How to configure Bazel's go_proto_library so Connect's plugin generates its file in a subdirectory?

[abitofhelp]

Please see solution at https://github.com/abitofhelp/connect-go-example.git

and issue/feature request at rules_go: bazel-contrib/rules_go#3951

---

Hello,

ISSUE <<<<<<<
When using the Connect plugin in a Bazel rule, the protobuf and connect .go files are generated in a single directory, which has two packages in a single directory and won't bulid. I'd appreciate your suggestions for resolving this issue. Otherwise, it seems that protobuf and connect generation in Bazel is working.

SOURCE: https://github.com/abitofhelp/bzlmod

// HAVE
'bazel-bin/proto/helloworld/v1/helloworld.go'
'bazel-bin/proto/helloworld/v1/helloworld.connect.go'

// NEED
'bazel-bin/proto/helloworld/v1/helloworld.go'
'bazel-bin/proto/helloworld/v1/helloworldv1connect/helloworld.connect.go'

I am able to properly generate the protobuf and connect files using protoc and 'buf generate':

protoc -I proto --go_out='internal/gen/' --go_opt=paths=source_relative --connect-go_out='internal/gen/' --connect-go_opt=paths=source_relative $(find proto -name '*.proto')

// From the directory where buf.yaml and buf.gen.yaml exist.
buf generate

I've configured BUILD.bazel where the helloworld.proto file exists with a rule defining Connect's plug-in compiler.

go_proto_compiler(
    name = "connect_go_proto_compiler",
    options = [
        "lang=go",
    ],
    plugin = "@com_connectrpc_connect//cmd/protoc-gen-connect-go:protoc-gen-connect-go",
    suffix = ".connect.go",
    valid_archive = False,
    visibility = ["//visibility:public"],
    deps = ["@com_connectrpc_connect//:go_default_library"],
)

// and a rule to generate the protobuf and connect .go files:
go_proto_library(
    name = "helloworldv1_go_proto",
    compilers = [
        "//proto/helloworld/v1:connect_go_proto_compiler",
        "@rules_go//proto:go_proto",
    ],
    importpath = "github.com/abitofhelp/bzlmod/proto/helloworld/v1",
    proto = ":helloworldv1_proto",
    visibility = ["//:__subpackages__"],
)