Integrate google internal changes.

10 files changed, 313 insertions, 48 deletions

diff --git a/src/google/protobuf/compiler/cpp/cpp_enum.cc b/src/google/protobuf/compiler/cpp/cpp_enum.cc
index 5ee6f000..415ae60f 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_enum.cc
@@ -69,11 +69,12 @@ EnumGenerator::EnumGenerator(const EnumDescriptor* descriptor,
 
 EnumGenerator::~EnumGenerator() {}
 
-void EnumGenerator::FillForwardDeclaration(set<string>* enum_names) {
+void EnumGenerator::FillForwardDeclaration(
+    map<string, const EnumDescriptor*>* enum_names) {
   if (!options_.proto_h) {
     return;
   }
-  enum_names->insert(classname_);
+  (*enum_names)[classname_] = descriptor_;
 }
 
 void EnumGenerator::GenerateDefinition(io::Printer* printer) {
@@ -83,6 +84,7 @@ void EnumGenerator::GenerateDefinition(io::Printer* printer) {
   vars["enumbase"] = classname_ + (options_.proto_h ? " : int" : "");
 
   printer->Print(vars, "enum $enumbase$ {\n");
+  printer->Annotate("enumbase", descriptor_);
   printer->Indent();
 
   const EnumValueDescriptor* min_value = descriptor_->value(0);
diff --git a/src/google/protobuf/compiler/cpp/cpp_enum.h b/src/google/protobuf/compiler/cpp/cpp_enum.h
index f3aa72e4..61e40346 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum.h
+++ b/src/google/protobuf/compiler/cpp/cpp_enum.h
@@ -64,8 +64,10 @@ class EnumGenerator {
   // Fills the name to use when declaring the enum. This is for use when
   // generating other .proto.h files. This code should be placed within the
   // enum's package namespace, but NOT within any class, even for nested
-  // enums.
-  void FillForwardDeclaration(set<string>* enum_names);
+  // enums. A given key in enum_names will map from an enum class name to the
+  // EnumDescriptor that was responsible for its inclusion in the map. This can
+  // be used to associate the descriptor with the code generated for it.
+  void FillForwardDeclaration(map<string, const EnumDescriptor*>* enum_names);
 
   // Generate header code defining the enum.  This code should be placed
   // within the enum's package namespace, but NOT within any class, even for
diff --git a/src/google/protobuf/compiler/cpp/cpp_file.cc b/src/google/protobuf/compiler/cpp/cpp_file.cc
index 37e4bae4..d48171b0 100644
--- a/src/google/protobuf/compiler/cpp/cpp_file.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_file.cc
@@ -94,7 +94,8 @@ FileGenerator::FileGenerator(const FileDescriptor* file, const Options& options)
 
 FileGenerator::~FileGenerator() {}
 
-void FileGenerator::GenerateProtoHeader(io::Printer* printer) {
+void FileGenerator::GenerateProtoHeader(io::Printer* printer,
+                                        const string& info_path) {
   if (!options_.proto_h) {
     return;
   }
@@ -114,6 +115,8 @@ void FileGenerator::GenerateProtoHeader(io::Printer* printer) {
       "dependency", dependency);
   }
 
+  GenerateMetadataPragma(printer, info_path);
+
   printer->Print(
     "// @@protoc_insertion_point(includes)\n");
 
@@ -167,7 +170,8 @@ void FileGenerator::GenerateProtoHeader(io::Printer* printer) {
   GenerateBottomHeaderGuard(printer, filename_identifier);
 }
 
-void FileGenerator::GeneratePBHeader(io::Printer* printer) {
+void FileGenerator::GeneratePBHeader(io::Printer* printer,
+                                     const string& info_path) {
   string filename_identifier =
       FilenameIdentifier(file_->name() + (options_.proto_h ? ".pb.h" : ""));
   GenerateTopHeaderGuard(printer, filename_identifier);
@@ -179,6 +183,7 @@ void FileGenerator::GeneratePBHeader(io::Printer* printer) {
     GenerateLibraryIncludes(printer);
   }
   GenerateDependencyIncludes(printer);
+  GenerateMetadataPragma(printer, info_path);
 
   printer->Print(
     "// @@protoc_insertion_point(includes)\n");
@@ -237,7 +242,7 @@ void FileGenerator::GeneratePBHeader(io::Printer* printer) {
 }
 
 void FileGenerator::GenerateSource(io::Printer* printer) {
-  bool well_known = IsWellKnownMessage(file_);
+  const bool use_system_include = IsWellKnownMessage(file_);
   string header =
       StripProto(file_->name()) + (options_.proto_h ? ".proto.h" : ".pb.h");
   printer->Print(
@@ -258,8 +263,8 @@ void FileGenerator::GenerateSource(io::Printer* printer) {
     "#include <google/protobuf/wire_format_lite_inl.h>\n",
     "filename", file_->name(),
     "header", header,
-    "left", well_known ? "<" : "\"",
-    "right", well_known ? ">" : "\"");
+    "left", use_system_include ? "<" : "\"",
+    "right", use_system_include ? ">" : "\"");
 
   // Unknown fields implementation in lite mode uses StringOutputStream
   if (!UseUnknownFieldSet(file_) && file_->message_type_count() > 0) {
@@ -401,20 +406,24 @@ class FileGenerator::ForwardDeclarations {
     return ns;
   }
 
-  set<string>& classes() { return classes_; }
-  set<string>& enums() { return enums_; }
+  map<string, const Descriptor*>& classes() { return classes_; }
+  map<string, const EnumDescriptor*>& enums() { return enums_; }
 
   void Print(io::Printer* printer) const {
-    for (set<string>::const_iterator it = enums_.begin(), end = enums_.end();
+    for (map<string, const EnumDescriptor *>::const_iterator
+             it = enums_.begin(),
+             end = enums_.end();
          it != end; ++it) {
-      printer->Print("enum $enumname$ : int;\n"
-                     "bool $enumname$_IsValid(int value);\n",
-                     "enumname", it->c_str());
+      printer->Print("enum $enumname$ : int;\n", "enumname", it->first);
+      printer->Annotate("enumname", it->second);
+      printer->Print("bool $enumname$_IsValid(int value);\n", "enumname",
+                     it->first);
     }
-    for (set<string>::const_iterator it = classes_.begin(),
-                                     end = classes_.end();
+    for (map<string, const Descriptor *>::const_iterator it = classes_.begin(),
+                                                         end = classes_.end();
          it != end; ++it) {
-      printer->Print("class $classname$;\n", "classname", it->c_str());
+      printer->Print("class $classname$;\n", "classname", it->first);
+      printer->Annotate("classname", it->second);
     }
     for (map<string, ForwardDeclarations *>::const_iterator
              it = namespaces_.begin(),
@@ -431,8 +440,8 @@ class FileGenerator::ForwardDeclarations {
 
  private:
   map<string, ForwardDeclarations*> namespaces_;
-  set<string> classes_;
-  set<string> enums_;
+  map<string, const Descriptor*> classes_;
+  map<string, const EnumDescriptor*> enums_;
 };
 
 void FileGenerator::GenerateBuildDescriptors(io::Printer* printer) {
@@ -854,6 +863,19 @@ void FileGenerator::GenerateLibraryIncludes(io::Printer* printer) {
   }
 }
 
+void FileGenerator::GenerateMetadataPragma(io::Printer* printer,
+                                           const string& info_path) {
+  if (!info_path.empty() && !options_.annotation_pragma_name.empty() &&
+      !options_.annotation_guard_name.empty()) {
+    printer->Print(
+        "#ifdef $guard$\n"
+        "#pragma $pragma$ \"$info_path$\"\n"
+        "#endif  // $guard$\n",
+        "guard", options_.annotation_guard_name, "pragma",
+        options_.annotation_pragma_name, "info_path", info_path);
+  }
+}
+
 void FileGenerator::GenerateDependencyIncludes(io::Printer* printer) {
   set<string> public_import_names;
   for (int i = 0; i < file_->public_dependency_count(); i++) {
@@ -861,16 +883,17 @@ void FileGenerator::GenerateDependencyIncludes(io::Printer* printer) {
   }
 
   for (int i = 0; i < file_->dependency_count(); i++) {
-    bool well_known = IsWellKnownMessage(file_->dependency(i));
+    const bool use_system_include = IsWellKnownMessage(file_->dependency(i));
     const string& name = file_->dependency(i)->name();
     bool public_import = (public_import_names.count(name) != 0);
 
+
     printer->Print(
       "#include $left$$dependency$.pb.h$right$$iwyu$\n",
       "dependency", StripProto(name),
       "iwyu", (public_import) ? "  // IWYU pragma: export" : "",
-      "left", well_known ? "<" : "\"",
-      "right", well_known ? ">" : "\"");
+      "left", use_system_include ? "<" : "\"",
+      "right", use_system_include ? ">" : "\"");
   }
 }
 
@@ -897,13 +920,15 @@ void FileGenerator::GenerateGlobalStateFunctionDeclarations(
 }
 
 void FileGenerator::GenerateMessageForwardDeclarations(io::Printer* printer) {
-  set<string> classes;
+  map<string, const Descriptor*> classes;
   for (int i = 0; i < file_->message_type_count(); i++) {
     message_generators_[i]->FillMessageForwardDeclarations(&classes);
   }
-  for (set<string>::const_iterator it = classes.begin(), end = classes.end();
+  for (map<string, const Descriptor *>::const_iterator it = classes.begin(),
+                                                       end = classes.end();
        it != end; ++it) {
-    printer->Print("class $classname$;\n", "classname", it->c_str());
+    printer->Print("class $classname$;\n", "classname", it->first);
+    printer->Annotate("classname", it->second);
   }
 }
 
diff --git a/src/google/protobuf/compiler/cpp/cpp_file.h b/src/google/protobuf/compiler/cpp/cpp_file.h
index 29cdaea5..ebe990c2 100644
--- a/src/google/protobuf/compiler/cpp/cpp_file.h
+++ b/src/google/protobuf/compiler/cpp/cpp_file.h
@@ -69,8 +69,14 @@ class FileGenerator {
                          const Options& options);
   ~FileGenerator();
 
-  void GenerateProtoHeader(io::Printer* printer);
-  void GeneratePBHeader(io::Printer* printer);
+  // info_path, if non-empty, should be the path (relative to printer's output)
+  // to the metadata file describing this proto header.
+  void GenerateProtoHeader(io::Printer* printer,
+                           const string& info_path);
+  // info_path, if non-empty, should be the path (relative to printer's output)
+  // to the metadata file describing this PB header.
+  void GeneratePBHeader(io::Printer* printer,
+                        const string& info_path);
   void GenerateSource(io::Printer* printer);
 
  private:
@@ -102,6 +108,10 @@ class FileGenerator {
   void GenerateLibraryIncludes(io::Printer* printer);
   void GenerateDependencyIncludes(io::Printer* printer);
 
+  // Generate a pragma to pull in metadata using the given info_path (if
+  // non-empty). info_path should be relative to printer's output.
+  void GenerateMetadataPragma(io::Printer* printer, const string& info_path);
+
   // Generates a couple of different pieces before definitions:
   void GenerateGlobalStateFunctionDeclarations(io::Printer* printer);
 
diff --git a/src/google/protobuf/compiler/cpp/cpp_generator.cc b/src/google/protobuf/compiler/cpp/cpp_generator.cc
index 781526b5..c7aec93a 100644
--- a/src/google/protobuf/compiler/cpp/cpp_generator.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_generator.cc
@@ -90,6 +90,12 @@ bool CppGenerator::Generate(const FileDescriptor* file,
       file_options.dllexport_decl = options[i].second;
     } else if (options[i].first == "safe_boundary_check") {
       file_options.safe_boundary_check = true;
+    } else if (options[i].first == "annotate_headers") {
+      file_options.annotate_headers = true;
+    } else if (options[i].first == "annotation_pragma_name") {
+      file_options.annotation_pragma_name = options[i].second;
+    } else if (options[i].first == "annotation_guard_name") {
+      file_options.annotation_guard_name = options[i].second;
     } else {
       *error = "Unknown generator option: " + options[i].first;
       return false;
@@ -107,16 +113,40 @@ bool CppGenerator::Generate(const FileDescriptor* file,
   if (file_options.proto_h) {
     google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(
         generator_context->Open(basename + ".proto.h"));
-    io::Printer printer(output.get(), '$');
-    file_generator.GenerateProtoHeader(&printer);
+    GeneratedCodeInfo annotations;
+    io::AnnotationProtoCollector<GeneratedCodeInfo> annotation_collector(
+        &annotations);
+    string info_path = basename + ".proto.h.meta";
+    io::Printer printer(output.get(), '$', file_options.annotate_headers
+                                               ? &annotation_collector
+                                               : NULL);
+    file_generator.GenerateProtoHeader(
+        &printer, file_options.annotate_headers ? info_path : "");
+    if (file_options.annotate_headers) {
+      scoped_ptr<io::ZeroCopyOutputStream> info_output(
+          generator_context->Open(info_path));
+      annotations.SerializeToZeroCopyStream(info_output.get());
+    }
   }
 
   basename.append(".pb");
   {
     google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(
         generator_context->Open(basename + ".h"));
-    io::Printer printer(output.get(), '$');
-    file_generator.GeneratePBHeader(&printer);
+    GeneratedCodeInfo annotations;
+    io::AnnotationProtoCollector<GeneratedCodeInfo> annotation_collector(
+        &annotations);
+    string info_path = basename + ".h.meta";
+    io::Printer printer(output.get(), '$', file_options.annotate_headers
+                                               ? &annotation_collector
+                                               : NULL);
+    file_generator.GeneratePBHeader(
+        &printer, file_options.annotate_headers ? info_path : "");
+    if (file_options.annotate_headers) {
+      scoped_ptr<io::ZeroCopyOutputStream> info_output(
+          generator_context->Open(info_path));
+      annotations.SerializeToZeroCopyStream(info_output.get());
+    }
   }
 
   // Generate cc file.
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.cc b/src/google/protobuf/compiler/cpp/cpp_message.cc
index 8304ebbd..c3166611 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message.cc
@@ -423,8 +423,8 @@ MessageGenerator::MessageGenerator(const Descriptor* descriptor,
 MessageGenerator::~MessageGenerator() {}
 
 void MessageGenerator::
-FillMessageForwardDeclarations(set<string>* class_names) {
-  class_names->insert(classname_);
+FillMessageForwardDeclarations(map<string, const Descriptor*>* class_names) {
+  (*class_names)[classname_] = descriptor_;
 
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
     // map entry message doesn't need forward declaration. Since map entry
@@ -436,7 +436,7 @@ FillMessageForwardDeclarations(set<string>* class_names) {
 }
 
 void MessageGenerator::
-FillEnumForwardDeclarations(set<string>* enum_names) {
+FillEnumForwardDeclarations(map<string, const EnumDescriptor*>* enum_names) {
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
     nested_generators_[i]->FillEnumForwardDeclarations(enum_names);
   }
@@ -892,6 +892,7 @@ GenerateClassDefinition(io::Printer* printer) {
   }
   printer->Print(vars,
     "class $dllexport$$classname$ : public $superclass$ {\n");
+  printer->Annotate("classname", descriptor_);
   if (use_dependent_base_) {
     printer->Print(vars, "  friend class $superclass$;\n");
   }
@@ -1027,6 +1028,8 @@ GenerateClassDefinition(io::Printer* printer) {
       "// implements Any -----------------------------------------------\n"
       "\n"
       "void PackFrom(const ::google::protobuf::Message& message);\n"
+      "void PackFrom(const ::google::protobuf::Message& message,\n"
+      "              const ::std::string& type_url_prefix);\n"
       "bool UnpackTo(::google::protobuf::Message* message) const;\n"
       "template<typename T> bool Is() const {\n"
       "  return _any_metadata_.Is<T>();\n"
@@ -1789,6 +1792,11 @@ GenerateClassMethods(io::Printer* printer) {
       "  _any_metadata_.PackFrom(message);\n"
       "}\n"
       "\n"
+      "void $classname$::PackFrom(const ::google::protobuf::Message& message,\n"
+      "                           const ::std::string& type_url_prefix) {\n"
+      "  _any_metadata_.PackFrom(message, type_url_prefix);\n"
+      "}\n"
+      "\n"
       "bool $classname$::UnpackTo(::google::protobuf::Message* message) const {\n"
       "  return _any_metadata_.UnpackTo(message);\n"
       "}\n"
@@ -1899,11 +1907,10 @@ GenerateClassMethods(io::Printer* printer) {
 
 void MessageGenerator::
 GenerateOffsets(io::Printer* printer) {
-  printer->Print(
-    "static const int $classname$_offsets_[$field_count$] = {\n",
-    "classname", classname_,
-    "field_count", SimpleItoa(max(
-        1, descriptor_->field_count() + descriptor_->oneof_decl_count())));
+  printer->Print("static const int $classname$_offsets_[$field_count$] = {\n",
+                 "classname", classname_, "field_count",
+                 SimpleItoa(std::max(1, descriptor_->field_count() +
+                                            descriptor_->oneof_decl_count())));
   printer->Indent();
 
   for (int i = 0; i < descriptor_->field_count(); i++) {
@@ -2907,7 +2914,7 @@ GenerateMergeFromCodedStream(io::Printer* printer) {
     // on the CodedOutputStream.
     printer->Print(
       "  ::google::protobuf::io::LazyStringOutputStream unknown_fields_string(\n"
-      "      ::google::protobuf::internal::NewPermanentCallback(\n"
+      "      google::protobuf::internal::NewPermanentCallback(\n"
       "          &MutableUnknownFieldsFor$classname$, this));\n"
       "  ::google::protobuf::io::CodedOutputStream unknown_fields_stream(\n"
       "      &unknown_fields_string, false);\n",
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.h b/src/google/protobuf/compiler/cpp/cpp_message.h
index 8e19a3f0..31223e13 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.h
+++ b/src/google/protobuf/compiler/cpp/cpp_message.h
@@ -67,9 +67,13 @@ class MessageGenerator {
   // Header stuff.
 
   // Return names for foward declarations of this class and all its nested
-  // types.
-  void FillMessageForwardDeclarations(set<string>* class_names);
-  void FillEnumForwardDeclarations(set<string>* enum_names);
+  // types. A given key in {class,enum}_names will map from a class name to the
+  // descriptor that was responsible for its inclusion in the map. This can be
+  // used to associate the descriptor with the code generated for it.
+  void FillMessageForwardDeclarations(
+      map<string, const Descriptor*>* class_names);
+  void FillEnumForwardDeclarations(
+      map<string, const EnumDescriptor*>* enum_names);
 
   // Generate definitions of all nested enums (must come before class
   // definitions because those classes use the enums definitions).
diff --git a/src/google/protobuf/compiler/cpp/cpp_options.h b/src/google/protobuf/compiler/cpp/cpp_options.h
index 4463f200..e908362b 100644
--- a/src/google/protobuf/compiler/cpp/cpp_options.h
+++ b/src/google/protobuf/compiler/cpp/cpp_options.h
@@ -43,11 +43,14 @@ namespace cpp {
 
 // Generator options (see generator.cc for a description of each):
 struct Options {
-  Options() : safe_boundary_check(false), proto_h(false) {
-  }
+  Options()
+      : safe_boundary_check(false), proto_h(false), annotate_headers(false) {}
   string dllexport_decl;
   bool safe_boundary_check;
   bool proto_h;
+  bool annotate_headers;
+  string annotation_pragma_name;
+  string annotation_guard_name;
 };
 
 }  // namespace cpp
diff --git a/src/google/protobuf/compiler/cpp/cpp_unittest.cc b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
index 9942a343..148da883 100644
--- a/src/google/protobuf/compiler/cpp/cpp_unittest.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_unittest.cc
@@ -82,7 +82,6 @@
 
 namespace google {
 namespace protobuf {
-using internal::NewPermanentCallback;
 namespace compiler {
 namespace cpp {
 
@@ -1253,7 +1252,7 @@ class GeneratedServiceTest : public testing::Test {
       foo_(descriptor_->FindMethodByName("Foo")),
       bar_(descriptor_->FindMethodByName("Bar")),
       stub_(&mock_channel_),
-      done_(NewPermanentCallback(&DoNothing)) {}
+      done_(google::protobuf::internal::NewPermanentCallback(&DoNothing)) {}
 
   virtual void SetUp() {
     ASSERT_TRUE(foo_ != NULL);
diff --git a/src/google/protobuf/compiler/cpp/metadata_test.cc b/src/google/protobuf/compiler/cpp/metadata_test.cc
index 422eb73b..61dc283a 100644
--- a/src/google/protobuf/compiler/cpp/metadata_test.cc
+++ b/src/google/protobuf/compiler/cpp/metadata_test.cc
@@ -51,6 +51,189 @@ namespace compiler {
 namespace cpp {
 namespace {
 
+// A CodeGenerator that captures the FileDescriptor it's passed as a
+// FileDescriptorProto.
+class DescriptorCapturingGenerator : public CodeGenerator {
+ public:
+  // Does not own file; file must outlive the Generator.
+  explicit DescriptorCapturingGenerator(FileDescriptorProto* file)
+      : file_(file) {}
+
+  virtual bool Generate(const FileDescriptor* file, const string& parameter,
+                        GeneratorContext* context, string* error) const {
+    file->CopyTo(file_);
+    return true;
+  }
+
+ private:
+  FileDescriptorProto* file_;
+};
+
+class CppMetadataTest : public ::testing::Test {
+ public:
+  // Adds a file with name `filename` and content `data`.
+  void AddFile(const string& filename, const string& data) {
+    GOOGLE_CHECK_OK(File::SetContents(TestTempDir() + "/" + filename, data,
+                               true));
+  }
+
+  // Tries to capture a FileDescriptorProto, GeneratedCodeInfo, and output
+  // code from the previously added file with name `filename`. Returns true on
+  // success. If pb_h is non-null, expects a .pb.h and a .pb.h.meta (copied to
+  // pb_h and pb_h_info respecfively); similarly for proto_h and proto_h_info.
+  bool CaptureMetadata(const string& filename, FileDescriptorProto* file,
+                       string* pb_h, GeneratedCodeInfo* pb_h_info,
+                       string* proto_h, GeneratedCodeInfo* proto_h_info,
+                       string* pb_cc) {
+    google::protobuf::compiler::CommandLineInterface cli;
+    cli.SetInputsAreProtoPathRelative(true);
+
+    CppGenerator cpp_generator;
+    DescriptorCapturingGenerator capturing_generator(file);
+    cli.RegisterGenerator("--cpp_out", &cpp_generator, "");
+    cli.RegisterGenerator("--capture_out", &capturing_generator, "");
+
+    string proto_path = "-I" + TestTempDir();
+    string cpp_out =
+        "--cpp_out=annotate_headers=true,"
+        "annotation_pragma_name=pragma_name,"
+        "annotation_guard_name=guard_name:" +
+        TestTempDir();
+    string capture_out = "--capture_out=" + TestTempDir();
+
+    const char* argv[] = {"protoc", proto_path.c_str(), cpp_out.c_str(),
+                          capture_out.c_str(), filename.c_str()};
+
+    if (cli.Run(5, argv) != 0) {
+      return false;
+    }
+
+    string output_base = TestTempDir() + "/" + StripProto(filename);
+
+    if (pb_cc != NULL) {
+      GOOGLE_CHECK_OK(
+          File::GetContents(output_base + ".pb.cc", pb_cc, true));
+    }
+
+    if (pb_h != NULL && pb_h_info != NULL) {
+      GOOGLE_CHECK_OK(
+          File::GetContents(output_base + ".pb.h", pb_h, true));
+      if (!DecodeMetadata(output_base + ".pb.h.meta", pb_h_info)) {
+        return false;
+      }
+    }
+
+    if (proto_h != NULL && proto_h_info != NULL) {
+      GOOGLE_CHECK_OK(File::GetContents(output_base + ".proto.h", proto_h,
+                                 true));
+      if (!DecodeMetadata(output_base + ".proto.h.meta", proto_h_info)) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+ private:
+  // Decodes GeneratedCodeInfo stored in path and copies it to info.
+  // Returns true on success.
+  bool DecodeMetadata(const string& path, GeneratedCodeInfo* info) {
+    string data;
+    GOOGLE_CHECK_OK(File::GetContents(path, &data, true));
+    io::ArrayInputStream input(data.data(), data.size());
+    return info->ParseFromZeroCopyStream(&input);
+  }
+};
+
+const char kSmallTestFile[] =
+    "syntax = \"proto2\";\n"
+    "package foo;\n"
+    "enum Enum { VALUE = 0; }\n"
+    "message Message { }\n";
+
+// Finds the Annotation for a given source file and path (or returns null if it
+// couldn't).
+const GeneratedCodeInfo::Annotation* FindAnnotationOnPath(
+    const GeneratedCodeInfo& info, const string& source_file,
+    const vector<int>& path) {
+  for (int i = 0; i < info.annotation_size(); ++i) {
+    const GeneratedCodeInfo::Annotation* annotation = &info.annotation(i);
+    if (annotation->source_file() != source_file ||
+        annotation->path_size() != path.size()) {
+      continue;
+    }
+    int node = 0;
+    for (; node < path.size(); ++node) {
+      if (annotation->path(node) != path[node]) {
+        break;
+      }
+    }
+    if (node == path.size()) {
+      return annotation;
+    }
+  }
+  return NULL;
+}
+
+// Returns true if the provided annotation covers a given substring in
+// file_content.
+bool AnnotationMatchesSubstring(const string& file_content,
+                                const GeneratedCodeInfo::Annotation* annotation,
+                                const string& expected_text) {
+  uint32 begin = annotation->begin();
+  uint32 end = annotation->end();
+  if (end < begin || end > file_content.size()) {
+    return false;
+  }
+  return file_content.substr(begin, end - begin) == expected_text;
+}
+
+TEST_F(CppMetadataTest, CapturesEnumNames) {
+  FileDescriptorProto file;
+  GeneratedCodeInfo info;
+  string pb_h;
+  AddFile("test.proto", kSmallTestFile);
+  EXPECT_TRUE(
+      CaptureMetadata("test.proto", &file, &pb_h, &info, NULL, NULL, NULL));
+  EXPECT_EQ("Enum", file.enum_type(0).name());
+  vector<int> enum_path;
+  enum_path.push_back(FileDescriptorProto::kEnumTypeFieldNumber);
+  enum_path.push_back(0);
+  const GeneratedCodeInfo::Annotation* enum_annotation =
+      FindAnnotationOnPath(info, "test.proto", enum_path);
+  EXPECT_TRUE(NULL != enum_annotation);
+  EXPECT_TRUE(AnnotationMatchesSubstring(pb_h, enum_annotation, "Enum"));
+}
+
+TEST_F(CppMetadataTest, AddsPragma) {
+  FileDescriptorProto file;
+  GeneratedCodeInfo info;
+  string pb_h;
+  AddFile("test.proto", kSmallTestFile);
+  EXPECT_TRUE(
+      CaptureMetadata("test.proto", &file, &pb_h, &info, NULL, NULL, NULL));
+  EXPECT_TRUE(pb_h.find("#ifdef guard_name") != string::npos);
+  EXPECT_TRUE(pb_h.find("#pragma pragma_name \"test.pb.h.meta\"") !=
+              string::npos);
+}
+
+TEST_F(CppMetadataTest, CapturesMessageNames) {
+  FileDescriptorProto file;
+  GeneratedCodeInfo info;
+  string pb_h;
+  AddFile("test.proto", kSmallTestFile);
+  EXPECT_TRUE(
+      CaptureMetadata("test.proto", &file, &pb_h, &info, NULL, NULL, NULL));
+  EXPECT_EQ("Message", file.message_type(0).name());
+  vector<int> message_path;
+  message_path.push_back(FileDescriptorProto::kMessageTypeFieldNumber);
+  message_path.push_back(0);
+  const GeneratedCodeInfo::Annotation* message_annotation =
+      FindAnnotationOnPath(info, "test.proto", message_path);
+  EXPECT_TRUE(NULL != message_annotation);
+  EXPECT_TRUE(AnnotationMatchesSubstring(pb_h, message_annotation, "Message"));
+}
+
 }  // namespace
 }  // namespace cpp
 }  // namespace compiler