proto_common.compile() should not require plugin_output parameter

[haberman]

Description of the bug:

proto_common.compile() has a plugin_output parameter that a user must pass to specify where the output must go. But specifying it properly requires some tricky logic to handle all edge cases. Users have to write something like this:

load("//tools/build_defs/proto:proto_common.bzl", "proto_common")

def output_dir(ctx, proto_info):
    """Returns the output directory where generated proto files will be placed.

    Args:
      ctx: Rule context.
      proto_info: ProtoInfo provider.

    Returns:
      A string specifying the output directory
    """
    proto_root = proto_info.proto_source_root
    if proto_root.startswith(ctx.bin_dir.path):
        path = proto_root
    else:
        path = ctx.bin_dir.path + "/" + proto_root

    if proto_root == ".":
        path = ctx.bin_dir.path
    return path

def proto_common_compile(ctx, proto_info, proto_lang_toolchain_info, generated_files):
    """A wrapper around proto_common.compile that automatically calculates the output dir.

    Args:
      ctx: Rule context.
      proto_info: ProtoInfo provider.
      proto_lang_toolchain_info: ProtoLangToolchainInfo provider.
      generated_files: The files we expect to be generated from this protoc invocation.
    """
    proto_common.compile(
        actions = ctx.actions,
        proto_info = proto_info,
        proto_lang_toolchain_info = proto_lang_toolchain_info,
        generated_files = generated_files,
        plugin_output = output_dir(ctx, proto_info),
    )

proto_common.compile() should handle this internally, rather than making users copy and paste this code.

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Use proto_common.compile() without the special code above and watch it break with errors like:

ERROR: /usr/local/google/home/haberman/.cache/bazel/_bazel_haberman/17449526a2508fe9f4def2619c761b7e/external/com_google_googleapis/BUILD.bazel:31:14: output 'external/com_google_googleapis/google/rpc/status.upb.h' was not created

Which operating system are you running Bazel on?

Linux

What is the output of bazel info release?

release 6.1.2

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse master; git rev-parse HEAD ?

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response

[comius]

I'm working on this. It's not completely true. The output parameter is formatted differently if protoc generates a single file. For example for desciptor sets, java .jar file. Possible solution is to add a that bit of information to proto_lang_toolchain and then completely remove the parameter from proto_common.compile