Remove objc_proto_library rule

[laurentlb]

objc_proto_library is not usable in Bazel. The code is present because it may be used inside Google. We should remove the rule from Bazel and from its documentation (https://docs.bazel.build/versions/master/be/objective-c.html#objc_proto_library).

(tracking bug in Google: b/123888674)

[lberki]

/cc @sergiocampama @aragos @thomasvl @lberki

[lberki]

What about e.g. apple_binary -> proto_library dependencies?

Removing the rule itself is a trivial amount of work, but it appears that apple_binary and apple_static_library also use the aspect. Does this mean that those rules can't depend directly on proto_library rules?

[aragos]

apple_binary cannot directly depend on proto_library targets. It does however register an aspect on its transitive dependencies to aid processing of any objc_proto_library target it ends up linking. We'll have to decide whether to remove this code as well (it does nothing without the presence of objc_proto_library) or to leave it in place.

[lberki]

What does that aspect do then? I mean, objc_proto_library propagates that aspect just as well, so what extra functionality does apple_binary / apple_static_library gain from it?

[sergiocampama]

apple_binary propagates the aspect to collect all proto_library sources and other files to generate a comprehensive list of protos and which symbols are required, and at that point generate/compile/link them into the binary.

We'd like to remove the processing done in apple_binary at some point, but disallowing the objc_proto_library rule from Bazel should be orthogonal to that cleanup.

Please ping me for a more in depth description of how objc protos work, if you want to gaze into the abyss.

[lberki]

Well, I thought it was simpler than that :) My motivation was to also remove the aspect implementation and not just objc_proto_library itself.

Let's continue the discussion on the "Bazel 1.0 and objc_proto_library" thread.

[dnkoutso]

Related #1802

[dslomov]

This P1 bazel 1.0 issue is unassigned. Please assign cc @aragos

[thomasvl]

@sergiocampama is working on this

[dslomov]

Does not seem to be on track for 1.0

[sergiocampama]

objc_proto_library has been deleted from the native codebase, but not all native support has been removed. We would have liked to remove this sooner, but there are still unresolved blockers.

[meisterT]

I think this is gone by now, isn't it? cc @c-parsons

[sgowroji]

Hi there! We're doing a clean up of old issues and will be closing this one. Please reopen if you’d like to discuss anything further. We’ll respond as soon as we have the bandwidth/resources to do so.