Use of undeclared method ProtobufMessage::read_varint

[felixnehrke-tradedoubler]

In the base-class of a message is a method called, which is not declared in the abstract class itself nor any implementation. The method actually belongs to the class Protobuf which is not in the inheritance-chain of the ProtobufMessage though.

https://github.com/nemoinho/protoc-gen-php/blob/master/protocolbuffers.inc.php#L86