[FR]: Allow `$(execpath output_label)` expansion in `js_run_binary`

[Silic0nS0ldier]

What is the current behavior?

Only inputs from srcs can be referenced in args and env via variable expansion. Attempting to reference something in outs or out_dirs results in an error.

label '//___:___' in $(location) expression is not a declared prerequisite of this rule

Describe the feature

Allow outs and out_dirs labels to be referenced in $(execpath ___) expansions.

[Silic0nS0ldier]

This actually is a change that needs to happen in https://github.com/bazel-contrib/bazel-lib, since js_run_binary is a wrapper around run_binary.

[jbedard]

Should this FR be closed and opened there then?

[Silic0nS0ldier]

I was wrong again, this is a limitation in Bazel (ctx.expand_location doesn't consider outputs, unlike genrule's own implementation of this). Closing, I'll open an issue in the Bazel repo.

[Silic0nS0ldier]

For anyone coming across this later: bazelbuild/bazel#24573

[jbedard]

Thanks for the info 👍