 @@ void TestUtil::ReflectionTester::ExpectClearViaReflection(
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_nested_message" )));
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_foreign_message")));
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_import_message" )));
+  EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_lazy_message"   )));
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_nested_enum"    )));
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_foreign_enum"   )));
   EXPECT_EQ(0, reflection->FieldSize(message, F("repeated_import_enum"    )));
@@ -2796,6 +2936,8 @@ void TestUtil::ReflectionTester::ModifyRepeatedFieldsViaReflection(
   sub_message->GetReflection()->SetInt32(sub_message, foreign_c_, 519);
   sub_message = reflection->MutableRepeatedMessage(message, F("repeated_import_message"), 1);
   sub_message->GetReflection()->SetInt32(sub_message, import_d_, 520);
+  sub_message = reflection->MutableRepeatedMessage(message, F("repeated_lazy_message"), 1);
+  sub_message->GetReflection()->SetInt32(sub_message, nested_b_, 527);
 
   reflection->SetRepeatedEnum(message, F("repeated_nested_enum" ), 1,  nested_foo_);
   reflection->SetRepeatedEnum(message, F("repeated_foreign_enum"), 1, foreign_foo_);
@@ -2824,7 +2966,8 @@ void TestUtil::ReflectionTester::ModifyPackedFieldsViaReflection(
   reflection->SetRepeatedEnum  (message, F("packed_enum"    ), 1, foreign_foo_);
 }
 
-void TestUtil::ReflectionTester::RemoveLastRepeatedsViaReflection(Message* message) {
+void TestUtil::ReflectionTester::RemoveLastRepeatedsViaReflection(
+    Message* message) {
   const Reflection* reflection = message->GetReflection();
 
   vector<const FieldDescriptor*> output;
@@ -2837,6 +2980,26 @@ void TestUtil::ReflectionTester::RemoveLastRepeatedsViaReflection(Message* messa
   }
 }
 
+void TestUtil::ReflectionTester::ReleaseLastRepeatedsViaReflection(
+    Message* message, bool expect_extensions_notnull) {
+  const Reflection* reflection = message->GetReflection();
+
+  vector<const FieldDescriptor*> output;
+  reflection->ListFields(*message, &output);
+  for (int i=0; i<output.size(); ++i) {
+    const FieldDescriptor* field = output[i];
+    if (!field->is_repeated()) continue;
+    if (field->cpp_type() != FieldDescriptor::CPPTYPE_MESSAGE) continue;
+
+    Message* released = reflection->ReleaseLast(message, field);
+    if (!field->is_extension() || expect_extensions_notnull) {
+      ASSERT_TRUE(released != NULL) << "ReleaseLast returned NULL for: "
+                                    << field->name();
+    }
+    delete released;
+  }
+}
+
 void TestUtil::ReflectionTester::SwapRepeatedsViaReflection(Message* message) {
   const Reflection* reflection = message->GetReflection();
 
@@ -2850,5 +3013,35 @@ void TestUtil::ReflectionTester::SwapRepeatedsViaReflection(Message* message) {
   }
 }
 
+void TestUtil::ReflectionTester::ExpectMessagesReleasedViaReflection(
+    Message* message,
+    TestUtil::ReflectionTester::MessageReleaseState expected_release_state) {
+  const Reflection* reflection = message->GetReflection();
+
+  static const char* fields[] = {
+    "optionalgroup",
+    "optional_nested_message",
+    "optional_foreign_message",
+    "optional_import_message",
+  };
+  for (int i = 0; i < GOOGLE_ARRAYSIZE(fields); i++) {
+    const Message& sub_message = reflection->GetMessage(*message, F(fields[i]));
+    Message* released = reflection->ReleaseMessage(message, F(fields[i]));
+    switch (expected_release_state) {
+      case IS_NULL:
+        EXPECT_TRUE(released == NULL);
+        break;
+      case NOT_NULL:
+        EXPECT_TRUE(released != NULL);
+        EXPECT_EQ(&sub_message, released);
+        break;
+      case CAN_BE_NULL:
+        break;
+    }
+    delete released;
+    EXPECT_FALSE(reflection->HasField(*message, F(fields[i])));
+  }
+}
+
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/test_util.h b/src/google/protobuf/test_util.h
index 25165f3a..45519573 100644
--- a/src/google/protobuf/test_util.h
+++ b/src/google/protobuf/test_util.h
@@ -43,13 +43,17 @@
 namespace google {
 namespace protobuf {
 
-namespace unittest = protobuf_unittest;
+namespace unittest = ::protobuf_unittest;
 namespace unittest_import = protobuf_unittest_import;
 
 class TestUtil {
  public:
   // Set every field in the message to a unique value.
   static void SetAllFields(unittest::TestAllTypes* message);
+  static void SetOptionalFields(unittest::TestAllTypes* message);
+  static void AddRepeatedFields1(unittest::TestAllTypes* message);
+  static void AddRepeatedFields2(unittest::TestAllTypes* message);
+  static void SetDefaultFields(unittest::TestAllTypes* message);
   static void SetAllExtensions(unittest::TestAllExtensions* message);
   static void SetAllFieldsAndExtensions(unittest::TestFieldOrderings* message);
   static void SetPackedFields(unittest::TestPackedTypes* message);
@@ -104,6 +108,10 @@ class TestUtil {
       const unittest::TestAllTypes& message);
   static void ExpectLastRepeatedExtensionsRemoved(
       const unittest::TestAllExtensions& message);
+  static void ExpectLastRepeatedsReleased(
+      const unittest::TestAllTypes& message);
+  static void ExpectLastRepeatedExtensionsReleased(
+      const unittest::TestAllExtensions& message);
 
   // Check that all repeated fields have had their first and last elements
   // swapped.
@@ -132,8 +140,18 @@ class TestUtil {
     void ExpectPackedClearViaReflection(const Message& message);
 
     void RemoveLastRepeatedsViaReflection(Message* message);
+    void ReleaseLastRepeatedsViaReflection(
+        Message* message, bool expect_extensions_notnull);
     void SwapRepeatedsViaReflection(Message* message);
 
+    enum MessageReleaseState {
+      IS_NULL,
+      CAN_BE_NULL,
+      NOT_NULL,
+    };
+    void ExpectMessagesReleasedViaReflection(
+        Message* message, MessageReleaseState expected_release_state);
+
    private:
     const FieldDescriptor* F(const string& name);
 
@@ -144,6 +162,7 @@ class TestUtil {
     const FieldDescriptor* nested_b_;
     const FieldDescriptor* foreign_c_;
     const FieldDescriptor* import_d_;
+    const FieldDescriptor* import_e_;
 
     const EnumValueDescriptor* nested_foo_;
     const EnumValueDescriptor* nested_bar_;
diff --git a/src/google/protobuf/test_util_lite.cc b/src/google/protobuf/test_util_lite.cc
index d7140e0c..9099292a 100644
--- a/src/google/protobuf/test_util_lite.cc
+++ b/src/google/protobuf/test_util_lite.cc
@@ -62,10 +62,12 @@ void TestUtilLite::SetAllFields(unittest::TestAllTypesLite* message) {
   message->set_optional_string  ("115");
   message->set_optional_bytes   ("116");
 
-  message->mutable_optionalgroup           ()->set_a(117);
-  message->mutable_optional_nested_message ()->set_bb(118);
-  message->mutable_optional_foreign_message()->set_c(119);
-  message->mutable_optional_import_message ()->set_d(120);
+  message->mutable_optionalgroup                 ()->set_a(117);
+  message->mutable_optional_nested_message       ()->set_bb(118);
+  message->mutable_optional_foreign_message      ()->set_c(119);
+  message->mutable_optional_import_message       ()->set_d(120);
+  message->mutable_optional_public_import_message()->set_e(126);
+  message->mutable_optional_lazy_message         ()->set_bb(127);
 
   message->set_optional_nested_enum (unittest::TestAllTypesLite::BAZ );
   message->set_optional_foreign_enum(unittest::FOREIGN_LITE_BAZ      );
@@ -94,6 +96,7 @@ void TestUtilLite::SetAllFields(unittest::TestAllTypesLite* message) {
   message->add_repeated_nested_message ()->set_bb(218);
   message->add_repeated_foreign_message()->set_c(219);
   message->add_repeated_import_message ()->set_d(220);
+  message->add_repeated_lazy_message   ()->set_bb(227);
 
   message->add_repeated_nested_enum (unittest::TestAllTypesLite::BAR );
   message->add_repeated_foreign_enum(unittest::FOREIGN_LITE_BAR      );
@@ -121,6 +124,7 @@ void TestUtilLite::SetAllFields(unittest::TestAllTypesLite* message) {
   message->add_repeated_nested_message ()->set_bb(318);
   message->add_repeated_foreign_message()->set_c(319);
   message->add_repeated_import_message ()->set_d(320);
+  message->add_repeated_lazy_message   ()->set_bb(327);
 
   message->add_repeated_nested_enum (unittest::TestAllTypesLite::BAZ );
   message->add_repeated_foreign_enum(unittest::FOREIGN_LITE_BAZ      );
@@ -174,6 +178,7 @@ void TestUtilLite::ModifyRepeatedFields(unittest::TestAllTypesLite* message) {
   message->mutable_repeated_nested_message (1)->set_bb(518);
   message->mutable_repeated_foreign_message(1)->set_c(519);
   message->mutable_repeated_import_message (1)->set_d(520);
+  message->mutable_repeated_lazy_message   (1)->set_bb(527);
 
   message->set_repeated_nested_enum (1, unittest::TestAllTypesLite::FOO );
   message->set_repeated_foreign_enum(1, unittest::FOREIGN_LITE_FOO      );
@@ -201,15 +206,19 @@ void TestUtilLite::ExpectAllFieldsSet(
   EXPECT_TRUE(message.has_optional_string  ());
   EXPECT_TRUE(message.has_optional_bytes   ());
 
-  EXPECT_TRUE(message.has_optionalgroup           ());
-  EXPECT_TRUE(message.has_optional_nested_message ());
-  EXPECT_TRUE(message.has_optional_foreign_message());
-  EXPECT_TRUE(message.has_optional_import_message ());
+  EXPECT_TRUE(message.has_optionalgroup                 ());
+  EXPECT_TRUE(message.has_optional_nested_message       ());
+  EXPECT_TRUE(message.has_optional_foreign_message      ());
+  EXPECT_TRUE(message.has_optional_import_message       ());
+  EXPECT_TRUE(message.has_optional_public_import_message());
+  EXPECT_TRUE(message.has_optional_lazy_message         ());
 
-  EXPECT_TRUE(message.optionalgroup           ().has_a());
-  EXPECT_TRUE(message.optional_nested_message ().has_bb());
-  EXPECT_TRUE(message.optional_foreign_message().has_c());
-  EXPECT_TRUE(message.optional_import_message ().has_d());
+  EXPECT_TRUE(message.optionalgroup                 ().has_a());
+  EXPECT_TRUE(message.optional_nested_message       ().has_bb());
+  EXPECT_TRUE(message.optional_foreign_message      ().has_c());
+  EXPECT_TRUE(message.optional_import_message       ().has_d());
+  EXPECT_TRUE(message.optional_public_import_message().has_e());
+  EXPECT_TRUE(message.optional_lazy_message         ().has_bb());
 
   EXPECT_TRUE(message.has_optional_nested_enum ());
   EXPECT_TRUE(message.has_optional_foreign_enum());
@@ -232,10 +241,12 @@ void TestUtilLite::ExpectAllFieldsSet(
   EXPECT_EQ("115", message.optional_string  ());
   EXPECT_EQ("116", message.optional_bytes   ());
 
-  EXPECT_EQ(117, message.optionalgroup           ().a());
-  EXPECT_EQ(118, message.optional_nested_message ().bb());
-  EXPECT_EQ(119, message.optional_foreign_message().c());
-  EXPECT_EQ(120, message.optional_import_message ().d());
+  EXPECT_EQ(117, message.optionalgroup                 ().a());
+  EXPECT_EQ(118, message.optional_nested_message       ().bb());
+  EXPECT_EQ(119, message.optional_foreign_message      ().c());
+  EXPECT_EQ(120, message.optional_import_message       ().d());
+  EXPECT_EQ(126, message.optional_public_import_message().e());
+  EXPECT_EQ(127, message.optional_lazy_message         ().bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAZ , message.optional_nested_enum ());
   EXPECT_EQ(unittest::FOREIGN_LITE_BAZ      , message.optional_foreign_enum());
@@ -264,6 +275,7 @@ void TestUtilLite::ExpectAllFieldsSet(
   ASSERT_EQ(2, message.repeated_nested_message_size ());
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   ASSERT_EQ(2, message.repeated_import_message_size ());
+  ASSERT_EQ(2, message.repeated_lazy_message_size   ());
   ASSERT_EQ(2, message.repeated_nested_enum_size    ());
   ASSERT_EQ(2, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(2, message.repeated_import_enum_size    ());
@@ -289,6 +301,7 @@ void TestUtilLite::ExpectAllFieldsSet(
   EXPECT_EQ(218, message.repeated_nested_message (0).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(0).c());
   EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(227, message.repeated_lazy_message   (0).bb());
 
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAR , message.repeated_nested_enum (0));
@@ -315,6 +328,7 @@ void TestUtilLite::ExpectAllFieldsSet(
   EXPECT_EQ(318, message.repeated_nested_message (1).bb());
   EXPECT_EQ(319, message.repeated_foreign_message(1).c());
   EXPECT_EQ(320, message.repeated_import_message (1).d());
+  EXPECT_EQ(327, message.repeated_lazy_message   (1).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAZ , message.repeated_nested_enum (1));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAZ      , message.repeated_foreign_enum(1));
@@ -386,10 +400,12 @@ void TestUtilLite::ExpectClear(const unittest::TestAllTypesLite& message) {
   EXPECT_FALSE(message.has_optional_string  ());
   EXPECT_FALSE(message.has_optional_bytes   ());
 
-  EXPECT_FALSE(message.has_optionalgroup           ());
-  EXPECT_FALSE(message.has_optional_nested_message ());
-  EXPECT_FALSE(message.has_optional_foreign_message());
-  EXPECT_FALSE(message.has_optional_import_message ());
+  EXPECT_FALSE(message.has_optionalgroup                 ());
+  EXPECT_FALSE(message.has_optional_nested_message       ());
+  EXPECT_FALSE(message.has_optional_foreign_message      ());
+  EXPECT_FALSE(message.has_optional_import_message       ());
+  EXPECT_FALSE(message.has_optional_public_import_message());
+  EXPECT_FALSE(message.has_optional_lazy_message         ());
 
   EXPECT_FALSE(message.has_optional_nested_enum ());
   EXPECT_FALSE(message.has_optional_foreign_enum());
@@ -414,10 +430,12 @@ void TestUtilLite::ExpectClear(const unittest::TestAllTypesLite& message) {
   EXPECT_EQ(""   , message.optional_bytes   ());
 
   // Embedded messages should also be clear.
-  EXPECT_FALSE(message.optionalgroup           ().has_a());
-  EXPECT_FALSE(message.optional_nested_message ().has_bb());
-  EXPECT_FALSE(message.optional_foreign_message().has_c());
-  EXPECT_FALSE(message.optional_import_message ().has_d());
+  EXPECT_FALSE(message.optionalgroup                 ().has_a());
+  EXPECT_FALSE(message.optional_nested_message       ().has_bb());
+  EXPECT_FALSE(message.optional_foreign_message      ().has_c());
+  EXPECT_FALSE(message.optional_import_message       ().has_d());
+  EXPECT_FALSE(message.optional_public_import_message().has_e());
+  EXPECT_FALSE(message.optional_lazy_message         ().has_bb());
 
   EXPECT_EQ(0, message.optionalgroup           ().a());
   EXPECT_EQ(0, message.optional_nested_message ().bb());
@@ -451,6 +469,7 @@ void TestUtilLite::ExpectClear(const unittest::TestAllTypesLite& message) {
   EXPECT_EQ(0, message.repeated_nested_message_size ());
   EXPECT_EQ(0, message.repeated_foreign_message_size());
   EXPECT_EQ(0, message.repeated_import_message_size ());
+  EXPECT_EQ(0, message.repeated_lazy_message_size   ());
   EXPECT_EQ(0, message.repeated_nested_enum_size    ());
   EXPECT_EQ(0, message.repeated_foreign_enum_size   ());
   EXPECT_EQ(0, message.repeated_import_enum_size    ());
@@ -528,6 +547,7 @@ void TestUtilLite::ExpectRepeatedFieldsModified(
   ASSERT_EQ(2, message.repeated_nested_message_size ());
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   ASSERT_EQ(2, message.repeated_import_message_size ());
+  ASSERT_EQ(2, message.repeated_lazy_message_size   ());
   ASSERT_EQ(2, message.repeated_nested_enum_size    ());
   ASSERT_EQ(2, message.repeated_foreign_enum_size   ());
   ASSERT_EQ(2, message.repeated_import_enum_size    ());
@@ -553,6 +573,7 @@ void TestUtilLite::ExpectRepeatedFieldsModified(
   EXPECT_EQ(218, message.repeated_nested_message (0).bb());
   EXPECT_EQ(219, message.repeated_foreign_message(0).c());
   EXPECT_EQ(220, message.repeated_import_message (0).d());
+  EXPECT_EQ(227, message.repeated_lazy_message   (0).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAR , message.repeated_nested_enum (0));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAR      , message.repeated_foreign_enum(0));
@@ -580,6 +601,7 @@ void TestUtilLite::ExpectRepeatedFieldsModified(
   EXPECT_EQ(518, message.repeated_nested_message (1).bb());
   EXPECT_EQ(519, message.repeated_foreign_message(1).c());
   EXPECT_EQ(520, message.repeated_import_message (1).d());
+  EXPECT_EQ(527, message.repeated_lazy_message   (1).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::FOO , message.repeated_nested_enum (1));
   EXPECT_EQ(unittest::FOREIGN_LITE_FOO      , message.repeated_foreign_enum(1));
@@ -787,10 +809,12 @@ void TestUtilLite::SetAllExtensions(unittest::TestAllExtensionsLite* message) {
   message->SetExtension(unittest::optional_string_extension_lite  , "115");
   message->SetExtension(unittest::optional_bytes_extension_lite   , "116");
 
-  message->MutableExtension(unittest::optionalgroup_extension_lite           )->set_a(117);
-  message->MutableExtension(unittest::optional_nested_message_extension_lite )->set_bb(118);
-  message->MutableExtension(unittest::optional_foreign_message_extension_lite)->set_c(119);
-  message->MutableExtension(unittest::optional_import_message_extension_lite )->set_d(120);
+  message->MutableExtension(unittest::optionalgroup_extension_lite                 )->set_a(117);
+  message->MutableExtension(unittest::optional_nested_message_extension_lite       )->set_bb(118);
+  message->MutableExtension(unittest::optional_foreign_message_extension_lite      )->set_c(119);
+  message->MutableExtension(unittest::optional_import_message_extension_lite       )->set_d(120);
+  message->MutableExtension(unittest::optional_public_import_message_extension_lite)->set_e(126);
+  message->MutableExtension(unittest::optional_lazy_message_extension_lite         )->set_bb(127);
 
   message->SetExtension(unittest::optional_nested_enum_extension_lite , unittest::TestAllTypesLite::BAZ );
   message->SetExtension(unittest::optional_foreign_enum_extension_lite, unittest::FOREIGN_LITE_BAZ      );
@@ -819,6 +843,7 @@ void TestUtilLite::SetAllExtensions(unittest::TestAllExtensionsLite* message) {
   message->AddExtension(unittest::repeated_nested_message_extension_lite )->set_bb(218);
   message->AddExtension(unittest::repeated_foreign_message_extension_lite)->set_c(219);
   message->AddExtension(unittest::repeated_import_message_extension_lite )->set_d(220);
+  message->AddExtension(unittest::repeated_lazy_message_extension_lite   )->set_bb(227);
 
   message->AddExtension(unittest::repeated_nested_enum_extension_lite , unittest::TestAllTypesLite::BAR );
   message->AddExtension(unittest::repeated_foreign_enum_extension_lite, unittest::FOREIGN_LITE_BAR      );
@@ -846,6 +871,7 @@ void TestUtilLite::SetAllExtensions(unittest::TestAllExtensionsLite* message) {
   message->AddExtension(unittest::repeated_nested_message_extension_lite )->set_bb(318);
   message->AddExtension(unittest::repeated_foreign_message_extension_lite)->set_c(319);
   message->AddExtension(unittest::repeated_import_message_extension_lite )->set_d(320);
+  message->AddExtension(unittest::repeated_lazy_message_extension_lite   )->set_bb(327);
 
   message->AddExtension(unittest::repeated_nested_enum_extension_lite , unittest::TestAllTypesLite::BAZ );
   message->AddExtension(unittest::repeated_foreign_enum_extension_lite, unittest::FOREIGN_LITE_BAZ      );
@@ -900,6 +926,7 @@ void TestUtilLite::ModifyRepeatedExtensions(
   message->MutableExtension(unittest::repeated_nested_message_extension_lite , 1)->set_bb(518);
   message->MutableExtension(unittest::repeated_foreign_message_extension_lite, 1)->set_c(519);
   message->MutableExtension(unittest::repeated_import_message_extension_lite , 1)->set_d(520);
+  message->MutableExtension(unittest::repeated_lazy_message_extension_lite   , 1)->set_bb(527);
 
   message->SetExtension(unittest::repeated_nested_enum_extension_lite , 1, unittest::TestAllTypesLite::FOO );
   message->SetExtension(unittest::repeated_foreign_enum_extension_lite, 1, unittest::FOREIGN_LITE_FOO      );
@@ -927,15 +954,19 @@ void TestUtilLite::ExpectAllExtensionsSet(
   EXPECT_TRUE(message.HasExtension(unittest::optional_string_extension_lite  ));
   EXPECT_TRUE(message.HasExtension(unittest::optional_bytes_extension_lite   ));
 
-  EXPECT_TRUE(message.HasExtension(unittest::optionalgroup_extension_lite           ));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_nested_message_extension_lite ));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_message_extension_lite));
-  EXPECT_TRUE(message.HasExtension(unittest::optional_import_message_extension_lite ));
+  EXPECT_TRUE(message.HasExtension(unittest::optionalgroup_extension_lite                 ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_nested_message_extension_lite       ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_message_extension_lite      ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_import_message_extension_lite       ));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_public_import_message_extension_lite));
+  EXPECT_TRUE(message.HasExtension(unittest::optional_lazy_message_extension_lite         ));
 
-  EXPECT_TRUE(message.GetExtension(unittest::optionalgroup_extension_lite           ).has_a());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_nested_message_extension_lite ).has_bb());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_foreign_message_extension_lite).has_c());
-  EXPECT_TRUE(message.GetExtension(unittest::optional_import_message_extension_lite ).has_d());
+  EXPECT_TRUE(message.GetExtension(unittest::optionalgroup_extension_lite                 ).has_a());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_nested_message_extension_lite       ).has_bb());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_foreign_message_extension_lite      ).has_c());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_import_message_extension_lite       ).has_d());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_public_import_message_extension_lite).has_e());
+  EXPECT_TRUE(message.GetExtension(unittest::optional_lazy_message_extension_lite         ).has_bb());
 
   EXPECT_TRUE(message.HasExtension(unittest::optional_nested_enum_extension_lite ));
   EXPECT_TRUE(message.HasExtension(unittest::optional_foreign_enum_extension_lite));
@@ -958,10 +989,12 @@ void TestUtilLite::ExpectAllExtensionsSet(
   EXPECT_EQ("115", message.GetExtension(unittest::optional_string_extension_lite  ));
   EXPECT_EQ("116", message.GetExtension(unittest::optional_bytes_extension_lite   ));
 
-  EXPECT_EQ(117, message.GetExtension(unittest::optionalgroup_extension_lite           ).a());
-  EXPECT_EQ(118, message.GetExtension(unittest::optional_nested_message_extension_lite ).bb());
-  EXPECT_EQ(119, message.GetExtension(unittest::optional_foreign_message_extension_lite).c());
-  EXPECT_EQ(120, message.GetExtension(unittest::optional_import_message_extension_lite ).d());
+  EXPECT_EQ(117, message.GetExtension(unittest::optionalgroup_extension_lite                 ).a());
+  EXPECT_EQ(118, message.GetExtension(unittest::optional_nested_message_extension_lite       ).bb());
+  EXPECT_EQ(119, message.GetExtension(unittest::optional_foreign_message_extension_lite      ).c());
+  EXPECT_EQ(120, message.GetExtension(unittest::optional_import_message_extension_lite       ).d());
+  EXPECT_EQ(126, message.GetExtension(unittest::optional_public_import_message_extension_lite).e());
+  EXPECT_EQ(127, message.GetExtension(unittest::optional_lazy_message_extension_lite         ).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAZ , message.GetExtension(unittest::optional_nested_enum_extension_lite ));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAZ      , message.GetExtension(unittest::optional_foreign_enum_extension_lite));
@@ -990,6 +1023,7 @@ void TestUtilLite::ExpectAllExtensionsSet(
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_message_extension_lite ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_message_extension_lite));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_message_extension_lite ));
+  ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_lazy_message_extension_lite   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_enum_extension_lite    ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_enum_extension_lite   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_enum_extension_lite    ));
@@ -1015,6 +1049,7 @@ void TestUtilLite::ExpectAllExtensionsSet(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension_lite , 0).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension_lite, 0).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension_lite , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension_lite   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAR , message.GetExtension(unittest::repeated_nested_enum_extension_lite , 0));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension_lite, 0));
@@ -1041,6 +1076,7 @@ void TestUtilLite::ExpectAllExtensionsSet(
   EXPECT_EQ(318, message.GetExtension(unittest::repeated_nested_message_extension_lite , 1).bb());
   EXPECT_EQ(319, message.GetExtension(unittest::repeated_foreign_message_extension_lite, 1).c());
   EXPECT_EQ(320, message.GetExtension(unittest::repeated_import_message_extension_lite , 1).d());
+  EXPECT_EQ(327, message.GetExtension(unittest::repeated_lazy_message_extension_lite   , 1).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAZ , message.GetExtension(unittest::repeated_nested_enum_extension_lite , 1));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAZ      , message.GetExtension(unittest::repeated_foreign_enum_extension_lite, 1));
@@ -1118,10 +1154,12 @@ void TestUtilLite::ExpectExtensionsClear(
   EXPECT_FALSE(message.HasExtension(unittest::optional_string_extension_lite  ));
   EXPECT_FALSE(message.HasExtension(unittest::optional_bytes_extension_lite   ));
 
-  EXPECT_FALSE(message.HasExtension(unittest::optionalgroup_extension_lite           ));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_nested_message_extension_lite ));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_message_extension_lite));
-  EXPECT_FALSE(message.HasExtension(unittest::optional_import_message_extension_lite ));
+  EXPECT_FALSE(message.HasExtension(unittest::optionalgroup_extension_lite                 ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_nested_message_extension_lite       ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_message_extension_lite      ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_import_message_extension_lite       ));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_public_import_message_extension_lite));
+  EXPECT_FALSE(message.HasExtension(unittest::optional_lazy_message_extension_lite         ));
 
   EXPECT_FALSE(message.HasExtension(unittest::optional_nested_enum_extension_lite ));
   EXPECT_FALSE(message.HasExtension(unittest::optional_foreign_enum_extension_lite));
@@ -1146,15 +1184,19 @@ void TestUtilLite::ExpectExtensionsClear(
   EXPECT_EQ(""   , message.GetExtension(unittest::optional_bytes_extension_lite   ));
 
   // Embedded messages should also be clear.
-  EXPECT_FALSE(message.GetExtension(unittest::optionalgroup_extension_lite           ).has_a());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_nested_message_extension_lite ).has_bb());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_foreign_message_extension_lite).has_c());
-  EXPECT_FALSE(message.GetExtension(unittest::optional_import_message_extension_lite ).has_d());
-
-  EXPECT_EQ(0, message.GetExtension(unittest::optionalgroup_extension_lite           ).a());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_nested_message_extension_lite ).bb());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_foreign_message_extension_lite).c());
-  EXPECT_EQ(0, message.GetExtension(unittest::optional_import_message_extension_lite ).d());
+  EXPECT_FALSE(message.GetExtension(unittest::optionalgroup_extension_lite                 ).has_a());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_nested_message_extension_lite       ).has_bb());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_foreign_message_extension_lite      ).has_c());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_import_message_extension_lite       ).has_d());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_public_import_message_extension_lite).has_e());
+  EXPECT_FALSE(message.GetExtension(unittest::optional_lazy_message_extension_lite         ).has_bb());
+
+  EXPECT_EQ(0, message.GetExtension(unittest::optionalgroup_extension_lite                 ).a());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_nested_message_extension_lite       ).bb());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_foreign_message_extension_lite      ).c());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_import_message_extension_lite       ).d());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_public_import_message_extension_lite).e());
+  EXPECT_EQ(0, message.GetExtension(unittest::optional_lazy_message_extension_lite         ).bb());
 
   // Enums without defaults are set to the first value in the enum.
   EXPECT_EQ(unittest::TestAllTypesLite::FOO , message.GetExtension(unittest::optional_nested_enum_extension_lite ));
@@ -1183,6 +1225,7 @@ void TestUtilLite::ExpectExtensionsClear(
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_nested_message_extension_lite ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_foreign_message_extension_lite));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_import_message_extension_lite ));
+  EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_lazy_message_extension_lite   ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_nested_enum_extension_lite    ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_foreign_enum_extension_lite   ));
   EXPECT_EQ(0, message.ExtensionSize(unittest::repeated_import_enum_extension_lite    ));
@@ -1260,6 +1303,7 @@ void TestUtilLite::ExpectRepeatedExtensionsModified(
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_message_extension_lite ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_message_extension_lite));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_message_extension_lite ));
+  ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_lazy_message_extension_lite   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_nested_enum_extension_lite    ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_foreign_enum_extension_lite   ));
   ASSERT_EQ(2, message.ExtensionSize(unittest::repeated_import_enum_extension_lite    ));
@@ -1285,6 +1329,7 @@ void TestUtilLite::ExpectRepeatedExtensionsModified(
   EXPECT_EQ(218, message.GetExtension(unittest::repeated_nested_message_extension_lite , 0).bb());
   EXPECT_EQ(219, message.GetExtension(unittest::repeated_foreign_message_extension_lite, 0).c());
   EXPECT_EQ(220, message.GetExtension(unittest::repeated_import_message_extension_lite , 0).d());
+  EXPECT_EQ(227, message.GetExtension(unittest::repeated_lazy_message_extension_lite   , 0).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::BAR , message.GetExtension(unittest::repeated_nested_enum_extension_lite , 0));
   EXPECT_EQ(unittest::FOREIGN_LITE_BAR      , message.GetExtension(unittest::repeated_foreign_enum_extension_lite, 0));
@@ -1312,6 +1357,7 @@ void TestUtilLite::ExpectRepeatedExtensionsModified(
   EXPECT_EQ(518, message.GetExtension(unittest::repeated_nested_message_extension_lite , 1).bb());
   EXPECT_EQ(519, message.GetExtension(unittest::repeated_foreign_message_extension_lite, 1).c());
   EXPECT_EQ(520, message.GetExtension(unittest::repeated_import_message_extension_lite , 1).d());
+  EXPECT_EQ(527, message.GetExtension(unittest::repeated_lazy_message_extension_lite   , 1).bb());
 
   EXPECT_EQ(unittest::TestAllTypesLite::FOO , message.GetExtension(unittest::repeated_nested_enum_extension_lite , 1));
   EXPECT_EQ(unittest::FOREIGN_LITE_FOO      , message.GetExtension(unittest::repeated_foreign_enum_extension_lite, 1));
diff --git a/src/google/protobuf/testdata/golden_message b/src/google/protobuf/testdata/golden_message
index 94898e49..4dd62cd3 100644
--- a/src/google/protobuf/testdata/golden_message
+++ b/src/google/protobuf/testdata/golden_message
diff --git a/src/google/protobuf/testdata/text_format_unittest_data.txt b/src/google/protobuf/testdata/text_format_unittest_data.txt
index feea8f7b..bbe58826 100644
--- a/src/google/protobuf/testdata/text_format_unittest_data.txt
+++ b/src/google/protobuf/testdata/text_format_unittest_data.txt
@@ -30,6 +30,12 @@ optional_foreign_enum: FOREIGN_BAZ
 optional_import_enum: IMPORT_BAZ
 optional_string_piece: "124"
 optional_cord: "125"
+optional_public_import_message {
+  e: 126
+}
+optional_lazy_message {
+  bb: 127
+}
 repeated_int32: 201
 repeated_int32: 301
 repeated_int64: 202
@@ -94,6 +100,12 @@ repeated_string_piece: "224"
 repeated_string_piece: "324"
 repeated_cord: "225"
 repeated_cord: "325"
+repeated_lazy_message {
+  bb: 227
+}
+repeated_lazy_message {
+  bb: 327
+}
 default_int32: 401
 default_int64: 402
 default_uint32: 403
diff --git a/src/google/protobuf/testdata/text_format_unittest_extensions_data.txt b/src/google/protobuf/testdata/text_format_unittest_extensions_data.txt
index 057beae8..0a217f02 100644
--- a/src/google/protobuf/testdata/text_format_unittest_extensions_data.txt
+++ b/src/google/protobuf/testdata/text_format_unittest_extensions_data.txt
@@ -30,6 +30,12 @@
 [protobuf_unittest.optional_import_enum_extension]: IMPORT_BAZ
 [protobuf_unittest.optional_string_piece_extension]: "124"
 [protobuf_unittest.optional_cord_extension]: "125"
+[protobuf_unittest.optional_public_import_message_extension] {
+  e: 126
+}
+[protobuf_unittest.optional_lazy_message_extension] {
+  bb: 127
+}
 [protobuf_unittest.repeated_int32_extension]: 201
 [protobuf_unittest.repeated_int32_extension]: 301
 [protobuf_unittest.repeated_int64_extension]: 202
@@ -94,6 +100,12 @@
 [protobuf_unittest.repeated_string_piece_extension]: "324"
 [protobuf_unittest.repeated_cord_extension]: "225"
 [protobuf_unittest.repeated_cord_extension]: "325"
+[protobuf_unittest.repeated_lazy_message_extension] {
+  bb: 227
+}
+[protobuf_unittest.repeated_lazy_message_extension] {
+  bb: 327
+}
 [protobuf_unittest.default_int32_extension]: 401
 [protobuf_unittest.default_int64_extension]: 402
 [protobuf_unittest.default_uint32_extension]: 403
diff --git a/src/google/protobuf/testing/googletest.cc b/src/google/protobuf/testing/googletest.cc
index cd094d0c..a8da6b1d 100644
--- a/src/google/protobuf/testing/googletest.cc
+++ b/src/google/protobuf/testing/googletest.cc
@@ -223,16 +223,17 @@ ScopedMemoryLog::~ScopedMemoryLog() {
   active_log_ = NULL;
 }
 
-const vector<string>& ScopedMemoryLog::GetMessages(LogLevel dummy) const {
-  GOOGLE_CHECK_EQ(dummy, ERROR);
-  return messages_;
+const vector<string>& ScopedMemoryLog::GetMessages(LogLevel level) {
+  GOOGLE_CHECK(level == ERROR ||
+               level == WARNING);
+  return messages_[level];
 }
 
 void ScopedMemoryLog::HandleLog(LogLevel level, const char* filename,
                                 int line, const string& message) {
   GOOGLE_CHECK(active_log_ != NULL);
-  if (level == ERROR) {
-    active_log_->messages_.push_back(message);
+  if (level == ERROR || level == WARNING) {
+    active_log_->messages_[level].push_back(message);
   }
 }
 
diff --git a/src/google/protobuf/testing/googletest.h b/src/google/protobuf/testing/googletest.h
index 71444c96..6b17ae4f 100644
--- a/src/google/protobuf/testing/googletest.h
+++ b/src/google/protobuf/testing/googletest.h
@@ -34,6 +34,7 @@
 #ifndef GOOGLE_PROTOBUF_GOOGLETEST_H__
 #define GOOGLE_PROTOBUF_GOOGLETEST_H__
 
+#include <map>
 #include <vector>
 #include <google/protobuf/stubs/common.h>
 
@@ -60,6 +61,7 @@ string GetCapturedTestStderr();
 // ScopedMemoryLog refers to LOGLEVEL_ERROR as just ERROR.
 #undef ERROR  // defend against promiscuous windows.h
 static const LogLevel ERROR = LOGLEVEL_ERROR;
+static const LogLevel WARNING = LOGLEVEL_WARNING;
 
 // Receives copies of all LOG(ERROR) messages while in scope.  Sample usage:
 //   {
@@ -74,14 +76,11 @@ class ScopedMemoryLog {
   ScopedMemoryLog();
   virtual ~ScopedMemoryLog();
 
-  // Fetches all messages logged.  The internal version of this class
-  // would only fetch messages at the given security level, but the protobuf
-  // open source version ignores the argument since we always pass ERROR
-  // anyway.
-  const vector<string>& GetMessages(LogLevel dummy) const;
+  // Fetches all messages with the given severity level.
+  const vector<string>& GetMessages(LogLevel error);
 
  private:
-  vector<string> messages_;
+  map<LogLevel, vector<string> > messages_;
   LogHandler* old_handler_;
 
   static void HandleLog(LogLevel level, const char* filename, int line,
diff --git a/src/google/protobuf/text_format.cc b/src/google/protobuf/text_format.cc
index 1494ebd7..1ee3df50 100644
--- a/src/google/protobuf/text_format.cc
+++ b/src/google/protobuf/text_format.cc
@@ -49,6 +49,8 @@
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/io/tokenizer.h>
 #include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/map-util.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -94,6 +96,73 @@ void Message::PrintDebugString() const {
 
 
 // ===========================================================================
+// Implementation of the parse information tree class.
+TextFormat::ParseInfoTree::ParseInfoTree() { }
+
+TextFormat::ParseInfoTree::~ParseInfoTree() {
+  // Remove any nested information trees, as they are owned by this tree.
+  for (NestedMap::iterator it = nested_.begin(); it != nested_.end(); ++it) {
+    STLDeleteElements(&(it->second));
+  }
+}
+
+void TextFormat::ParseInfoTree::RecordLocation(
+    const FieldDescriptor* field,
+    TextFormat::ParseLocation location) {
+  locations_[field].push_back(location);
+}
+
+TextFormat::ParseInfoTree* TextFormat::ParseInfoTree::CreateNested(
+    const FieldDescriptor* field) {
+  // Owned by us in the map.
+  TextFormat::ParseInfoTree* instance = new TextFormat::ParseInfoTree();
+  vector<TextFormat::ParseInfoTree*>* trees = &nested_[field];
+  GOOGLE_CHECK(trees);
+  trees->push_back(instance);
+  return instance;
+}
+
+void CheckFieldIndex(const FieldDescriptor* field, int index) {
+  if (field == NULL) { return; }
+
+  if (field->is_repeated() && index == -1) {
+    GOOGLE_LOG(DFATAL) << "Index must be in range of repeated field values. "
+                << "Field: " << field->name();
+  } else if (!field->is_repeated() && index != -1) {
+    GOOGLE_LOG(DFATAL) << "Index must be -1 for singular fields."
+                << "Field: " << field->name();
+  }
+}
+
+TextFormat::ParseLocation TextFormat::ParseInfoTree::GetLocation(
+    const FieldDescriptor* field, int index) const {
+  CheckFieldIndex(field, index);
+  if (index == -1) { index = 0; }
+
+  const vector<TextFormat::ParseLocation>* locations =
+      FindOrNull(locations_, field);
+  if (locations == NULL || index >= locations->size()) {
+    return TextFormat::ParseLocation();
+  }
+
+  return (*locations)[index];
+}
+
+TextFormat::ParseInfoTree* TextFormat::ParseInfoTree::GetTreeForNested(
+    const FieldDescriptor* field, int index) const {
+  CheckFieldIndex(field, index);
+  if (index == -1) { index = 0; }
+
+  const vector<TextFormat::ParseInfoTree*>* trees = FindOrNull(nested_, field);
+  if (trees == NULL || index >= trees->size()) {
+    return NULL;
+  }
+
+  return (*trees)[index];
+}
+
+
+// ===========================================================================
 // Internal class for parsing an ASCII representation of a Protocol Message.
 // This class makes use of the Protocol Message compiler's tokenizer found
 // in //google/protobuf/io/tokenizer.h. Note that class's Parse
@@ -120,13 +189,17 @@ class TextFormat::Parser::ParserImpl {
              io::ZeroCopyInputStream* input_stream,
              io::ErrorCollector* error_collector,
              TextFormat::Finder* finder,
-             SingularOverwritePolicy singular_overwrite_policy)
+             ParseInfoTree* parse_info_tree,
+             SingularOverwritePolicy singular_overwrite_policy,
+             bool allow_unknown_field)
     : error_collector_(error_collector),
       finder_(finder),
+      parse_info_tree_(parse_info_tree),
       tokenizer_error_collector_(this),
       tokenizer_(input_stream, &tokenizer_error_collector_),
       root_message_type_(root_message_type),
       singular_overwrite_policy_(singular_overwrite_policy),
+      allow_unknown_field_(allow_unknown_field),
       had_errors_(false) {
     // For backwards-compatibility with proto1, we need to allow the 'f' suffix
     // for floats.
@@ -240,6 +313,8 @@ class TextFormat::Parser::ParserImpl {
     string field_name;
 
     const FieldDescriptor* field = NULL;
+    int start_line = tokenizer_.current().line;
+    int start_column = tokenizer_.current().column;
 
     if (TryConsume("[")) {
       // Extension.
@@ -257,10 +332,16 @@ class TextFormat::Parser::ParserImpl {
                : reflection->FindKnownExtensionByName(field_name));
 
       if (field == NULL) {
-        ReportError("Extension \"" + field_name + "\" is not defined or "
-                    "is not an extension of \"" +
-                    descriptor->full_name() + "\".");
-        return false;
+        if (!allow_unknown_field_) {
+          ReportError("Extension \"" + field_name + "\" is not defined or "
+                      "is not an extension of \"" +
+                      descriptor->full_name() + "\".");
+          return false;
+        } else {
+          ReportWarning("Extension \"" + field_name + "\" is not defined or "
+                        "is not an extension of \"" +
+                        descriptor->full_name() + "\".");
+        }
       }
     } else {
       DO(ConsumeIdentifier(&field_name));
@@ -285,9 +366,30 @@ class TextFormat::Parser::ParserImpl {
       }
 
       if (field == NULL) {
-        ReportError("Message type \"" + descriptor->full_name() +
-                    "\" has no field named \"" + field_name + "\".");
-        return false;
+        if (!allow_unknown_field_) {
+          ReportError("Message type \"" + descriptor->full_name() +
+                      "\" has no field named \"" + field_name + "\".");
+          return false;
+        } else {
+          ReportWarning("Message type \"" + descriptor->full_name() +
+                        "\" has no field named \"" + field_name + "\".");
+        }
+      }
+    }
+
+    // Skips unknown field.
+    if (field == NULL) {
+      GOOGLE_CHECK(allow_unknown_field_);
+      // Try to guess the type of this field.
+      // If this field is not a message, there should be a ":" between the
+      // field name and the field value and also the field value should not
+      // start with "{" or "<" which indicates the begining of a message body.
+      // If there is no ":" or there is a "{" or "<" after ":", this field has
+      // to be a message or the input is ill-formed.
+      if (TryConsume(":") && !LookingAt("{") && !LookingAt("<")) {
+        return SkipFieldValue();
+      } else {
+        return SkipFieldMessage();
       }
     }
 
@@ -329,12 +431,61 @@ class TextFormat::Parser::ParserImpl {
                     + field_name + "\"");
     }
 
+    // If a parse info tree exists, add the location for the parsed
+    // field.
+    if (parse_info_tree_ != NULL) {
+      parse_info_tree_->RecordLocation(field,
+                                       ParseLocation(start_line, start_column));
+    }
+
+    return true;
+  }
+
+  // Skips the next field including the field's name and value.
+  bool SkipField() {
+    string field_name;
+    if (TryConsume("[")) {
+      // Extension name.
+      DO(ConsumeIdentifier(&field_name));
+      while (TryConsume(".")) {
+        string part;
+        DO(ConsumeIdentifier(&part));
+        field_name += ".";
+        field_name += part;
+      }
+      DO(Consume("]"));
+    } else {
+      DO(ConsumeIdentifier(&field_name));
+    }
+
+    // Try to guess the type of this field.
+    // If this field is not a message, there should be a ":" between the
+    // field name and the field value and also the field value should not
+    // start with "{" or "<" which indicates the begining of a message body.
+    // If there is no ":" or there is a "{" or "<" after ":", this field has
+    // to be a message or the input is ill-formed.
+    if (TryConsume(":") && !LookingAt("{") && !LookingAt("<")) {
+      DO(SkipFieldValue());
+    } else {
+      DO(SkipFieldMessage());
+    }
+    // For historical reasons, fields may optionally be separated by commas or
+    // semicolons.
+    TryConsume(";") || TryConsume(",");
     return true;
   }
 
   bool ConsumeFieldMessage(Message* message,
                            const Reflection* reflection,
                            const FieldDescriptor* field) {
+
+    // If the parse information tree is not NULL, create a nested one
+    // for the nested message.
+    ParseInfoTree* parent = parse_info_tree_;
+    if (parent != NULL) {
+      parse_info_tree_ = parent->CreateNested(field);
+    }
+
     string delimeter;
     if (TryConsume("<")) {
       delimeter = ">";
@@ -349,6 +500,26 @@ class TextFormat::Parser::ParserImpl {
       DO(ConsumeMessage(reflection->MutableMessage(message, field),
                         delimeter));
     }
+
+    // Reset the parse information tree.
+    parse_info_tree_ = parent;
+    return true;
+  }
+
+  // Skips the whole body of a message including the begining delimeter and
+  // the ending delimeter.
+  bool SkipFieldMessage() {
+    string delimeter;
+    if (TryConsume("<")) {
+      delimeter = ">";
+    } else {
+      DO(Consume("{"));
+      delimeter = "}";
+    }
+    while (!LookingAt(">") &&  !LookingAt("}")) {
+      DO(SkipField());
+    }
+    DO(Consume(delimeter));
     return true;
   }
 
@@ -479,6 +650,60 @@ class TextFormat::Parser::ParserImpl {
     return true;
   }
 
+  bool SkipFieldValue() {
+    if (LookingAtType(io::Tokenizer::TYPE_STRING)) {
+      while (LookingAtType(io::Tokenizer::TYPE_STRING)) {
+        tokenizer_.Next();
+      }
+      return true;
+    }
+    // Possible field values other than string:
+    //   12345        => TYPE_INTEGER
+    //   -12345       => TYPE_SYMBOL + TYPE_INTEGER
+    //   1.2345       => TYPE_FLOAT
+    //   -1.2345      => TYPE_SYMBOL + TYPE_FLOAT
+    //   inf          => TYPE_IDENTIFIER
+    //   -inf         => TYPE_SYMBOL + TYPE_IDENTIFIER
+    //   TYPE_INTEGER => TYPE_IDENTIFIER
+    // Divides them into two group, one with TYPE_SYMBOL
+    // and the other without:
+    //   Group one:
+    //     12345        => TYPE_INTEGER
+    //     1.2345       => TYPE_FLOAT
+    //     inf          => TYPE_IDENTIFIER
+    //     TYPE_INTEGER => TYPE_IDENTIFIER
+    //   Group two:
+    //     -12345       => TYPE_SYMBOL + TYPE_INTEGER
+    //     -1.2345      => TYPE_SYMBOL + TYPE_FLOAT
+    //     -inf         => TYPE_SYMBOL + TYPE_IDENTIFIER
+    // As we can see, the field value consists of an optional '-' and one of
+    // TYPE_INTEGER, TYPE_FLOAT and TYPE_IDENTIFIER.
+    bool has_minus = TryConsume("-");
+    if (!LookingAtType(io::Tokenizer::TYPE_INTEGER) &&
+        !LookingAtType(io::Tokenizer::TYPE_FLOAT) &&
+        !LookingAtType(io::Tokenizer::TYPE_IDENTIFIER)) {
+      return false;
+    }
+    // Combination of '-' and TYPE_IDENTIFIER may result in an invalid field
+    // value while other combinations all generate valid values.
+    // We check if the value of this combination is valid here.
+    // TYPE_IDENTIFIER after a '-' should be one of the float values listed
+    // below:
+    //   inf, inff, infinity, nan
+    if (has_minus && LookingAtType(io::Tokenizer::TYPE_IDENTIFIER)) {
+      string text = tokenizer_.current().text;
+      LowerString(&text);
+      if (text != "inf" &&
+          text != "infinity" &&
+          text != "nan") {
+        ReportError("Invalid float number: " + text);
+        return false;
+      }
+    }
+    tokenizer_.Next();
+    return true;
+  }
+
   // Returns true if the current token's text is equal to that specified.
   bool LookingAt(const string& text) {
     return tokenizer_.current().text == text;
@@ -596,7 +821,8 @@ class TextFormat::Parser::ParserImpl {
     } else if (LookingAtType(io::Tokenizer::TYPE_IDENTIFIER)) {
       string text = tokenizer_.current().text;
       LowerString(&text);
-      if (text == "inf" || text == "infinity") {
+      if (text == "inf" ||
+          text == "infinity") {
         *value = std::numeric_limits<double>::infinity();
         tokenizer_.Next();
       } else if (text == "nan") {
@@ -670,10 +896,12 @@ class TextFormat::Parser::ParserImpl {
 
   io::ErrorCollector* error_collector_;
   TextFormat::Finder* finder_;
+  ParseInfoTree* parse_info_tree_;
   ParserErrorCollector tokenizer_error_collector_;
   io::Tokenizer tokenizer_;
   const Descriptor* root_message_type_;
   SingularOverwritePolicy singular_overwrite_policy_;
+  bool allow_unknown_field_;
   bool had_errors_;
 };
 
@@ -699,7 +927,7 @@ class TextFormat::Printer::TextGenerator {
   ~TextGenerator() {
     // Only BackUp() if we're sure we've successfully called Next() at least
     // once.
-    if (buffer_size_ > 0) {
+    if (!failed_ && buffer_size_ > 0) {
       output_->BackUp(buffer_size_);
     }
   }
@@ -809,7 +1037,9 @@ TextFormat::Finder::~Finder() {
 TextFormat::Parser::Parser()
   : error_collector_(NULL),
     finder_(NULL),
-    allow_partial_(false) {
+    parse_info_tree_(NULL),
+    allow_partial_(false),
+    allow_unknown_field_(false) {
 }
 
 TextFormat::Parser::~Parser() {}
@@ -818,7 +1048,9 @@ bool TextFormat::Parser::Parse(io::ZeroCopyInputStream* input,
                                Message* output) {
   output->Clear();
   ParserImpl parser(output->GetDescriptor(), input, error_collector_,
-                    finder_, ParserImpl::FORBID_SINGULAR_OVERWRITES);
+                    finder_, parse_info_tree_,
+                    ParserImpl::FORBID_SINGULAR_OVERWRITES,
+                    allow_unknown_field_);
   return MergeUsingImpl(input, output, &parser);
 }
 
@@ -831,7 +1063,9 @@ bool TextFormat::Parser::ParseFromString(const string& input,
 bool TextFormat::Parser::Merge(io::ZeroCopyInputStream* input,
                                Message* output) {
   ParserImpl parser(output->GetDescriptor(), input, error_collector_,
-                    finder_, ParserImpl::ALLOW_SINGULAR_OVERWRITES);
+                    finder_, parse_info_tree_,
+                    ParserImpl::ALLOW_SINGULAR_OVERWRITES,
+                    allow_unknown_field_);
   return MergeUsingImpl(input, output, &parser);
 }
 
@@ -861,7 +1095,9 @@ bool TextFormat::Parser::ParseFieldValueFromString(
     Message* output) {
   io::ArrayInputStream input_stream(input.data(), input.size());
   ParserImpl parser(output->GetDescriptor(), &input_stream, error_collector_,
-                    finder_, ParserImpl::ALLOW_SINGULAR_OVERWRITES);
+                    finder_, parse_info_tree_,
+                    ParserImpl::ALLOW_SINGULAR_OVERWRITES,
+                    allow_unknown_field_);
   return parser.ParseField(field, output);
 }
 
diff --git a/src/google/protobuf/text_format.h b/src/google/protobuf/text_format.h
index 03c04910..09741397 100644
--- a/src/google/protobuf/text_format.h
+++ b/src/google/protobuf/text_format.h
@@ -38,7 +38,10 @@
 #ifndef GOOGLE_PROTOBUF_TEXT_FORMAT_H__
 #define GOOGLE_PROTOBUF_TEXT_FORMAT_H__
 
+#include <map>
 #include <string>
+#include <vector>
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/message.h>
 #include <google/protobuf/descriptor.h>
 
@@ -220,6 +223,57 @@ class LIBPROTOBUF_EXPORT TextFormat {
         const string& name) const = 0;
   };
 
+  // A location in the parsed text.
+  struct ParseLocation {
+    int line;
+    int column;
+
+    ParseLocation() : line(-1), column(-1) {}
+    ParseLocation(int line_param, int column_param)
+        : line(line_param), column(column_param) {}
+  };
+
+  // Data structure which is populated with the locations of each field
+  // value parsed from the text.
+  class LIBPROTOBUF_EXPORT ParseInfoTree {
+   public:
+    ParseInfoTree();
+    ~ParseInfoTree();
+
+    // Returns the parse location for index-th value of the field in the parsed
+    // text. If none exists, returns a location with line = -1. Index should be
+    // -1 for not-repeated fields.
+    ParseLocation GetLocation(const FieldDescriptor* field, int index) const;
+
+    // Returns the parse info tree for the given field, which must be a message
+    // type. The nested information tree is owned by the root tree and will be
+    // deleted when it is deleted.
+    ParseInfoTree* GetTreeForNested(const FieldDescriptor* field,
+                                    int index) const;
+
+   private:
+    // Allow the text format parser to record information into the tree.
+    friend class TextFormat;
+
+    // Records the starting location of a single value for a field.
+    void RecordLocation(const FieldDescriptor* field, ParseLocation location);
+
+    // Create and records a nested tree for a nested message field.
+    ParseInfoTree* CreateNested(const FieldDescriptor* field);
+
+    // Defines the map from the index-th field descriptor to its parse location.
+    typedef map<const FieldDescriptor*, vector<ParseLocation> > LocationMap;
+
+    // Defines the map from the index-th field descriptor to the nested parse
+    // info tree.
+    typedef map<const FieldDescriptor*, vector<ParseInfoTree*> > NestedMap;
+
+    LocationMap locations_;
+    NestedMap nested_;
+
+    GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ParseInfoTree);
+  };
+
   // For more control over parsing, use this class.
   class LIBPROTOBUF_EXPORT Parser {
    public:
@@ -248,6 +302,12 @@ class LIBPROTOBUF_EXPORT TextFormat {
       finder_ = finder;
     }
 
+    // Sets where location information about the parse will be written. If NULL
+    // (the default), then no location will be written.
+    void WriteLocationsTo(ParseInfoTree* tree) {
+      parse_info_tree_ = tree;
+    }
+
     // Normally parsing fails if, after parsing, output->IsInitialized()
     // returns false.  Call AllowPartialMessage(true) to skip this check.
     void AllowPartialMessage(bool allow) {
@@ -259,6 +319,7 @@ class LIBPROTOBUF_EXPORT TextFormat {
                                    const FieldDescriptor* field,
                                    Message* output);
 
+
    private:
     // Forward declaration of an internal class used to parse text
     // representations (see text_format.cc for implementation).
@@ -272,7 +333,9 @@ class LIBPROTOBUF_EXPORT TextFormat {
 
     io::ErrorCollector* error_collector_;
     Finder* finder_;
+    ParseInfoTree* parse_info_tree_;
     bool allow_partial_;
+    bool allow_unknown_field_;
   };
 
  private:
diff --git a/src/google/protobuf/text_format_unittest.cc b/src/google/protobuf/text_format_unittest.cc
index 00ea8c3c..353a5e49 100644
--- a/src/google/protobuf/text_format_unittest.cc
+++ b/src/google/protobuf/text_format_unittest.cc
@@ -339,6 +339,21 @@ TEST_F(TextFormatTest, PrintMessageSingleLine) {
     text);
 }
 
+TEST_F(TextFormatTest, PrintBufferTooSmall) {
+  // Test printing a message to a buffer that is too small.
+
+  protobuf_unittest::TestAllTypes message;
+
+  message.add_repeated_string("abc");
+  message.add_repeated_string("def");
+
+  char buffer[1] = "";
+  io::ArrayOutputStream output_stream(buffer, 1);
+  EXPECT_FALSE(TextFormat::Print(message, &output_stream));
+  EXPECT_EQ(buffer[0], 'r');
+  EXPECT_EQ(output_stream.ByteCount(), 1);
+}
+
 TEST_F(TextFormatTest, ParseBasic) {
   io::ArrayInputStream input_stream(proto_debug_string_.data(),
                                     proto_debug_string_.size());
@@ -728,6 +743,25 @@ class TextFormatParserTest : public testing::Test {
               error_collector.text_);
   }
 
+  void ExpectSuccessAndTree(const string& input, Message* proto,
+                            TextFormat::ParseInfoTree* info_tree) {
+    TextFormat::Parser parser;
+    MockErrorCollector error_collector;
+    parser.RecordErrorsTo(&error_collector);
+    parser.WriteLocationsTo(info_tree);
+
+    EXPECT_TRUE(parser.ParseFromString(input, proto));
+  }
+
+  void ExpectLocation(TextFormat::ParseInfoTree* tree,
+                      const Descriptor* d, const string& field_name,
+                      int index, int line, int column) {
+    TextFormat::ParseLocation location = tree->GetLocation(
+        d->FindFieldByName(field_name), index);
+    EXPECT_EQ(line, location.line);
+    EXPECT_EQ(column, location.column);
+  }
+
   // An error collector which simply concatenates all its errors into a big
   // block of text which can be checked.
   class MockErrorCollector : public io::ErrorCollector {
@@ -749,6 +783,71 @@ class TextFormatParserTest : public testing::Test {
   };
 };
 
+TEST_F(TextFormatParserTest, ParseInfoTreeBuilding) {
+  scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
+  const Descriptor* d = message->GetDescriptor();
+
+  string stringData =
+      "optional_int32: 1\n"
+      "optional_int64: 2\n"
+      "  optional_double: 2.4\n"
+      "repeated_int32: 5\n"
+      "repeated_int32: 10\n"
+      "optional_nested_message <\n"
+      "  bb: 78\n"
+      ">\n"
+      "repeated_nested_message <\n"
+      "  bb: 79\n"
+      ">\n"
+      "repeated_nested_message <\n"
+      "  bb: 80\n"
+      ">";
+
+
+  TextFormat::ParseInfoTree tree;
+  ExpectSuccessAndTree(stringData, message.get(), &tree);
+
+  // Verify that the tree has the correct positions.
+  ExpectLocation(&tree, d, "optional_int32", -1, 0, 0);
+  ExpectLocation(&tree, d, "optional_int64", -1, 1, 0);
+  ExpectLocation(&tree, d, "optional_double", -1, 2, 2);
+
+  ExpectLocation(&tree, d, "repeated_int32", 0, 3, 0);
+  ExpectLocation(&tree, d, "repeated_int32", 1, 4, 0);
+
+  ExpectLocation(&tree, d, "optional_nested_message", -1, 5, 0);
+  ExpectLocation(&tree, d, "repeated_nested_message", 0, 8, 0);
+  ExpectLocation(&tree, d, "repeated_nested_message", 1, 11, 0);
+
+  // Check for fields not set. For an invalid field, the location returned
+  // should be -1, -1.
+  ExpectLocation(&tree, d, "repeated_int64", 0, -1, -1);
+  ExpectLocation(&tree, d, "repeated_int32", 6, -1, -1);
+  ExpectLocation(&tree, d, "some_unknown_field", -1, -1, -1);
+
+  // Verify inside the nested message.
+  const FieldDescriptor* nested_field =
+      d->FindFieldByName("optional_nested_message");
+
+  TextFormat::ParseInfoTree* nested_tree =
+      tree.GetTreeForNested(nested_field, -1);
+  ExpectLocation(nested_tree, nested_field->message_type(), "bb", -1, 6, 2);
+
+  // Verify inside another nested message.
+  nested_field = d->FindFieldByName("repeated_nested_message");
+  nested_tree = tree.GetTreeForNested(nested_field, 0);
+  ExpectLocation(nested_tree, nested_field->message_type(), "bb", -1, 9, 2);
+
+  nested_tree = tree.GetTreeForNested(nested_field, 1);
+  ExpectLocation(nested_tree, nested_field->message_type(), "bb", -1, 12, 2);
+
+  // Verify a NULL tree for an unknown nested field.
+  TextFormat::ParseInfoTree* unknown_nested_tree =
+      tree.GetTreeForNested(nested_field, 2);
+
+  EXPECT_EQ(NULL, unknown_nested_tree);
+}
+
 TEST_F(TextFormatParserTest, ParseFieldValueFromString) {
   scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
   const Descriptor* d = message->GetDescriptor();
@@ -921,10 +1020,10 @@ TEST_F(TextFormatParserTest, InvalidFieldValues) {
                 1, 16);
   ExpectFailure("optional_int32: 0x80000000\n",
                 "Integer out of range.", 1, 17);
-  ExpectFailure("optional_int32: -0x80000001\n",
-                "Integer out of range.", 1, 18);
   ExpectFailure("optional_int64: 0x8000000000000000\n",
                 "Integer out of range.", 1, 17);
+  ExpectFailure("optional_int32: -0x80000001\n",
+                "Integer out of range.", 1, 18);
   ExpectFailure("optional_int64: -0x8000000000000001\n",
                 "Integer out of range.", 1, 18);
 
@@ -1136,6 +1235,7 @@ TEST_F(TextFormatMessageSetTest, Deserialize) {
   EXPECT_EQ(2, descriptors.size());
 }
 
+
 }  // namespace text_format_unittest
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/unittest.proto b/src/google/protobuf/unittest.proto
index 97ec6747..0305be65 100644
--- a/src/google/protobuf/unittest.proto
+++ b/src/google/protobuf/unittest.proto
@@ -103,6 +103,12 @@ message TestAllTypes {
   optional string optional_string_piece = 24 [ctype=STRING_PIECE];
   optional string optional_cord = 25 [ctype=CORD];
 
+  // Defined in unittest_import_public.proto
+  optional protobuf_unittest_import.PublicImportMessage
+      optional_public_import_message = 26;
+
+  optional NestedMessage optional_lazy_message = 27 [lazy=true];
+
   // Repeated
   repeated    int32 repeated_int32    = 31;
   repeated    int64 repeated_int64    = 32;
@@ -135,6 +141,8 @@ message TestAllTypes {
   repeated string repeated_string_piece = 54 [ctype=STRING_PIECE];
   repeated string repeated_cord = 55 [ctype=CORD];
 
+  repeated NestedMessage repeated_lazy_message = 57 [lazy=true];
+
   // Singular with defaults
   optional    int32 default_int32    = 61 [default =  41    ];
   optional    int64 default_int64    = 62 [default =  42    ];
@@ -216,6 +224,12 @@ extend TestAllExtensions {
   optional string optional_string_piece_extension = 24 [ctype=STRING_PIECE];
   optional string optional_cord_extension = 25 [ctype=CORD];
 
+  optional protobuf_unittest_import.PublicImportMessage
+    optional_public_import_message_extension = 26;
+
+  optional TestAllTypes.NestedMessage
+    optional_lazy_message_extension = 27 [lazy=true];
+
   // Repeated
   repeated    int32 repeated_int32_extension    = 31;
   repeated    int64 repeated_int64_extension    = 32;
@@ -250,6 +264,9 @@ extend TestAllExtensions {
   repeated string repeated_string_piece_extension = 54 [ctype=STRING_PIECE];
   repeated string repeated_cord_extension = 55 [ctype=CORD];
 
+  repeated TestAllTypes.NestedMessage
+    repeated_lazy_message_extension = 57 [lazy=true];
+
   // Singular with defaults
   optional    int32 default_int32_extension    = 61 [default =  41    ];
   optional    int64 default_int64_extension    = 62 [default =  42    ];
@@ -397,6 +414,13 @@ message TestDupFieldNumber {                        // NO_PROTO1
   optional group Bar = 3 { optional int32 a = 1; }  // NO_PROTO1
 }                                                   // NO_PROTO1
 
+// Additional messages for testing lazy fields.
+message TestEagerMessage {
+  optional TestAllTypes sub_message = 1 [lazy=false];
+}
+message TestLazyMessage {
+  optional TestAllTypes sub_message = 1 [lazy=true];
+}
 
 // Needed for a Python test.
 message TestNestedMessageHasBits {
@@ -470,6 +494,8 @@ message TestExtremeDefaultValues {
   optional uint64 large_uint64 = 3 [default = 0xFFFFFFFFFFFFFFFF];
   optional  int32 small_int32  = 4 [default = -0x7FFFFFFF];
   optional  int64 small_int64  = 5 [default = -0x7FFFFFFFFFFFFFFF];
+  optional  int32 really_small_int32 = 21 [default = -0x80000000];
+  optional  int64 really_small_int64 = 22 [default = -0x8000000000000000];
 
   // The default value here is UTF-8 for "\u1234".  (We could also just type
   // the UTF-8 text directly into this text file rather than escape it, but
@@ -500,6 +526,14 @@ message TestExtremeDefaultValues {
   // Note that in .proto file, "\?" is a valid way to escape ? in string
   // literals.
   optional string cpp_trigraph = 20 [default = "? \? ?? \?? \??? ??/ ?\?-"];
+
+  // String defaults containing the character '\000'
+  optional string string_with_zero       = 23 [default = "hel\000lo"];
+  optional  bytes bytes_with_zero        = 24 [default = "wor\000ld"];
+  optional string string_piece_with_zero = 25 [ctype=STRING_PIECE,
+                                               default="ab\000c"];
+  optional string cord_with_zero         = 26 [ctype=CORD,
+                                               default="12\0003"];
 }
 
 message SparseEnumMessage {
@@ -511,10 +545,19 @@ message OneString {
   optional string data = 1;
 }
 
+message MoreString {
+  repeated string data = 1;
+}
+
 message OneBytes {
   optional bytes data = 1;
 }
 
+message MoreBytes {
+  repeated bytes data = 1;
+}
+
+
 // Test messages for packed fields
 
 message TestPackedTypes {
@@ -615,11 +658,56 @@ message TestRepeatedScalarDifferentTagSizes {
   repeated uint64  repeated_uint64  = 262143;
 }
 
+// Test that if an optional or required message/group field appears multiple
+// times in the input, they need to be merged.
+message TestParsingMerge {
+  // RepeatedFieldsGenerator defines matching field types as TestParsingMerge,
+  // except that all fields are repeated. In the tests, we will serialize the
+  // RepeatedFieldsGenerator to bytes, and parse the bytes to TestParsingMerge.
+  // Repeated fields in RepeatedFieldsGenerator are expected to be merged into
+  // the corresponding required/optional fields in TestParsingMerge.
+  message RepeatedFieldsGenerator {
+    repeated TestAllTypes field1 = 1;
+    repeated TestAllTypes field2 = 2;
+    repeated TestAllTypes field3 = 3;
+    repeated group Group1 = 10 {
+      optional TestAllTypes field1 = 11;
+    }
+    repeated group Group2 = 20 {
+      optional TestAllTypes field1 = 21;
+    }
+    repeated TestAllTypes ext1 = 1000;
+    repeated TestAllTypes ext2 = 1001;
+  }
+  required TestAllTypes required_all_types = 1;
+  optional TestAllTypes optional_all_types = 2;
+  repeated TestAllTypes repeated_all_types = 3;
+  optional group OptionalGroup = 10 {
+    optional TestAllTypes optional_group_all_types = 11;
+  }
+  repeated group RepeatedGroup = 20 {
+    optional TestAllTypes repeated_group_all_types = 21;
+  }
+  extensions 1000 to max;
+  extend TestParsingMerge {
+    optional TestAllTypes optional_ext = 1000;
+    repeated TestAllTypes repeated_ext = 1001;
+  }
+}
+
+message TestCommentInjectionMessage {
+  // */ <- This should not close the generated doc comment
+  optional string a = 1 [default="*/ <- Neither should this."];
+}
+
 
 // Test that RPC services work.
 message FooRequest  {}
 message FooResponse {}
 
+message FooClientMessage {}
+message FooServerMessage{}
+
 service TestService {
   rpc Foo(FooRequest) returns (FooResponse);
   rpc Bar(BarRequest) returns (BarResponse);
diff --git a/src/google/protobuf/unittest_custom_options.proto b/src/google/protobuf/unittest_custom_options.proto
index a610785f..e591d294 100644
--- a/src/google/protobuf/unittest_custom_options.proto
+++ b/src/google/protobuf/unittest_custom_options.proto
@@ -116,6 +116,12 @@ message CustomOptionFooRequest {
 message CustomOptionFooResponse {
 }
 
+message CustomOptionFooClientMessage {
+}
+
+message CustomOptionFooServerMessage {
+}
+
 service TestServiceWithCustomOptions {
   option (service_opt1) = -9876543210;
 
@@ -364,3 +370,18 @@ enum AggregateEnum {
   option (enumopt) = { s:'EnumAnnotation' };
   VALUE = 1 [(enumvalopt) = { s:'EnumValueAnnotation' }];
 }
+
+// Test custom options for nested type.
+message NestedOptionType {
+  message NestedMessage {
+    option (message_opt1) = 1001;
+    optional int32 nested_field = 1 [(field_opt1) = 1002];
+  }
+  enum NestedEnum {
+    option (enum_opt1) = 1003;
+    NESTED_ENUM_VALUE = 1 [(enum_value_opt1) = 1004];
+  }
+  extend google.protobuf.FileOptions {
+    optional int32 nested_extension = 7912573 [(field_opt2) = 1005];
+  }
+}
diff --git a/src/google/protobuf/unittest_import.proto b/src/google/protobuf/unittest_import.proto
index cd533ecd..c115b111 100644
--- a/src/google/protobuf/unittest_import.proto
+++ b/src/google/protobuf/unittest_import.proto
@@ -49,6 +49,9 @@ option java_package = "com.google.protobuf.test";
 // Do not set a java_outer_classname here to verify that Proto2 works without
 // one.
 
+// Test public import
+import public "google/protobuf/unittest_import_public.proto";
+
 message ImportMessage {
   optional int32 d = 1;
 }
diff --git a/src/google/protobuf/unittest_import_lite.proto b/src/google/protobuf/unittest_import_lite.proto
index ebaab5c0..81b117fe 100644
--- a/src/google/protobuf/unittest_import_lite.proto
+++ b/src/google/protobuf/unittest_import_lite.proto
@@ -38,6 +38,8 @@ option optimize_for = LITE_RUNTIME;
 
 option java_package = "com.google.protobuf";
 
+import public "google/protobuf/unittest_import_public_lite.proto";
+
 message ImportMessageLite {
   optional int32 d = 1;
 }
diff --git a/src/google/protobuf/unittest_import_public.proto b/src/google/protobuf/unittest_import_public.proto
new file mode 100644
index 00000000..ea5d1b13
--- /dev/null
+++ b/src/google/protobuf/unittest_import_public.proto
@@ -0,0 +1,40 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: liujisi@google.com (Pherl Liu)
+
+
+package protobuf_unittest_import;
+
+option java_package = "com.google.protobuf.test";
+
+message PublicImportMessage {
+  optional int32 e = 1;
+}
diff --git a/src/google/protobuf/unittest_import_public_lite.proto b/src/google/protobuf/unittest_import_public_lite.proto
new file mode 100644
index 00000000..d077563c
--- /dev/null
+++ b/src/google/protobuf/unittest_import_public_lite.proto
@@ -0,0 +1,42 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: liujisi@google.com (Pherl Liu)
+
+
+package protobuf_unittest_import;
+
+option optimize_for = LITE_RUNTIME;
+
+option java_package = "com.google.protobuf";
+
+message PublicImportMessageLite {
+  optional int32 e = 1;
+}
diff --git a/src/google/protobuf/unittest_lite.proto b/src/google/protobuf/unittest_lite.proto
index cca6b497..a1764aac 100644
--- a/src/google/protobuf/unittest_lite.proto
+++ b/src/google/protobuf/unittest_lite.proto
@@ -85,6 +85,12 @@ message TestAllTypesLite {
   optional string optional_string_piece = 24 [ctype=STRING_PIECE];
   optional string optional_cord = 25 [ctype=CORD];
 
+  // Defined in unittest_import_public.proto
+  optional protobuf_unittest_import.PublicImportMessageLite
+      optional_public_import_message = 26;
+
+  optional NestedMessage optional_lazy_message = 27 [lazy=true];
+
   // Repeated
   repeated    int32 repeated_int32    = 31;
   repeated    int64 repeated_int64    = 32;
@@ -118,6 +124,8 @@ message TestAllTypesLite {
   repeated string repeated_string_piece = 54 [ctype=STRING_PIECE];
   repeated string repeated_cord = 55 [ctype=CORD];
 
+  repeated NestedMessage repeated_lazy_message = 57 [lazy=true];
+
   // Singular with defaults
   optional    int32 default_int32    = 61 [default =  41    ];
   optional    int64 default_int64    = 62 [default =  42    ];
@@ -213,6 +221,12 @@ extend TestAllExtensionsLite {
       [ctype=STRING_PIECE];
   optional string optional_cord_extension_lite = 25 [ctype=CORD];
 
+  optional protobuf_unittest_import.PublicImportMessageLite
+    optional_public_import_message_extension_lite = 26;
+
+  optional TestAllTypesLite.NestedMessage
+    optional_lazy_message_extension_lite = 27 [lazy=true];
+
   // Repeated
   repeated    int32 repeated_int32_extension_lite    = 31;
   repeated    int64 repeated_int64_extension_lite    = 32;
@@ -249,6 +263,9 @@ extend TestAllExtensionsLite {
       [ctype=STRING_PIECE];
   repeated string repeated_cord_extension_lite = 55 [ctype=CORD];
 
+  repeated TestAllTypesLite.NestedMessage
+    repeated_lazy_message_extension_lite = 57 [lazy=true];
+
   // Singular with defaults
   optional    int32 default_int32_extension_lite    = 61 [default =  41    ];
   optional    int64 default_int64_extension_lite    = 62 [default =  42    ];
@@ -310,3 +327,34 @@ message TestNestedExtensionLite {
 message TestDeprecatedLite {
   optional int32 deprecated_field = 1 [deprecated = true];
 }
+
+// See the comments of the same type in unittest.proto.
+message TestParsingMergeLite {
+  message RepeatedFieldsGenerator {
+    repeated TestAllTypesLite field1 = 1;
+    repeated TestAllTypesLite field2 = 2;
+    repeated TestAllTypesLite field3 = 3;
+    repeated group Group1 = 10 {
+      optional TestAllTypesLite field1 = 11;
+    }
+    repeated group Group2 = 20 {
+      optional TestAllTypesLite field1 = 21;
+    }
+    repeated TestAllTypesLite ext1 = 1000;
+    repeated TestAllTypesLite ext2 = 1001;
+  }
+  required TestAllTypesLite required_all_types = 1;
+  optional TestAllTypesLite optional_all_types = 2;
+  repeated TestAllTypesLite repeated_all_types = 3;
+  optional group OptionalGroup = 10 {
+    optional TestAllTypesLite optional_group_all_types = 11;
+  }
+  repeated group RepeatedGroup = 20 {
+    optional TestAllTypesLite repeated_group_all_types = 21;
+  }
+  extensions 1000 to max;
+  extend TestParsingMergeLite {
+    optional TestAllTypesLite optional_ext = 1000;
+    repeated TestAllTypesLite repeated_ext = 1001;
+  }
+}
diff --git a/src/google/protobuf/unknown_field_set.cc b/src/google/protobuf/unknown_field_set.cc
index e1f8b838..841433d5 100644
--- a/src/google/protobuf/unknown_field_set.cc
+++ b/src/google/protobuf/unknown_field_set.cc
@@ -32,13 +32,14 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/unknown_field_set.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include <google/protobuf/wire_format.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -59,6 +60,14 @@ void UnknownFieldSet::ClearFallback() {
   fields_->clear();
 }
 
+void UnknownFieldSet::ClearAndFreeMemory() {
+  if (fields_ != NULL) {
+    Clear();
+    delete fields_;
+    fields_ = NULL;
+  }
+}
+
 void UnknownFieldSet::MergeFrom(const UnknownFieldSet& other) {
   for (int i = 0; i < other.field_count(); i++) {
     AddField(other.field(i));
@@ -73,8 +82,9 @@ int UnknownFieldSet::SpaceUsedExcludingSelf() const {
     const UnknownField& field = (*fields_)[i];
     switch (field.type()) {
       case UnknownField::TYPE_LENGTH_DELIMITED:
-        total_size += sizeof(*field.length_delimited_) +
-          internal::StringSpaceUsedExcludingSelf(*field.length_delimited_);
+        total_size += sizeof(*field.length_delimited_.string_value_) +
+                      internal::StringSpaceUsedExcludingSelf(
+                          *field.length_delimited_.string_value_);
         break;
       case UnknownField::TYPE_GROUP:
         total_size += field.group_->SpaceUsed();
@@ -122,11 +132,12 @@ string* UnknownFieldSet::AddLengthDelimited(int number) {
   UnknownField field;
   field.number_ = number;
   field.type_ = UnknownField::TYPE_LENGTH_DELIMITED;
-  field.length_delimited_ = new string;
+  field.length_delimited_.string_value_ = new string;
   fields_->push_back(field);
-  return field.length_delimited_;
+  return field.length_delimited_.string_value_;
 }
 
+
 UnknownFieldSet* UnknownFieldSet::AddGroup(int number) {
   if (fields_ == NULL) fields_ = new vector<UnknownField>;
   UnknownField field;
@@ -143,6 +154,39 @@ void UnknownFieldSet::AddField(const UnknownField& field) {
   fields_->back().DeepCopy();
 }
 
+void UnknownFieldSet::DeleteSubrange(int start, int num) {
+  GOOGLE_DCHECK(fields_ != NULL);
+  // Delete the specified fields.
+  for (int i = 0; i < num; ++i) {
+    (*fields_)[i + start].Delete();
+  }
+  // Slide down the remaining fields.
+  for (int i = start + num; i < fields_->size(); ++i) {
+    (*fields_)[i - num] = (*fields_)[i];
+  }
+  // Pop off the # of deleted fields.
+  for (int i = 0; i < num; ++i) {
+    fields_->pop_back();
+  }
+}
+
+void UnknownFieldSet::DeleteByNumber(int number) {
+  if (fields_ == NULL) return;
+  int left = 0;  // The number of fields left after deletion.
+  for (int i = 0; i < fields_->size(); ++i) {
+    UnknownField* field = &(*fields_)[i];
+    if (field->number() == number) {
+      field->Delete();
+    } else {
+      if (i != left) {
+        (*fields_)[left] = (*fields_)[i];
+      }
+      ++left;
+    }
+  }
+  fields_->resize(left);
+}
+
 bool UnknownFieldSet::MergeFromCodedStream(io::CodedInputStream* input) {
 
   UnknownFieldSet other;
@@ -174,7 +218,7 @@ bool UnknownFieldSet::ParseFromArray(const void* data, int size) {
 void UnknownField::Delete() {
   switch (type()) {
     case UnknownField::TYPE_LENGTH_DELIMITED:
-      delete length_delimited_;
+      delete length_delimited_.string_value_;
       break;
     case UnknownField::TYPE_GROUP:
       delete group_;
@@ -187,7 +231,8 @@ void UnknownField::Delete() {
 void UnknownField::DeepCopy() {
   switch (type()) {
     case UnknownField::TYPE_LENGTH_DELIMITED:
-      length_delimited_ = new string(*length_delimited_);
+      length_delimited_.string_value_ = new string(
+          *length_delimited_.string_value_);
       break;
     case UnknownField::TYPE_GROUP: {
       UnknownFieldSet* group = new UnknownFieldSet;
@@ -200,5 +245,22 @@ void UnknownField::DeepCopy() {
   }
 }
 
+
+void UnknownField::SerializeLengthDelimitedNoTag(
+    io::CodedOutputStream* output) const {
+  GOOGLE_DCHECK_EQ(TYPE_LENGTH_DELIMITED, type_);
+  const string& data = *length_delimited_.string_value_;
+  output->WriteVarint32(data.size());
+  output->WriteString(data);
+}
+
+uint8* UnknownField::SerializeLengthDelimitedNoTagToArray(uint8* target) const {
+  GOOGLE_DCHECK_EQ(TYPE_LENGTH_DELIMITED, type_);
+  const string& data = *length_delimited_.string_value_;
+  target = io::CodedOutputStream::WriteVarint32ToArray(data.size(), target);
+  target = io::CodedOutputStream::WriteStringToArray(data, target);
+  return target;
+}
+
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/unknown_field_set.h b/src/google/protobuf/unknown_field_set.h
index 84c2e2b6..825bba83 100644
--- a/src/google/protobuf/unknown_field_set.h
+++ b/src/google/protobuf/unknown_field_set.h
@@ -38,12 +38,24 @@
 #ifndef GOOGLE_PROTOBUF_UNKNOWN_FIELD_SET_H__
 #define GOOGLE_PROTOBUF_UNKNOWN_FIELD_SET_H__
 
+#include <assert.h>
 #include <string>
 #include <vector>
-#include <google/protobuf/repeated_field.h>
+#include <google/protobuf/stubs/common.h>
+// TODO(jasonh): some people seem to rely on protobufs to include this for them!
 
 namespace google {
 namespace protobuf {
+  namespace io {
+    class CodedInputStream;         // coded_stream.h
+    class CodedOutputStream;        // coded_stream.h
+    class ZeroCopyInputStream;      // zero_copy_stream.h
+  }
+  namespace internal {
+    class WireFormat;               // wire_format.h
+    class UnknownFieldSetFieldSkipperUsingCord;
+                                    // extension_set_heavy.cc
+  }
 
 class Message;                      // message.h
 class UnknownField;                 // below
@@ -68,6 +80,9 @@ class LIBPROTOBUF_EXPORT UnknownFieldSet {
   // Remove all fields.
   inline void Clear();
 
+  // Remove all fields and deallocate internal data objects
+  void ClearAndFreeMemory();
+
   // Is this set empty?
   inline bool empty() const;
 
@@ -107,6 +122,15 @@ class LIBPROTOBUF_EXPORT UnknownFieldSet {
   // Adds an unknown field from another set.
   void AddField(const UnknownField& field);
 
+  // Delete fields with indices in the range [start .. start+num-1].
+  // Caution: implementation moves all fields with indices [start+num .. ].
+  void DeleteSubrange(int start, int num);
+
+  // Delete all fields with a specific field number. The order of left fields
+  // is preserved.
+  // Caution: implementation moves all fields after the first deleted field.
+  void DeleteByNumber(int number);
+
   // Parsing helpers -------------------------------------------------
   // These work exactly like the similarly-named methods of Message.
 
@@ -119,6 +143,7 @@ class LIBPROTOBUF_EXPORT UnknownFieldSet {
   }
 
  private:
+
   void ClearFallback();
 
   vector<UnknownField>* fields_;
@@ -159,6 +184,15 @@ class LIBPROTOBUF_EXPORT UnknownField {
   inline string* mutable_length_delimited();
   inline UnknownFieldSet* mutable_group();
 
+  // Serialization API.
+  // These methods can take advantage of the underlying implementation and may
+  // archieve a better performance than using getters to retrieve the data and
+  // do the serialization yourself.
+  void SerializeLengthDelimitedNoTag(io::CodedOutputStream* output) const;
+  uint8* SerializeLengthDelimitedNoTagToArray(uint8* target) const;
+
+  inline int GetLengthDelimitedSize() const;
+
  private:
   friend class UnknownFieldSet;
 
@@ -168,13 +202,16 @@ class LIBPROTOBUF_EXPORT UnknownField {
   // Make a deep copy of any pointers in this UnknownField.
   void DeepCopy();
 
+
   unsigned int number_ : 29;
   unsigned int type_   : 3;
   union {
     uint64 varint_;
     uint32 fixed32_;
     uint64 fixed64_;
-    string* length_delimited_;
+    mutable union {
+      string* string_value_;
+    } length_delimited_;
     UnknownFieldSet* group_;
   };
 };
@@ -211,57 +248,63 @@ inline void UnknownFieldSet::AddLengthDelimited(
   AddLengthDelimited(number)->assign(value);
 }
 
+
 inline int UnknownField::number() const { return number_; }
 inline UnknownField::Type UnknownField::type() const {
   return static_cast<Type>(type_);
 }
 
 inline uint64 UnknownField::varint () const {
-  GOOGLE_DCHECK_EQ(type_, TYPE_VARINT);
+  assert(type_ == TYPE_VARINT);
   return varint_;
 }
 inline uint32 UnknownField::fixed32() const {
-  GOOGLE_DCHECK_EQ(type_, TYPE_FIXED32);
+  assert(type_ == TYPE_FIXED32);
   return fixed32_;
 }
 inline uint64 UnknownField::fixed64() const {
-  GOOGLE_DCHECK_EQ(type_, TYPE_FIXED64);
+  assert(type_ == TYPE_FIXED64);
   return fixed64_;
 }
 inline const string& UnknownField::length_delimited() const {
-  GOOGLE_DCHECK_EQ(type_, TYPE_LENGTH_DELIMITED);
-  return *length_delimited_;
+  assert(type_ == TYPE_LENGTH_DELIMITED);
+  return *length_delimited_.string_value_;
 }
 inline const UnknownFieldSet& UnknownField::group() const {
-  GOOGLE_DCHECK_EQ(type_, TYPE_GROUP);
+  assert(type_ == TYPE_GROUP);
   return *group_;
 }
 
 inline void UnknownField::set_varint(uint64 value) {
-  GOOGLE_DCHECK_EQ(type_, TYPE_VARINT);
+  assert(type_ == TYPE_VARINT);
   varint_ = value;
 }
 inline void UnknownField::set_fixed32(uint32 value) {
-  GOOGLE_DCHECK_EQ(type_, TYPE_FIXED32);
+  assert(type_ == TYPE_FIXED32);
   fixed32_ = value;
 }
 inline void UnknownField::set_fixed64(uint64 value) {
-  GOOGLE_DCHECK_EQ(type_, TYPE_FIXED64);
+  assert(type_ == TYPE_FIXED64);
   fixed64_ = value;
 }
 inline void UnknownField::set_length_delimited(const string& value) {
-  GOOGLE_DCHECK_EQ(type_, TYPE_LENGTH_DELIMITED);
-  length_delimited_->assign(value);
+  assert(type_ == TYPE_LENGTH_DELIMITED);
+  length_delimited_.string_value_->assign(value);
 }
 inline string* UnknownField::mutable_length_delimited() {
-  GOOGLE_DCHECK_EQ(type_, TYPE_LENGTH_DELIMITED);
-  return length_delimited_;
+  assert(type_ == TYPE_LENGTH_DELIMITED);
+  return length_delimited_.string_value_;
 }
 inline UnknownFieldSet* UnknownField::mutable_group() {
-  GOOGLE_DCHECK_EQ(type_, TYPE_GROUP);
+  assert(type_ == TYPE_GROUP);
   return group_;
 }
 
+inline int UnknownField::GetLengthDelimitedSize() const {
+  GOOGLE_DCHECK_EQ(TYPE_LENGTH_DELIMITED, type_);
+  return length_delimited_.string_value_->size();
+}
+
 }  // namespace protobuf
 
 }  // namespace google
diff --git a/src/google/protobuf/unknown_field_set_unittest.cc b/src/google/protobuf/unknown_field_set_unittest.cc
index 1235c9ee..c6b8769f 100644
--- a/src/google/protobuf/unknown_field_set_unittest.cc
+++ b/src/google/protobuf/unknown_field_set_unittest.cc
@@ -46,15 +46,13 @@
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
 
 using internal::WireFormat;
 
-namespace {
-
 class UnknownFieldSetTest : public testing::Test {
  protected:
   virtual void SetUp() {
@@ -107,6 +105,8 @@ class UnknownFieldSetTest : public testing::Test {
   UnknownFieldSet* unknown_fields_;
 };
 
+namespace {
+
 TEST_F(UnknownFieldSetTest, AllFieldsPresent) {
   // All fields of TestAllTypes should be present, in numeric order (because
   // that's the order we parsed them in).  Fields that are not valid field
@@ -297,12 +297,21 @@ TEST_F(UnknownFieldSetTest, MergeFrom) {
     destination.DebugString());
 }
 
+
 TEST_F(UnknownFieldSetTest, Clear) {
   // Clear the set.
   empty_message_.Clear();
   EXPECT_EQ(0, unknown_fields_->field_count());
 }
 
+TEST_F(UnknownFieldSetTest, ClearAndFreeMemory) {
+  EXPECT_GT(unknown_fields_->field_count(), 0);
+  unknown_fields_->ClearAndFreeMemory();
+  EXPECT_EQ(0, unknown_fields_->field_count());
+  unknown_fields_->AddVarint(123456, 654321);
+  EXPECT_EQ(1, unknown_fields_->field_count());
+}
+
 TEST_F(UnknownFieldSetTest, ParseKnownAndUnknown) {
   // Test mixing known and unknown fields when parsing.
 
@@ -498,6 +507,7 @@ TEST_F(UnknownFieldSetTest, SpaceUsed) {
   EXPECT_LT(base_size, empty_message.SpaceUsed());
 }
 
+
 TEST_F(UnknownFieldSetTest, Empty) {
   UnknownFieldSet unknown_fields;
   EXPECT_TRUE(unknown_fields.empty());
@@ -507,6 +517,78 @@ TEST_F(UnknownFieldSetTest, Empty) {
   EXPECT_TRUE(unknown_fields.empty());
 }
 
+TEST_F(UnknownFieldSetTest, DeleteSubrange) {
+  // Exhaustively test the deletion of every possible subrange in arrays of all
+  // sizes from 0 through 9.
+  for (int size = 0; size < 10; ++size) {
+    for (int num = 0; num <= size; ++num) {
+      for (int start = 0; start < size - num; ++start) {
+        // Create a set with "size" fields.
+        UnknownFieldSet unknown;
+        for (int i = 0; i < size; ++i) {
+          unknown.AddFixed32(i, i);
+        }
+        // Delete the specified subrange.
+        unknown.DeleteSubrange(start, num);
+        // Make sure the resulting field values are still correct.
+        EXPECT_EQ(size - num, unknown.field_count());
+        for (int i = 0; i < unknown.field_count(); ++i) {
+          if (i < start) {
+            EXPECT_EQ(i, unknown.field(i).fixed32());
+          } else {
+            EXPECT_EQ(i + num, unknown.field(i).fixed32());
+          }
+        }
+      }
+    }
+  }
+}
+
+void CheckDeleteByNumber(const vector<int>& field_numbers, int deleted_number,
+                        const vector<int>& expected_field_nubmers) {
+  UnknownFieldSet unknown_fields;
+  for (int i = 0; i < field_numbers.size(); ++i) {
+    unknown_fields.AddFixed32(field_numbers[i], i);
+  }
+  unknown_fields.DeleteByNumber(deleted_number);
+  ASSERT_EQ(expected_field_nubmers.size(), unknown_fields.field_count());
+  for (int i = 0; i < expected_field_nubmers.size(); ++i) {
+    EXPECT_EQ(expected_field_nubmers[i],
+              unknown_fields.field(i).number());
+  }
+}
+
+#define MAKE_VECTOR(x) vector<int>(x, x + GOOGLE_ARRAYSIZE(x))
+TEST_F(UnknownFieldSetTest, DeleteByNumber) {
+  CheckDeleteByNumber(vector<int>(), 1, vector<int>());
+  static const int kTestFieldNumbers1[] = {1, 2, 3};
+  static const int kFieldNumberToDelete1 = 1;
+  static const int kExpectedFieldNumbers1[] = {2, 3};
+  CheckDeleteByNumber(MAKE_VECTOR(kTestFieldNumbers1), kFieldNumberToDelete1,
+                      MAKE_VECTOR(kExpectedFieldNumbers1));
+  static const int kTestFieldNumbers2[] = {1, 2, 3};
+  static const int kFieldNumberToDelete2 = 2;
+  static const int kExpectedFieldNumbers2[] = {1, 3};
+  CheckDeleteByNumber(MAKE_VECTOR(kTestFieldNumbers2), kFieldNumberToDelete2,
+                      MAKE_VECTOR(kExpectedFieldNumbers2));
+  static const int kTestFieldNumbers3[] = {1, 2, 3};
+  static const int kFieldNumberToDelete3 = 3;
+  static const int kExpectedFieldNumbers3[] = {1, 2};
+  CheckDeleteByNumber(MAKE_VECTOR(kTestFieldNumbers3), kFieldNumberToDelete3,
+                      MAKE_VECTOR(kExpectedFieldNumbers3));
+  static const int kTestFieldNumbers4[] = {1, 2, 1, 4, 1};
+  static const int kFieldNumberToDelete4 = 1;
+  static const int kExpectedFieldNumbers4[] = {2, 4};
+  CheckDeleteByNumber(MAKE_VECTOR(kTestFieldNumbers4), kFieldNumberToDelete4,
+                      MAKE_VECTOR(kExpectedFieldNumbers4));
+  static const int kTestFieldNumbers5[] = {1, 2, 3, 4, 5};
+  static const int kFieldNumberToDelete5 = 6;
+  static const int kExpectedFieldNumbers5[] = {1, 2, 3, 4, 5};
+  CheckDeleteByNumber(MAKE_VECTOR(kTestFieldNumbers5), kFieldNumberToDelete5,
+                      MAKE_VECTOR(kExpectedFieldNumbers5));
+}
+#undef MAKE_VECTOR
 }  // namespace
+
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/wire_format.cc b/src/google/protobuf/wire_format.cc
index 831a5794..ead763b1 100644
--- a/src/google/protobuf/wire_format.cc
+++ b/src/google/protobuf/wire_format.cc
@@ -48,12 +48,11 @@
 #include <google/protobuf/unknown_field_set.h>
 
 
+
 namespace google {
 namespace protobuf {
 namespace internal {
 
-using internal::WireFormatLite;
-
 namespace {
 
 // This function turns out to be convenient when using some macros later.
@@ -239,8 +238,6 @@ void WireFormat::SerializeUnknownMessageSetItems(
     // The only unknown fields that are allowed to exist in a MessageSet are
     // messages, which are length-delimited.
     if (field.type() == UnknownField::TYPE_LENGTH_DELIMITED) {
-      const string& data = field.length_delimited();
-
       // Start group.
       output->WriteVarint32(WireFormatLite::kMessageSetItemStartTag);
 
@@ -250,8 +247,7 @@ void WireFormat::SerializeUnknownMessageSetItems(
 
       // Write message.
       output->WriteVarint32(WireFormatLite::kMessageSetMessageTag);
-      output->WriteVarint32(data.size());
-      output->WriteString(data);
+      field.SerializeLengthDelimitedNoTag(output);
 
       // End group.
       output->WriteVarint32(WireFormatLite::kMessageSetItemEndTag);
@@ -268,8 +264,6 @@ uint8* WireFormat::SerializeUnknownMessageSetItemsToArray(
     // The only unknown fields that are allowed to exist in a MessageSet are
     // messages, which are length-delimited.
     if (field.type() == UnknownField::TYPE_LENGTH_DELIMITED) {
-      const string& data = field.length_delimited();
-
       // Start group.
       target = io::CodedOutputStream::WriteTagToArray(
           WireFormatLite::kMessageSetItemStartTag, target);
@@ -283,8 +277,7 @@ uint8* WireFormat::SerializeUnknownMessageSetItemsToArray(
       // Write message.
       target = io::CodedOutputStream::WriteTagToArray(
           WireFormatLite::kMessageSetMessageTag, target);
-      target = io::CodedOutputStream::WriteVarint32ToArray(data.size(), target);
-      target = io::CodedOutputStream::WriteStringToArray(data, target);
+      target = field.SerializeLengthDelimitedNoTagToArray(target);
 
       // End group.
       target = io::CodedOutputStream::WriteTagToArray(
@@ -354,9 +347,10 @@ int WireFormat::ComputeUnknownMessageSetItemsSize(
     if (field.type() == UnknownField::TYPE_LENGTH_DELIMITED) {
       size += WireFormatLite::kMessageSetItemTagsSize;
       size += io::CodedOutputStream::VarintSize32(field.number());
-      size += io::CodedOutputStream::VarintSize32(
-        field.length_delimited().size());
-      size += field.length_delimited().size();
+
+      int field_size = field.GetLengthDelimitedSize();
+      size += io::CodedOutputStream::VarintSize32(field_size);
+      size += field_size;
     }
   }
 
@@ -642,10 +636,7 @@ bool WireFormat::ParseAndMergeMessageSetItem(
   const FieldDescriptor* field = NULL;
 
   // If we see message data before the type_id, we'll append it to this so
-  // we can parse it later.  This will probably never happen in practice,
-  // as no MessageSet encoder I know of writes the message before the type ID.
-  // But, it's technically valid so we should allow it.
-  // TODO(kenton):  Use a Cord instead?  Do I care?
+  // we can parse it later.
   string message_data;
 
   while (true) {
@@ -683,7 +674,10 @@ bool WireFormat::ParseAndMergeMessageSetItem(
           uint32 length;
           if (!input->ReadVarint32(&length)) return false;
           if (!input->ReadString(&temp, length)) return false;
-          message_data.append(temp);
+          io::StringOutputStream output_stream(&message_data);
+          io::CodedOutputStream coded_output(&output_stream);
+          coded_output.WriteVarint32(length);
+          coded_output.WriteString(temp);
         } else {
           // Already saw type_id, so we can parse this directly.
           if (!ParseAndMergeField(fake_tag, field, message, input)) {
@@ -1056,10 +1050,10 @@ void WireFormat::VerifyUTF8StringFallback(const char* data,
         break;
       // no default case: have the compiler warn if a case is not covered.
     }
-    GOOGLE_LOG(ERROR) << "Encountered string containing invalid UTF-8 data while "
+    GOOGLE_LOG(ERROR) << "String field contains invalid UTF-8 data when "
                << operation_str
-               << " protocol buffer. Strings must contain only UTF-8; "
-                  "use the 'bytes' type for raw bytes.";
+               << " a protocol buffer. Use the 'bytes' type if you intend to "
+                  "send raw bytes.";
   }
 }
 
diff --git a/src/google/protobuf/wire_format.h b/src/google/protobuf/wire_format.h
index c7539250..6c3f44a4 100644
--- a/src/google/protobuf/wire_format.h
+++ b/src/google/protobuf/wire_format.h
@@ -40,6 +40,7 @@
 #define GOOGLE_PROTOBUF_WIRE_FORMAT_H__
 
 #include <string>
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/message.h>
@@ -253,7 +254,7 @@ class LIBPROTOBUF_EXPORT UnknownFieldSetFieldSkipper : public FieldSkipper {
   virtual bool SkipMessage(io::CodedInputStream* input);
   virtual void SkipUnknownEnum(int field_number, int value);
 
- private:
+ protected:
   UnknownFieldSet* unknown_fields_;
 };
 
diff --git a/src/google/protobuf/wire_format_lite.cc b/src/google/protobuf/wire_format_lite.cc
index dbd29b47..738fc421 100644
--- a/src/google/protobuf/wire_format_lite.cc
+++ b/src/google/protobuf/wire_format_lite.cc
@@ -40,7 +40,7 @@
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/io/coded_stream_inl.h>
 #include <google/protobuf/io/zero_copy_stream.h>
-#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
 
 namespace google {
 namespace protobuf {
@@ -281,12 +281,14 @@ void WireFormatLite::WriteString(int field_number, const string& value,
                                  io::CodedOutputStream* output) {
   // String is for UTF-8 text only
   WriteTag(field_number, WIRETYPE_LENGTH_DELIMITED, output);
+  GOOGLE_CHECK(value.size() <= kint32max);
   output->WriteVarint32(value.size());
   output->WriteString(value);
 }
 void WireFormatLite::WriteBytes(int field_number, const string& value,
                                 io::CodedOutputStream* output) {
   WriteTag(field_number, WIRETYPE_LENGTH_DELIMITED, output);
+  GOOGLE_CHECK(value.size() <= kint32max);
   output->WriteVarint32(value.size());
   output->WriteString(value);
 }
diff --git a/src/google/protobuf/wire_format_lite.h b/src/google/protobuf/wire_format_lite.h
index e3d5b2d8..cb4fc918 100644
--- a/src/google/protobuf/wire_format_lite.h
+++ b/src/google/protobuf/wire_format_lite.h
@@ -41,16 +41,14 @@
 #define GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__
 
 #include <string>
+#include <google/protobuf/stubs/common.h>
 #include <google/protobuf/message_lite.h>
+#include <google/protobuf/io/coded_stream.h>  // for CodedOutputStream::Varint32Size
 
 namespace google {
 
 namespace protobuf {
   template <typename T> class RepeatedField;  // repeated_field.h
-  namespace io {
-    class CodedInputStream;             // coded_stream.h
-    class CodedOutputStream;            // coded_stream.h
-  }
 }
 
 namespace protobuf {
@@ -477,6 +475,10 @@ class LIBPROTOBUF_EXPORT WireFormatLite {
   template<typename MessageType>
   static inline int MessageSizeNoVirtual(const MessageType& value);
 
+  // Given the length of data, calculate the byte size of the data on the
+  // wire if we encode the data as a length delimited field.
+  static inline int LengthDelimitedSize(int length);
+
  private:
   // A helper method for the repeated primitive reader. This method has
   // optimizations for primitive types that have fixed size on the wire, and
diff --git a/src/google/protobuf/wire_format_lite_inl.h b/src/google/protobuf/wire_format_lite_inl.h
index 103b0bd0..0f97386d 100644
--- a/src/google/protobuf/wire_format_lite_inl.h
+++ b/src/google/protobuf/wire_format_lite_inl.h
@@ -41,7 +41,6 @@
 #include <google/protobuf/message_lite.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/wire_format_lite.h>
-#include <google/protobuf/generated_message_util.h>
 #include <google/protobuf/io/coded_stream.h>
 
 
@@ -749,8 +748,7 @@ inline int WireFormatLite::GroupSize(const MessageLite& value) {
   return value.ByteSize();
 }
 inline int WireFormatLite::MessageSize(const MessageLite& value) {
-  int size = value.ByteSize();
-  return io::CodedOutputStream::VarintSize32(size) + size;
+  return LengthDelimitedSize(value.ByteSize());
 }
 
 // See comment on ReadGroupNoVirtual to understand the need for this template
@@ -763,8 +761,12 @@ inline int WireFormatLite::GroupSizeNoVirtual(
 template<typename MessageType_WorkAroundCppLookupDefect>
 inline int WireFormatLite::MessageSizeNoVirtual(
     const MessageType_WorkAroundCppLookupDefect& value) {
-  int size = value.MessageType_WorkAroundCppLookupDefect::ByteSize();
-  return io::CodedOutputStream::VarintSize32(size) + size;
+  return LengthDelimitedSize(
+      value.MessageType_WorkAroundCppLookupDefect::ByteSize());
+}
+
+inline int WireFormatLite::LengthDelimitedSize(int length) {
+  return io::CodedOutputStream::VarintSize32(length) + length;
 }
 
 }  // namespace internal
diff --git a/src/google/protobuf/wire_format_unittest.cc b/src/google/protobuf/wire_format_unittest.cc
index 867970c4..98c066a2 100644
--- a/src/google/protobuf/wire_format_unittest.cc
+++ b/src/google/protobuf/wire_format_unittest.cc
@@ -44,7 +44,7 @@
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
-#include <google/protobuf/stubs/stl_util-inl.h>
+#include <google/protobuf/stubs/stl_util.h>
 
 namespace google {
 namespace protobuf {
@@ -480,6 +480,54 @@ TEST(WireFormatTest, ParseMessageSet) {
   EXPECT_EQ(message_set.DebugString(), dynamic_message_set.DebugString());
 }
 
+TEST(WireFormatTest, ParseMessageSetWithReverseTagOrder) {
+  string data;
+  {
+    unittest::TestMessageSetExtension1 message;
+    message.set_i(123);
+    // Build a MessageSet manually with its message content put before its
+    // type_id.
+    io::StringOutputStream output_stream(&data);
+    io::CodedOutputStream coded_output(&output_stream);
+    coded_output.WriteTag(WireFormatLite::kMessageSetItemStartTag);
+    // Write the message content first.
+    WireFormatLite::WriteTag(WireFormatLite::kMessageSetMessageNumber,
+                             WireFormatLite::WIRETYPE_LENGTH_DELIMITED,
+                             &coded_output);
+    coded_output.WriteVarint32(message.ByteSize());
+    message.SerializeWithCachedSizes(&coded_output);
+    // Write the type id.
+    uint32_t type_id = message.GetDescriptor()->extension(0)->number();
+    WireFormatLite::WriteUInt32(WireFormatLite::kMessageSetTypeIdNumber,
+                                type_id, &coded_output);
+    coded_output.WriteTag(WireFormatLite::kMessageSetItemEndTag);
+  }
+  {
+    unittest::TestMessageSet message_set;
+    ASSERT_TRUE(message_set.ParseFromString(data));
+
+    EXPECT_EQ(123, message_set.GetExtension(
+        unittest::TestMessageSetExtension1::message_set_extension).i());
+  }
+  {
+    // Test parse the message via Reflection.
+    unittest::TestMessageSet message_set;
+    io::CodedInputStream input(
+        reinterpret_cast<const uint8*>(data.data()), data.size());
+    EXPECT_TRUE(WireFormat::ParseAndMergePartial(&input, &message_set));
+    EXPECT_TRUE(input.ConsumedEntireMessage());
+
+    EXPECT_EQ(123, message_set.GetExtension(
+        unittest::TestMessageSetExtension1::message_set_extension).i());
+  }
+}
+
+TEST(WireFormatTest, ParseBrokenMessageSet) {
+  unittest::TestMessageSet message_set;
+  string input("goodbye");  // Invalid wire format data.
+  EXPECT_FALSE(message_set.ParseFromString(input));
+}
+
 TEST(WireFormatTest, RecursionLimit) {
   unittest::TestRecursiveMessage message;
   message.mutable_a()->mutable_a()->mutable_a()->mutable_a()->set_i(1);
@@ -800,6 +848,10 @@ bool ReadMessage(const string &wire_buffer, T *message) {
   return message->ParseFromArray(wire_buffer.data(), wire_buffer.size());
 }
 
+bool StartsWith(const string& s, const string& prefix) {
+  return s.substr(0, prefix.length()) == prefix;
+}
+
 TEST(Utf8ValidationTest, WriteInvalidUTF8String) {
   string wire_buffer;
   protobuf_unittest::OneString input;
@@ -811,11 +863,10 @@ TEST(Utf8ValidationTest, WriteInvalidUTF8String) {
   }
 #ifdef GOOGLE_PROTOBUF_UTF8_VALIDATION_ENABLED
   ASSERT_EQ(1, errors.size());
-  EXPECT_EQ("Encountered string containing invalid UTF-8 data while "
-            "serializing protocol buffer. Strings must contain only UTF-8; "
-            "use the 'bytes' type for raw bytes.",
-            errors[0]);
-
+  EXPECT_TRUE(StartsWith(errors[0],
+                         "String field contains invalid UTF-8 data when "
+                         "serializing a protocol buffer. Use the "
+                         "'bytes' type if you intend to send raw bytes."));
 #else
   ASSERT_EQ(0, errors.size());
 #endif  // GOOGLE_PROTOBUF_UTF8_VALIDATION_ENABLED
@@ -834,10 +885,10 @@ TEST(Utf8ValidationTest, ReadInvalidUTF8String) {
   }
 #ifdef GOOGLE_PROTOBUF_UTF8_VALIDATION_ENABLED
   ASSERT_EQ(1, errors.size());
-  EXPECT_EQ("Encountered string containing invalid UTF-8 data while "
-            "parsing protocol buffer. Strings must contain only UTF-8; "
-            "use the 'bytes' type for raw bytes.",
-            errors[0]);
+  EXPECT_TRUE(StartsWith(errors[0],
+                         "String field contains invalid UTF-8 data when "
+                         "parsing a protocol buffer. Use the "
+                         "'bytes' type if you intend to send raw bytes."));
 
 #else
   ASSERT_EQ(0, errors.size());
@@ -899,6 +950,28 @@ TEST(Utf8ValidationTest, ReadArbitraryBytes) {
   EXPECT_EQ(input.data(), output.data());
 }
 
+TEST(Utf8ValidationTest, ParseRepeatedString) {
+  protobuf_unittest::MoreBytes input;
+  input.add_data(kValidUTF8String);
+  input.add_data(kInvalidUTF8String);
+  input.add_data(kInvalidUTF8String);
+  string wire_buffer = input.SerializeAsString();
+
+  protobuf_unittest::MoreString output;
+  vector<string> errors;
+  {
+    ScopedMemoryLog log;
+    ReadMessage(wire_buffer, &output);
+    errors = log.GetMessages(ERROR);
+  }
+#ifdef GOOGLE_PROTOBUF_UTF8_VALIDATION_ENABLED
+  ASSERT_EQ(2, errors.size());
+#else
+  ASSERT_EQ(0, errors.size());
+#endif  // GOOGLE_PROTOBUF_UTF8_VALIDATION_ENABLED
+  EXPECT_EQ(wire_buffer, output.SerializeAsString());
+}
+
 }  // namespace
 }  // namespace internal
 }  // namespace protobuf