Fix outer classname for javamicro/javanano.

- File class name is defined as the java_outer_classname option value
  or the file name ToCamelCase; never the single message's ClassName.
- File-scope enums are translated to constants in the file class,
  regardless of java_multiple_files.
- If java_multiple_files=true, and file's class name equals a message's
  class name, no error. This is done by detecting that the outer class
  is not needed and skipping the outer class codegen and clash checks.
  Note: there is a disparity between java[lite] and the previous
  java{micr|nan}o: when generating code for a single-message proto, the
  outer class is omitted by java{micr|nan}o if the file does not have
  java_outer_classname. This change makes java{micr|nan}o align with
  java[lite] codegen and create the outer class, but will print some
  info to warn of potential change of code.
- Also fixed the "is_own_file" detection and made all parseX() methods
  static. Previously, all messages in a java_multiple_files=true file
  are (incorrectly) considered to be in their own files, including
  nested messages, causing them to become inner classes (instance-
  bound) and forcing the parseX() methods to lose the static modifier.
- This change supersedes c/60164 and c/60086, which causes javanano to
  put enum values into enum shell classes if java_multiple_files=true.
  We now always use the parent class to host the enum values. A future
  change will add a command line option to provide more flexibility.
- Elaborated in java/README.txt.

Change-Id: I684932f90e0a028ef37c662b221def5ffa202439

23 files changed, 384 insertions, 405 deletions

diff --git a/src/google/protobuf/compiler/javamicro/javamicro_file.cc b/src/google/protobuf/compiler/javamicro/javamicro_file.cc
index 9513aec..43bf012 100644
--- a/src/google/protobuf/compiler/javamicro/javamicro_file.cc
+++ b/src/google/protobuf/compiler/javamicro/javamicro_file.cc
@@ -32,6 +32,8 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
+#include <iostream>
+
 #include <google/protobuf/compiler/javamicro/javamicro_file.h>
 #include <google/protobuf/compiler/javamicro/javamicro_enum.h>
 #include <google/protobuf/compiler/javamicro/javamicro_helpers.h>
@@ -101,56 +103,48 @@ bool FileGenerator::Validate(string* error) {
     return false;
   }
 
-  // If there is no outer class name then there must be only
-  // message and no enums defined in the file scope.
-  if (!params_.has_java_outer_classname(file_->name())) {
-    if (file_->message_type_count() != 1) {
-      error->assign(file_->name());
-      error->append(
-        ": Java MICRO_RUNTIME may only have 1 message if there is no 'option java_outer_classname'\"");
-      return false;
-    }
+  if (file_->service_count() != 0) {
+    error->assign(file_->name());
+    error->append(
+      ": Java MICRO_RUNTIME does not support services\"");
+    return false;
+  }
 
-    if (file_->enum_type_count() != 0) {
-      error->assign(file_->name());
-      error->append(
-        ": Java MICRO_RUNTIME must have an 'option java_outer_classname' if file scope enums are present\"");
-      return false;
-    }
+  if (!IsOuterClassNeeded(params_, file_)) {
+    return true;
+  }
+
+  // Check whether legacy javamicro generator would omit the outer class.
+  if (!params_.has_java_outer_classname(file_->name())
+      && file_->message_type_count() == 1
+      && file_->enum_type_count() == 0 && file_->extension_count() == 0) {
+    cout << "INFO: " << file_->name() << ":" << endl;
+    cout << "Javamicro generator has changed to align with java generator. "
+        "An outer class will be created for this file and the single message "
+        "in the file will become a nested class. Use java_multiple_files to "
+        "skip generating the outer class, or set an explicit "
+        "java_outer_classname to suppress this message." << endl;
   }
 
   // Check that no class name matches the file's class name.  This is a common
   // problem that leads to Java compile errors that can be hard to understand.
   // It's especially bad when using the java_multiple_files, since we would
   // end up overwriting the outer class with one of the inner ones.
-  int found_fileName = 0;
-  for (int i = 0; i < file_->enum_type_count(); i++) {
-    if (file_->enum_type(i)->name() == classname_) {
-      found_fileName += 1;
-    }
-  }
-  for (int i = 0; i < file_->message_type_count(); i++) {
+  bool found_conflict = false;
+  for (int i = 0; !found_conflict && i < file_->message_type_count(); i++) {
     if (file_->message_type(i)->name() == classname_) {
-      found_fileName += 1;
+      found_conflict = true;
     }
   }
-  if (file_->service_count() != 0) {
+  if (found_conflict) {
     error->assign(file_->name());
     error->append(
-      ": Java MICRO_RUNTIME does not support services\"");
-    return false;
-  }
-
-  if (found_fileName > 1) {
-    error->assign(file_->name());
-    error->append(
-      ": Cannot generate Java output because there is more than one class name, \"");
+      ": Cannot generate Java output because the file's outer class name, \"");
     error->append(classname_);
     error->append(
       "\", matches the name of one of the types declared inside it.  "
       "Please either rename the type or use the java_outer_classname "
-      "option to specify a different outer class name for the .proto file."
-      " -- FIX THIS MESSAGE");
+      "option to specify a different outer class name for the .proto file.");
     return false;
   }
   return true;
@@ -169,20 +163,19 @@ void FileGenerator::Generate(io::Printer* printer) {
       "package", java_package_);
   }
 
-  if (params_.has_java_outer_classname(file_->name())) {
-    printer->Print(
-      "public final class $classname$ {\n"
-      "  private $classname$() {}\n",
-      "classname", classname_);
-    printer->Indent();
-  }
+  printer->Print(
+    "public final class $classname$ {\n"
+    "  private $classname$() {}\n",
+    "classname", classname_);
+  printer->Indent();
 
   // -----------------------------------------------------------------
 
+  for (int i = 0; i < file_->enum_type_count(); i++) {
+    EnumGenerator(file_->enum_type(i), params_).Generate(printer);
+  }
+
   if (!params_.java_multiple_files(file_->name())) {
-    for (int i = 0; i < file_->enum_type_count(); i++) {
-      EnumGenerator(file_->enum_type(i), params_).Generate(printer);
-    }
     for (int i = 0; i < file_->message_type_count(); i++) {
       MessageGenerator(file_->message_type(i), params_).Generate(printer);
     }
@@ -194,11 +187,9 @@ void FileGenerator::Generate(io::Printer* printer) {
     MessageGenerator(file_->message_type(i), params_).GenerateStaticVariables(printer);
   }
 
-  if (params_.has_java_outer_classname(file_->name())) {
-    printer->Outdent();
-    printer->Print(
-      "}\n");
-  }
+  printer->Outdent();
+  printer->Print(
+    "}\n");
 }
 
 template<typename GeneratorClass, typename DescriptorClass>
@@ -232,11 +223,6 @@ void FileGenerator::GenerateSiblings(const string& package_dir,
                                      OutputDirectory* output_directory,
                                      vector<string>* file_list) {
   if (params_.java_multiple_files(file_->name())) {
-    for (int i = 0; i < file_->enum_type_count(); i++) {
-      GenerateSibling<EnumGenerator>(package_dir, java_package_,
-                                     file_->enum_type(i),
-                                     output_directory, file_list, params_);
-    }
     for (int i = 0; i < file_->message_type_count(); i++) {
       GenerateSibling<MessageGenerator>(package_dir, java_package_,
                                         file_->message_type(i),
diff --git a/src/google/protobuf/compiler/javamicro/javamicro_generator.cc b/src/google/protobuf/compiler/javamicro/javamicro_generator.cc
index 4643899..1b74509 100644
--- a/src/google/protobuf/compiler/javamicro/javamicro_generator.cc
+++ b/src/google/protobuf/compiler/javamicro/javamicro_generator.cc
@@ -173,16 +173,18 @@ bool JavaMicroGenerator::Generate(const FileDescriptor* file,
 
   vector<string> all_files;
 
-  string java_filename = package_dir;
-  java_filename += file_generator.classname();
-  java_filename += ".java";
-  all_files.push_back(java_filename);
-
-  // Generate main java file.
-  scoped_ptr<io::ZeroCopyOutputStream> output(
-    output_directory->Open(java_filename));
-  io::Printer printer(output.get(), '$');
-  file_generator.Generate(&printer);
+  if (IsOuterClassNeeded(params, file)) {
+    string java_filename = package_dir;
+    java_filename += file_generator.classname();
+    java_filename += ".java";
+    all_files.push_back(java_filename);
+
+    // Generate main java file.
+    scoped_ptr<io::ZeroCopyOutputStream> output(
+      output_directory->Open(java_filename));
+    io::Printer printer(output.get(), '$');
+    file_generator.Generate(&printer);
+  }
 
   // Generate sibling files.
   file_generator.GenerateSiblings(package_dir, output_directory, &all_files);
diff --git a/src/google/protobuf/compiler/javamicro/javamicro_helpers.cc b/src/google/protobuf/compiler/javamicro/javamicro_helpers.cc
index 3647ec3..f6ce653 100644
--- a/src/google/protobuf/compiler/javamicro/javamicro_helpers.cc
+++ b/src/google/protobuf/compiler/javamicro/javamicro_helpers.cc
@@ -120,31 +120,20 @@ string StripProto(const string& filename) {
 }
 
 string FileClassName(const Params& params, const FileDescriptor* file) {
-  string name;
-
   if (params.has_java_outer_classname(file->name())) {
-      name = params.java_outer_classname(file->name());
+    return params.java_outer_classname(file->name());
   } else {
-    if ((file->message_type_count() == 1)
-        || (file->enum_type_count() == 0)) {
-      // If no outer calls and only one message then
-      // use the message name as the file name
-      name = file->message_type(0)->name();
+    // Use the filename itself with underscores removed
+    // and a CamelCase style name.
+    string basename;
+    string::size_type last_slash = file->name().find_last_of('/');
+    if (last_slash == string::npos) {
+      basename = file->name();
     } else {
-      // Use the filename it self with underscores removed
-      // and a CamelCase style name.
-      string basename;
-      string::size_type last_slash = file->name().find_last_of('/');
-      if (last_slash == string::npos) {
-        basename = file->name();
-      } else {
-        basename = file->name().substr(last_slash + 1);
-      }
-      name = UnderscoresToCamelCaseImpl(StripProto(basename), true);
+      basename = file->name().substr(last_slash + 1);
     }
+    return UnderscoresToCamelCaseImpl(StripProto(basename), true);
   }
-
-  return name;
 }
 
 string FileJavaPackage(const Params& params, const FileDescriptor* file) {
@@ -160,38 +149,27 @@ string FileJavaPackage(const Params& params, const FileDescriptor* file) {
   }
 }
 
-string ToJavaName(const Params& params, const string& full_name,
-    const FileDescriptor* file) {
-  string result;
-  if (params.java_multiple_files(file->name())) {
-    result = FileJavaPackage(params, file);
-  } else {
-    result = ClassName(params, file);
+bool IsOuterClassNeeded(const Params& params, const FileDescriptor* file) {
+  // Enums and extensions need the outer class as the scope.
+  if (file->enum_type_count() != 0 || file->extension_count() != 0) {
+    return true;
   }
-  if (file->package().empty()) {
-    result += '.';
-    result += full_name;
+  // Messages need the outer class only if java_multiple_files is false.
+  return !params.java_multiple_files(file->name());
+}
+
+string ToJavaName(const Params& params, const string& name, bool is_class,
+    const Descriptor* parent, const FileDescriptor* file) {
+  string result;
+  if (parent != NULL) {
+    result.append(ClassName(params, parent));
+  } else if (is_class && params.java_multiple_files(file->name())) {
+    result.append(FileJavaPackage(params, file));
   } else {
-    // Strip the proto package from full_name since we've replaced it with
-    // the Java package. If there isn't an outer classname then strip it too.
-    int sizeToSkipPackageName = file->package().size();
-    int sizeToSkipOutClassName;
-    if (params.has_java_outer_classname(file->name())) {
-      sizeToSkipOutClassName = 0;
-    } else {
-      sizeToSkipOutClassName =
-                full_name.find_first_of('.', sizeToSkipPackageName + 1);
-    }
-    int sizeToSkip = sizeToSkipOutClassName > 0 ?
-            sizeToSkipOutClassName : sizeToSkipPackageName;
-    string class_name = full_name.substr(sizeToSkip + 1);
-    if (class_name == FileClassName(params, file)) {
-      // Done class_name is already present.
-    } else {
-      result += '.';
-      result += class_name;
-    }
+    result.append(ClassName(params, file));
   }
+  if (!result.empty()) result.append(1, '.');
+  result.append(name); // TODO(maxtroy): add '_' if name is a Java keyword.
   return result;
 }
 
@@ -203,51 +181,14 @@ string ClassName(const Params& params, const FileDescriptor* descriptor) {
 }
 
 string ClassName(const Params& params, const EnumDescriptor* descriptor) {
-  string result;
-  const FileDescriptor* file = descriptor->file();
-  const string file_name = file->name();
-  const string full_name = descriptor->full_name();
-
-  // Remove enum class name as we use int's for enums
-  string base_name = full_name.substr(0, full_name.find_last_of('.'));
-
-  if (!file->package().empty()) {
-    if (file->package() == base_name.substr(0, file->package().size())) {
-      // Remove package name leaving just the parent class of the enum
-      int offset = file->package().size();
-      if (base_name.size() > offset) {
-        // Remove period between package and class name if there is a classname
-        offset += 1;
-      }
-      base_name = base_name.substr(offset);
-    } else {
-      GOOGLE_LOG(FATAL) << "Expected package name to start an enum";
-    }
-  }
-
-  // Construct the path name from the package and outer class
-
-  // Add the java package name if it exsits
-  if (params.has_java_package(file_name)) {
-    result += params.java_package(file_name);
-  }
-
-  // Add the outer classname if it exists
-  if (params.has_java_outer_classname(file_name)) {
-    if (!result.empty()) {
-      result += ".";
-    }
-    result += params.java_outer_classname(file_name);
-  }
-
-  // Create the full class name from the base and path
-  if (!base_name.empty()) {
-    if (!result.empty()) {
-      result += ".";
-    }
-    result += base_name;
+  // An enum's class name is the enclosing message's class name or the outer
+  // class name.
+  const Descriptor* parent = descriptor->containing_type();
+  if (parent != NULL) {
+    return ClassName(params, parent);
+  } else {
+    return ClassName(params, descriptor->file());
   }
-  return result;
 }
 
 string FieldConstantName(const FieldDescriptor *field) {
diff --git a/src/google/protobuf/compiler/javamicro/javamicro_helpers.h b/src/google/protobuf/compiler/javamicro/javamicro_helpers.h
index eeddbf9..6131c15 100644
--- a/src/google/protobuf/compiler/javamicro/javamicro_helpers.h
+++ b/src/google/protobuf/compiler/javamicro/javamicro_helpers.h
@@ -69,25 +69,35 @@ string FileClassName(const Params& params, const FileDescriptor* file);
 // Returns the file's Java package name.
 string FileJavaPackage(const Params& params, const FileDescriptor* file);
 
-// Converts the given fully-qualified name in the proto namespace to its
-// fully-qualified name in the Java namespace, given that it is in the given
-// file.
-string ToJavaName(const Params& params, const string& full_name,
-    const FileDescriptor* file);
+// Returns whether the Java outer class is needed, i.e. whether the option
+// java_multiple_files is false, or the proto file contains any file-scope
+// enums/extensions.
+bool IsOuterClassNeeded(const Params& params, const FileDescriptor* file);
+
+// Converts the given simple name of a proto entity to its fully-qualified name
+// in the Java namespace, given that it is in the given file enclosed in the
+// given parent message (or NULL for file-scope entities). Whether the file's
+// outer class name should be included in the return value depends on factors
+// inferrable from the given arguments, including is_class which indicates
+// whether the entity translates to a Java class.
+string ToJavaName(const Params& params, const string& name, bool is_class,
+    const Descriptor* parent, const FileDescriptor* file);
 
 // These return the fully-qualified class name corresponding to the given
 // descriptor.
 inline string ClassName(const Params& params, const Descriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), true,
+                    descriptor->containing_type(), descriptor->file());
 }
 string ClassName(const Params& params, const EnumDescriptor* descriptor);
 inline string ClassName(const Params& params,
     const ServiceDescriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), true, NULL, descriptor->file());
 }
 inline string ExtensionIdentifierName(const Params& params,
     const FieldDescriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), false,
+                    descriptor->extension_scope(), descriptor->file());
 }
 string ClassName(const Params& params, const FileDescriptor* descriptor);
 
diff --git a/src/google/protobuf/compiler/javamicro/javamicro_message.cc b/src/google/protobuf/compiler/javamicro/javamicro_message.cc
index 6f67e74..cf48b3c 100644
--- a/src/google/protobuf/compiler/javamicro/javamicro_message.cc
+++ b/src/google/protobuf/compiler/javamicro/javamicro_message.cc
@@ -173,15 +173,7 @@ void MessageGenerator::Generate(io::Printer* printer) {
   const string& file_name = descriptor_->file()->name();
   bool is_own_file =
     params_.java_multiple_files(file_name)
-      || ((descriptor_->containing_type() == NULL)
-        && !params_.has_java_outer_classname(file_name));
-
-#if 0
-  GOOGLE_LOG(INFO) << "is_own_file=" << is_own_file;
-  GOOGLE_LOG(INFO) << "containing_type()=" << ((descriptor_->containing_type() == NULL) ? "NULL" : "not null");
-  GOOGLE_LOG(INFO) << "java_multiple_files()=" << params_.java_multiple_files();
-  GOOGLE_LOG(INFO) << "has_java_outer_classname()=" << params_.has_java_outer_classname(file_->name());
-#endif
+      && descriptor_->containing_type() == NULL;
 
   if ((descriptor_->extension_count() != 0)
       || (descriptor_->extension_range_count() != 0)) {
@@ -362,25 +354,21 @@ void MessageGenerator::GenerateMergeFromMethods(io::Printer* printer) {
 
 void MessageGenerator::
 GenerateParseFromMethods(io::Printer* printer) {
-  bool is_own_file =
-    descriptor_->containing_type() == NULL;
-
   // Note:  These are separate from GenerateMessageSerializationMethods()
   //   because they need to be generated even for messages that are optimized
   //   for code size.
   printer->Print(
-    "public $static$ $classname$ parseFrom(byte[] data)\n"
+    "public static $classname$ parseFrom(byte[] data)\n"
     "    throws com.google.protobuf.micro.InvalidProtocolBufferMicroException {\n"
     "  return ($classname$) (new $classname$().mergeFrom(data));\n"
     "}\n"
     "\n"
-    "public $static$ $classname$ parseFrom(\n"
+    "public static $classname$ parseFrom(\n"
     "        com.google.protobuf.micro.CodedInputStreamMicro input)\n"
     "    throws java.io.IOException {\n"
     "  return new $classname$().mergeFrom(input);\n"
     "}\n"
     "\n",
-    "static", (is_own_file ? "static" : ""),
     "classname", descriptor_->name());
 }
 
diff --git a/src/google/protobuf/compiler/javanano/javanano_enum.cc b/src/google/protobuf/compiler/javanano/javanano_enum.cc
index 973ef68..634943b 100644
--- a/src/google/protobuf/compiler/javanano/javanano_enum.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_enum.cc
@@ -69,18 +69,6 @@ EnumGenerator::~EnumGenerator() {}
 
 void EnumGenerator::Generate(io::Printer* printer) {
   printer->Print("// enum $classname$\n", "classname", descriptor_->name());
-  const string& file_name = descriptor_->file()->name();
-  bool is_own_file = params_.java_multiple_files(file_name) ||
-      ((descriptor_->containing_type() == NULL) &&
-       !params_.has_java_outer_classname(file_name));
-
-  if (is_own_file) {
-    printer->Print("public final class $classname$ {\n", "classname",
-        descriptor_->name());
-    printer->Indent();
-    printer->Print("private $classname$() {}\n", "classname",
-        descriptor_->name());
-  }
   for (int i = 0; i < canonical_values_.size(); i++) {
     map<string, string> vars;
     vars["name"] = RenameJavaKeywords(canonical_values_[i]->name());
@@ -99,10 +87,6 @@ void EnumGenerator::Generate(io::Printer* printer) {
       "public static final int $name$ = $canonical_name$;\n");
   }
 
-  if (is_own_file) {
-    printer->Outdent();
-    printer->Print("}");
-  }
   printer->Print("\n");
 }
 
diff --git a/src/google/protobuf/compiler/javanano/javanano_file.cc b/src/google/protobuf/compiler/javanano/javanano_file.cc
index 7113699..1a7b2a7 100644
--- a/src/google/protobuf/compiler/javanano/javanano_file.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_file.cc
@@ -32,6 +32,8 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
+#include <iostream>
+
 #include <google/protobuf/compiler/javanano/javanano_file.h>
 #include <google/protobuf/compiler/javanano/javanano_enum.h>
 #include <google/protobuf/compiler/javanano/javanano_extension.h>
@@ -103,56 +105,48 @@ bool FileGenerator::Validate(string* error) {
     return false;
   }
 
-  // If there is no outer class name then there must be only
-  // message and no enums defined in the file scope.
-  if (!params_.has_java_outer_classname(file_->name())) {
-    if (file_->message_type_count() != 1) {
-      error->assign(file_->name());
-      error->append(
-        ": Java NANO_RUNTIME may only have 1 message if there is no 'option java_outer_classname'\"");
-      return false;
-    }
+  if (file_->service_count() != 0) {
+    error->assign(file_->name());
+    error->append(
+      ": Java NANO_RUNTIME does not support services\"");
+    return false;
+  }
 
-    if (file_->enum_type_count() != 0) {
-      error->assign(file_->name());
-      error->append(
-        ": Java NANO_RUNTIME must have an 'option java_outer_classname' if file scope enums are present\"");
-      return false;
-    }
+  if (!IsOuterClassNeeded(params_, file_)) {
+    return true;
+  }
+
+  // Check whether legacy javanano generator would omit the outer class.
+  if (!params_.has_java_outer_classname(file_->name())
+      && file_->message_type_count() == 1
+      && file_->enum_type_count() == 0 && file_->extension_count() == 0) {
+    cout << "INFO: " << file_->name() << ":" << endl;
+    cout << "Javanano generator has changed to align with java generator. "
+        "An outer class will be created for this file and the single message "
+        "in the file will become a nested class. Use java_multiple_files to "
+        "skip generating the outer class, or set an explicit "
+        "java_outer_classname to suppress this message." << endl;
   }
 
   // Check that no class name matches the file's class name.  This is a common
   // problem that leads to Java compile errors that can be hard to understand.
   // It's especially bad when using the java_multiple_files, since we would
   // end up overwriting the outer class with one of the inner ones.
-  int found_fileName = 0;
-  for (int i = 0; i < file_->enum_type_count(); i++) {
-    if (file_->enum_type(i)->name() == classname_) {
-      found_fileName += 1;
-    }
-  }
-  for (int i = 0; i < file_->message_type_count(); i++) {
+  bool found_conflict = false;
+  for (int i = 0; !found_conflict && i < file_->message_type_count(); i++) {
     if (file_->message_type(i)->name() == classname_) {
-      found_fileName += 1;
+      found_conflict = true;
     }
   }
-  if (file_->service_count() != 0) {
+  if (found_conflict) {
     error->assign(file_->name());
     error->append(
-      ": Java NANO_RUNTIME does not support services\"");
-    return false;
-  }
-
-  if (found_fileName > 1) {
-    error->assign(file_->name());
-    error->append(
-      ": Cannot generate Java output because there is more than one class name, \"");
+      ": Cannot generate Java output because the file's outer class name, \"");
     error->append(classname_);
     error->append(
       "\", matches the name of one of the types declared inside it.  "
       "Please either rename the type or use the java_outer_classname "
-      "option to specify a different outer class name for the .proto file."
-      " -- FIX THIS MESSAGE");
+      "option to specify a different outer class name for the .proto file.");
     return false;
   }
   return true;
@@ -171,13 +165,11 @@ void FileGenerator::Generate(io::Printer* printer) {
       "package", java_package_);
   }
 
-  if (params_.has_java_outer_classname(file_->name())) {
-    printer->Print(
-      "public final class $classname$ {\n"
-      "  private $classname$() {}\n",
-      "classname", classname_);
-    printer->Indent();
-  }
+  printer->Print(
+    "public final class $classname$ {\n"
+    "  private $classname$() {}\n",
+    "classname", classname_);
+  printer->Indent();
 
   // -----------------------------------------------------------------
 
@@ -186,10 +178,13 @@ void FileGenerator::Generate(io::Printer* printer) {
     ExtensionGenerator(file_->extension(i), params_).Generate(printer);
   }
 
+  // Enums.
+  for (int i = 0; i < file_->enum_type_count(); i++) {
+    EnumGenerator(file_->enum_type(i), params_).Generate(printer);
+  }
+
+  // Messages.
   if (!params_.java_multiple_files(file_->name())) {
-    for (int i = 0; i < file_->enum_type_count(); i++) {
-      EnumGenerator(file_->enum_type(i), params_).Generate(printer);
-    }
     for (int i = 0; i < file_->message_type_count(); i++) {
       MessageGenerator(file_->message_type(i), params_).Generate(printer);
     }
@@ -201,11 +196,9 @@ void FileGenerator::Generate(io::Printer* printer) {
     MessageGenerator(file_->message_type(i), params_).GenerateStaticVariables(printer);
   }
 
-  if (params_.has_java_outer_classname(file_->name())) {
-    printer->Outdent();
-    printer->Print(
-      "}\n");
-  }
+  printer->Outdent();
+  printer->Print(
+    "}\n");
 }
 
 template<typename GeneratorClass, typename DescriptorClass>
@@ -239,11 +232,6 @@ void FileGenerator::GenerateSiblings(const string& package_dir,
                                      OutputDirectory* output_directory,
                                      vector<string>* file_list) {
   if (params_.java_multiple_files(file_->name())) {
-    for (int i = 0; i < file_->enum_type_count(); i++) {
-      GenerateSibling<EnumGenerator>(package_dir, java_package_,
-                                     file_->enum_type(i),
-                                     output_directory, file_list, params_);
-    }
     for (int i = 0; i < file_->message_type_count(); i++) {
       GenerateSibling<MessageGenerator>(package_dir, java_package_,
                                         file_->message_type(i),
diff --git a/src/google/protobuf/compiler/javanano/javanano_generator.cc b/src/google/protobuf/compiler/javanano/javanano_generator.cc
index 76e7263..5bed1b1 100644
--- a/src/google/protobuf/compiler/javanano/javanano_generator.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_generator.cc
@@ -138,16 +138,18 @@ bool JavaNanoGenerator::Generate(const FileDescriptor* file,
 
   vector<string> all_files;
 
-  string java_filename = package_dir;
-  java_filename += file_generator.classname();
-  java_filename += ".java";
-  all_files.push_back(java_filename);
-
-  // Generate main java file.
-  scoped_ptr<io::ZeroCopyOutputStream> output(
-    output_directory->Open(java_filename));
-  io::Printer printer(output.get(), '$');
-  file_generator.Generate(&printer);
+  if (IsOuterClassNeeded(params, file)) {
+    string java_filename = package_dir;
+    java_filename += file_generator.classname();
+    java_filename += ".java";
+    all_files.push_back(java_filename);
+
+    // Generate main java file.
+    scoped_ptr<io::ZeroCopyOutputStream> output(
+      output_directory->Open(java_filename));
+    io::Printer printer(output.get(), '$');
+    file_generator.Generate(&printer);
+  }
 
   // Generate sibling files.
   file_generator.GenerateSiblings(package_dir, output_directory, &all_files);
diff --git a/src/google/protobuf/compiler/javanano/javanano_helpers.cc b/src/google/protobuf/compiler/javanano/javanano_helpers.cc
index 525b9dd..22b4302 100644
--- a/src/google/protobuf/compiler/javanano/javanano_helpers.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_helpers.cc
@@ -167,31 +167,20 @@ string StripProto(const string& filename) {
 }
 
 string FileClassName(const Params& params, const FileDescriptor* file) {
-  string name;
-
   if (params.has_java_outer_classname(file->name())) {
-      name = params.java_outer_classname(file->name());
+    return params.java_outer_classname(file->name());
   } else {
-    if ((file->message_type_count() == 1)
-        || (file->enum_type_count() == 0)) {
-      // If no outer calls and only one message then
-      // use the message name as the file name
-      name = file->message_type(0)->name();
+    // Use the filename itself with underscores removed
+    // and a CamelCase style name.
+    string basename;
+    string::size_type last_slash = file->name().find_last_of('/');
+    if (last_slash == string::npos) {
+      basename = file->name();
     } else {
-      // Use the filename it self with underscores removed
-      // and a CamelCase style name.
-      string basename;
-      string::size_type last_slash = file->name().find_last_of('/');
-      if (last_slash == string::npos) {
-        basename = file->name();
-      } else {
-        basename = file->name().substr(last_slash + 1);
-      }
-      name = UnderscoresToCamelCaseImpl(StripProto(basename), true);
+      basename = file->name().substr(last_slash + 1);
     }
+    return UnderscoresToCamelCaseImpl(StripProto(basename), true);
   }
-
-  return name;
 }
 
 string FileJavaPackage(const Params& params, const FileDescriptor* file) {
@@ -207,38 +196,27 @@ string FileJavaPackage(const Params& params, const FileDescriptor* file) {
   }
 }
 
-string ToJavaName(const Params& params, const string& full_name,
-    const FileDescriptor* file) {
-  string result;
-  if (params.java_multiple_files(file->name())) {
-    result = FileJavaPackage(params, file);
-  } else {
-    result = ClassName(params, file);
+bool IsOuterClassNeeded(const Params& params, const FileDescriptor* file) {
+  // Enums and extensions need the outer class as the scope.
+  if (file->enum_type_count() != 0 || file->extension_count() != 0) {
+    return true;
   }
-  if (file->package().empty()) {
-    result += '.';
-    result += full_name;
+  // Messages need the outer class only if java_multiple_files is false.
+  return !params.java_multiple_files(file->name());
+}
+
+string ToJavaName(const Params& params, const string& name, bool is_class,
+    const Descriptor* parent, const FileDescriptor* file) {
+  string result;
+  if (parent != NULL) {
+    result.append(ClassName(params, parent));
+  } else if (is_class && params.java_multiple_files(file->name())) {
+    result.append(FileJavaPackage(params, file));
   } else {
-    // Strip the proto package from full_name since we've replaced it with
-    // the Java package. If there isn't an outer classname then strip it too.
-    int sizeToSkipPackageName = file->package().size();
-    int sizeToSkipOutClassName;
-    if (params.has_java_outer_classname(file->name())) {
-      sizeToSkipOutClassName = 0;
-    } else {
-      sizeToSkipOutClassName =
-                full_name.find_first_of('.', sizeToSkipPackageName + 1);
-    }
-    int sizeToSkip = sizeToSkipOutClassName > 0 ?
-            sizeToSkipOutClassName : sizeToSkipPackageName;
-    string class_name = full_name.substr(sizeToSkip + 1);
-    if (class_name == FileClassName(params, file)) {
-      // Done class_name is already present.
-    } else {
-      result += '.';
-      result += class_name;
-    }
+    result.append(ClassName(params, file));
   }
+  if (!result.empty()) result.append(1, '.');
+  result.append(RenameJavaKeywords(name));
   return result;
 }
 
@@ -250,61 +228,14 @@ string ClassName(const Params& params, const FileDescriptor* descriptor) {
 }
 
 string ClassName(const Params& params, const EnumDescriptor* descriptor) {
-  string result;
-  const FileDescriptor* file = descriptor->file();
-  const string file_name = file->name();
-  const string full_name = descriptor->full_name();
-
-  // Remove enum class name as we use int's for enums
-  int last_dot_in_name = full_name.find_last_of('.');
-  string base_name = full_name.substr(0, last_dot_in_name);
-
-  if (!file->package().empty()) {
-    if (file->package() == base_name.substr(0, file->package().size())) {
-      // Remove package name leaving just the parent class of the enum
-      int offset = file->package().size();
-      if (base_name.size() > offset) {
-        // Remove period between package and class name if there is a classname
-        offset += 1;
-      }
-      base_name = base_name.substr(offset);
-    } else {
-      GOOGLE_LOG(FATAL) << "Expected package name to start an enum";
-    }
-  }
-
-  // Construct the path name from the package and outer class
-
-  // Add the java package name if it exists
-  if (params.has_java_package(file_name)) {
-    result += params.java_package(file_name);
-  }
-
-  // If the java_multiple_files option is present, we will generate enums into separate
-  // classes, each named after the original enum type. This takes precedence over
-  // any outer_classname.
-  if (params.java_multiple_files(file_name) && last_dot_in_name != string::npos) {
-    string enum_simple_name = full_name.substr(last_dot_in_name + 1);
-    if (!result.empty()) {
-      result += ".";
-    }
-    result += enum_simple_name;
-  } else if (params.has_java_outer_classname(file_name)) {
-    // Add the outer classname if it exists
-    if (!result.empty()) {
-      result += ".";
-    }
-    result += params.java_outer_classname(file_name);
-  }
-
-  // Create the full class name from the base and path
-  if (!base_name.empty()) {
-    if (!result.empty()) {
-      result += ".";
-    }
-    result += base_name;
+  // An enum's class name is the enclosing message's class name or the outer
+  // class name.
+  const Descriptor* parent = descriptor->containing_type();
+  if (parent != NULL) {
+    return ClassName(params, parent);
+  } else {
+    return ClassName(params, descriptor->file());
   }
-  return result;
 }
 
 string FieldConstantName(const FieldDescriptor *field) {
diff --git a/src/google/protobuf/compiler/javanano/javanano_helpers.h b/src/google/protobuf/compiler/javanano/javanano_helpers.h
index afadf60..430969b 100644
--- a/src/google/protobuf/compiler/javanano/javanano_helpers.h
+++ b/src/google/protobuf/compiler/javanano/javanano_helpers.h
@@ -73,25 +73,35 @@ string FileClassName(const Params& params, const FileDescriptor* file);
 // Returns the file's Java package name.
 string FileJavaPackage(const Params& params, const FileDescriptor* file);
 
-// Converts the given fully-qualified name in the proto namespace to its
-// fully-qualified name in the Java namespace, given that it is in the given
-// file.
-string ToJavaName(const Params& params, const string& full_name,
-    const FileDescriptor* file);
+// Returns whether the Java outer class is needed, i.e. whether the option
+// java_multiple_files is false, or the proto file contains any file-scope
+// enums/extensions.
+bool IsOuterClassNeeded(const Params& params, const FileDescriptor* file);
+
+// Converts the given simple name of a proto entity to its fully-qualified name
+// in the Java namespace, given that it is in the given file enclosed in the
+// given parent message (or NULL for file-scope entities). Whether the file's
+// outer class name should be included in the return value depends on factors
+// inferrable from the given arguments, including is_class which indicates
+// whether the entity translates to a Java class.
+string ToJavaName(const Params& params, const string& name, bool is_class,
+    const Descriptor* parent, const FileDescriptor* file);
 
 // These return the fully-qualified class name corresponding to the given
 // descriptor.
 inline string ClassName(const Params& params, const Descriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), true,
+                    descriptor->containing_type(), descriptor->file());
 }
 string ClassName(const Params& params, const EnumDescriptor* descriptor);
 inline string ClassName(const Params& params,
     const ServiceDescriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), true, NULL, descriptor->file());
 }
 inline string ExtensionIdentifierName(const Params& params,
     const FieldDescriptor* descriptor) {
-  return ToJavaName(params, descriptor->full_name(), descriptor->file());
+  return ToJavaName(params, descriptor->name(), false,
+                    descriptor->extension_scope(), descriptor->file());
 }
 string ClassName(const Params& params, const FileDescriptor* descriptor);
 
diff --git a/src/google/protobuf/compiler/javanano/javanano_message.cc b/src/google/protobuf/compiler/javanano/javanano_message.cc
index de56944..851c443 100644
--- a/src/google/protobuf/compiler/javanano/javanano_message.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_message.cc
@@ -114,7 +114,7 @@ void MessageGenerator::GenerateStaticVariableInitializers(
     io::Printer* printer) {
   // Generate static member initializers for all nested types.
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    // TODO(kenton):  Reuse MessageGenerator objects?
+   // TODO(kenton):  Reuse MessageGenerator objects?
     MessageGenerator(descriptor_->nested_type(i), params_)
       .GenerateStaticVariableInitializers(printer);
   }
@@ -124,15 +124,7 @@ void MessageGenerator::Generate(io::Printer* printer) {
   const string& file_name = descriptor_->file()->name();
   bool is_own_file =
     params_.java_multiple_files(file_name)
-      || ((descriptor_->containing_type() == NULL)
-        && !params_.has_java_outer_classname(file_name));
-
-#if 0
-  GOOGLE_LOG(INFO) << "is_own_file=" << is_own_file;
-  GOOGLE_LOG(INFO) << "containing_type()=" << ((descriptor_->containing_type() == NULL) ? "NULL" : "not null");
-  GOOGLE_LOG(INFO) << "java_multiple_files()=" << params_.java_multiple_files();
-  GOOGLE_LOG(INFO) << "has_java_outer_classname()=" << params_.has_java_outer_classname(file_->name());
-#endif
+      && descriptor_->containing_type() == NULL;
 
   if (!params_.store_unknown_fields() &&
       (descriptor_->extension_count() != 0 || descriptor_->extension_range_count() != 0)) {
@@ -355,25 +347,21 @@ void MessageGenerator::GenerateMergeFromMethods(io::Printer* printer) {
 
 void MessageGenerator::
 GenerateParseFromMethods(io::Printer* printer) {
-  bool is_own_file =
-    descriptor_->containing_type() == NULL;
-
   // Note:  These are separate from GenerateMessageSerializationMethods()
   //   because they need to be generated even for messages that are optimized
   //   for code size.
   printer->Print(
-    "public $static$ $classname$ parseFrom(byte[] data)\n"
+    "public static $classname$ parseFrom(byte[] data)\n"
     "    throws com.google.protobuf.nano.InvalidProtocolBufferNanoException {\n"
     "  return com.google.protobuf.nano.MessageNano.mergeFrom(new $classname$(), data);\n"
     "}\n"
     "\n"
-    "public $static$ $classname$ parseFrom(\n"
+    "public static $classname$ parseFrom(\n"
     "        com.google.protobuf.nano.CodedInputByteBufferNano input)\n"
     "    throws java.io.IOException {\n"
     "  return new $classname$().mergeFrom(input);\n"
     "}\n"
     "\n",
-    "static", (is_own_file ? "static" : ""),
     "classname", descriptor_->name());
 }
 
diff --git a/src/google/protobuf/unittest_multiple_micro.proto b/src/google/protobuf/unittest_multiple_micro.proto
index 0b64283..fee8edc 100644
--- a/src/google/protobuf/unittest_multiple_micro.proto
+++ b/src/google/protobuf/unittest_multiple_micro.proto
@@ -35,9 +35,25 @@ package protobuf_unittest_import;
 import "google/protobuf/unittest_import_micro.proto";
 
 option java_package = "com.google.protobuf.micro";
-option java_outer_classname = "MicroMultipleImportingNonMultiple";
 option java_multiple_files = true;
 
+enum FileScopeEnum {
+  ONE = 1;
+  TWO = 2;
+}
+
+message FileScopeEnumRefMicro {
+  optional FileScopeEnum enum_field = 1;
+}
+
+message MessageScopeEnumRefMicro {
+  enum MessageScopeEnum {
+    ONE = 1;
+    TWO = 2;
+  }
+  optional MessageScopeEnum enum_field = 1;
+}
+
 message MultipleImportingNonMultipleMicro1 {
   optional ImportMessageMicro field = 1;
 }
diff --git a/src/google/protobuf/unittest_multiple_nameclash_micro.proto b/src/google/protobuf/unittest_multiple_nameclash_micro.proto
new file mode 100644
index 0000000..089fd85
--- /dev/null
+++ b/src/google/protobuf/unittest_multiple_nameclash_micro.proto
@@ -0,0 +1,41 @@
+// 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: maxtroy@google.com (Max Cai)
+
+package protobuf_unittest_import;
+
+option java_package = "com.google.protobuf.micro";
+option java_outer_classname = "MultipleNameClashMicro";
+option java_multiple_files = true;
+
+message MultipleNameClashMicro {
+  optional int32 field = 1;
+}
diff --git a/src/google/protobuf/unittest_enum_multiplejava_nano.proto b/src/google/protobuf/unittest_multiple_nameclash_nano.proto
index adf017d..f2f62c4 100644
--- a/src/google/protobuf/unittest_enum_multiplejava_nano.proto
+++ b/src/google/protobuf/unittest_multiple_nameclash_nano.proto
@@ -28,26 +28,14 @@
 // (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: bduff@google.com (Brian Duff)
-//
+// Author: maxtroy@google.com (Max Cai)
 
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.nano";
-option java_outer_classname = "NanoEnumsWithMultipleFiles";
+option java_outer_classname = "MultipleNameClashNano";
 option java_multiple_files = true;
 
-enum FirstTopLevelEnum {
-  FIRST_TOP_LEVEL_FIRST = 1;
-  FIRST_TOP_LEVEL_SECOND = 2;
-}
-
-enum SecondTopLevelEnum {
-  SECOND_TOP_LEVEL_FIRST = 1;
-  SECOND_TOP_LEVEL_SECOND = 2;
-}
-
-message SomeMessage {
-  optional FirstTopLevelEnum first = 1;
-  optional SecondTopLevelEnum second = 2;
+message MultipleNameClashNano {
+  optional int32 field = 1;
 }
diff --git a/src/google/protobuf/unittest_multiple_nano.proto b/src/google/protobuf/unittest_multiple_nano.proto
index bd174c2..5ae790b 100644
--- a/src/google/protobuf/unittest_multiple_nano.proto
+++ b/src/google/protobuf/unittest_multiple_nano.proto
@@ -35,9 +35,25 @@ package protobuf_unittest_import;
 import "google/protobuf/unittest_import_nano.proto";
 
 option java_package = "com.google.protobuf.nano";
-option java_outer_classname = "NanoMultipleImportingNonMultiple";
 option java_multiple_files = true;
 
+enum FileScopeEnum {
+  ONE = 1;
+  TWO = 2;
+}
+
+message FileScopeEnumRefNano {
+  optional FileScopeEnum enum_field = 1;
+}
+
+message MessageScopeEnumRefNano {
+  enum MessageScopeEnum {
+    ONE = 1;
+    TWO = 2;
+  }
+  optional MessageScopeEnum enum_field = 1;
+}
+
 message MultipleImportingNonMultipleNano1 {
   optional ImportMessageNano field = 1;
 }
diff --git a/src/google/protobuf/unittest_recursive_micro.proto b/src/google/protobuf/unittest_recursive_micro.proto
index a256852..078ca9c 100644
--- a/src/google/protobuf/unittest_recursive_micro.proto
+++ b/src/google/protobuf/unittest_recursive_micro.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.micro";
+// Explicit outer classname to suppress legacy info.
+option java_outer_classname = "UnittestRecursiveMicro";
 
 message RecursiveMessageMicro {
   message NestedMessage {
diff --git a/src/google/protobuf/unittest_recursive_nano.proto b/src/google/protobuf/unittest_recursive_nano.proto
index a62613e..3d3a6aa 100644
--- a/src/google/protobuf/unittest_recursive_nano.proto
+++ b/src/google/protobuf/unittest_recursive_nano.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.nano";
+// Explicit outer classname to suppress legacy info.
+option java_outer_classname = "UnittestRecursiveNano";
 
 message RecursiveMessageNano {
   message NestedMessage {
diff --git a/src/google/protobuf/unittest_simple_micro.proto b/src/google/protobuf/unittest_simple_micro.proto
index 057bf3d..09d4aab 100644
--- a/src/google/protobuf/unittest_simple_micro.proto
+++ b/src/google/protobuf/unittest_simple_micro.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.micro";
+// Explicit outer classname to suppress legacy info
+option java_outer_classname = "UnittestSimpleMicro";
 
 message SimpleMessageMicro {
   message NestedMessage {
diff --git a/src/google/protobuf/unittest_simple_nano.proto b/src/google/protobuf/unittest_simple_nano.proto
index 287e962..0c780c7 100644
--- a/src/google/protobuf/unittest_simple_nano.proto
+++ b/src/google/protobuf/unittest_simple_nano.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.nano";
+// Explicit outer classname to suppress legacy info.
+option java_outer_classname = "UnittestSimpleNano";
 
 message SimpleMessageNano {
   message NestedMessage {
diff --git a/src/google/protobuf/unittest_single_micro.proto b/src/google/protobuf/unittest_single_micro.proto
new file mode 100644
index 0000000..17e0645
--- /dev/null
+++ b/src/google/protobuf/unittest_single_micro.proto
@@ -0,0 +1,38 @@
+// 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: maxtroy@google.com (Max Cai)
+
+package protobuf_unittest_import;
+
+option java_package = "com.google.protobuf.micro";
+
+message SingleMessageMicro {
+}
diff --git a/src/google/protobuf/unittest_single_nano.proto b/src/google/protobuf/unittest_single_nano.proto
new file mode 100644
index 0000000..fcb1539
--- /dev/null
+++ b/src/google/protobuf/unittest_single_nano.proto
@@ -0,0 +1,38 @@
+// 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: maxtroy@google.com (Max Cai)
+
+package protobuf_unittest_import;
+
+option java_package = "com.google.protobuf.nano";
+
+message SingleMessageNano {
+}
diff --git a/src/google/protobuf/unittest_stringutf8_micro.proto b/src/google/protobuf/unittest_stringutf8_micro.proto
index e4bbe3d..68bd5ef 100644
--- a/src/google/protobuf/unittest_stringutf8_micro.proto
+++ b/src/google/protobuf/unittest_stringutf8_micro.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.micro";
+// Explicit outer classname to suppress legacy info.
+option java_outer_classname = "UnittestStringutf8Micro";
 
 message StringUtf8 {
   optional string id = 1;
diff --git a/src/google/protobuf/unittest_stringutf8_nano.proto b/src/google/protobuf/unittest_stringutf8_nano.proto
index da624b0..2bbf2b7 100644
--- a/src/google/protobuf/unittest_stringutf8_nano.proto
+++ b/src/google/protobuf/unittest_stringutf8_nano.proto
@@ -34,6 +34,8 @@
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.nano";
+// Explicit outer classname to suppress legacy info.
+option java_outer_classname = "UnittestStringutf8Nano";
 
 message StringUtf8 {
   optional string id = 1;