Make strip_include_prefix apply to textual_hdrs

[keith]

Mirror of bazelbuild/bazel#26327

[keith]

cc @trybka

[armandomontanez]

Will probably take a bit to get this one merged.

[armandomontanez]

Still seeing failures internally, we might need to put this behind a flag if we don't want to block on Whatever Problems Google Has.

[keith]

are you thinking a top level bazel flag, or a magic feature to opt out of this behavior, or?

also is there a bug in the implementation that only google is seeing? or is it just that maybe you have to update your #include if the textual_hdrs match the strip_include_prefix? (I thought you would still be able to access them through the fully path 🤔 )

[trybka]

I think we could handle it in semantics.bzl rather than a flag or a feature.

The former would need to either be in Java or Starlark Build Flags both of which seem pretty onerous, the latter of which would need to be yet-another-feature we need to check and we've already encoutered issues using features for this in the past (notably things like platform.flags dropping them on the floor: https://bazel.build/reference/be/platforms-and-toolchains#platform_flags_repeated).

[keith]

pushed a boolean to that file which can disable this behavior, wdyt about that? idk how your replacements for that file work but I assume it might have the downside that it cannot be enabled in some places and not others (notably the original feature requester of this is a googler)

[trybka]

(Replied to the wrong PR...)

The goal would be to enable it internally soon as well, but to be able to approve this change without blocking on said clean-up.

(The buildkite failures are only in the other PR)

It looks like this is passing most of the builds that were failing before.

[eric-wieser]

Should this be updating system_include_dirs_for_context too / instead? That is, perhaps

Suggested change

	if external or feature_configuration.is_requested("system_include_paths"):
	external_include_dirs.append(textual_headers.virtual_include_path)
	if external:
	external_include_dirs.append(textual_headers.virtual_include_path)
	elif feature_configuration.is_requested("system_include_paths"):
	system_include_dirs_for_context.append(textual_headers.virtual_include_path)

[keith]

thanks! #800