[FR]: Should `output_dir` use `output` as the dir name rather than `name?

[surma]

What is the current behavior?

It seems that if output_dir is true, a directory artifact is declared using the rule name as the folder name.

rules_esbuild/esbuild/private/esbuild.bzl

Lines 255 to 257 in cede902

	if ctx.attr.output_dir:
	js_out = ctx.actions.declare_directory("%s" % ctx.attr.name)
	output_sources.append(js_out)

Describe the feature

I was surprised that when I defined output = "dist" with output_dir = True, that the rule would fail with “The following files have no generating action: .../dist". After digging into the code, it seems that name is used for the folder name. Is that intentional?

[jbedard]

I believe this is because the output attribute is a predeclared output file and can not be a directory.

Would an error message have helped if both output and output_dir are set? I think that would be harmless and maybe improve the DX. Want to open a PR adding that?