rules_proto is using 3.13 but I'm building with 4.

[Martin Blais]

Hi,

I'm a little confused regarding how to use this.

I'm importing this module in order to - I think - get proto_library rules in Bazel.

I'm also - in my project - defining a "@com_google_protobuf" namespace that contains the version of protobuf I'm using for my project (4.0.0rc2), and use its own protobuf.bzl Bazel to build it.  (Why that project itself doesn't provide Bazel rules to build protos is 

I've just noticed that this rules_proto defines a different protobuf under https://github.com/bazelbuild/rules_proto/blob/master/proto/private/dependencies.bzl#L25, as of v3.13, under namespace "@com_github_protocolbuffers_protobuf". I noticed this because checking the version of protoc that's invoked, I see it's not the same version as that which I'm building with.

Do I need rules_proto? Well, if I said no, protobuffers/protobuf/protobuf.bzl imports it anyhow. How does that jive with the fact that protobuf at version vY imports rules proto, which builds a protoc at version vX, where vX != vY?  Is that not a problem?

And if it is, is it recommended I fork this to place the same version of the library I'm otherwise using?

How is it SUPPOSED to work?

[Martin Blais]

Is it sufficient to just redefine my own proto repository as "@com_github_protocolbuffers_protobuf", and making sure to call rules_proto_dependencies() after I define it, to get a consistent version?

(If so, this may be worthwhile documenting.)

[Martin Blais]

I think I just found something:

        http_archive(
            name = "rules_proto",
..

            repo_mapping = {"@com_github_protocolbuffers_protobuf": "@com_google_protobuf"}
        )

In other words, if I tell @rules_proto about the repository in the name it's expecting, it'll override that (via maybe()).

Except it doesn't appear to work, I'm still getting a 3.13 protoc.

Hmmm

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[Martin Blais]

On Wednesday, December 9, 2020 at 3:16:27 AM UTC-5 Martin Blais wrote:

I think I just found something:

        http_archive(
            name = "rules_proto",
..

            repo_mapping = {"@com_github_protocolbuffers_protobuf": "@com_google_protobuf"}
        )

In other words, if I tell @rules_proto about the repository in the name it's expecting, it'll override that (via maybe()).

Except it doesn't appear to work, I'm still getting a 3.13 protoc.

Hmmm

No! Actually this *does* work.

There's another reason I was seeing the old version number. I modified the source code of my custom proto repo and it's reflected in the output. Also, using this with a released proto version also shows the correct version. I check like this:

./bazel-bin/external/com_google_protobuf/protoc --version

Thank you,