1 files changed, 5 insertions, 0 deletions
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index 0f54506b..ef75acab 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -2065,6 +2065,11 @@ static PyObject* MergeFromString(CMessage* self, PyObject* arg) {
   input.SetExtensionRegistry(factory->pool->pool, factory->message_factory);
   bool success = self->message->MergePartialFromCodedStream(&input);
   if (success) {
+    if (!input.ConsumedEntireMessage()) {
+      // TODO(jieluo): Raise error and return NULL instead.
+      // b/27494216
+      PyErr_Warn(NULL, "Unexpected end-group tag: Not all data was converted");
+    }
     return PyInt_FromLong(input.CurrentPosition());
   } else {
     PyErr_Format(DecodeError_class, "Error parsing message");