tree 41e89be29e52bf32a3a8f1dfb54adc515ce10bfb
parent 1e2e1956ce9f23ef6f57e2a3cfd267bdd6530290
author Fabian Meumertzheim <fabian@meumertzhe.im> 1666621205 -0700
committer Copybara-Service <copybara-worker@google.com> 1666621264 -0700

Fail `Label` call referencing invalid repository with strict visibility

With Bzlmod's enforcement of strict visibility of repositories based on repository mapping, a `Label` created from a repo-absolute (but not canonical) label string such as `@repo//foo:bar` will be in an error state if there is no repository visible from the calling .bzl module under the apparent name `repo`.

Before this commit, such instances of `Label` could be freely constructed and used from Starlark, even though some of their fields return nonsensical values (for example, `workspace_root` will be `"external"` for `Label("@//foo:bar")` called from a repo without visibility into the main repository).

This commit ensures that instead the `Label` call (and also analogous calls to `relative`) fail with an error such as:
```
Invalid label string '@//foo:bar': no repository visible as '@' from repository '@current_repo'
```

Fixes #16528

Closes #16530.

PiperOrigin-RevId: 483373288
Change-Id: I4831e179a2d0363aa2f27ca4a25d79a634103f8f