Fail eagerly on invalid labels

[fmeum]

Description of the feature request:

Bazel should fall immediately with a helpful stack trace when a label with an unknown apparent repo name is constructed in any context. Such labels are never useful as essentially all their methods fail, but delaying these failures makes it more difficult to fix these errors.

This would require an incompatible flag.

Which category does this issue belong to?

No response

What underlying problem are you trying to solve with this feature?

No response

Which operating system are you running Bazel on?

No response

What is the output of bazel info release?

No response

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 ?

Have you found anything relevant by searching the web?

No response

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

No response

[fmeum]

@Wyverald @meteorcloudy

[Wyverald]

I do agree it's probably time to start looking into this. If we can flip and delete the incompatible flag, we might even able to remove the concept of "invisible" RepositoryName objects altogether.

For some historical context, lazy failure was a conscious design decision in the early days of Bzlmod. Having eager failure would mean that one needed to migrate every single target in a BUILD file to be Bzlmod-friendly before any of them could be built.