Use released protoc binaries

[simuons]

Description

Based on change in rules_proto
bazelbuild/rules_proto#36

rules_proto_dependencies() declares a @com_google_protobuf//:protoc
which points to released protoc binary.

The tricks is to load that before scala_repositories() which has
conditional load for @com_google_protobuf

Motivation

Avoid compiling protoc during bazel build.

[ittaiz]

Thanks!
2 questions:

1. If existing clients don't have this will they break?
2. Update the readme?

[simuons]

If existing clients don't have this will they break?

Clients won't break. rules_proto and com_google_protobuf are defined in rules_scala_setup and guarded by if. So they will get current defaults or whatever they configure.

Update the readme?

Ok I'll remove current recommendation for com_google_protobuf from README and add rules_proto setup after skylib.

[liucijus]

Ok I'll remove current recommendation for com_google_protobuf from README and add rules_proto setup after skylib.

I think it's more important to explain in the REDAME what's going on. I would say that this change in the first place is intended for rules_scala development. I would keep this change out user attention until we properly refactor repository.bzl's - meaning no update to README or setup instructions.

[ittaiz]

Why? Maybe I'm missing the point here. Is this really only meant for rules_scala development or do you just want to keep it internal until the repository.bzl refactor?

[liucijus]

At the moment rules_proto are also loaded in scala_repositories.bzl. Until this duplication is refactored (which isn't a trivial change), I consider it will be confusing to users.

[ittaiz]

Then why do we need to load them twice?

[simuons]

It's loaded twice because I didn't want to change existing macro and break users. Well technically it isn't loaded twice because definition in macro is guarded by the if. I had to define rules_proto before scala_repositories macro because it contains definition for com_google_protobuf and I want to use definition of com_google_protobuf from rules_proto.

Guys can we agree that I'll revert readme change. And will treat this PR as an optimization for rules_scala build. And I'll look at repository.bzl refactoring to align setup of rules_scala and what user have to setup.

[simuons]

Or feel free to close this PR if you think it should be done as a "proper refactoring of repositories.bzl"

[ittaiz]

Let's revert the PR and merge.
Maybe just add a comment about why our WORKSPACE setup is different than the readme? If there is already a comment and I forgot about it then 👍🏽