protoc-gen-go: regression in handling of source_relative parameter

[kevinburke1]

I am attempting to generate a Go pb.go file. This is the command I am running to generate it with the old binary:

cd pb && protoc --ruby_out=source_relative:../ruby/pb --go_out=source_relative:/Users/kevin/src api.proto

I run that command from $GOPATH/src/github.com/myorg/myproject. It writes a file to $GOPATH/src/github.com/myorg/myproject/pb/api.pb.go.

With the new cmd/protoc-gen-go, I get the following error:

cd pb && protoc --ruby_out=source_relative:../ruby/pb --go_out=source_relative:/Users/kevin/src api.proto
protoc-gen-go: no such flag -source_relative
--go_out: protoc-gen-go: Plugin failed with status code 1.
make: *** [Makefile:13: pb/api.pb.go] Error 1

Confusingly, I can see references to source_relative in the source code, but the references in the README of the new project have disappeared.

I can get it to generate a file by changing the command to read:

cd pb && protoc --ruby_out=source_relative:../ruby/pb --go_out=paths=source_relative:/Users/kevin/src api.proto

However, this writes api.pb.go to $GOPATH/src/api.pb.go, not $GOPATH/src/github.com/myorg/myproject/pb/api.pb.go as I expect.

[kevinburke1]

I should add, I have this in api.proto

option go_package = "github.com/myorg/myproject/pb";

[dsnet]

It is a surprise to me that --go_out=source_relative:output_dir worked. If it did, that was actually a bug in the old implementation and was not the intention of how the flag worked. The documentation for source_relative says it should actually be like: --go_out=paths=source_relative:output_dir.

\cc @neild to decide whether we should forward port this "feature" to the new implementation.

[neild]

I don't understand how --go_out=source_relative:output_dir could ever have worked. The only reference to source_relative in the source code only applies to a paths=source_relative parameter:

https://github.com/golang/protobuf/blob/master/protoc-gen-go/generator/generator.go#L488

[neild]

Also, so far as I can tell, the Ruby code generator has no support for a source_relative option. I don't see one anywhere: https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/compiler/ruby/ruby_generator.cc

[kevinburke1]

Ah, doing some more experiments, with the old generator I get the same results if I remove source_relative:, so it just reads --go_out=/Users/kevin/src.

I believe it took a large amount of tinkering to get the outputs the way I wanted so I probably stopped once I got it working.

[kevinburke1]

I think this should be closed, tightening argument parsing so things that had no effect, and should not have been allowed, are now not allowed, doesn't seem like a regression. My mistake was in assuming that this was doing something.