proto c++ implementation - "marked ‘override’, but does not override" error

// api_internal.proto
service InvoiceTemplateMatcher { rpc Process(InvoiceFilePath) returns (UploadStatus) {}
}
message InvoiceFilePath { string invoice_id = 1; string file_path = 2;
}
// template_matcher/src/main.cc
class OrkaEngineInvoiceTemplateMatcherImpl final : public InvoiceTemplateMatcher::Service {
private: Status Process( ServerContext* context, orka_engine_internal::InvoiceFilePath* invoicefp, orka_engine_internal::UploadStatus* response) override { // do stuff }
};

Class InvoiceTemplateMatcher::Service is generated during compile time from that .proto file.

When I try to compile, I get an error

‘grpc::Status OrkaEngineInvoiceTemplateMatcherImpl::Process(grpc::ServerContext*, orka_engine_internal::InvoiceFilePath*, orka_engine_internal::UploadStatus*)’ marked ‘override’, but does not override Status Process(ServerContext* context, orka_engine_internal::InvoiceFilePath* invoicefp, orka_engine_internal::UploadStatus* response) override {

As far as I can tell, my code is written in the same way as in Route Guide example. What am I missing?

2 Answers

Such an error is issued by the compiler when the the function is not marked virtual in the base class.

Consider the following minimal example:

class Base{ void Foo() {}
};
class Derived : Base{ void Foo() override {}
};

Compiler issues the error:

error: 'void Derived::Foo()' marked 'override', but does not override void Foo() override {}

See Demo

The override specifier specifies that a virtual function overrides another virtual function.

I know that this post is quite old but I will give a correct answer for any future troubleshoots that person might across while wokring with protobufs.

You are correct saying that the class implementation has been generated automatically and protobuf c++ generation has this class function by default:

virtual ::grpc::Status Process(::grpc::ServerContext* context, const ::orka_engine_internal::InvoiceFilePath* request, ::orka_engine_internal::UploadStatus* response);

So you need to match your function exactly to virtual function. In your example, just change invoicefp to request