Also emit missing_docs lint with --test to fulfil expectations

[Urgau]

This PR removes the "test harness" suppression of the missing_docs lint to be able to fulfil #[expect] (expectations) as it is now "relevant".

I think the goal was to maybe avoid false-positive while linting on public items under #[cfg(test)] but with effective visibility we should no longer have any false-positive.

Another possibility would be to query the lint level and only emit the lint if it's of expect level, but that is even more hacky.

Fixes #130021

try-job: x86_64-gnu-aux

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[lcnr]

r? compiler

[petrochenkov]

@bors r+

📌 Commit ae661dd has been approved by petrochenkov

It is now in the queue for this repository.

I'm wondering if this could have the potential to break cargo tests #130109 (comment)

Seems so, actually looking at the test?

https://github.com/rust-lang/cargo/blob/1149535a6fe347bf0eb80c67eb71d9f06d8e5db0/tests/testsuite/rustdocflags.rs#L155-L192

@bors r-

@bors try

⌛ Trying commit ae661dd with merge d453327...

Hi, thanks for the contribution. May I ask if this PR would be cherry-picked to a patch release like 1.81.1?

Due to our fast release cycle, we don't backport to stable simple bug-fixes, only security fixes or major regressions fixes.

#[expect(missing_bugs)] never worked on stable, so it's not technically a regression either, making it unlikely to get beta-backported either.

great new lint, expect(missing_bugs) so that you can be sure your code is buggy :^)