Integrate changes from internal code.

protoc
* Enum values may now have custom options, using syntax similar to field
  options.
* Fixed bug where .proto files which use custom options but don't actually
  define them (i.e. they import another .proto file defining the options)
  had to explicitly import descriptor.proto.
* Adjacent string literals in .proto files will now be concatenated, like in
  C.

C++
* Generated message classes now have a Swap() method which efficiently swaps
  the contents of two objects.
* All message classes now have a SpaceUsed() method which returns an estimate
  of the number of bytes of allocated memory currently owned by the object.
  This is particularly useful when you are reusing a single message object
  to improve performance but want to make sure it doesn't bloat up too large.
* New method Message::SerializeAsString() returns a string containing the
  serialized data.  May be more convenient than calling
  SerializeToString(string*).
* In debug mode, log error messages when string-type fields are found to
  contain bytes that are not valid UTF-8.
* Fixed bug where a message with multiple extension ranges couldn't parse
  extensions.
* Fixed bug where MergeFrom(const Message&) didn't do anything if invoked on
  a message that contained no fields (but possibly contained extensions).
* Fixed ShortDebugString() to not be O(n^2).  Durr.
* Fixed crash in TextFormat parsing if the first token in the input caused a
  tokenization error.

Java
* New overload of mergeFrom() which parses a slice of a byte array instead
  of the whole thing.
* New method ByteString.asReadOnlyByteBuffer() does what it sounds like.
* Improved performance of isInitialized() when optimizing for code size.

Python
* Corrected ListFields() signature in Message base class to match what
  subclasses actually implement.
* Some minor refactoring.

12 files changed, 234 insertions, 28 deletions

diff --git a/src/google/protobuf/compiler/cpp/cpp_enum_field.cc b/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
index 6f0bc270..c998f20b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_enum_field.cc
@@ -111,6 +111,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void EnumFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "std::swap($name$_, other->$name$_);\n");
+}
+
+void EnumFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   printer->Print(variables_, ",\n$name$_($default$)");
 }
@@ -201,6 +206,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void RepeatedEnumFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "$name$_.Swap(&other->$name$_);\n");
+}
+
+void RepeatedEnumFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   // Not needed for repeated fields.
 }
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum_field.h b/src/google/protobuf/compiler/cpp/cpp_enum_field.h
index 6bcd0b1b..f67b7ac0 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_enum_field.h
@@ -55,6 +55,7 @@ class EnumFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
@@ -78,6 +79,7 @@ class RepeatedEnumFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/cpp/cpp_field.h b/src/google/protobuf/compiler/cpp/cpp_field.h
index 925483a7..e5f8258f 100644
--- a/src/google/protobuf/compiler/cpp/cpp_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_field.h
@@ -87,6 +87,13 @@ class FieldGenerator {
   // GenerateMergeFrom method.
   virtual void GenerateMergingCode(io::Printer* printer) const = 0;
 
+  // Generate lines of code (statements, not declarations) which swaps
+  // this field and the corresponding field of another message, which
+  // is stored in the generated code variable "other". This is used to
+  // define the Swap method. Details of usage can be found in
+  // message.cc under the GenerateSwap method.
+  virtual void GenerateSwappingCode(io::Printer* printer) const = 0;
+
   // Generate any initializers needed for the private members declared by
   // GeneratePrivateMembers().  These go into the message class's
   // constructor's initializer list.  For each initializer, this method
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.cc b/src/google/protobuf/compiler/cpp/cpp_message.cc
index f3fd48d1..eacceeaf 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message.cc
@@ -416,7 +416,8 @@ GenerateClassDefinition(io::Printer* printer) {
     "}\n"
     "\n"
     "static const ::google::protobuf::Descriptor* descriptor();\n"
-    "static const $classname$& default_instance();"
+    "static const $classname$& default_instance();\n"
+    "void Swap($classname$* other);\n"
     "\n"
     "// implements Message ----------------------------------------------\n"
     "\n"
@@ -617,7 +618,8 @@ GenerateDescriptorInitializer(io::Printer* printer, int index) {
       "    -1,\n");
   }
   printer->Print(vars,
-    "    ::google::protobuf::DescriptorPool::generated_pool());\n");
+    "    ::google::protobuf::DescriptorPool::generated_pool(),\n"
+    "    sizeof($classname$));\n");
 
   // Handle nested types.
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
@@ -693,6 +695,9 @@ GenerateClassMethods(io::Printer* printer) {
     GenerateCopyFrom(printer);
     printer->Print("\n");
 
+    GenerateSwap(printer);
+    printer->Print("\n");
+
     GenerateIsInitialized(printer);
     printer->Print("\n");
   }
@@ -947,6 +952,37 @@ GenerateClear(io::Printer* printer) {
 }
 
 void MessageGenerator::
+GenerateSwap(io::Printer* printer) {
+  // Generate the Swap member function.
+  printer->Print("void $classname$::Swap($classname$* other) {\n",
+                 "classname", classname_);
+  printer->Indent();
+  printer->Print("if (other != this) {\n");
+  printer->Indent();
+
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldDescriptor* field = descriptor_->field(i);
+    field_generators_.get(field).GenerateSwappingCode(printer);
+  }
+
+  for (int i = 0; i < (descriptor_->field_count() + 31) / 32; ++i) {
+    printer->Print("std::swap(_has_bits_[$i$], other->_has_bits_[$i$]);\n",
+                   "i", SimpleItoa(i));
+  }
+
+  printer->Print("_unknown_fields_.Swap(&other->_unknown_fields_);\n");
+  printer->Print("std::swap(_cached_size_, other->_cached_size_);\n");
+  if (descriptor_->extension_range_count() > 0) {
+    printer->Print("_extensions_.Swap(&other->_extensions_);\n");
+  }
+
+  printer->Outdent();
+  printer->Print("}\n");
+  printer->Outdent();
+  printer->Print("}\n");
+}
+
+void MessageGenerator::
 GenerateMergeFrom(io::Printer* printer) {
   // Generate the generalized MergeFrom (aka that which takes in the Message
   // base class as a parameter).
@@ -956,22 +992,20 @@ GenerateMergeFrom(io::Printer* printer) {
     "classname", classname_);
   printer->Indent();
 
-  if (descriptor_->field_count() > 0) {
-    // Cast the message to the proper type. If we find that the message is
-    // *not* of the proper type, we can still call Merge via the reflection
-    // system, as the GOOGLE_CHECK above ensured that we have the same descriptor
-    // for each message.
-    printer->Print(
-      "const $classname$* source =\n"
-      "  ::google::protobuf::internal::dynamic_cast_if_available<const $classname$*>(\n"
-      "    &from);\n"
-      "if (source == NULL) {\n"
-      "  ::google::protobuf::internal::ReflectionOps::Merge(from, this);\n"
-      "} else {\n"
-      "  MergeFrom(*source);\n"
-      "}\n",
-      "classname", classname_);
-  }
+  // Cast the message to the proper type. If we find that the message is
+  // *not* of the proper type, we can still call Merge via the reflection
+  // system, as the GOOGLE_CHECK above ensured that we have the same descriptor
+  // for each message.
+  printer->Print(
+    "const $classname$* source =\n"
+    "  ::google::protobuf::internal::dynamic_cast_if_available<const $classname$*>(\n"
+    "    &from);\n"
+    "if (source == NULL) {\n"
+    "  ::google::protobuf::internal::ReflectionOps::Merge(from, this);\n"
+    "} else {\n"
+    "  MergeFrom(*source);\n"
+    "}\n",
+    "classname", classname_);
 
   printer->Outdent();
   printer->Print("}\n\n");
@@ -1199,7 +1233,7 @@ GenerateMergeFromCodedStream(io::Printer* printer) {
     for (int i = 0; i < descriptor_->extension_range_count(); i++) {
       const Descriptor::ExtensionRange* range =
         descriptor_->extension_range(i);
-      if (i > 0) printer->Print(" &&\n    ");
+      if (i > 0) printer->Print(" ||\n    ");
 
       uint32 start_tag = WireFormat::MakeTag(
         range->start, static_cast<WireFormat::WireType>(0));
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.h b/src/google/protobuf/compiler/cpp/cpp_message.h
index 037ddd85..d6669a34 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.h
+++ b/src/google/protobuf/compiler/cpp/cpp_message.h
@@ -115,6 +115,7 @@ class MessageGenerator {
   void GenerateByteSize(io::Printer* printer);
   void GenerateMergeFrom(io::Printer* printer);
   void GenerateCopyFrom(io::Printer* printer);
+  void GenerateSwap(io::Printer* printer);
   void GenerateIsInitialized(io::Printer* printer);
 
   // Helpers for GenerateSerializeWithCachedSizes().
diff --git a/src/google/protobuf/compiler/cpp/cpp_message_field.cc b/src/google/protobuf/compiler/cpp/cpp_message_field.cc
index 8904974f..d1c31067 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message_field.cc
@@ -111,6 +111,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void MessageFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "std::swap($name$_, other->$name$_);\n");
+}
+
+void MessageFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   printer->Print(variables_, ",\n$name$_(NULL)");
 }
@@ -202,6 +207,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void RepeatedMessageFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "$name$_.Swap(&other->$name$_);\n");
+}
+
+void RepeatedMessageFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   // Not needed for repeated fields.
 }
diff --git a/src/google/protobuf/compiler/cpp/cpp_message_field.h b/src/google/protobuf/compiler/cpp/cpp_message_field.h
index 0405cbc8..7ce4c32b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_message_field.h
@@ -55,6 +55,7 @@ class MessageFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
@@ -78,6 +79,7 @@ class RepeatedMessageFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc b/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
index 0b437d68..ef4072f0 100644
--- a/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_primitive_field.cc
@@ -175,6 +175,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void PrimitiveFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "std::swap($name$_, other->$name$_);\n");
+}
+
+void PrimitiveFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   printer->Print(variables_, ",\n$name$_($default$)");
 }
@@ -267,6 +272,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void RepeatedPrimitiveFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "$name$_.Swap(&other->$name$_);\n");
+}
+
+void RepeatedPrimitiveFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   // Not needed for repeated fields.
 }
diff --git a/src/google/protobuf/compiler/cpp/cpp_primitive_field.h b/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
index 25b7fba4..c7f7f310 100644
--- a/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_primitive_field.h
@@ -55,6 +55,7 @@ class PrimitiveFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
@@ -78,6 +79,7 @@ class RepeatedPrimitiveFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/cpp/cpp_string_field.cc b/src/google/protobuf/compiler/cpp/cpp_string_field.cc
index 66a0496c..3e694ab7 100644
--- a/src/google/protobuf/compiler/cpp/cpp_string_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_string_field.cc
@@ -163,12 +163,12 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
     "inline ::std::string* $classname$::mutable_$name$() {\n"
     "  _set_bit($index$);\n"
     "  if ($name$_ == &_default_$name$_) {\n");
-  if (descriptor_->has_default_value()) {
+  if (descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
-      "    $name$_ = new ::std::string(_default_$name$_);\n");
+      "    $name$_ = new ::std::string;\n");
   } else {
     printer->Print(variables_,
-      "    $name$_ = new ::std::string;\n");
+      "    $name$_ = new ::std::string(_default_$name$_);\n");
   }
   printer->Print(variables_,
     "  }\n"
@@ -178,26 +178,26 @@ GenerateInlineAccessorDefinitions(io::Printer* printer) const {
 
 void StringFieldGenerator::
 GenerateNonInlineAccessorDefinitions(io::Printer* printer) const {
-  if (descriptor_->has_default_value()) {
+  if (descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
-      "const ::std::string $classname$::_default_$name$_($default$);");
+      "const ::std::string $classname$::_default_$name$_;");
   } else {
     printer->Print(variables_,
-      "const ::std::string $classname$::_default_$name$_;");
+      "const ::std::string $classname$::_default_$name$_($default$);");
   }
 }
 
 void StringFieldGenerator::
 GenerateClearingCode(io::Printer* printer) const {
-  if (descriptor_->has_default_value()) {
+  if (descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
       "if ($name$_ != &_default_$name$_) {\n"
-      "  $name$_->assign(_default_$name$_);\n"
+      "  $name$_->clear();\n"
       "}\n");
   } else {
     printer->Print(variables_,
       "if ($name$_ != &_default_$name$_) {\n"
-      "  $name$_->clear();\n"
+      "  $name$_->assign(_default_$name$_);\n"
       "}\n");
   }
 }
@@ -208,6 +208,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void StringFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "std::swap($name$_, other->$name$_);\n");
+}
+
+void StringFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   printer->Print(variables_,
     ",\n$name$_(const_cast< ::std::string*>(&_default_$name$_))");
@@ -350,6 +355,11 @@ GenerateMergingCode(io::Printer* printer) const {
 }
 
 void RepeatedStringFieldGenerator::
+GenerateSwappingCode(io::Printer* printer) const {
+  printer->Print(variables_, "$name$_.Swap(&other->$name$_);\n");
+}
+
+void RepeatedStringFieldGenerator::
 GenerateInitializer(io::Printer* printer) const {
   // Not needed for repeated fields.
 }
diff --git a/src/google/protobuf/compiler/cpp/cpp_string_field.h b/src/google/protobuf/compiler/cpp/cpp_string_field.h
index a0e5dce9..2244bd77 100644
--- a/src/google/protobuf/compiler/cpp/cpp_string_field.h
+++ b/src/google/protobuf/compiler/cpp/cpp_string_field.h
@@ -56,6 +56,7 @@ class StringFieldGenerator : public FieldGenerator {
   void GenerateNonInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateDestructorCode(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
@@ -80,6 +81,7 @@ class RepeatedStringFieldGenerator : public FieldGenerator {
   void GenerateInlineAccessorDefinitions(io::Printer* printer) const;
   void GenerateClearingCode(io::Printer* printer) const;
   void GenerateMergingCode(io::Printer* printer) const;
+  void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateInitializer(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/cpp/cpp_unittest.cc b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
index ce7d0c88..393c923b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_unittest.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
@@ -236,6 +236,83 @@ TEST(GeneratedMessageTest, CopyFrom) {
   TestUtil::ExpectAllFieldsSet(message2);
 }
 
+TEST(GeneratedMessageTest, SwapWithEmpty) {
+  unittest::TestAllTypes message1, message2;
+  TestUtil::SetAllFields(&message1);
+
+  TestUtil::ExpectAllFieldsSet(message1);
+  TestUtil::ExpectClear(message2);
+  message1.Swap(&message2);
+  TestUtil::ExpectAllFieldsSet(message2);
+  TestUtil::ExpectClear(message1);
+}
+
+TEST(GeneratedMessageTest, SwapWithSelf) {
+  unittest::TestAllTypes message;
+  TestUtil::SetAllFields(&message);
+  TestUtil::ExpectAllFieldsSet(message);
+  message.Swap(&message);
+  TestUtil::ExpectAllFieldsSet(message);
+}
+
+TEST(GeneratedMessageTest, SwapWithOther) {
+  unittest::TestAllTypes message1, message2;
+
+  message1.set_optional_int32(123);
+  message1.set_optional_string("abc");
+  message1.mutable_optional_nested_message()->set_bb(1);
+  message1.set_optional_nested_enum(unittest::TestAllTypes::FOO);
+  message1.add_repeated_int32(1);
+  message1.add_repeated_int32(2);
+  message1.add_repeated_string("a");
+  message1.add_repeated_string("b");
+  message1.add_repeated_nested_message()->set_bb(7);
+  message1.add_repeated_nested_message()->set_bb(8);
+  message1.add_repeated_nested_enum(unittest::TestAllTypes::FOO);
+  message1.add_repeated_nested_enum(unittest::TestAllTypes::BAR);
+
+  message2.set_optional_int32(456);
+  message2.set_optional_string("def");
+  message2.mutable_optional_nested_message()->set_bb(2);
+  message2.set_optional_nested_enum(unittest::TestAllTypes::BAR);
+  message2.add_repeated_int32(3);
+  message2.add_repeated_string("c");
+  message2.add_repeated_nested_message()->set_bb(9);
+  message2.add_repeated_nested_enum(unittest::TestAllTypes::BAZ);
+
+  message1.Swap(&message2);
+
+  EXPECT_EQ(456, message1.optional_int32());
+  EXPECT_EQ("def", message1.optional_string());
+  EXPECT_EQ(2, message1.optional_nested_message().bb());
+  EXPECT_EQ(unittest::TestAllTypes::BAR, message1.optional_nested_enum());
+  ASSERT_EQ(1, message1.repeated_int32_size());
+  EXPECT_EQ(3, message1.repeated_int32(0));
+  ASSERT_EQ(1, message1.repeated_string_size());
+  EXPECT_EQ("c", message1.repeated_string(0));
+  ASSERT_EQ(1, message1.repeated_nested_message_size());
+  EXPECT_EQ(9, message1.repeated_nested_message(0).bb());
+  ASSERT_EQ(1, message1.repeated_nested_enum_size());
+  EXPECT_EQ(unittest::TestAllTypes::BAZ, message1.repeated_nested_enum(0));
+
+  EXPECT_EQ(123, message2.optional_int32());
+  EXPECT_EQ("abc", message2.optional_string());
+  EXPECT_EQ(1, message2.optional_nested_message().bb());
+  EXPECT_EQ(unittest::TestAllTypes::FOO, message2.optional_nested_enum());
+  ASSERT_EQ(2, message2.repeated_int32_size());
+  EXPECT_EQ(1, message2.repeated_int32(0));
+  EXPECT_EQ(2, message2.repeated_int32(1));
+  ASSERT_EQ(2, message2.repeated_string_size());
+  EXPECT_EQ("a", message2.repeated_string(0));
+  EXPECT_EQ("b", message2.repeated_string(1));
+  ASSERT_EQ(2, message2.repeated_nested_message_size());
+  EXPECT_EQ(7, message2.repeated_nested_message(0).bb());
+  EXPECT_EQ(8, message2.repeated_nested_message(1).bb());
+  ASSERT_EQ(2, message2.repeated_nested_enum_size());
+  EXPECT_EQ(unittest::TestAllTypes::FOO, message2.repeated_nested_enum(0));
+  EXPECT_EQ(unittest::TestAllTypes::BAR, message2.repeated_nested_enum(1));
+}
+
 TEST(GeneratedMessageTest, CopyConstructor) {
   unittest::TestAllTypes message1;
   TestUtil::SetAllFields(&message1);
@@ -492,6 +569,45 @@ TEST(GeneratedMessageTest, TestEmbedOptimizedForSize) {
   EXPECT_EQ(2, message2.repeated_message(0).msg().c());
 }
 
+TEST(GeneratedMessageTest, TestSpaceUsed) {
+  unittest::TestAllTypes message1;
+  // sizeof provides a lower bound on SpaceUsed().
+  EXPECT_LE(sizeof(unittest::TestAllTypes), message1.SpaceUsed());
+  const int empty_message_size = message1.SpaceUsed();
+
+  // Setting primitive types shouldn't affect the space used.
+  message1.set_optional_int32(123);
+  message1.set_optional_int64(12345);
+  message1.set_optional_uint32(123);
+  message1.set_optional_uint64(12345);
+  EXPECT_EQ(empty_message_size, message1.SpaceUsed());
+
+  // On some STL implementations, setting the string to a small value should
+  // only increase SpaceUsed() by the size of a string object, though this is
+  // not true everywhere.
+  message1.set_optional_string("abc");
+  EXPECT_LE(empty_message_size + sizeof(string), message1.SpaceUsed());
+
+  // Setting a string to a value larger than the string object itself should
+  // increase SpaceUsed(), because it cannot store the value internally.
+  message1.set_optional_string(string(sizeof(string) + 1, 'x'));
+  int min_expected_increase = message1.optional_string().capacity() +
+      sizeof(string);
+  EXPECT_LE(empty_message_size + min_expected_increase,
+            message1.SpaceUsed());
+
+  int previous_size = message1.SpaceUsed();
+  // Adding an optional message should increase the size by the size of the
+  // nested message type. NestedMessage is simple enough (1 int field) that it
+  // is equal to sizeof(NestedMessage)
+  message1.mutable_optional_nested_message();
+  ASSERT_EQ(sizeof(unittest::TestAllTypes::NestedMessage),
+            message1.optional_nested_message().SpaceUsed());
+  EXPECT_EQ(previous_size +
+            sizeof(unittest::TestAllTypes::NestedMessage),
+            message1.SpaceUsed());
+}
+
 // ===================================================================
 
 TEST(GeneratedEnumTest, EnumValuesAsSwitchCases) {