CI: check that new lints use the correct stabilization version

[samueltardieu]

New lints are found by comparing the metadata with the base one. The declared version must be equal to the stabilization version.

Inspired by #13497.

changelog: none

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[alex-semenyuk]

Might make sense to add tests on this stuff

[xFrednet]

I think a solution that doesn't fail the CI would be preferable instead. Something like a temporary value that is replaced during the release process. I believe @blyxyas was looking into something like that for a while. But I'm not sure.

Otherwise, I'm also used to updating these attributes as part of the release process.

[samueltardieu]

I think a solution that doesn't fail the CI would be preferable instead.

I'm not sure I understand why failing the CI would be wrong. Having the right version from the start (and having to update it if there is a release before it is merged in) ensures that the documentation is up-to-date, and let the user see what is in stable, beta, or nightly for example.

Something like a temporary value that is replaced during the release process. I believe @blyxyas was looking into something like that for a while. But I'm not sure.

This temporary value would mean "unreleased"? Maybe something like version 0.0.0, or 99.99.99 could be used for this this indeed (and be checked against during the release).

Otherwise, I'm also used to updating these attributes as part of the release process.

Is that done manually? If this is the case, maybe this code could be used to automate the check during the release process, by checking new lints (unless this is done already by some other script).

[y21]

We can still end up with wrong versions if a beta cutoff happens after the PR is merged but before the next clippy->rust sync happens, right? So we would still need to go through all lints and correct/verify the attribute every version anyway.

You might be interested in the discussion on zulip:
https://rust-lang.zulipchat.com/#narrow/stream/257328-clippy/topic/Using.20CURRENT_RUSTC_VERSION.20in.20clippy.3A.3Aversion.3F

The CURRENT_RUSTC_VERSION temporary value was brought up here which is already being used by the rust-lang/rust repo and is already automatically replaced, so it wouldn't be much extra work from the release team's point of view.

[samueltardieu]

Right. Thanks for the pointer to the zulip discussion.

I'll close this PR.