Integrated internal changes from Google

13 files changed, 394 insertions, 276 deletions

diff --git a/python/google/protobuf/pyext/descriptor.cc b/python/google/protobuf/pyext/descriptor.cc
index 9634ea05..bacaaf31 100644
--- a/python/google/protobuf/pyext/descriptor.cc
+++ b/python/google/protobuf/pyext/descriptor.cc
@@ -188,39 +188,36 @@ const FileDescriptor* GetFileDescriptor(const MethodDescriptor* descriptor) {
 // Always returns a new reference.
 template<class DescriptorClass>
 static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
-  // Options (and their extensions) are completely resolved in the proto file
-  // containing the descriptor.
-  PyDescriptorPool* pool = GetDescriptorPool_FromPool(
+  // Options are cached in the pool that owns the descriptor.
+  // First search in the cache.
+  PyDescriptorPool* caching_pool = GetDescriptorPool_FromPool(
       GetFileDescriptor(descriptor)->pool());
-
   hash_map<const void*, PyObject*>* descriptor_options =
-      pool->descriptor_options;
-  // First search in the cache.
+      caching_pool->descriptor_options;
   if (descriptor_options->find(descriptor) != descriptor_options->end()) {
     PyObject *value = (*descriptor_options)[descriptor];
     Py_INCREF(value);
     return value;
   }
 
+  // Similar to the C++ implementation, we return an Options object from the
+  // default (generated) factory, so that client code know that they can use
+  // extensions from generated files:
+  //    d.GetOptions().Extensions[some_pb2.extension]
+  //
+  // The consequence is that extensions not defined in the default pool won't
+  // be available.  If needed, we could add an optional 'message_factory'
+  // parameter to the GetOptions() function.
+  PyMessageFactory* message_factory =
+      GetDefaultDescriptorPool()->py_message_factory;
+
   // Build the Options object: get its Python class, and make a copy of the C++
   // read-only instance.
   const Message& options(descriptor->options());
   const Descriptor *message_type = options.GetDescriptor();
-  PyMessageFactory* message_factory = pool->py_message_factory;
-  CMessageClass* message_class = message_factory::GetMessageClass(
+  CMessageClass* message_class = message_factory::GetOrCreateMessageClass(
       message_factory, message_type);
   if (message_class == NULL) {
-    // The Options message was not found in the current DescriptorPool.
-    // This means that the pool cannot contain any extensions to the Options
-    // message either, so falling back to the basic pool we can only increase
-    // the chances of successfully parsing the options.
-    PyErr_Clear();
-    pool = GetDefaultDescriptorPool();
-    message_factory = pool->py_message_factory;
-    message_class = message_factory::GetMessageClass(
-      message_factory, message_type);
-  }
-  if (message_class == NULL) {
     PyErr_Format(PyExc_TypeError, "Could not retrieve class for Options: %s",
                  message_type->full_name().c_str());
     return NULL;
@@ -248,7 +245,8 @@ static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
     options.SerializeToString(&serialized);
     io::CodedInputStream input(
         reinterpret_cast<const uint8*>(serialized.c_str()), serialized.size());
-    input.SetExtensionRegistry(pool->pool, message_factory->message_factory);
+    input.SetExtensionRegistry(message_factory->pool->pool,
+                               message_factory->message_factory);
     bool success = cmsg->message->MergePartialFromCodedStream(&input);
     if (!success) {
       PyErr_Format(PyExc_ValueError, "Error parsing Options message");
@@ -564,6 +562,11 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyBaseDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
+
 static PyObject* CopyToProto(PyBaseDescriptor *self, PyObject *target) {
   return CopyToPythonProto<DescriptorProto>(_GetDescriptor(self), target);
 }
@@ -623,6 +626,8 @@ static PyGetSetDef Getters[] = {
   { "is_extendable", (getter)IsExtendable, (setter)NULL},
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   { "syntax", (getter)GetSyntax, (setter)NULL, "Syntax"},
   {NULL}
 };
@@ -785,7 +790,7 @@ static PyObject* GetDefaultValue(PyBaseDescriptor *self, void *closure) {
       break;
     }
     case FieldDescriptor::CPPTYPE_STRING: {
-      string value = _GetDescriptor(self)->default_value_string();
+      const string& value = _GetDescriptor(self)->default_value_string();
       result = ToStringObject(_GetDescriptor(self), value);
       break;
     }
@@ -897,6 +902,10 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyBaseDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
 
 static PyGetSetDef Getters[] = {
   { "full_name", (getter)GetFullName, NULL, "Full name"},
@@ -926,6 +935,8 @@ static PyGetSetDef Getters[] = {
     "Containing oneof"},
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   {NULL}
 };
 
@@ -1055,6 +1066,11 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyBaseDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
+
 static PyObject* CopyToProto(PyBaseDescriptor *self, PyObject *target) {
   return CopyToPythonProto<EnumDescriptorProto>(_GetDescriptor(self), target);
 }
@@ -1079,6 +1095,8 @@ static PyGetSetDef Getters[] = {
     "Containing type"},
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   {NULL}
 };
 
@@ -1179,6 +1197,10 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyBaseDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
 
 static PyGetSetDef Getters[] = {
   { "name", (getter)GetName, NULL, "name"},
@@ -1188,6 +1210,8 @@ static PyGetSetDef Getters[] = {
 
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   {NULL}
 };
 
@@ -1330,6 +1354,11 @@ static int SetOptions(PyFileDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyFileDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
+
 static PyObject* GetSyntax(PyFileDescriptor *self, void *closure) {
   return PyString_InternFromString(
       FileDescriptor::SyntaxName(_GetDescriptor(self)->syntax()));
@@ -1355,6 +1384,8 @@ static PyGetSetDef Getters[] = {
 
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   { "syntax", (getter)GetSyntax, (setter)NULL, "Syntax"},
   {NULL}
 };
@@ -1500,6 +1531,11 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
   return CheckCalledFromGeneratedFile("_options");
 }
 
+static int SetSerializedOptions(PyBaseDescriptor *self, PyObject *value,
+                                void *closure) {
+  return CheckCalledFromGeneratedFile("_serialized_options");
+}
+
 static PyGetSetDef Getters[] = {
   { "name", (getter)GetName, NULL, "Name"},
   { "full_name", (getter)GetFullName, NULL, "Full name"},
@@ -1508,6 +1544,8 @@ static PyGetSetDef Getters[] = {
   { "containing_type", (getter)GetContainingType, NULL, "Containing type"},
   { "has_options", (getter)GetHasOptions, (setter)SetHasOptions, "Has Options"},
   { "_options", (getter)NULL, (setter)SetOptions, "Options"},
+  { "_serialized_options", (getter)NULL, (setter)SetSerializedOptions,
+    "Serialized Options"},
   { "fields", (getter)GetFields, NULL, "Fields"},
   {NULL}
 };
diff --git a/python/google/protobuf/pyext/descriptor_pool.cc b/python/google/protobuf/pyext/descriptor_pool.cc
index 16f4d49d..95882aeb 100644
--- a/python/google/protobuf/pyext/descriptor_pool.cc
+++ b/python/google/protobuf/pyext/descriptor_pool.cc
@@ -149,7 +149,8 @@ static PyObject* New(PyTypeObject* type,
       PyDescriptorPool_NewWithDatabase(database));
 }
 
-static void Dealloc(PyDescriptorPool* self) {
+static void Dealloc(PyObject* pself) {
+  PyDescriptorPool* self = reinterpret_cast<PyDescriptorPool*>(pself);
   descriptor_pool_map.erase(self->pool);
   Py_CLEAR(self->py_message_factory);
   for (hash_map<const void*, PyObject*>::iterator it =
@@ -163,7 +164,7 @@ static void Dealloc(PyDescriptorPool* self) {
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
-PyObject* FindMessageByName(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindMessageByName(PyObject* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
   if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
@@ -171,7 +172,8 @@ PyObject* FindMessageByName(PyDescriptorPool* self, PyObject* arg) {
   }
 
   const Descriptor* message_descriptor =
-      self->pool->FindMessageTypeByName(string(name, name_size));
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindMessageTypeByName(
+          string(name, name_size));
 
   if (message_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find message %.200s", name);
@@ -184,7 +186,7 @@ PyObject* FindMessageByName(PyDescriptorPool* self, PyObject* arg) {
 
 
 
-PyObject* FindFileByName(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindFileByName(PyObject* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
   if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
@@ -192,7 +194,8 @@ PyObject* FindFileByName(PyDescriptorPool* self, PyObject* arg) {
   }
 
   const FileDescriptor* file_descriptor =
-      self->pool->FindFileByName(string(name, name_size));
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindFileByName(
+          string(name, name_size));
   if (file_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find file %.200s", name);
     return NULL;
@@ -218,6 +221,10 @@ PyObject* FindFieldByName(PyDescriptorPool* self, PyObject* arg) {
   return PyFieldDescriptor_FromDescriptor(field_descriptor);
 }
 
+static PyObject* FindFieldByNameMethod(PyObject* self, PyObject* arg) {
+  return FindFieldByName(reinterpret_cast<PyDescriptorPool*>(self), arg);
+}
+
 PyObject* FindExtensionByName(PyDescriptorPool* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
@@ -235,6 +242,10 @@ PyObject* FindExtensionByName(PyDescriptorPool* self, PyObject* arg) {
   return PyFieldDescriptor_FromDescriptor(field_descriptor);
 }
 
+static PyObject* FindExtensionByNameMethod(PyObject* self, PyObject* arg) {
+  return FindExtensionByName(reinterpret_cast<PyDescriptorPool*>(self), arg);
+}
+
 PyObject* FindEnumTypeByName(PyDescriptorPool* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
@@ -252,6 +263,10 @@ PyObject* FindEnumTypeByName(PyDescriptorPool* self, PyObject* arg) {
   return PyEnumDescriptor_FromDescriptor(enum_descriptor);
 }
 
+static PyObject* FindEnumTypeByNameMethod(PyObject* self, PyObject* arg) {
+  return FindEnumTypeByName(reinterpret_cast<PyDescriptorPool*>(self), arg);
+}
+
 PyObject* FindOneofByName(PyDescriptorPool* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
@@ -269,7 +284,11 @@ PyObject* FindOneofByName(PyDescriptorPool* self, PyObject* arg) {
   return PyOneofDescriptor_FromDescriptor(oneof_descriptor);
 }
 
-PyObject* FindServiceByName(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindOneofByNameMethod(PyObject* self, PyObject* arg) {
+  return FindOneofByName(reinterpret_cast<PyDescriptorPool*>(self), arg);
+}
+
+static PyObject* FindServiceByName(PyObject* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
   if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
@@ -277,7 +296,8 @@ PyObject* FindServiceByName(PyDescriptorPool* self, PyObject* arg) {
   }
 
   const ServiceDescriptor* service_descriptor =
-      self->pool->FindServiceByName(string(name, name_size));
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindServiceByName(
+          string(name, name_size));
   if (service_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find service %.200s", name);
     return NULL;
@@ -286,7 +306,7 @@ PyObject* FindServiceByName(PyDescriptorPool* self, PyObject* arg) {
   return PyServiceDescriptor_FromDescriptor(service_descriptor);
 }
 
-PyObject* FindMethodByName(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindMethodByName(PyObject* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
   if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
@@ -294,7 +314,8 @@ PyObject* FindMethodByName(PyDescriptorPool* self, PyObject* arg) {
   }
 
   const MethodDescriptor* method_descriptor =
-      self->pool->FindMethodByName(string(name, name_size));
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindMethodByName(
+          string(name, name_size));
   if (method_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find method %.200s", name);
     return NULL;
@@ -303,7 +324,7 @@ PyObject* FindMethodByName(PyDescriptorPool* self, PyObject* arg) {
   return PyMethodDescriptor_FromDescriptor(method_descriptor);
 }
 
-PyObject* FindFileContainingSymbol(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindFileContainingSymbol(PyObject* self, PyObject* arg) {
   Py_ssize_t name_size;
   char* name;
   if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
@@ -311,7 +332,8 @@ PyObject* FindFileContainingSymbol(PyDescriptorPool* self, PyObject* arg) {
   }
 
   const FileDescriptor* file_descriptor =
-      self->pool->FindFileContainingSymbol(string(name, name_size));
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindFileContainingSymbol(
+          string(name, name_size));
   if (file_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find symbol %.200s", name);
     return NULL;
@@ -320,7 +342,7 @@ PyObject* FindFileContainingSymbol(PyDescriptorPool* self, PyObject* arg) {
   return PyFileDescriptor_FromDescriptor(file_descriptor);
 }
 
-PyObject* FindExtensionByNumber(PyDescriptorPool* self, PyObject* args) {
+static PyObject* FindExtensionByNumber(PyObject* self, PyObject* args) {
   PyObject* message_descriptor;
   int number;
   if (!PyArg_ParseTuple(args, "Oi", &message_descriptor, &number)) {
@@ -333,7 +355,8 @@ PyObject* FindExtensionByNumber(PyDescriptorPool* self, PyObject* args) {
   }
 
   const FieldDescriptor* extension_descriptor =
-      self->pool->FindExtensionByNumber(descriptor, number);
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindExtensionByNumber(
+          descriptor, number);
   if (extension_descriptor == NULL) {
     PyErr_Format(PyExc_KeyError, "Couldn't find extension %d", number);
     return NULL;
@@ -342,14 +365,15 @@ PyObject* FindExtensionByNumber(PyDescriptorPool* self, PyObject* args) {
   return PyFieldDescriptor_FromDescriptor(extension_descriptor);
 }
 
-PyObject* FindAllExtensions(PyDescriptorPool* self, PyObject* arg) {
+static PyObject* FindAllExtensions(PyObject* self, PyObject* arg) {
   const Descriptor* descriptor = PyMessageDescriptor_AsDescriptor(arg);
   if (descriptor == NULL) {
     return NULL;
   }
 
   std::vector<const FieldDescriptor*> extensions;
-  self->pool->FindAllExtensions(descriptor, &extensions);
+  reinterpret_cast<PyDescriptorPool*>(self)->pool->FindAllExtensions(
+      descriptor, &extensions);
 
   ScopedPyObjectPtr result(PyList_New(extensions.size()));
   if (result == NULL) {
@@ -374,14 +398,15 @@ PyObject* FindAllExtensions(PyDescriptorPool* self, PyObject* arg) {
 // call a function that will just be a no-op?
 // TODO(amauryfa): Need to investigate further.
 
-PyObject* AddFileDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+static PyObject* AddFileDescriptor(PyObject* self, PyObject* descriptor) {
   const FileDescriptor* file_descriptor =
       PyFileDescriptor_AsDescriptor(descriptor);
   if (!file_descriptor) {
     return NULL;
   }
   if (file_descriptor !=
-      self->pool->FindFileByName(file_descriptor->name())) {
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindFileByName(
+          file_descriptor->name())) {
     PyErr_Format(PyExc_ValueError,
                  "The file descriptor %s does not belong to this pool",
                  file_descriptor->name().c_str());
@@ -390,14 +415,15 @@ PyObject* AddFileDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
   Py_RETURN_NONE;
 }
 
-PyObject* AddDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+static PyObject* AddDescriptor(PyObject* self, PyObject* descriptor) {
   const Descriptor* message_descriptor =
       PyMessageDescriptor_AsDescriptor(descriptor);
   if (!message_descriptor) {
     return NULL;
   }
   if (message_descriptor !=
-      self->pool->FindMessageTypeByName(message_descriptor->full_name())) {
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindMessageTypeByName(
+          message_descriptor->full_name())) {
     PyErr_Format(PyExc_ValueError,
                  "The message descriptor %s does not belong to this pool",
                  message_descriptor->full_name().c_str());
@@ -406,14 +432,15 @@ PyObject* AddDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
   Py_RETURN_NONE;
 }
 
-PyObject* AddEnumDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+static PyObject* AddEnumDescriptor(PyObject* self, PyObject* descriptor) {
   const EnumDescriptor* enum_descriptor =
       PyEnumDescriptor_AsDescriptor(descriptor);
   if (!enum_descriptor) {
     return NULL;
   }
   if (enum_descriptor !=
-      self->pool->FindEnumTypeByName(enum_descriptor->full_name())) {
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindEnumTypeByName(
+          enum_descriptor->full_name())) {
     PyErr_Format(PyExc_ValueError,
                  "The enum descriptor %s does not belong to this pool",
                  enum_descriptor->full_name().c_str());
@@ -422,14 +449,15 @@ PyObject* AddEnumDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
   Py_RETURN_NONE;
 }
 
-PyObject* AddExtensionDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+static PyObject* AddExtensionDescriptor(PyObject* self, PyObject* descriptor) {
   const FieldDescriptor* extension_descriptor =
       PyFieldDescriptor_AsDescriptor(descriptor);
   if (!extension_descriptor) {
     return NULL;
   }
   if (extension_descriptor !=
-      self->pool->FindExtensionByName(extension_descriptor->full_name())) {
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindExtensionByName(
+          extension_descriptor->full_name())) {
     PyErr_Format(PyExc_ValueError,
                  "The extension descriptor %s does not belong to this pool",
                  extension_descriptor->full_name().c_str());
@@ -438,14 +466,15 @@ PyObject* AddExtensionDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
   Py_RETURN_NONE;
 }
 
-PyObject* AddServiceDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+static PyObject* AddServiceDescriptor(PyObject* self, PyObject* descriptor) {
   const ServiceDescriptor* service_descriptor =
       PyServiceDescriptor_AsDescriptor(descriptor);
   if (!service_descriptor) {
     return NULL;
   }
   if (service_descriptor !=
-      self->pool->FindServiceByName(service_descriptor->full_name())) {
+      reinterpret_cast<PyDescriptorPool*>(self)->pool->FindServiceByName(
+          service_descriptor->full_name())) {
     PyErr_Format(PyExc_ValueError,
                  "The service descriptor %s does not belong to this pool",
                  service_descriptor->full_name().c_str());
@@ -481,7 +510,8 @@ class BuildFileErrorCollector : public DescriptorPool::ErrorCollector {
   bool had_errors;
 };
 
-PyObject* AddSerializedFile(PyDescriptorPool* self, PyObject* serialized_pb) {
+static PyObject* AddSerializedFile(PyObject* pself, PyObject* serialized_pb) {
+  PyDescriptorPool* self = reinterpret_cast<PyDescriptorPool*>(pself);
   char* message_type;
   Py_ssize_t message_len;
 
@@ -529,7 +559,7 @@ PyObject* AddSerializedFile(PyDescriptorPool* self, PyObject* serialized_pb) {
       descriptor, serialized_pb);
 }
 
-PyObject* Add(PyDescriptorPool* self, PyObject* file_descriptor_proto) {
+static PyObject* Add(PyObject* self, PyObject* file_descriptor_proto) {
   ScopedPyObjectPtr serialized_pb(
       PyObject_CallMethod(file_descriptor_proto, "SerializeToString", NULL));
   if (serialized_pb == NULL) {
@@ -539,46 +569,46 @@ PyObject* Add(PyDescriptorPool* self, PyObject* file_descriptor_proto) {
 }
 
 static PyMethodDef Methods[] = {
-  { "Add", (PyCFunction)Add, METH_O,
+  { "Add", Add, METH_O,
     "Adds the FileDescriptorProto and its types to this pool." },
-  { "AddSerializedFile", (PyCFunction)AddSerializedFile, METH_O,
+  { "AddSerializedFile", AddSerializedFile, METH_O,
     "Adds a serialized FileDescriptorProto to this pool." },
 
   // TODO(amauryfa): Understand why the Python implementation differs from
   // this one, ask users to use another API and deprecate these functions.
-  { "AddFileDescriptor", (PyCFunction)AddFileDescriptor, METH_O,
+  { "AddFileDescriptor", AddFileDescriptor, METH_O,
     "No-op. Add() must have been called before." },
-  { "AddDescriptor", (PyCFunction)AddDescriptor, METH_O,
+  { "AddDescriptor", AddDescriptor, METH_O,
     "No-op. Add() must have been called before." },
-  { "AddEnumDescriptor", (PyCFunction)AddEnumDescriptor, METH_O,
+  { "AddEnumDescriptor", AddEnumDescriptor, METH_O,
     "No-op. Add() must have been called before." },
-  { "AddExtensionDescriptor", (PyCFunction)AddExtensionDescriptor, METH_O,
+  { "AddExtensionDescriptor", AddExtensionDescriptor, METH_O,
     "No-op. Add() must have been called before." },
-  { "AddServiceDescriptor", (PyCFunction)AddServiceDescriptor, METH_O,
+  { "AddServiceDescriptor", AddServiceDescriptor, METH_O,
     "No-op. Add() must have been called before." },
 
-  { "FindFileByName", (PyCFunction)FindFileByName, METH_O,
+  { "FindFileByName", FindFileByName, METH_O,
     "Searches for a file descriptor by its .proto name." },
-  { "FindMessageTypeByName", (PyCFunction)FindMessageByName, METH_O,
+  { "FindMessageTypeByName", FindMessageByName, METH_O,
     "Searches for a message descriptor by full name." },
-  { "FindFieldByName", (PyCFunction)FindFieldByName, METH_O,
+  { "FindFieldByName", FindFieldByNameMethod, METH_O,
     "Searches for a field descriptor by full name." },
-  { "FindExtensionByName", (PyCFunction)FindExtensionByName, METH_O,
+  { "FindExtensionByName", FindExtensionByNameMethod, METH_O,
     "Searches for extension descriptor by full name." },
-  { "FindEnumTypeByName", (PyCFunction)FindEnumTypeByName, METH_O,
+  { "FindEnumTypeByName", FindEnumTypeByNameMethod, METH_O,
     "Searches for enum type descriptor by full name." },
-  { "FindOneofByName", (PyCFunction)FindOneofByName, METH_O,
+  { "FindOneofByName", FindOneofByNameMethod, METH_O,
     "Searches for oneof descriptor by full name." },
-  { "FindServiceByName", (PyCFunction)FindServiceByName, METH_O,
+  { "FindServiceByName", FindServiceByName, METH_O,
     "Searches for service descriptor by full name." },
-  { "FindMethodByName", (PyCFunction)FindMethodByName, METH_O,
+  { "FindMethodByName", FindMethodByName, METH_O,
     "Searches for method descriptor by full name." },
 
-  { "FindFileContainingSymbol", (PyCFunction)FindFileContainingSymbol, METH_O,
+  { "FindFileContainingSymbol", FindFileContainingSymbol, METH_O,
     "Gets the FileDescriptor containing the specified symbol." },
-  { "FindExtensionByNumber", (PyCFunction)FindExtensionByNumber, METH_VARARGS,
+  { "FindExtensionByNumber", FindExtensionByNumber, METH_VARARGS,
     "Gets the extension descriptor for the given number." },
-  { "FindAllExtensions", (PyCFunction)FindAllExtensions, METH_O,
+  { "FindAllExtensions", FindAllExtensions, METH_O,
     "Gets all known extensions of the given message descriptor." },
   {NULL}
 };
@@ -590,7 +620,7 @@ PyTypeObject PyDescriptorPool_Type = {
   FULL_MODULE_NAME ".DescriptorPool",  // tp_name
   sizeof(PyDescriptorPool),            // tp_basicsize
   0,                                   // tp_itemsize
-  (destructor)cdescriptor_pool::Dealloc,  // tp_dealloc
+  cdescriptor_pool::Dealloc,           // tp_dealloc
   0,                                   // tp_print
   0,                                   // tp_getattr
   0,                                   // tp_setattr
diff --git a/python/google/protobuf/pyext/extension_dict.cc b/python/google/protobuf/pyext/extension_dict.cc
index 6830b10d..018b5c2c 100644
--- a/python/google/protobuf/pyext/extension_dict.cc
+++ b/python/google/protobuf/pyext/extension_dict.cc
@@ -33,9 +33,6 @@
 
 #include <google/protobuf/pyext/extension_dict.h>
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
diff --git a/python/google/protobuf/pyext/extension_dict.h b/python/google/protobuf/pyext/extension_dict.h
index 65b87862..0de2c4ee 100644
--- a/python/google/protobuf/pyext/extension_dict.h
+++ b/python/google/protobuf/pyext/extension_dict.h
@@ -37,9 +37,8 @@
 #include <Python.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
+
+#include <google/protobuf/pyext/message.h>
 
 namespace google {
 namespace protobuf {
@@ -47,16 +46,8 @@ namespace protobuf {
 class Message;
 class FieldDescriptor;
 
-#ifdef _SHARED_PTR_H
-using std::shared_ptr;
-#else
-using internal::shared_ptr;
-#endif
-
 namespace python {
 
-struct CMessage;
-
 typedef struct ExtensionDict {
   PyObject_HEAD;
 
@@ -64,7 +55,7 @@ typedef struct ExtensionDict {
   // proto tree.  Every Python container class holds a
   // reference to it in order to keep it alive as long as there's a
   // Python object that references any part of the tree.
-  shared_ptr<Message> owner;
+  CMessage::OwnerRef owner;
 
   // Weak reference to parent message. Used to make sure
   // the parent is writable when an extension field is modified.
diff --git a/python/google/protobuf/pyext/map_container.cc b/python/google/protobuf/pyext/map_container.cc
index abd15b77..6d7ee285 100644
--- a/python/google/protobuf/pyext/map_container.cc
+++ b/python/google/protobuf/pyext/map_container.cc
@@ -33,9 +33,6 @@
 #include <google/protobuf/pyext/map_container.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
@@ -76,7 +73,7 @@ class MapReflectionFriend {
 struct MapIterator {
   PyObject_HEAD;
 
-  google::protobuf::scoped_ptr< ::google::protobuf::MapIterator> iter;
+  std::unique_ptr<::google::protobuf::MapIterator> iter;
 
   // A pointer back to the container, so we can notice changes to the version.
   // We own a ref on this.
@@ -94,7 +91,7 @@ struct MapIterator {
   // as this iterator does.  This is solely for the benefit of the MapIterator
   // destructor -- we should never actually access the iterator in this state
   // except to delete it.
-  shared_ptr<Message> owner;
+  CMessage::OwnerRef owner;
 
   // The version of the map when we took the iterator to it.
   //
@@ -339,6 +336,24 @@ PyObject* GetEntryClass(PyObject* _self) {
   return reinterpret_cast<PyObject*>(message_class);
 }
 
+PyObject* MergeFrom(PyObject* _self, PyObject* arg) {
+  MapContainer* self = GetMap(_self);
+  MapContainer* other_map = GetMap(arg);
+  Message* message = self->GetMutableMessage();
+  const Message* other_message = other_map->message;
+  const Reflection* reflection = message->GetReflection();
+  const Reflection* other_reflection = other_message->GetReflection();
+  int count = other_reflection->FieldSize(
+      *other_message, other_map->parent_field_descriptor);
+  for (int i = 0 ; i < count; i ++) {
+    reflection->AddMessage(message, self->parent_field_descriptor)->MergeFrom(
+        other_reflection->GetRepeatedMessage(
+            *other_message, other_map->parent_field_descriptor, i));
+  }
+  self->version++;
+  Py_RETURN_NONE;
+}
+
 PyObject* MapReflectionFriend::Contains(PyObject* _self, PyObject* key) {
   MapContainer* self = GetMap(_self);
 
@@ -535,6 +550,8 @@ static PyMethodDef ScalarMapMethods[] = {
     "Gets the value for the given key if present, or otherwise a default" },
   { "GetEntryClass", (PyCFunction)GetEntryClass, METH_NOARGS,
     "Return the class used to build Entries of (key, value) pairs." },
+  { "MergeFrom", (PyCFunction)MergeFrom, METH_O,
+    "Merges a map into the current map." },
   /*
   { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
     "Makes a deep copy of the class." },
@@ -810,6 +827,8 @@ static PyMethodDef MessageMapMethods[] = {
     "Alias for getitem, useful to make explicit that the map is mutated." },
   { "GetEntryClass", (PyCFunction)GetEntryClass, METH_NOARGS,
     "Return the class used to build Entries of (key, value) pairs." },
+  { "MergeFrom", (PyCFunction)MergeFrom, METH_O,
+    "Merges a map into the current map." },
   /*
   { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
     "Makes a deep copy of the class." },
diff --git a/python/google/protobuf/pyext/map_container.h b/python/google/protobuf/pyext/map_container.h
index 615657b0..111fafbf 100644
--- a/python/google/protobuf/pyext/map_container.h
+++ b/python/google/protobuf/pyext/map_container.h
@@ -34,27 +34,18 @@
 #include <Python.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/message.h>
+#include <google/protobuf/pyext/message.h>
 
 namespace google {
 namespace protobuf {
 
 class Message;
 
-#ifdef _SHARED_PTR_H
-using std::shared_ptr;
-#else
-using internal::shared_ptr;
-#endif
-
 namespace python {
 
-struct CMessage;
 struct CMessageClass;
 
 // This struct is used directly for ScalarMap, and is the base class of
@@ -66,7 +57,7 @@ struct MapContainer {
   // proto tree.  Every Python MapContainer holds a
   // reference to it in order to keep it alive as long as there's a
   // Python object that references any part of the tree.
-  shared_ptr<Message> owner;
+  CMessage::OwnerRef owner;
 
   // Pointer to the C++ Message that contains this container.  The
   // MapContainer does not own this pointer.
@@ -99,9 +90,7 @@ struct MapContainer {
   int Release();
 
   // Set the owner field of self and any children of self.
-  void SetOwner(const shared_ptr<Message>& new_owner) {
-    owner = new_owner;
-  }
+  void SetOwner(const CMessage::OwnerRef& new_owner) { owner = new_owner; }
 };
 
 struct MessageMapContainer : public MapContainer {
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index f515b560..5893533a 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -35,9 +35,6 @@
 
 #include <map>
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 #include <string>
 #include <vector>
 #include <structmember.h>  // A Python header file.
@@ -658,7 +655,7 @@ bool CheckAndGetInteger(PyObject* arg, T* value) {
       // Unlike PyLong_AsLongLong, PyLong_AsUnsignedLongLong is very
       // picky about the exact type.
       PyObject* casted = PyNumber_Long(arg);
-      if (GOOGLE_PREDICT_FALSE(casted == NULL)) {
+      if (GOOGLE_PREDICT_FALSE(casted == nullptr)) {
         // Propagate existing error.
         return false;
         }
@@ -683,7 +680,7 @@ bool CheckAndGetInteger(PyObject* arg, T* value) {
       // Valid subclasses of numbers.Integral should have a __long__() method
       // so fall back to that.
       PyObject* casted = PyNumber_Long(arg);
-      if (GOOGLE_PREDICT_FALSE(casted == NULL)) {
+      if (GOOGLE_PREDICT_FALSE(casted == nullptr)) {
         // Propagate existing error.
         return false;
         }
@@ -830,7 +827,8 @@ bool CheckAndSetString(
   return true;
 }
 
-PyObject* ToStringObject(const FieldDescriptor* descriptor, string value) {
+PyObject* ToStringObject(const FieldDescriptor* descriptor,
+                         const string& value) {
   if (descriptor->type() != FieldDescriptor::TYPE_STRING) {
     return PyBytes_FromStringAndSize(value.c_str(), value.length());
   }
@@ -1318,6 +1316,8 @@ CMessage* NewEmptyMessage(CMessageClass* type) {
     return NULL;
   }
 
+  // Use "placement new" syntax to initialize the C++ object.
+  new (&self->owner) CMessage::OwnerRef(NULL);
   self->message = NULL;
   self->parent = NULL;
   self->parent_field_descriptor = NULL;
@@ -1414,7 +1414,7 @@ static void Dealloc(CMessage* self) {
 
   Py_CLEAR(self->extensions);
   Py_CLEAR(self->composite_fields);
-  self->owner.reset();
+  self->owner.~ThreadUnsafeSharedPtr<Message>();
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
@@ -1616,9 +1616,10 @@ PyObject* HasExtension(CMessage* self, PyObject* extension) {
 // * Clear the weak references from the released container to the
 //   parent.
 
-struct SetOwnerVisitor : public ChildVisitor {
+class SetOwnerVisitor : public ChildVisitor {
+ public:
   // new_owner must outlive this object.
-  explicit SetOwnerVisitor(const shared_ptr<Message>& new_owner)
+  explicit SetOwnerVisitor(const CMessage::OwnerRef& new_owner)
       : new_owner_(new_owner) {}
 
   int VisitRepeatedCompositeContainer(RepeatedCompositeContainer* container) {
@@ -1642,11 +1643,11 @@ struct SetOwnerVisitor : public ChildVisitor {
   }
 
  private:
-  const shared_ptr<Message>& new_owner_;
+  const CMessage::OwnerRef& new_owner_;
 };
 
 // Change the owner of this CMessage and all its children, recursively.
-int SetOwner(CMessage* self, const shared_ptr<Message>& new_owner) {
+int SetOwner(CMessage* self, const CMessage::OwnerRef& new_owner) {
   self->owner = new_owner;
   if (ForEachCompositeField(self, SetOwnerVisitor(new_owner)) == -1)
     return -1;
@@ -1679,7 +1680,7 @@ int ReleaseSubMessage(CMessage* self,
                       const FieldDescriptor* field_descriptor,
                       CMessage* child_cmessage) {
   // Release the Message
-  shared_ptr<Message> released_message(ReleaseMessage(
+  CMessage::OwnerRef released_message(ReleaseMessage(
       self, child_cmessage->message->GetDescriptor(), field_descriptor));
   child_cmessage->message = released_message.get();
   child_cmessage->owner.swap(released_message);
@@ -2329,7 +2330,9 @@ PyObject* InternalGetScalar(const Message* message,
       break;
     }
     case FieldDescriptor::CPPTYPE_STRING: {
-      string value = reflection->GetString(*message, field_descriptor);
+      string scratch;
+      const string& value =
+          reflection->GetStringReference(*message, field_descriptor, &scratch);
       result = ToStringObject(field_descriptor, value);
       break;
     }
diff --git a/python/google/protobuf/pyext/message.h b/python/google/protobuf/pyext/message.h
index 576d098c..7050f876 100644
--- a/python/google/protobuf/pyext/message.h
+++ b/python/google/protobuf/pyext/message.h
@@ -37,11 +37,11 @@
 #include <Python.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 #include <string>
 
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/pyext/thread_unsafe_shared_ptr.h>
+
 namespace google {
 namespace protobuf {
 
@@ -71,7 +71,9 @@ typedef struct CMessage {
   // proto tree.  Every Python CMessage holds a reference to it in
   // order to keep it alive as long as there's a Python object that
   // references any part of the tree.
-  shared_ptr<Message> owner;
+
+  typedef ThreadUnsafeSharedPtr<Message> OwnerRef;
+  OwnerRef owner;
 
   // Weak reference to a parent CMessage object. This is NULL for any top-level
   // message and is set for any child message (i.e. a child submessage or a
@@ -255,7 +257,7 @@ PyObject* FindInitializationErrors(CMessage* self);
 // Set the owner field of self and any children of self, recursively.
 // Used when self is being released and thus has a new owner (the
 // released Message.)
-int SetOwner(CMessage* self, const shared_ptr<Message>& new_owner);
+int SetOwner(CMessage* self, const CMessage::OwnerRef& new_owner);
 
 int AssureWritable(CMessage* self);
 
@@ -336,7 +338,8 @@ bool CheckAndSetString(
     const Reflection* reflection,
     bool append,
     int index);
-PyObject* ToStringObject(const FieldDescriptor* descriptor, string value);
+PyObject* ToStringObject(const FieldDescriptor* descriptor,
+                         const string& value);
 
 // Check if the passed field descriptor belongs to the given message.
 // If not, return false and set a Python exception (a KeyError)
@@ -347,6 +350,15 @@ extern PyObject* PickleError_class;
 
 bool InitProto2MessageModule(PyObject *m);
 
+#if LANG_CXX11
+// These are referenced by repeated_scalar_container, and must
+// be explicitly instantiated.
+extern template bool CheckAndGetInteger<int32>(PyObject*, int32*);
+extern template bool CheckAndGetInteger<int64>(PyObject*, int64*);
+extern template bool CheckAndGetInteger<uint32>(PyObject*, uint32*);
+extern template bool CheckAndGetInteger<uint64>(PyObject*, uint64*);
+#endif
+
 }  // namespace python
 }  // namespace protobuf
 
diff --git a/python/google/protobuf/pyext/message_factory.cc b/python/google/protobuf/pyext/message_factory.cc
index 571bae2b..bacc76a6 100644
--- a/python/google/protobuf/pyext/message_factory.cc
+++ b/python/google/protobuf/pyext/message_factory.cc
@@ -100,7 +100,9 @@ PyObject* New(PyTypeObject* type, PyObject* args, PyObject* kwargs) {
       NewMessageFactory(type, reinterpret_cast<PyDescriptorPool*>(pool)));
 }
 
-static void Dealloc(PyMessageFactory* self) {
+static void Dealloc(PyObject* pself) {
+  PyMessageFactory* self = reinterpret_cast<PyMessageFactory*>(pself);
+
   // TODO(amauryfa): When the MessageFactory is not created from the
   // DescriptorPool this reference should be owned, not borrowed.
   // Py_CLEAR(self->pool);
@@ -111,7 +113,7 @@ static void Dealloc(PyMessageFactory* self) {
   }
   delete self->classes_by_descriptor;
   delete self->message_factory;
-  Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
+  Py_TYPE(self)->tp_free(pself);
 }
 
 // Add a message class to our database.
@@ -231,7 +233,7 @@ PyTypeObject PyMessageFactory_Type = {
     ".MessageFactory",                        // tp_name
     sizeof(PyMessageFactory),                 // tp_basicsize
     0,                                        // tp_itemsize
-    (destructor)message_factory::Dealloc,     // tp_dealloc
+    message_factory::Dealloc,                 // tp_dealloc
     0,                                        // tp_print
     0,                                        // tp_getattr
     0,                                        // tp_setattr
diff --git a/python/google/protobuf/pyext/repeated_composite_container.cc b/python/google/protobuf/pyext/repeated_composite_container.cc
index 5ad71db5..5874d5de 100644
--- a/python/google/protobuf/pyext/repeated_composite_container.cc
+++ b/python/google/protobuf/pyext/repeated_composite_container.cc
@@ -34,9 +34,6 @@
 #include <google/protobuf/pyext/repeated_composite_container.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
@@ -81,7 +78,10 @@ namespace repeated_composite_container {
 // ---------------------------------------------------------------------
 // len()
 
-static Py_ssize_t Length(RepeatedCompositeContainer* self) {
+static Py_ssize_t Length(PyObject* pself) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   Message* message = self->message;
   if (message != NULL) {
     return message->GetReflection()->FieldSize(*message,
@@ -102,7 +102,7 @@ static int UpdateChildMessages(RepeatedCompositeContainer* self) {
   // A MergeFrom on a parent message could have caused extra messages to be
   // added in the underlying protobuf so add them to our list. They can never
   // be removed in such a way so there's no need to worry about that.
-  Py_ssize_t message_length = Length(self);
+  Py_ssize_t message_length = Length(reinterpret_cast<PyObject*>(self));
   Py_ssize_t child_length = PyList_GET_SIZE(self->child_messages);
   Message* message = self->message;
   const Reflection* reflection = message->GetReflection();
@@ -191,6 +191,10 @@ PyObject* Add(RepeatedCompositeContainer* self,
     return AddToAttached(self, args, kwargs);
 }
 
+static PyObject* AddMethod(PyObject* self, PyObject* args, PyObject* kwargs) {
+  return Add(reinterpret_cast<RepeatedCompositeContainer*>(self), args, kwargs);
+}
+
 // ---------------------------------------------------------------------
 // extend()
 
@@ -226,6 +230,10 @@ PyObject* Extend(RepeatedCompositeContainer* self, PyObject* value) {
   Py_RETURN_NONE;
 }
 
+static PyObject* ExtendMethod(PyObject* self, PyObject* value) {
+  return Extend(reinterpret_cast<RepeatedCompositeContainer*>(self), value);
+}
+
 PyObject* MergeFrom(RepeatedCompositeContainer* self, PyObject* other) {
   if (UpdateChildMessages(self) < 0) {
     return NULL;
@@ -233,6 +241,10 @@ PyObject* MergeFrom(RepeatedCompositeContainer* self, PyObject* other) {
   return Extend(self, other);
 }
 
+static PyObject* MergeFromMethod(PyObject* self, PyObject* other) {
+  return MergeFrom(reinterpret_cast<RepeatedCompositeContainer*>(self), other);
+}
+
 PyObject* Subscript(RepeatedCompositeContainer* self, PyObject* slice) {
   if (UpdateChildMessages(self) < 0) {
     return NULL;
@@ -242,6 +254,10 @@ PyObject* Subscript(RepeatedCompositeContainer* self, PyObject* slice) {
   return PyObject_GetItem(self->child_messages, slice);
 }
 
+static PyObject* SubscriptMethod(PyObject* self, PyObject* slice) {
+  return Subscript(reinterpret_cast<RepeatedCompositeContainer*>(self), slice);
+}
+
 int AssignSubscript(RepeatedCompositeContainer* self,
                     PyObject* slice,
                     PyObject* value) {
@@ -265,7 +281,7 @@ int AssignSubscript(RepeatedCompositeContainer* self,
     Py_ssize_t from;
     Py_ssize_t to;
     Py_ssize_t step;
-    Py_ssize_t length = Length(self);
+    Py_ssize_t length = Length(reinterpret_cast<PyObject*>(self));
     Py_ssize_t slicelength;
     if (PySlice_Check(slice)) {
 #if PY_MAJOR_VERSION >= 3
@@ -290,7 +306,16 @@ int AssignSubscript(RepeatedCompositeContainer* self,
   return 0;
 }
 
-static PyObject* Remove(RepeatedCompositeContainer* self, PyObject* value) {
+static int AssignSubscriptMethod(PyObject* self, PyObject* slice,
+                                 PyObject* value) {
+  return AssignSubscript(reinterpret_cast<RepeatedCompositeContainer*>(self),
+                         slice, value);
+}
+
+static PyObject* Remove(PyObject* pself, PyObject* value) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   if (UpdateChildMessages(self) < 0) {
     return NULL;
   }
@@ -305,9 +330,10 @@ static PyObject* Remove(RepeatedCompositeContainer* self, PyObject* value) {
   Py_RETURN_NONE;
 }
 
-static PyObject* RichCompare(RepeatedCompositeContainer* self,
-                             PyObject* other,
-                             int opid) {
+static PyObject* RichCompare(PyObject* pself, PyObject* other, int opid) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   if (UpdateChildMessages(self) < 0) {
     return NULL;
   }
@@ -340,12 +366,13 @@ static PyObject* RichCompare(RepeatedCompositeContainer* self,
   }
 }
 
-static PyObject* ToStr(RepeatedCompositeContainer* self) {
+static PyObject* ToStr(PyObject* pself) {
   ScopedPyObjectPtr full_slice(PySlice_New(NULL, NULL, NULL));
   if (full_slice == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr list(Subscript(
+      reinterpret_cast<RepeatedCompositeContainer*>(pself), full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
@@ -359,7 +386,7 @@ static void ReorderAttached(RepeatedCompositeContainer* self) {
   Message* message = self->message;
   const Reflection* reflection = message->GetReflection();
   const FieldDescriptor* descriptor = self->parent_field_descriptor;
-  const Py_ssize_t length = Length(self);
+  const Py_ssize_t length = Length(reinterpret_cast<PyObject*>(self));
 
   // Since Python protobuf objects are never arena-allocated, adding and
   // removing message pointers to the underlying array is just updating
@@ -390,9 +417,10 @@ static int SortPythonMessages(RepeatedCompositeContainer* self,
   return 0;
 }
 
-static PyObject* Sort(RepeatedCompositeContainer* self,
-                      PyObject* args,
-                      PyObject* kwds) {
+static PyObject* Sort(PyObject* pself, PyObject* args, PyObject* kwds) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   // Support the old sort_function argument for backwards
   // compatibility.
   if (kwds != NULL) {
@@ -416,11 +444,14 @@ static PyObject* Sort(RepeatedCompositeContainer* self,
 
 // ---------------------------------------------------------------------
 
-static PyObject* Item(RepeatedCompositeContainer* self, Py_ssize_t index) {
+static PyObject* Item(PyObject* pself, Py_ssize_t index) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   if (UpdateChildMessages(self) < 0) {
     return NULL;
   }
-  Py_ssize_t length = Length(self);
+  Py_ssize_t length = Length(pself);
   if (index < 0) {
     index = length + index;
   }
@@ -432,17 +463,17 @@ static PyObject* Item(RepeatedCompositeContainer* self, Py_ssize_t index) {
   return item;
 }
 
-static PyObject* Pop(RepeatedCompositeContainer* self,
-                     PyObject* args) {
+static PyObject* Pop(PyObject* pself, PyObject* args) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   Py_ssize_t index = -1;
   if (!PyArg_ParseTuple(args, "|n", &index)) {
     return NULL;
   }
-  PyObject* item = Item(self, index);
+  PyObject* item = Item(pself, index);
   if (item == NULL) {
-    PyErr_Format(PyExc_IndexError,
-                 "list index (%zd) out of range",
-                 index);
+    PyErr_Format(PyExc_IndexError, "list index (%zd) out of range", index);
     return NULL;
   }
   ScopedPyObjectPtr py_index(PyLong_FromSsize_t(index));
@@ -460,7 +491,7 @@ void ReleaseLastTo(CMessage* parent,
   GOOGLE_CHECK_NOTNULL(field);
   GOOGLE_CHECK_NOTNULL(target);
 
-  shared_ptr<Message> released_message(
+  CMessage::OwnerRef released_message(
       parent->message->GetReflection()->ReleaseLast(parent->message, field));
   // TODO(tibell): Deal with proto1.
 
@@ -503,7 +534,10 @@ int Release(RepeatedCompositeContainer* self) {
   return 0;
 }
 
-PyObject* DeepCopy(RepeatedCompositeContainer* self, PyObject* arg) {
+PyObject* DeepCopy(PyObject* pself, PyObject* arg) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   ScopedPyObjectPtr cloneObj(
       PyType_GenericAlloc(&RepeatedCompositeContainer_Type, 0));
   if (cloneObj == NULL) {
@@ -530,7 +564,7 @@ PyObject* DeepCopy(RepeatedCompositeContainer* self, PyObject* arg) {
 }
 
 int SetOwner(RepeatedCompositeContainer* self,
-             const shared_ptr<Message>& new_owner) {
+             const CMessage::OwnerRef& new_owner) {
   GOOGLE_CHECK_ATTACHED(self);
 
   self->owner = new_owner;
@@ -571,43 +605,46 @@ PyObject *NewContainer(
   return reinterpret_cast<PyObject*>(self);
 }
 
-static void Dealloc(RepeatedCompositeContainer* self) {
+static void Dealloc(PyObject* pself) {
+  RepeatedCompositeContainer* self =
+      reinterpret_cast<RepeatedCompositeContainer*>(pself);
+
   Py_CLEAR(self->child_messages);
   Py_CLEAR(self->child_message_class);
   // TODO(tibell): Do we need to call delete on these objects to make
   // sure their destructors are called?
   self->owner.reset();
 
-  Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
+  Py_TYPE(self)->tp_free(pself);
 }
 
 static PySequenceMethods SqMethods = {
-  (lenfunc)Length,        /* sq_length */
-  0, /* sq_concat */
-  0, /* sq_repeat */
-  (ssizeargfunc)Item /* sq_item */
+  Length,                 /* sq_length */
+  0,                      /* sq_concat */
+  0,                      /* sq_repeat */
+  Item                    /* sq_item */
 };
 
 static PyMappingMethods MpMethods = {
-  (lenfunc)Length,               /* mp_length */
-  (binaryfunc)Subscript,      /* mp_subscript */
-  (objobjargproc)AssignSubscript,/* mp_ass_subscript */
+  Length,                 /* mp_length */
+  SubscriptMethod,        /* mp_subscript */
+  AssignSubscriptMethod,  /* mp_ass_subscript */
 };
 
 static PyMethodDef Methods[] = {
-  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
+  { "__deepcopy__", DeepCopy, METH_VARARGS,
     "Makes a deep copy of the class." },
-  { "add", (PyCFunction) Add, METH_VARARGS | METH_KEYWORDS,
+  { "add", (PyCFunction)AddMethod, METH_VARARGS | METH_KEYWORDS,
     "Adds an object to the repeated container." },
-  { "extend", (PyCFunction) Extend, METH_O,
+  { "extend", ExtendMethod, METH_O,
     "Adds objects to the repeated container." },
-  { "pop", (PyCFunction)Pop, METH_VARARGS,
+  { "pop", Pop, METH_VARARGS,
     "Removes an object from the repeated container and returns it." },
-  { "remove", (PyCFunction) Remove, METH_O,
+  { "remove", Remove, METH_O,
     "Removes an object from the repeated container." },
-  { "sort", (PyCFunction) Sort, METH_VARARGS | METH_KEYWORDS,
+  { "sort", (PyCFunction)Sort, METH_VARARGS | METH_KEYWORDS,
     "Sorts the repeated container." },
-  { "MergeFrom", (PyCFunction) MergeFrom, METH_O,
+  { "MergeFrom", MergeFromMethod, METH_O,
     "Adds objects to the repeated container." },
   { NULL, NULL }
 };
@@ -619,12 +656,12 @@ PyTypeObject RepeatedCompositeContainer_Type = {
   FULL_MODULE_NAME ".RepeatedCompositeContainer",  // tp_name
   sizeof(RepeatedCompositeContainer),  // tp_basicsize
   0,                                   //  tp_itemsize
-  (destructor)repeated_composite_container::Dealloc,  //  tp_dealloc
+  repeated_composite_container::Dealloc,  //  tp_dealloc
   0,                                   //  tp_print
   0,                                   //  tp_getattr
   0,                                   //  tp_setattr
   0,                                   //  tp_compare
-  (reprfunc)repeated_composite_container::ToStr,      //  tp_repr
+  repeated_composite_container::ToStr,      //  tp_repr
   0,                                   //  tp_as_number
   &repeated_composite_container::SqMethods,   //  tp_as_sequence
   &repeated_composite_container::MpMethods,   //  tp_as_mapping
@@ -638,7 +675,7 @@ PyTypeObject RepeatedCompositeContainer_Type = {
   "A Repeated scalar container",       //  tp_doc
   0,                                   //  tp_traverse
   0,                                   //  tp_clear
-  (richcmpfunc)repeated_composite_container::RichCompare,  //  tp_richcompare
+  repeated_composite_container::RichCompare,  //  tp_richcompare
   0,                                   //  tp_weaklistoffset
   0,                                   //  tp_iter
   0,                                   //  tp_iternext
diff --git a/python/google/protobuf/pyext/repeated_composite_container.h b/python/google/protobuf/pyext/repeated_composite_container.h
index a7b56b61..e5e946aa 100644
--- a/python/google/protobuf/pyext/repeated_composite_container.h
+++ b/python/google/protobuf/pyext/repeated_composite_container.h
@@ -37,27 +37,19 @@
 #include <Python.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 #include <string>
 #include <vector>
 
+#include <google/protobuf/pyext/message.h>
+
 namespace google {
 namespace protobuf {
 
 class FieldDescriptor;
 class Message;
 
-#ifdef _SHARED_PTR_H
-using std::shared_ptr;
-#else
-using internal::shared_ptr;
-#endif
-
 namespace python {
 
-struct CMessage;
 struct CMessageClass;
 
 // A RepeatedCompositeContainer can be in one of two states: attached
@@ -77,7 +69,7 @@ typedef struct RepeatedCompositeContainer {
   // proto tree.  Every Python RepeatedCompositeContainer holds a
   // reference to it in order to keep it alive as long as there's a
   // Python object that references any part of the tree.
-  shared_ptr<Message> owner;
+  CMessage::OwnerRef owner;
 
   // Weak reference to parent object. May be NULL. Used to make sure
   // the parent is writable before modifying the
@@ -148,11 +140,6 @@ int AssignSubscript(RepeatedCompositeContainer* self,
                     PyObject* slice,
                     PyObject* value);
 
-// Releases the messages in the container to the given message.
-//
-// Returns 0 on success, -1 on failure.
-int ReleaseToMessage(RepeatedCompositeContainer* self, Message* new_message);
-
 // Releases the messages in the container to a new message.
 //
 // Returns 0 on success, -1 on failure.
@@ -160,7 +147,7 @@ int Release(RepeatedCompositeContainer* self);
 
 // Returns 0 on success, -1 on failure.
 int SetOwner(RepeatedCompositeContainer* self,
-             const shared_ptr<Message>& new_owner);
+             const CMessage::OwnerRef& new_owner);
 
 // Removes the last element of the repeated message field 'field' on
 // the Message 'parent', and transfers the ownership of the released
diff --git a/python/google/protobuf/pyext/repeated_scalar_container.cc b/python/google/protobuf/pyext/repeated_scalar_container.cc
index 5a7832cd..1517e654 100644
--- a/python/google/protobuf/pyext/repeated_scalar_container.cc
+++ b/python/google/protobuf/pyext/repeated_scalar_container.cc
@@ -34,9 +34,6 @@
 #include <google/protobuf/pyext/repeated_scalar_container.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/stubs/logging.h>
@@ -77,15 +74,18 @@ static int InternalAssignRepeatedField(
   return 0;
 }
 
-static Py_ssize_t Len(RepeatedScalarContainer* self) {
+static Py_ssize_t Len(PyObject* pself) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
   Message* message = self->message;
   return message->GetReflection()->FieldSize(*message,
                                              self->parent_field_descriptor);
 }
 
-static int AssignItem(RepeatedScalarContainer* self,
-                      Py_ssize_t index,
-                      PyObject* arg) {
+static int AssignItem(PyObject* pself, Py_ssize_t index, PyObject* arg) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   cmessage::AssureWritable(self->parent);
   Message* message = self->message;
   const FieldDescriptor* field_descriptor = self->parent_field_descriptor;
@@ -188,7 +188,10 @@ static int AssignItem(RepeatedScalarContainer* self,
   return 0;
 }
 
-static PyObject* Item(RepeatedScalarContainer* self, Py_ssize_t index) {
+static PyObject* Item(PyObject* pself, Py_ssize_t index) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   Message* message = self->message;
   const FieldDescriptor* field_descriptor = self->parent_field_descriptor;
   const Reflection* reflection = message->GetReflection();
@@ -256,8 +259,9 @@ static PyObject* Item(RepeatedScalarContainer* self, Py_ssize_t index) {
       break;
     }
     case FieldDescriptor::CPPTYPE_STRING: {
-      string value = reflection->GetRepeatedString(
-          *message, field_descriptor, index);
+      string scratch;
+      const string& value = reflection->GetRepeatedStringReference(
+          *message, field_descriptor, index, &scratch);
       result = ToStringObject(field_descriptor, value);
       break;
     }
@@ -271,7 +275,10 @@ static PyObject* Item(RepeatedScalarContainer* self, Py_ssize_t index) {
   return result;
 }
 
-static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
+static PyObject* Subscript(PyObject* pself, PyObject* slice) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   Py_ssize_t from;
   Py_ssize_t to;
   Py_ssize_t step;
@@ -286,14 +293,13 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
   if (PyLong_Check(slice)) {
     from = to = PyLong_AsLong(slice);
   } else if (PySlice_Check(slice)) {
-    length = Len(self);
+    length = Len(pself);
 #if PY_MAJOR_VERSION >= 3
     if (PySlice_GetIndicesEx(slice,
                              length, &from, &to, &step, &slicelength) == -1) {
 #else
     if (PySlice_GetIndicesEx(reinterpret_cast<PySliceObject*>(slice),
                              length, &from, &to, &step, &slicelength) == -1) {
-
 #endif
       return NULL;
     }
@@ -304,7 +310,7 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
   }
 
   if (!return_list) {
-    return Item(self, from);
+    return Item(pself, from);
   }
 
   PyObject* list = PyList_New(0);
@@ -319,7 +325,7 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
       if (index < 0 || index >= length) {
         break;
       }
-      ScopedPyObjectPtr s(Item(self, index));
+      ScopedPyObjectPtr s(Item(pself, index));
       PyList_Append(list, s.get());
     }
   } else {
@@ -330,7 +336,7 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
       if (index < 0 || index >= length) {
         break;
       }
-      ScopedPyObjectPtr s(Item(self, index));
+      ScopedPyObjectPtr s(Item(pself, index));
       PyList_Append(list, s.get());
     }
   }
@@ -417,9 +423,14 @@ PyObject* Append(RepeatedScalarContainer* self, PyObject* item) {
   Py_RETURN_NONE;
 }
 
-static int AssSubscript(RepeatedScalarContainer* self,
-                        PyObject* slice,
-                        PyObject* value) {
+static PyObject* AppendMethod(PyObject* self, PyObject* item) {
+  return Append(reinterpret_cast<RepeatedScalarContainer*>(self), item);
+}
+
+static int AssSubscript(PyObject* pself, PyObject* slice, PyObject* value) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   Py_ssize_t from;
   Py_ssize_t to;
   Py_ssize_t step;
@@ -435,7 +446,7 @@ static int AssSubscript(RepeatedScalarContainer* self,
 #if PY_MAJOR_VERSION < 3
   if (PyInt_Check(slice)) {
     from = to = PyInt_AsLong(slice);
-  } else
+  } else  // NOLINT
 #endif
   if (PyLong_Check(slice)) {
     from = to = PyLong_AsLong(slice);
@@ -463,14 +474,14 @@ static int AssSubscript(RepeatedScalarContainer* self,
   }
 
   if (!create_list) {
-    return AssignItem(self, from, value);
+    return AssignItem(pself, from, value);
   }
 
   ScopedPyObjectPtr full_slice(PySlice_New(NULL, NULL, NULL));
   if (full_slice == NULL) {
     return -1;
   }
-  ScopedPyObjectPtr new_list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr new_list(Subscript(pself, full_slice.get()));
   if (new_list == NULL) {
     return -1;
   }
@@ -509,14 +520,17 @@ PyObject* Extend(RepeatedScalarContainer* self, PyObject* value) {
   Py_RETURN_NONE;
 }
 
-static PyObject* Insert(RepeatedScalarContainer* self, PyObject* args) {
+static PyObject* Insert(PyObject* pself, PyObject* args) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   Py_ssize_t index;
   PyObject* value;
   if (!PyArg_ParseTuple(args, "lO", &index, &value)) {
     return NULL;
   }
   ScopedPyObjectPtr full_slice(PySlice_New(NULL, NULL, NULL));
-  ScopedPyObjectPtr new_list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr new_list(Subscript(pself, full_slice.get()));
   if (PyList_Insert(new_list.get(), index, value) < 0) {
     return NULL;
   }
@@ -527,10 +541,13 @@ static PyObject* Insert(RepeatedScalarContainer* self, PyObject* args) {
   Py_RETURN_NONE;
 }
 
-static PyObject* Remove(RepeatedScalarContainer* self, PyObject* value) {
+static PyObject* Remove(PyObject* pself, PyObject* value) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   Py_ssize_t match_index = -1;
-  for (Py_ssize_t i = 0; i < Len(self); ++i) {
-    ScopedPyObjectPtr elem(Item(self, i));
+  for (Py_ssize_t i = 0; i < Len(pself); ++i) {
+    ScopedPyObjectPtr elem(Item(pself, i));
     if (PyObject_RichCompareBool(elem.get(), value, Py_EQ)) {
       match_index = i;
       break;
@@ -540,15 +557,20 @@ static PyObject* Remove(RepeatedScalarContainer* self, PyObject* value) {
     PyErr_SetString(PyExc_ValueError, "remove(x): x not in container");
     return NULL;
   }
-  if (AssignItem(self, match_index, NULL) < 0) {
+  if (AssignItem(pself, match_index, NULL) < 0) {
     return NULL;
   }
   Py_RETURN_NONE;
 }
 
-static PyObject* RichCompare(RepeatedScalarContainer* self,
-                             PyObject* other,
-                             int opid) {
+static PyObject* ExtendMethod(PyObject* self, PyObject* value) {
+  return Extend(reinterpret_cast<RepeatedScalarContainer*>(self), value);
+}
+
+static PyObject* RichCompare(PyObject* pself, PyObject* other, int opid) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   if (opid != Py_EQ && opid != Py_NE) {
     Py_INCREF(Py_NotImplemented);
     return Py_NotImplemented;
@@ -565,28 +587,25 @@ static PyObject* RichCompare(RepeatedScalarContainer* self,
 
   ScopedPyObjectPtr other_list_deleter;
   if (PyObject_TypeCheck(other, &RepeatedScalarContainer_Type)) {
-    other_list_deleter.reset(Subscript(
-        reinterpret_cast<RepeatedScalarContainer*>(other), full_slice.get()));
+    other_list_deleter.reset(Subscript(other, full_slice.get()));
     other = other_list_deleter.get();
   }
 
-  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr list(Subscript(pself, full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
   return PyObject_RichCompare(list.get(), other, opid);
 }
 
-PyObject* Reduce(RepeatedScalarContainer* unused_self) {
+PyObject* Reduce(PyObject* unused_self, PyObject* unused_other) {
   PyErr_Format(
       PickleError_class,
       "can't pickle repeated message fields, convert to list first");
   return NULL;
 }
 
-static PyObject* Sort(RepeatedScalarContainer* self,
-                      PyObject* args,
-                      PyObject* kwds) {
+static PyObject* Sort(PyObject* pself, PyObject* args, PyObject* kwds) {
   // Support the old sort_function argument for backwards
   // compatibility.
   if (kwds != NULL) {
@@ -605,7 +624,7 @@ static PyObject* Sort(RepeatedScalarContainer* self,
   if (full_slice == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr list(Subscript(pself, full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
@@ -617,38 +636,39 @@ static PyObject* Sort(RepeatedScalarContainer* self,
   if (res == NULL) {
     return NULL;
   }
-  int ret = InternalAssignRepeatedField(self, list.get());
+  int ret = InternalAssignRepeatedField(
+      reinterpret_cast<RepeatedScalarContainer*>(pself), list.get());
   if (ret < 0) {
     return NULL;
   }
   Py_RETURN_NONE;
 }
 
-static PyObject* Pop(RepeatedScalarContainer* self,
-                     PyObject* args) {
+static PyObject* Pop(PyObject* pself, PyObject* args) {
   Py_ssize_t index = -1;
   if (!PyArg_ParseTuple(args, "|n", &index)) {
     return NULL;
   }
-  PyObject* item = Item(self, index);
+  PyObject* item = Item(pself, index);
   if (item == NULL) {
-    PyErr_Format(PyExc_IndexError,
-                 "list index (%zd) out of range",
-                 index);
+    PyErr_Format(PyExc_IndexError, "list index (%zd) out of range", index);
     return NULL;
   }
-  if (AssignItem(self, index, NULL) < 0) {
+  if (AssignItem(pself, index, NULL) < 0) {
     return NULL;
   }
   return item;
 }
 
-static PyObject* ToStr(RepeatedScalarContainer* self) {
+static PyObject* ToStr(PyObject* pself) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   ScopedPyObjectPtr full_slice(PySlice_New(NULL, NULL, NULL));
   if (full_slice == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
+  ScopedPyObjectPtr list(Subscript(pself, full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
@@ -687,7 +707,8 @@ static int InitializeAndCopyToParentContainer(
   if (full_slice == NULL) {
     return -1;
   }
-  ScopedPyObjectPtr values(Subscript(from, full_slice.get()));
+  ScopedPyObjectPtr values(
+      Subscript(reinterpret_cast<PyObject*>(from), full_slice.get()));
   if (values == NULL) {
     return -1;
   }
@@ -706,7 +727,10 @@ int Release(RepeatedScalarContainer* self) {
   return InitializeAndCopyToParentContainer(self, self);
 }
 
-PyObject* DeepCopy(RepeatedScalarContainer* self, PyObject* arg) {
+PyObject* DeepCopy(PyObject* pself, PyObject* arg) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
+
   RepeatedScalarContainer* clone = reinterpret_cast<RepeatedScalarContainer*>(
       PyType_GenericAlloc(&RepeatedScalarContainer_Type, 0));
   if (clone == NULL) {
@@ -720,45 +744,47 @@ PyObject* DeepCopy(RepeatedScalarContainer* self, PyObject* arg) {
   return reinterpret_cast<PyObject*>(clone);
 }
 
-static void Dealloc(RepeatedScalarContainer* self) {
+static void Dealloc(PyObject* pself) {
+  RepeatedScalarContainer* self =
+      reinterpret_cast<RepeatedScalarContainer*>(pself);
   self->owner.reset();
-  Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
+  Py_TYPE(self)->tp_free(pself);
 }
 
 void SetOwner(RepeatedScalarContainer* self,
-              const shared_ptr<Message>& new_owner) {
+              const CMessage::OwnerRef& new_owner) {
   self->owner = new_owner;
 }
 
 static PySequenceMethods SqMethods = {
-  (lenfunc)Len,           /* sq_length */
-  0, /* sq_concat */
-  0, /* sq_repeat */
-  (ssizeargfunc)Item, /* sq_item */
-  0, /* sq_slice */
-  (ssizeobjargproc)AssignItem /* sq_ass_item */
+  Len,        /* sq_length */
+  0,          /* sq_concat */
+  0,          /* sq_repeat */
+  Item,       /* sq_item */
+  0,          /* sq_slice */
+  AssignItem  /* sq_ass_item */
 };
 
 static PyMappingMethods MpMethods = {
-  (lenfunc)Len,               /* mp_length */
-  (binaryfunc)Subscript,      /* mp_subscript */
-  (objobjargproc)AssSubscript, /* mp_ass_subscript */
+  Len,               /* mp_length */
+  Subscript,      /* mp_subscript */
+  AssSubscript, /* mp_ass_subscript */
 };
 
 static PyMethodDef Methods[] = {
-  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
+  { "__deepcopy__", DeepCopy, METH_VARARGS,
     "Makes a deep copy of the class." },
-  { "__reduce__", (PyCFunction)Reduce, METH_NOARGS,
+  { "__reduce__", Reduce, METH_NOARGS,
     "Outputs picklable representation of the repeated field." },
-  { "append", (PyCFunction)Append, METH_O,
+  { "append", AppendMethod, METH_O,
     "Appends an object to the repeated container." },
-  { "extend", (PyCFunction)Extend, METH_O,
-    "Appends objects to the repeated container." },
-  { "insert", (PyCFunction)Insert, METH_VARARGS,
+  { "extend", ExtendMethod, METH_O,
     "Appends objects to the repeated container." },
-  { "pop", (PyCFunction)Pop, METH_VARARGS,
+  { "insert", Insert, METH_VARARGS,
+    "Inserts an object at the specified position in the container." },
+  { "pop", Pop, METH_VARARGS,
     "Removes an object from the repeated container and returns it." },
-  { "remove", (PyCFunction)Remove, METH_O,
+  { "remove", Remove, METH_O,
     "Removes an object from the repeated container." },
   { "sort", (PyCFunction)Sort, METH_VARARGS | METH_KEYWORDS,
     "Sorts the repeated container."},
@@ -772,12 +798,12 @@ PyTypeObject RepeatedScalarContainer_Type = {
   FULL_MODULE_NAME ".RepeatedScalarContainer",  // tp_name
   sizeof(RepeatedScalarContainer),     // tp_basicsize
   0,                                   //  tp_itemsize
-  (destructor)repeated_scalar_container::Dealloc,  //  tp_dealloc
+  repeated_scalar_container::Dealloc,  //  tp_dealloc
   0,                                   //  tp_print
   0,                                   //  tp_getattr
   0,                                   //  tp_setattr
   0,                                   //  tp_compare
-  (reprfunc)repeated_scalar_container::ToStr,      //  tp_repr
+  repeated_scalar_container::ToStr,    //  tp_repr
   0,                                   //  tp_as_number
   &repeated_scalar_container::SqMethods,   //  tp_as_sequence
   &repeated_scalar_container::MpMethods,   //  tp_as_mapping
@@ -791,7 +817,7 @@ PyTypeObject RepeatedScalarContainer_Type = {
   "A Repeated scalar container",       //  tp_doc
   0,                                   //  tp_traverse
   0,                                   //  tp_clear
-  (richcmpfunc)repeated_scalar_container::RichCompare,  //  tp_richcompare
+  repeated_scalar_container::RichCompare,  //  tp_richcompare
   0,                                   //  tp_weaklistoffset
   0,                                   //  tp_iter
   0,                                   //  tp_iternext
diff --git a/python/google/protobuf/pyext/repeated_scalar_container.h b/python/google/protobuf/pyext/repeated_scalar_container.h
index 555e621c..559dec98 100644
--- a/python/google/protobuf/pyext/repeated_scalar_container.h
+++ b/python/google/protobuf/pyext/repeated_scalar_container.h
@@ -37,27 +37,14 @@
 #include <Python.h>
 
 #include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/pyext/message.h>
 
 namespace google {
 namespace protobuf {
-
-class Message;
-
-#ifdef _SHARED_PTR_H
-using std::shared_ptr;
-#else
-using internal::shared_ptr;
-#endif
-
 namespace python {
 
-struct CMessage;
-
 typedef struct RepeatedScalarContainer {
   PyObject_HEAD;
 
@@ -65,7 +52,7 @@ typedef struct RepeatedScalarContainer {
   // proto tree.  Every Python RepeatedScalarContainer holds a
   // reference to it in order to keep it alive as long as there's a
   // Python object that references any part of the tree.
-  shared_ptr<Message> owner;
+  CMessage::OwnerRef owner;
 
   // Pointer to the C++ Message that contains this container.  The
   // RepeatedScalarContainer does not own this pointer.
@@ -112,7 +99,7 @@ PyObject* Extend(RepeatedScalarContainer* self, PyObject* value);
 
 // Set the owner field of self and any children of self.
 void SetOwner(RepeatedScalarContainer* self,
-              const shared_ptr<Message>& new_owner);
+              const CMessage::OwnerRef& new_owner);
 
 }  // namespace repeated_scalar_container
 }  // namespace python