rules_cc dependency marked as dev causes rules_cc module visibility issues

[steeve]

When trying to use the following code:

load("@rules_proto//proto:defs.bzl", "proto_descriptor_set")

proto_descriptor_set(
    name = "my_fdset",
    deps = ["...."],
)

This causes the following error:

ERROR: error loading package '@@rules_proto~6.0.0-rc2//tools/file_concat': Unable to find package for @@[unknown repo 'rules_cc' requested from @@rules_proto~6.0.0-rc2]//cc:defs.bzl: The repository '@@[unknown repo 'rules_cc' requested from @@rules_proto~6.0.0-rc2]' could not be resolved: No repository visible as '@rules_cc' from repository '@@rules_proto~6.0.0-rc2'.

[comius]

cc @alexeagle @thesayyn, please triage/fix

[alexeagle]

Yup, that tool is written in C++ which is naughty since we only declare that as a devDep: https://github.com/bazelbuild/rules_proto/blob/f889a1b532fdca5f5051691f023a6a9f37ce494f/MODULE.bazel#L16 and many users have broken C++ toolchains.

The program itself is very small https://github.com/bazelbuild/rules_proto/blob/f889a1b532fdca5f5051691f023a6a9f37ce494f/tools/file_concat/main.cc

I think we should avoid having tools live in rules_proto.

[SanjayVas]

It looks like despite being reported against v6.0.0-rc2, this bug continued into both v6.0.0-rc3 and the final v6.0.0 release. Can we get a fix either in rules_proto itself (v6.0.1) or in BCR (6.0.0.bcr.1)?

[alexeagle]

What do you propose as the fix? I suppose our only choice per semver is to make rules_cc a non-dev dependency, rather than remove this tool or ship pre-built binaries for it.

[SanjayVas]

I suppose our only choice per semver is to make rules_cc a non-dev dependency

Yes, exactly this for the short term as right now the module definition is just incorrect/broken. Anything like what was proposed in https://github.com/bazelbuild/rules_proto/issues/203#issuecomment-2070932477 would need to come later.