Location expansion with some APIs differ from others

[keith]

Description of the bug:

When you have a simple py_binary, that you use in a genrule:

py_binary(
    name = "py_binary",
    srcs = ["py_binary.py"],
)

genrule(
    name = "genrule",
    outs = ["genrule.txt"],
    cmd = "$(location :py_binary) $(OUTS) from-genrule",
    tools = [":py_binary"],
)

This works fine. But if you try to create your own rule that handles something similar, the ctx.expand_location API results in this error:

BUILD.bazel:23:15: in broken_genrule rule //:custom_broken_genrule: label '//:py_binary' in $(location) expression expands to more than one file, please use $(locations //:py_binary) instead.  Files (at most 5 shown) are: [./py_binary.py, bazel-out/darwin_arm64-fastbuild/bin/py_binary]

Using the ctx.resolve_command API does seem to solve this, but it returns an array as the command, which might not be preferred, and requires post-processing any escaped $ signs.

I tried passing specific files to expand_location, but it seems to require a Target not any files, so it doesn't seem like something I can filter to only the inputs I care about.

Which category does this issue belong to?

No response

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

bazel build :all in repro.zip

Which operating system are you running Bazel on?

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What is the output of bazel info release?

7.x

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 HEAD ?

No response

If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

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