Pass real crate-level attributes to pre_expansion_lint

[smoelius]

The PR concerns the unstable feature register_tool (#66079).

The feature's implementation requires the attributes of the crate being compiled, so that when attributes like allow(foo::bar) are encountered, it can be verified that register_tool(foo) appears in the crate root.

However, the crate's attributes are not readily available during early lint passes. Specifically, on this line, krate.attrs appears to be the attributes of the current source file, not the attributes of the whole crate:

rust/compiler/rustc_lint/src/context.rs

Line 815 in bf64232

builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store, &krate.attrs),

Consequently, "unknown tool" errors were being produced when allow(foo::bar) appeared in a submodule, even though register_tool(foo) appeared in the crate root.

EDITED: The proposed fix is to obtain the real crate-level attributes in configure_and_expand and pass them to pre_expansion_lint. (See @petrochenkov's comment below.)

The original "prosed fix" text follows.

---

The proposed fix is to add an error_on_unknown_tool flag to LintLevelsBuilder. The flag controls whether "unknown tool" errors are emitted. The flag is set during late passes, but not earlier.

More specifically, this PR contains two commits:

• The first adds a known-tool-in-submodule UI test that does not currently pass.
• The second adds the error_on_unknown_tool flag. The new test passes with the addition of this flag.

This change has the added benefit of eliminating some errors that were duplicated in existing tests.

To the reviewer: please check that I implemented the UI test correctly.

[rust-highfive]

r? @nagisa

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[nagisa]

r? @petrochenkov

[petrochenkov]

krate.attrs appears to be the attributes of the current source file, not the attributes of the whole crate

This is a bug and a regression from #69838.
pre_expansion_lint is called after loading any new module, and that module is passed to it after being artificially turned into ast::Crate, just because pre_expansion_lint works with ast::Crate.
Real crate-level attributes are available at that point and just need to be additionally passed to pre_expansion_lint.

[smoelius]

Thanks, @petrochenkov. Please leave the PR open for now while I try to find a proper fix.

[smoelius]

@petrochenkov Is this about what you had in mind?

[petrochenkov]

Yes, this is exactly what I meant.
@bors r+

@smoelius Could you also update the PR description before the merge? (It's outdated, but I'll be included into the merge commit.)

[bors]

📌 Commit 1e15bbe has been approved by petrochenkov

[smoelius]

@smoelius Could you also update the PR description before the merge? (It's outdated, but I'll be included into the merge commit.)

Absolutely. Please let me know if what I wrote is insufficient.

[bors]

⌛ Testing commit 1e15bbe with merge 98c8619...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 98c8619 to master...

[rust-timer]

Finished benchmarking commit (98c8619): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression