https://github.com/protobuf-c/protobuf-c/pull/673

Index: protoc-c/c_message_field.h
--- protoc-c/c_message_field.h.orig
+++ protoc-c/c_message_field.h
@@ -82,10 +82,6 @@ class MessageFieldGenerator : public FieldGenerator {
   void GenerateDescriptorInitializer(io::Printer* printer) const;
   std::string GetDefaultValue(void) const;
   void GenerateStaticInit(io::Printer* printer) const;
-
- private:
-
-  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageFieldGenerator);
 };