Down-integrate from internal branch

21 files changed, 1296 insertions, 299 deletions

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;