plugin.proto and descriptor.proto contains the wrong go_package

[dcaiafa]

plugin.proto's go_package is currently set to "plugin_go". It should be set to "compiler" because protoc-gen-go will place generated files into google/protobuf/compiler.

Similarly, descriptor.proto's go_package is currently set to "descriptor". It should be set to "protobuf".

In 2.6.1, both proto files contained no go_package statement. While not ideal, this at least allowed the package name to be specified in the --go_out=import_path parameters. In 3.0.0, it's currently impossible (to the best of my knowledge) to generate valid Go for plugin.proto and descriptor.proto without modifications.

[haberman]

@neild could you weigh in on this? Should we change go_package in these .proto files?

[neild]

(Sorry for the delay, traveling.)

Here's what I'm seeing for descriptor.proto:
option go_package = "github.com/golang/protobuf/protoc-gen-go/descriptor;descriptor";

That looks right to me. (The /protoc-gen-go/ is pretty unfortunate, but there are historical reasons for it.)

plugin.proto's go_package looks wrong, though:
option go_package = "plugin_go";

That should either be "github.com/golang/protobuf/protoc-gen-go/plugin;plugin_go" or "github.com/golang/protobuf/protoc-gen-go/plugin;plugin". The former matches the pregenerated in the Go protobuf repo, but the latter is the better choice if we don't worry about compatibility.

To expand on that: The import path for the generated package for plugin.proto is "github.com/golang/protobuf/protoc-gen-go/plugin". By Go convention, we would expect the package name to be the last component of the import path: "plugin". However, the generated package in the github.com/golang/protobuf repo is using the package name "plugin_go".

If we change the name to "plugin", we break anyone depending on the existing name. I don't know whether anyone does depend on it.

I'm inclined to say that we should stick with the existing, unfortunate, package name, in which case the go_package option should be set to "github.com/golang/protobuf/protoc-gen-go/plugin;plugin_go". I'm happy to hear arguments for changing the package name, however.