Removed all warnings from the Python/C++ build.

Also made the Travis build ensure that no warnings
are present.

These builds were previously spewing many warnings,
which was hiding warnings for important things like
accidentally using C++11-only features.

Change-Id: I56caeee9db48bc78756a3e8d7c14874630627037

13 files changed, 133 insertions, 134 deletions

diff --git a/python/google/protobuf/pyext/descriptor.cc b/python/google/protobuf/pyext/descriptor.cc
index b238fd02..61a3d237 100644
--- a/python/google/protobuf/pyext/descriptor.cc
+++ b/python/google/protobuf/pyext/descriptor.cc
@@ -232,7 +232,7 @@ static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
   }
 
   // Cache the result.
-  Py_INCREF(value);
+  Py_INCREF(value.get());
   (*pool->descriptor_options)[descriptor] = value.get();
 
   return value.release();
@@ -1489,7 +1489,8 @@ static bool AddEnumValues(PyTypeObject *type,
     if (obj == NULL) {
       return false;
     }
-    if (PyDict_SetItemString(type->tp_dict, value->name().c_str(), obj) < 0) {
+    if (PyDict_SetItemString(type->tp_dict, value->name().c_str(), obj.get()) <
+        0) {
       return false;
     }
   }
@@ -1498,7 +1499,7 @@ static bool AddEnumValues(PyTypeObject *type,
 
 static bool AddIntConstant(PyTypeObject *type, const char* name, int value) {
   ScopedPyObjectPtr obj(PyInt_FromLong(value));
-  if (PyDict_SetItemString(type->tp_dict, name, obj) < 0) {
+  if (PyDict_SetItemString(type->tp_dict, name, obj.get()) < 0) {
     return false;
   }
   return true;
diff --git a/python/google/protobuf/pyext/descriptor_containers.cc b/python/google/protobuf/pyext/descriptor_containers.cc
index b20f5e4f..e505d812 100644
--- a/python/google/protobuf/pyext/descriptor_containers.cc
+++ b/python/google/protobuf/pyext/descriptor_containers.cc
@@ -355,7 +355,7 @@ static int DescriptorSequence_Equal(PyContainer* self, PyObject* other) {
       if (value2 == NULL) {
         return -1;
       }
-      int cmp = PyObject_RichCompareBool(value1, value2, Py_EQ);
+      int cmp = PyObject_RichCompareBool(value1.get(), value2, Py_EQ);
       if (cmp != 1)  // error or not equal
           return cmp;
     }
@@ -399,12 +399,12 @@ static int DescriptorMapping_Equal(PyContainer* self, PyObject* other) {
       if (value1 == NULL) {
         return -1;
       }
-      PyObject* value2 = PyDict_GetItem(other, key);
+      PyObject* value2 = PyDict_GetItem(other, key.get());
       if (value2 == NULL) {
         // Not found in the other dictionary
         return 0;
       }
-      int cmp = PyObject_RichCompareBool(value1, value2, Py_EQ);
+      int cmp = PyObject_RichCompareBool(value1.get(), value2, Py_EQ);
       if (cmp != 1)  // error or not equal
           return cmp;
     }
diff --git a/python/google/protobuf/pyext/descriptor_pool.cc b/python/google/protobuf/pyext/descriptor_pool.cc
index 6443a7d5..0f7487fa 100644
--- a/python/google/protobuf/pyext/descriptor_pool.cc
+++ b/python/google/protobuf/pyext/descriptor_pool.cc
@@ -394,7 +394,7 @@ PyObject* Add(PyDescriptorPool* self, PyObject* file_descriptor_proto) {
   if (serialized_pb == NULL) {
     return NULL;
   }
-  return AddSerializedFile(self, serialized_pb);
+  return AddSerializedFile(self, serialized_pb.get());
 }
 
 static PyMethodDef Methods[] = {
diff --git a/python/google/protobuf/pyext/extension_dict.cc b/python/google/protobuf/pyext/extension_dict.cc
index 9c9b4178..b361b342 100644
--- a/python/google/protobuf/pyext/extension_dict.cc
+++ b/python/google/protobuf/pyext/extension_dict.cc
@@ -211,7 +211,7 @@ PyObject* _FindExtensionByName(ExtensionDict* self, PyObject* name) {
   if (extensions_by_name == NULL) {
     return NULL;
   }
-  PyObject* result = PyDict_GetItem(extensions_by_name, name);
+  PyObject* result = PyDict_GetItem(extensions_by_name.get(), name);
   if (result == NULL) {
     Py_RETURN_NONE;
   } else {
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index 9318c834..db58df54 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -142,7 +142,7 @@ static bool AddFieldNumberToClass(
   if (number == NULL) {
     return false;
   }
-  if (PyObject_SetAttr(cls, attr_name, number) == -1) {
+  if (PyObject_SetAttr(cls, attr_name.get(), number.get()) == -1) {
     return false;
   }
   return true;
@@ -155,11 +155,11 @@ static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
   // classes will register themselves in this class.
   if (descriptor->extension_range_count() > 0) {
     ScopedPyObjectPtr by_name(PyDict_New());
-    if (PyObject_SetAttr(cls, k_extensions_by_name, by_name) < 0) {
+    if (PyObject_SetAttr(cls, k_extensions_by_name, by_name.get()) < 0) {
       return -1;
     }
     ScopedPyObjectPtr by_number(PyDict_New());
-    if (PyObject_SetAttr(cls, k_extensions_by_number, by_number) < 0) {
+    if (PyObject_SetAttr(cls, k_extensions_by_number, by_number.get()) < 0) {
       return -1;
     }
   }
@@ -190,7 +190,7 @@ static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
       return -1;
     }
     if (PyObject_SetAttrString(
-            cls, enum_descriptor->name().c_str(), wrapped) == -1) {
+            cls, enum_descriptor->name().c_str(), wrapped.get()) == -1) {
       return -1;
     }
 
@@ -203,8 +203,8 @@ static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
       if (value_number == NULL) {
         return -1;
       }
-      if (PyObject_SetAttrString(
-              cls, enum_value_descriptor->name().c_str(), value_number) == -1) {
+      if (PyObject_SetAttrString(cls, enum_value_descriptor->name().c_str(),
+                                 value_number.get()) == -1) {
         return -1;
       }
     }
@@ -224,7 +224,7 @@ static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
 
     // Add the extension field to the message class.
     if (PyObject_SetAttrString(
-            cls, field->name().c_str(), extension_field) == -1) {
+            cls, field->name().c_str(), extension_field.get()) == -1) {
       return -1;
     }
 
@@ -280,7 +280,7 @@ static PyObject* New(PyTypeObject* type,
     return NULL;
   }
   // Call the base metaclass.
-  ScopedPyObjectPtr result(PyType_Type.tp_new(type, new_args, NULL));
+  ScopedPyObjectPtr result(PyType_Type.tp_new(type, new_args.get(), NULL));
   if (result == NULL) {
     return NULL;
   }
@@ -318,7 +318,7 @@ static PyObject* New(PyTypeObject* type,
   }
 
   // Continue with type initialization: add other descriptors, enum values...
-  if (AddDescriptors(result, descriptor) < 0) {
+  if (AddDescriptors(result.get(), descriptor) < 0) {
     return NULL;
   }
   return result.release();
@@ -330,11 +330,6 @@ static void Dealloc(PyMessageMeta *self) {
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
-static PyObject* GetDescriptor(PyMessageMeta *self, void *closure) {
-  Py_INCREF(self->py_message_descriptor);
-  return self->py_message_descriptor;
-}
-
 
 // This function inserts and empty weakref at the end of the list of
 // subclasses for the main protocol buffer Message class.
@@ -862,7 +857,6 @@ int AssureWritable(CMessage* self) {
       return -1;
 
     // Make self->message writable.
-    Message* parent_message = self->parent->message;
     Message* mutable_message = GetMutableMessage(
         self->parent,
         self->parent_field_descriptor);
@@ -1106,8 +1100,8 @@ int InitAttributes(CMessage* self, PyObject* kwargs) {
           return -1;
         }
         ScopedPyObjectPtr next;
-        while ((next.reset(PyIter_Next(iter))) != NULL) {
-          PyObject* kwargs = (PyDict_Check(next) ? next.get() : NULL);
+        while ((next.reset(PyIter_Next(iter.get()))) != NULL) {
+          PyObject* kwargs = (PyDict_Check(next.get()) ? next.get() : NULL);
           ScopedPyObjectPtr new_msg(
               repeated_composite_container::Add(rc_container, NULL, kwargs));
           if (new_msg == NULL) {
@@ -1115,9 +1109,9 @@ int InitAttributes(CMessage* self, PyObject* kwargs) {
           }
           if (kwargs == NULL) {
             // next was not a dict, it's a message we need to merge
-            ScopedPyObjectPtr merged(
-                MergeFrom(reinterpret_cast<CMessage*>(new_msg.get()), next));
-            if (merged == NULL) {
+            ScopedPyObjectPtr merged(MergeFrom(
+                reinterpret_cast<CMessage*>(new_msg.get()), next.get()));
+            if (merged.get() == NULL) {
               return -1;
             }
           }
@@ -1135,13 +1129,14 @@ int InitAttributes(CMessage* self, PyObject* kwargs) {
           return -1;
         }
         ScopedPyObjectPtr next;
-        while ((next.reset(PyIter_Next(iter))) != NULL) {
-          ScopedPyObjectPtr enum_value(GetIntegerEnumValue(*descriptor, next));
+        while ((next.reset(PyIter_Next(iter.get()))) != NULL) {
+          ScopedPyObjectPtr enum_value(
+              GetIntegerEnumValue(*descriptor, next.get()));
           if (enum_value == NULL) {
             return -1;
           }
-          ScopedPyObjectPtr new_msg(
-              repeated_scalar_container::Append(rs_container, enum_value));
+          ScopedPyObjectPtr new_msg(repeated_scalar_container::Append(
+              rs_container, enum_value.get()));
           if (new_msg == NULL) {
             return -1;
           }
@@ -1182,7 +1177,8 @@ int InitAttributes(CMessage* self, PyObject* kwargs) {
           return -1;
         }
       }
-      if (SetAttr(self, name, (new_val == NULL) ? value : new_val) < 0) {
+      if (SetAttr(self, name, (new_val.get() == NULL) ? value : new_val.get()) <
+          0) {
         return -1;
       }
     }
@@ -1769,13 +1765,13 @@ static PyObject* SerializeToString(CMessage* self, PyObject* args) {
     }
 
     ScopedPyObjectPtr encode_error(
-        PyObject_GetAttrString(message_module, "EncodeError"));
+        PyObject_GetAttrString(message_module.get(), "EncodeError"));
     if (encode_error.get() == NULL) {
       return NULL;
     }
     PyErr_Format(encode_error.get(),
                  "Message %s is missing required fields: %s",
-                 GetMessageName(self).c_str(), PyString_AsString(joined));
+                 GetMessageName(self).c_str(), PyString_AsString(joined.get()));
     return NULL;
   }
   int size = self->message->ByteSize();
@@ -1965,7 +1961,8 @@ static PyObject* RegisterExtension(PyObject* cls,
   }
 
   // If the extension was already registered, check that it is the same.
-  PyObject* existing_extension = PyDict_GetItem(extensions_by_name, full_name);
+  PyObject* existing_extension =
+      PyDict_GetItem(extensions_by_name.get(), full_name.get());
   if (existing_extension != NULL) {
     const FieldDescriptor* existing_extension_descriptor =
         GetExtensionDescriptor(existing_extension);
@@ -1977,7 +1974,8 @@ static PyObject* RegisterExtension(PyObject* cls,
     Py_RETURN_NONE;
   }
 
-  if (PyDict_SetItem(extensions_by_name, full_name, extension_handle) < 0) {
+  if (PyDict_SetItem(extensions_by_name.get(), full_name.get(),
+                     extension_handle) < 0) {
     return NULL;
   }
 
@@ -1992,7 +1990,8 @@ static PyObject* RegisterExtension(PyObject* cls,
   if (number == NULL) {
     return NULL;
   }
-  if (PyDict_SetItem(extensions_by_number, number, extension_handle) < 0) {
+  if (PyDict_SetItem(extensions_by_number.get(), number.get(),
+                     extension_handle) < 0) {
     return NULL;
   }
 
@@ -2008,7 +2007,8 @@ static PyObject* RegisterExtension(PyObject* cls,
     if (message_name == NULL) {
       return NULL;
     }
-    PyDict_SetItem(extensions_by_name, message_name, extension_handle);
+    PyDict_SetItem(extensions_by_name.get(), message_name.get(),
+                   extension_handle);
   }
 
   Py_RETURN_NONE;
@@ -2058,7 +2058,7 @@ static PyObject* ListFields(CMessage* self) {
   // the field information.  Thus the actual size of the py list will be
   // smaller than the size of fields.  Set the actual size at the end.
   Py_ssize_t actual_size = 0;
-  for (Py_ssize_t i = 0; i < fields.size(); ++i) {
+  for (size_t i = 0; i < fields.size(); ++i) {
     ScopedPyObjectPtr t(PyTuple_New(2));
     if (t == NULL) {
       return NULL;
@@ -2086,7 +2086,7 @@ static PyObject* ListFields(CMessage* self) {
         return NULL;
       }
       // 'extension' reference later stolen by PyTuple_SET_ITEM.
-      PyObject* extension = PyObject_GetItem(extensions, extension_field);
+      PyObject* extension = PyObject_GetItem(extensions, extension_field.get());
       if (extension == NULL) {
         return NULL;
       }
@@ -2108,9 +2108,9 @@ static PyObject* ListFields(CMessage* self) {
         return NULL;
       }
 
-      PyObject* field_value = GetAttr(self, py_field_name);
+      PyObject* field_value = GetAttr(self, py_field_name.get());
       if (field_value == NULL) {
-        PyErr_SetObject(PyExc_ValueError, py_field_name);
+        PyErr_SetObject(PyExc_ValueError, py_field_name.get());
         return NULL;
       }
       PyTuple_SET_ITEM(t.get(), 0, field_descriptor.release());
@@ -2132,7 +2132,7 @@ PyObject* FindInitializationErrors(CMessage* self) {
   if (error_list == NULL) {
     return NULL;
   }
-  for (Py_ssize_t i = 0; i < errors.size(); ++i) {
+  for (size_t i = 0; i < errors.size(); ++i) {
     const string& error = errors[i];
     PyObject* error_string = PyString_FromStringAndSize(
         error.c_str(), error.length());
@@ -2430,16 +2430,16 @@ PyObject* ToUnicode(CMessage* self) {
     return NULL;
   }
   Py_INCREF(Py_True);
-  ScopedPyObjectPtr encoded(PyObject_CallMethodObjArgs(text_format, method_name,
-                                                       self, Py_True, NULL));
+  ScopedPyObjectPtr encoded(PyObject_CallMethodObjArgs(
+      text_format.get(), method_name.get(), self, Py_True, NULL));
   Py_DECREF(Py_True);
   if (encoded == NULL) {
     return NULL;
   }
 #if PY_MAJOR_VERSION < 3
-  PyObject* decoded = PyString_AsDecodedObject(encoded, "utf-8", NULL);
+  PyObject* decoded = PyString_AsDecodedObject(encoded.get(), "utf-8", NULL);
 #else
-  PyObject* decoded = PyUnicode_FromEncodedObject(encoded, "utf-8", NULL);
+  PyObject* decoded = PyUnicode_FromEncodedObject(encoded.get(), "utf-8", NULL);
 #endif
   if (decoded == NULL) {
     return NULL;
@@ -2462,7 +2462,7 @@ PyObject* Reduce(CMessage* self) {
   if (serialized == NULL) {
     return NULL;
   }
-  if (PyDict_SetItemString(state, "serialized", serialized) < 0) {
+  if (PyDict_SetItemString(state.get(), "serialized", serialized.get()) < 0) {
     return NULL;
   }
   return Py_BuildValue("OOO", constructor.get(), args.get(), state.get());
@@ -2817,16 +2817,16 @@ bool InitProto2MessageModule(PyObject *m) {
   if (empty_dict == NULL) {
     return false;
   }
-  ScopedPyObjectPtr immutable_dict(PyDictProxy_New(empty_dict));
+  ScopedPyObjectPtr immutable_dict(PyDictProxy_New(empty_dict.get()));
   if (immutable_dict == NULL) {
     return false;
   }
   if (PyDict_SetItem(CMessage_Type.tp_dict,
-                     k_extensions_by_name, immutable_dict) < 0) {
+                     k_extensions_by_name, immutable_dict.get()) < 0) {
     return false;
   }
   if (PyDict_SetItem(CMessage_Type.tp_dict,
-                     k_extensions_by_number, immutable_dict) < 0) {
+                     k_extensions_by_number, immutable_dict.get()) < 0) {
     return false;
   }
 
@@ -2856,19 +2856,19 @@ bool InitProto2MessageModule(PyObject *m) {
     if (collections == NULL) {
       return false;
     }
-    ScopedPyObjectPtr mutable_sequence(PyObject_GetAttrString(
-        collections, "MutableSequence"));
+    ScopedPyObjectPtr mutable_sequence(
+        PyObject_GetAttrString(collections.get(), "MutableSequence"));
     if (mutable_sequence == NULL) {
       return false;
     }
-    if (ScopedPyObjectPtr(PyObject_CallMethod(mutable_sequence, "register", "O",
-                                              &RepeatedScalarContainer_Type))
-        == NULL) {
+    if (ScopedPyObjectPtr(
+            PyObject_CallMethod(mutable_sequence.get(), "register", "O",
+                                &RepeatedScalarContainer_Type)) == NULL) {
       return false;
     }
-    if (ScopedPyObjectPtr(PyObject_CallMethod(mutable_sequence, "register", "O",
-                                              &RepeatedCompositeContainer_Type))
-        == NULL) {
+    if (ScopedPyObjectPtr(
+            PyObject_CallMethod(mutable_sequence.get(), "register", "O",
+                                &RepeatedCompositeContainer_Type)) == NULL) {
       return false;
     }
   }
@@ -2883,16 +2883,16 @@ bool InitProto2MessageModule(PyObject *m) {
     }
 
     ScopedPyObjectPtr mutable_mapping(
-        PyObject_GetAttrString(containers, "MutableMapping"));
+        PyObject_GetAttrString(containers.get(), "MutableMapping"));
     if (mutable_mapping == NULL) {
       return false;
     }
 
-    if (!PyObject_TypeCheck(mutable_mapping, &PyType_Type)) {
+    if (!PyObject_TypeCheck(mutable_mapping.get(), &PyType_Type)) {
       return false;
     }
 
-    Py_INCREF(mutable_mapping);
+    Py_INCREF(mutable_mapping.get());
 #if PY_MAJOR_VERSION >= 3
     PyObject* bases = PyTuple_New(1);
     PyTuple_SET_ITEM(bases, 0, mutable_mapping.get());
@@ -2925,7 +2925,7 @@ bool InitProto2MessageModule(PyObject *m) {
         PyType_FromSpecWithBases(&MessageMapContainer_Type_spec, bases);
     PyModule_AddObject(m, "MessageMapContainer", MessageMapContainer_Type);
 #else
-    Py_INCREF(mutable_mapping);
+    Py_INCREF(mutable_mapping.get());
     MessageMapContainer_Type.tp_base =
         reinterpret_cast<PyTypeObject*>(mutable_mapping.get());
 
diff --git a/python/google/protobuf/pyext/message_map_container.cc b/python/google/protobuf/pyext/message_map_container.cc
index f54d2015..8902fa00 100644
--- a/python/google/protobuf/pyext/message_map_container.cc
+++ b/python/google/protobuf/pyext/message_map_container.cc
@@ -155,7 +155,7 @@ static PyObject* GetCMessage(MessageMapContainer* self, Message* entry) {
   Message* message = entry->GetReflection()->MutableMessage(
       entry, self->value_field_descriptor);
   ScopedPyObjectPtr key(PyLong_FromVoidPtr(message));
-  PyObject* ret = PyDict_GetItem(self->message_dict, key);
+  PyObject* ret = PyDict_GetItem(self->message_dict, key.get());
 
   if (ret == NULL) {
     CMessage* cmsg = cmessage::NewEmptyMessage(self->subclass_init,
@@ -169,7 +169,7 @@ static PyObject* GetCMessage(MessageMapContainer* self, Message* entry) {
     cmsg->message = message;
     cmsg->parent = self->parent;
 
-    if (PyDict_SetItem(self->message_dict, key, ret) < 0) {
+    if (PyDict_SetItem(self->message_dict, key.get(), ret) < 0) {
       Py_DECREF(ret);
       return NULL;
     }
@@ -202,7 +202,7 @@ int MapKeyMatches(MessageMapContainer* self, const Message* entry,
   // TODO(haberman): do we need more strict type checking?
   ScopedPyObjectPtr entry_key(
       cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-  int ret = PyObject_RichCompareBool(key, entry_key, Py_EQ);
+  int ret = PyObject_RichCompareBool(key, entry_key.get(), Py_EQ);
   return ret;
 }
 
@@ -237,7 +237,7 @@ int SetItem(PyObject *_self, PyObject *key, PyObject *v) {
     if (matches < 0) return -1;
     if (matches) {
       found = true;
-      if (i != size - 1) {
+      if (i != (int)size - 1) {
         reflection->SwapElements(message, self->parent_field_descriptor, i,
                                  size - 1);
       }
@@ -266,7 +266,7 @@ PyObject* GetIterator(PyObject *_self) {
     return PyErr_Format(PyExc_KeyError, "Could not allocate iterator");
   }
 
-  MessageMapIterator* iter = GetIter(obj);
+  MessageMapIterator* iter = GetIter(obj.get());
 
   Py_INCREF(self);
   iter->container = self;
@@ -354,7 +354,7 @@ PyObject* Contains(PyObject* _self, PyObject* key) {
   // via linear search.
   //
   // TODO(haberman): add lookup API to Reflection API.
-  size_t size =
+  int size =
       reflection->FieldSize(*message, self->parent_field_descriptor);
   for (int i = 0; i < size; i++) {
     Message* entry = reflection->MutableRepeatedMessage(
@@ -405,12 +405,6 @@ PyObject* Get(PyObject* self, PyObject* args) {
   }
 }
 
-static PyMappingMethods MpMethods = {
-  Length,    // mp_length
-  GetItem,   // mp_subscript
-  SetItem,   // mp_ass_subscript
-};
-
 static void Dealloc(PyObject* _self) {
   MessageMapContainer* self = GetMap(_self);
   self->owner.reset();
@@ -485,6 +479,12 @@ PyObject* IterNext(PyObject* _self) {
   PyObject *MessageMapContainer_Type;
 
 #else
+  static PyMappingMethods MpMethods = {
+    message_map_container::Length,    // mp_length
+    message_map_container::GetItem,   // mp_subscript
+    message_map_container::SetItem,   // mp_ass_subscript
+  };
+
   PyTypeObject MessageMapContainer_Type = {
     PyVarObject_HEAD_INIT(&PyType_Type, 0)
     FULL_MODULE_NAME ".MessageMapContainer",  //  tp_name
@@ -498,7 +498,7 @@ PyObject* IterNext(PyObject* _self) {
     0,                                   //  tp_repr
     0,                                   //  tp_as_number
     0,                                   //  tp_as_sequence
-    &message_map_container::MpMethods,   //  tp_as_mapping
+    &MpMethods,                          //  tp_as_mapping
     0,                                   //  tp_hash
     0,                                   //  tp_call
     0,                                   //  tp_str
diff --git a/python/google/protobuf/pyext/repeated_composite_container.cc b/python/google/protobuf/pyext/repeated_composite_container.cc
index fe2e600b..b01123b4 100644
--- a/python/google/protobuf/pyext/repeated_composite_container.cc
+++ b/python/google/protobuf/pyext/repeated_composite_container.cc
@@ -116,7 +116,7 @@ static int UpdateChildMessages(RepeatedCompositeContainer* self) {
     cmsg->owner = self->owner;
     cmsg->message = const_cast<Message*>(&sub_message);
     cmsg->parent = self->parent;
-    if (PyList_Append(self->child_messages, py_cmsg) < 0) {
+    if (PyList_Append(self->child_messages, py_cmsg.get()) < 0) {
       return -1;
     }
   }
@@ -202,8 +202,8 @@ PyObject* Extend(RepeatedCompositeContainer* self, PyObject* value) {
     return NULL;
   }
   ScopedPyObjectPtr next;
-  while ((next.reset(PyIter_Next(iter))) != NULL) {
-    if (!PyObject_TypeCheck(next, &CMessage_Type)) {
+  while ((next.reset(PyIter_Next(iter.get()))) != NULL) {
+    if (!PyObject_TypeCheck(next.get(), &CMessage_Type)) {
       PyErr_SetString(PyExc_TypeError, "Not a cmessage");
       return NULL;
     }
@@ -212,7 +212,8 @@ PyObject* Extend(RepeatedCompositeContainer* self, PyObject* value) {
       return NULL;
     }
     CMessage* new_cmessage = reinterpret_cast<CMessage*>(new_message.get());
-    if (ScopedPyObjectPtr(cmessage::MergeFrom(new_cmessage, next)) == NULL) {
+    if (ScopedPyObjectPtr(cmessage::MergeFrom(new_cmessage, next.get())) ==
+        NULL) {
       return NULL;
     }
   }
@@ -294,7 +295,7 @@ static PyObject* Remove(RepeatedCompositeContainer* self, PyObject* value) {
     return NULL;
   }
   ScopedPyObjectPtr py_index(PyLong_FromLong(index));
-  if (AssignSubscript(self, py_index, NULL) < 0) {
+  if (AssignSubscript(self, py_index.get(), NULL) < 0) {
     return NULL;
   }
   Py_RETURN_NONE;
@@ -318,17 +319,17 @@ static PyObject* RichCompare(RepeatedCompositeContainer* self,
     if (full_slice == NULL) {
       return NULL;
     }
-    ScopedPyObjectPtr list(Subscript(self, full_slice));
+    ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
     if (list == NULL) {
       return NULL;
     }
     ScopedPyObjectPtr other_list(
-        Subscript(
-            reinterpret_cast<RepeatedCompositeContainer*>(other), full_slice));
+        Subscript(reinterpret_cast<RepeatedCompositeContainer*>(other),
+                  full_slice.get()));
     if (other_list == NULL) {
       return NULL;
     }
-    return PyObject_RichCompare(list, other_list, opid);
+    return PyObject_RichCompare(list.get(), other_list.get(), opid);
   } else {
     Py_INCREF(Py_NotImplemented);
     return Py_NotImplemented;
@@ -365,7 +366,7 @@ static int SortPythonMessages(RepeatedCompositeContainer* self,
   ScopedPyObjectPtr m(PyObject_GetAttrString(self->child_messages, "sort"));
   if (m == NULL)
     return -1;
-  if (PyObject_Call(m, args, kwds) == NULL)
+  if (PyObject_Call(m.get(), args, kwds) == NULL)
     return -1;
   if (self->message != NULL) {
     ReorderAttached(self);
@@ -429,7 +430,7 @@ static PyObject* Pop(RepeatedCompositeContainer* self,
     return NULL;
   }
   ScopedPyObjectPtr py_index(PyLong_FromSsize_t(index));
-  if (AssignSubscript(self, py_index, NULL) < 0) {
+  if (AssignSubscript(self, py_index.get(), NULL) < 0) {
     return NULL;
   }
   return item;
diff --git a/python/google/protobuf/pyext/repeated_composite_container.h b/python/google/protobuf/pyext/repeated_composite_container.h
index e0f21360..3013aba9 100644
--- a/python/google/protobuf/pyext/repeated_composite_container.h
+++ b/python/google/protobuf/pyext/repeated_composite_container.h
@@ -108,9 +108,6 @@ PyObject *NewContainer(
     const FieldDescriptor* parent_field_descriptor,
     PyObject *concrete_class);
 
-// Returns the number of items in this repeated composite container.
-static Py_ssize_t Length(RepeatedCompositeContainer* self);
-
 // Appends a new CMessage to the container and returns it.  The
 // CMessage is initialized using the content of kwargs.
 //
diff --git a/python/google/protobuf/pyext/repeated_scalar_container.cc b/python/google/protobuf/pyext/repeated_scalar_container.cc
index 7565c6fd..95da85f8 100644
--- a/python/google/protobuf/pyext/repeated_scalar_container.cc
+++ b/python/google/protobuf/pyext/repeated_scalar_container.cc
@@ -105,7 +105,7 @@ static int AssignItem(RepeatedScalarContainer* self,
   if (arg == NULL) {
     ScopedPyObjectPtr py_index(PyLong_FromLong(index));
     return cmessage::InternalDeleteRepeatedField(self->parent, field_descriptor,
-                                                 py_index, NULL);
+                                                 py_index.get(), NULL);
   }
 
   if (PySequence_Check(arg) && !(PyBytes_Check(arg) || PyUnicode_Check(arg))) {
@@ -172,7 +172,7 @@ static int AssignItem(RepeatedScalarContainer* self,
           ScopedPyObjectPtr s(PyObject_Str(arg));
           if (s != NULL) {
             PyErr_Format(PyExc_ValueError, "Unknown enum value: %s",
-                         PyString_AsString(s));
+                         PyString_AsString(s.get()));
           }
           return -1;
         }
@@ -334,7 +334,7 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
         break;
       }
       ScopedPyObjectPtr s(Item(self, index));
-      PyList_Append(list, s);
+      PyList_Append(list, s.get());
     }
   } else {
     if (step > 0) {
@@ -345,7 +345,7 @@ static PyObject* Subscript(RepeatedScalarContainer* self, PyObject* slice) {
         break;
       }
       ScopedPyObjectPtr s(Item(self, index));
-      PyList_Append(list, s);
+      PyList_Append(list, s.get());
     }
   }
   return list;
@@ -414,7 +414,7 @@ PyObject* Append(RepeatedScalarContainer* self, PyObject* item) {
           ScopedPyObjectPtr s(PyObject_Str(item));
           if (s != NULL) {
             PyErr_Format(PyExc_ValueError, "Unknown enum value: %s",
-                         PyString_AsString(s));
+                         PyString_AsString(s.get()));
           }
           return NULL;
         }
@@ -483,15 +483,15 @@ static int AssSubscript(RepeatedScalarContainer* self,
   if (full_slice == NULL) {
     return -1;
   }
-  ScopedPyObjectPtr new_list(Subscript(self, full_slice));
+  ScopedPyObjectPtr new_list(Subscript(self, full_slice.get()));
   if (new_list == NULL) {
     return -1;
   }
-  if (PySequence_SetSlice(new_list, from, to, value) < 0) {
+  if (PySequence_SetSlice(new_list.get(), from, to, value) < 0) {
     return -1;
   }
 
-  return InternalAssignRepeatedField(self, new_list);
+  return InternalAssignRepeatedField(self, new_list.get());
 }
 
 PyObject* Extend(RepeatedScalarContainer* self, PyObject* value) {
@@ -511,8 +511,8 @@ PyObject* Extend(RepeatedScalarContainer* self, PyObject* value) {
     return NULL;
   }
   ScopedPyObjectPtr next;
-  while ((next.reset(PyIter_Next(iter))) != NULL) {
-    if (ScopedPyObjectPtr(Append(self, next)) == NULL) {
+  while ((next.reset(PyIter_Next(iter.get()))) != NULL) {
+    if (ScopedPyObjectPtr(Append(self, next.get())) == NULL) {
       return NULL;
     }
   }
@@ -529,11 +529,11 @@ static PyObject* Insert(RepeatedScalarContainer* self, PyObject* args) {
     return NULL;
   }
   ScopedPyObjectPtr full_slice(PySlice_New(NULL, NULL, NULL));
-  ScopedPyObjectPtr new_list(Subscript(self, full_slice));
-  if (PyList_Insert(new_list, index, value) < 0) {
+  ScopedPyObjectPtr new_list(Subscript(self, full_slice.get()));
+  if (PyList_Insert(new_list.get(), index, value) < 0) {
     return NULL;
   }
-  int ret = InternalAssignRepeatedField(self, new_list);
+  int ret = InternalAssignRepeatedField(self, new_list.get());
   if (ret < 0) {
     return NULL;
   }
@@ -544,7 +544,7 @@ static PyObject* Remove(RepeatedScalarContainer* self, PyObject* value) {
   Py_ssize_t match_index = -1;
   for (Py_ssize_t i = 0; i < Len(self); ++i) {
     ScopedPyObjectPtr elem(Item(self, i));
-    if (PyObject_RichCompareBool(elem, value, Py_EQ)) {
+    if (PyObject_RichCompareBool(elem.get(), value, Py_EQ)) {
       match_index = i;
       break;
     }
@@ -579,15 +579,15 @@ 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));
+        reinterpret_cast<RepeatedScalarContainer*>(other), full_slice.get()));
     other = other_list_deleter.get();
   }
 
-  ScopedPyObjectPtr list(Subscript(self, full_slice));
+  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
-  return PyObject_RichCompare(list, other, opid);
+  return PyObject_RichCompare(list.get(), other, opid);
 }
 
 PyObject* Reduce(RepeatedScalarContainer* unused_self) {
@@ -618,19 +618,19 @@ static PyObject* Sort(RepeatedScalarContainer* self,
   if (full_slice == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr list(Subscript(self, full_slice));
+  ScopedPyObjectPtr list(Subscript(self, full_slice.get()));
   if (list == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr m(PyObject_GetAttrString(list, "sort"));
+  ScopedPyObjectPtr m(PyObject_GetAttrString(list.get(), "sort"));
   if (m == NULL) {
     return NULL;
   }
-  ScopedPyObjectPtr res(PyObject_Call(m, args, kwds));
+  ScopedPyObjectPtr res(PyObject_Call(m.get(), args, kwds));
   if (res == NULL) {
     return NULL;
   }
-  int ret = InternalAssignRepeatedField(self, list);
+  int ret = InternalAssignRepeatedField(self, list.get());
   if (ret < 0) {
     return NULL;
   }
@@ -688,7 +688,7 @@ static int InitializeAndCopyToParentContainer(
   if (full_slice == NULL) {
     return -1;
   }
-  ScopedPyObjectPtr values(Subscript(from, full_slice));
+  ScopedPyObjectPtr values(Subscript(from, full_slice.get()));
   if (values == NULL) {
     return -1;
   }
@@ -697,7 +697,7 @@ static int InitializeAndCopyToParentContainer(
   to->parent_field_descriptor = from->parent_field_descriptor;
   to->message = new_message;
   to->owner.reset(new_message);
-  if (InternalAssignRepeatedField(to, values) < 0) {
+  if (InternalAssignRepeatedField(to, values.get()) < 0) {
     return -1;
   }
   return 0;
diff --git a/python/google/protobuf/pyext/scalar_map_container.cc b/python/google/protobuf/pyext/scalar_map_container.cc
index a355edb2..0b0d5a3d 100644
--- a/python/google/protobuf/pyext/scalar_map_container.cc
+++ b/python/google/protobuf/pyext/scalar_map_container.cc
@@ -94,7 +94,7 @@ PyObject *NewContainer(
                         "Could not allocate new container.");
   }
 
-  ScalarMapContainer* self = GetMap(obj);
+  ScalarMapContainer* self = GetMap(obj.get());
 
   self->message = parent->message;
   self->parent = parent;
@@ -160,7 +160,7 @@ int MapKeyMatches(ScalarMapContainer* self, const Message* entry,
   // TODO(haberman): do we need more strict type checking?
   ScopedPyObjectPtr entry_key(
       cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-  int ret = PyObject_RichCompareBool(key, entry_key, Py_EQ);
+  int ret = PyObject_RichCompareBool(key, entry_key.get(), Py_EQ);
   return ret;
 }
 
@@ -251,7 +251,7 @@ int SetItem(PyObject *_self, PyObject *key, PyObject *v) {
       if (matches < 0) return -1;
       if (matches) {
         found = true;
-        if (i != size - 1) {
+        if (i != (int)size - 1) {
           reflection->SwapElements(message, self->parent_field_descriptor, i,
                                    size - 1);
         }
@@ -303,7 +303,7 @@ PyObject* GetIterator(PyObject *_self) {
   // TODO(haberman): add lookup API to Reflection API.
   size_t size =
       reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = 0; i < size; i++) {
+  for (size_t i = 0; i < size; i++) {
     Message* entry = reflection->MutableRepeatedMessage(
         message, self->parent_field_descriptor, i);
     ScopedPyObjectPtr key(
@@ -382,12 +382,6 @@ PyObject* Get(PyObject* self, PyObject* args) {
   }
 }
 
-static PyMappingMethods MpMethods = {
-  Length,    // mp_length
-  GetItem,   // mp_subscript
-  SetItem,   // mp_ass_subscript
-};
-
 static void Dealloc(PyObject* _self) {
   ScalarMapContainer* self = GetMap(_self);
   self->owner.reset();
@@ -458,6 +452,12 @@ PyObject* IterNext(PyObject* _self) {
   };
   PyObject *ScalarMapContainer_Type;
 #else
+  static PyMappingMethods MpMethods = {
+    scalar_map_container::Length,    // mp_length
+    scalar_map_container::GetItem,   // mp_subscript
+    scalar_map_container::SetItem,   // mp_ass_subscript
+  };
+
   PyTypeObject ScalarMapContainer_Type = {
     PyVarObject_HEAD_INIT(&PyType_Type, 0)
     FULL_MODULE_NAME ".ScalarMapContainer",  //  tp_name
@@ -471,7 +471,7 @@ PyObject* IterNext(PyObject* _self) {
     0,                                   //  tp_repr
     0,                                   //  tp_as_number
     0,                                   //  tp_as_sequence
-    &scalar_map_container::MpMethods,    //  tp_as_mapping
+    &MpMethods,                          //  tp_as_mapping
     0,                                   //  tp_hash
     0,                                   //  tp_call
     0,                                   //  tp_str
diff --git a/python/google/protobuf/pyext/scoped_pyobject_ptr.h b/python/google/protobuf/pyext/scoped_pyobject_ptr.h
index 9979b83b..a128cd4c 100644
--- a/python/google/protobuf/pyext/scoped_pyobject_ptr.h
+++ b/python/google/protobuf/pyext/scoped_pyobject_ptr.h
@@ -60,11 +60,6 @@ class ScopedPyObjectPtr {
     return ptr_;
   }
 
-  // ScopedPyObjectPtr should not be copied.
-  // We explicitly list and delete this overload to avoid automatic conversion
-  // to PyObject*, which is wrong in this case.
-  PyObject* reset(const ScopedPyObjectPtr& other) = delete;
-
   // Releases ownership of the object.
   // The caller now owns the returned reference.
   PyObject* release() {
@@ -73,8 +68,6 @@ class ScopedPyObjectPtr {
     return p;
   }
 
-  operator PyObject*() { return ptr_; }
-
   PyObject* operator->() const  {
     assert(ptr_ != NULL);
     return ptr_;
diff --git a/python/setup.py b/python/setup.py
index cda56867..662a145a 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -148,17 +148,24 @@ class build_py(_build_py):
 if __name__ == '__main__':
   ext_module_list = []
   cpp_impl = '--cpp_implementation'
+  warnings_as_errors = '--warnings_as_errors'
   if cpp_impl in sys.argv:
     sys.argv.remove(cpp_impl)
+    extra_compile_args = ['-Wno-write-strings']
+
+    if warnings_as_errors in sys.argv:
+      extra_compile_args.append('-Werror')
+      sys.argv.remove(warnings_as_errors)
+
     # C++ implementation extension
     ext_module_list.append(
         Extension(
             "google.protobuf.pyext._message",
             glob.glob('google/protobuf/pyext/*.cc'),
-            define_macros=[('GOOGLE_PROTOBUF_HAS_ONEOF', '1')],
             include_dirs=[".", "../src"],
             libraries=['protobuf'],
             library_dirs=['../src/.libs'],
+            extra_compile_args=extra_compile_args,
         )
     )
     os.environ['PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'] = 'cpp'
diff --git a/python/tox.ini b/python/tox.ini
index a6352ef4..7deb3ba3 100644
--- a/python/tox.ini
+++ b/python/tox.ini
@@ -13,7 +13,7 @@ setenv =
 commands =
     python setup.py -q build_py
     python: python setup.py -q build
-    cpp: python setup.py -q build --cpp_implementation
+    cpp: python setup.py -q build --cpp_implementation --warnings_as_errors
     python: python setup.py -q test -q
     cpp: python setup.py -q test -q --cpp_implementation
 deps =