Deprecated if_let_mutex due to stabilization in 2024 edition

[alex-semenyuk]

Close #13679

As mentioned at #131154 if_let_rescope is now stable for Edition 2024, so no need if_let_mutex

changelog: [if_let_mutex]: deprecation

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[xFrednet]

Does the stabilization effect all editions or only Edition 2024 and onwards?

[alex-semenyuk]

Does the stabilization effect all editions or only Edition 2024 and onwards?

Suppose only 2024

[xFrednet]

I haven't looked at the lint in detail, but would it make sense to make the linting dependent on the edition instead of deprecating it?

[alex-semenyuk]

Make sense, might you know examples such edition dependent issues

[y21]

Make sense, might you know examples such edition dependent issues

manual_c_str_literals is one that only lints in Edition >= 2021 crates

rust-clippy/clippy_lints/src/methods/manual_c_str_literals.rs

Line 29 in 786fbd6

&& cx.tcx.sess.edition() >= Edition2021

[alex-semenyuk]

When I try to use //@edition:2024 something like here
it gives
error: edition 2024 is unstable and only available with -Z unstable-options

[est31]

One can work around that issue by passing the option manually. I don't know how that test doesn't trip the same issue. Maybe CI specifies RUSTFLAGS and adds -Zunstable-options for some other reason?

//@ compile-flags: -Zunstable-options

[Alexendoo]

The linked test is fine since it's only editions 2018 and 2021