Auto merge of #120924 - xFrednet:rfc-2383-stabilization-party, r=Urgau,blyxyas

Let's `#[expect]` some lints: Stabilize `lint_reasons` (RFC 2383)

Let's give this another try! The [previous stabilization attempt](rust-lang/rust#99063) was stalled by some unresolved questions. These have been discussed in a [lang team](rust-lang/lang-team#191) meeting. The last open question, regarding the semantics of the `#[expect]` attribute was decided on in rust-lang/rust#115980

I've just updated the [stabilization report](rust-lang/rust#54503 (comment)) with the discussed questions and decisions. Luckily, the decision is inline with the current implementation.

This hopefully covers everything. Let's hope that the CI will be green like the spring.

fixes #115980
fixes #54503

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r? `@wesleywiser`

Tacking Issue: rust-lang/rust#54503
Stabilization Report: rust-lang/rust#54503 (comment)
Documentation Update: rust-lang/reference#1237

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For Clippy:

changelog: [`allow_attributes`]: Is now available on stable, since the `lint_reasons` feature was stabilized
changelog: [`allow_attributes_without_reason`]: Is now available on stable, since the `lint_reasons` feature was stabilized
-->

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Roses are red,
Violets are blue,
Let's expect lints,
With reason clues

Author: bors

src/lib.rs

@@ -10,7 +10,7 @@
 #![feature(yeet_expr)]
 #![feature(nonzero_ops)]
 #![feature(let_chains)]
-#![feature(lint_reasons)]
+#![cfg_attr(bootstrap, feature(lint_reasons))]
 #![feature(trait_upcasting)]
 #![feature(strict_overflow_ops)]
 #![feature(is_none_or)]