Select Rust edition 2024 for compiling Clippy

[samueltardieu]

The Cargo feature is no longer experimental and is enabled by default in our nightly compiler.

changelog: Clippy now uses Rust edition 2024

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[samueltardieu]

r? @flip1995

[samueltardieu]

The compiler sources still use edition 2021. However, even though the Clippy sources are synced back into the rust-lang repo, I think this would cause no bootstrapping issues as Clippy is always built with the newly built compiler.

[flip1995]

I'll take a closer look at the edition update during the Christmas holidays. Should be good to go, I just want to take the time so that I didn't miss anything.

[flip1995]

Now that edition=2024 hit beta, we're definitely good to update it in Clippy.

There are a few more places where we might want to consider to update the edition:

rustfmt.toml
5:edition = "2021"

rustc_tools_util/Cargo.toml
10:edition = "2018"

Cargo.toml
13:edition = "2021"

clippy_dummy/Cargo.toml
4:edition = "2018"

book/src/development/adding_lints.md
540:[author_example]: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=9a12cb60e5c6ad4e3003ac6d5e63cf55
555:[print_hir_example]: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=daf14db3a7f39ca467cd1b86c34b9afb

book/book.toml
9:edition = "2018"

I think updating it in clippy_dummy is not necessary. In the book I'm also not sure. The rest should be updated IMO.

[samueltardieu]

I think updating it in clippy_dummy is not necessary. In the book I'm also not sure. The rest should be updated IMO.

I updated everything except clippy_dummy and the book. I had to modify some test files in order to accommodate with gen being a keyword in edition 2024, and to put a std::env::set_var() into an unsafe block. I did this in separate commit to facilitate your review, but I can squash them together if you prefer.

[samueltardieu]

Since everything seems to work fine locally, I've also updated the book and clippy_dummy in this latest push.

[samueltardieu]

mdbook 0.4.34 doesn't understand edition 2024, I'll try updating it to 0.4.43 which is the latest one and also the one I use locally.

[flip1995]

Thanks!