Rust: Parser Updates and Lint Improvements

Transcript

Good morning, this is your Rust development briefing for May 25th, 2026.

Yesterday saw significant activity with 15 merged pull requests across the Rust compiler and standard library.

The most substantial change came from CoCo-Japan-pan, who merged parser improvements for `mut` restrictions, adding over 1,000 lines of code across 26 files. This work advances the handling of mutability constraints in the compiler's AST.

Several important lint fixes landed. Dnreikronos addressed garbled suggestions from strict provenance lints when code appears inside macros, preventing broken output like `$e as ).addr()`. Meanwhile, sappho3 fixed suggestion formatting for unused variables with raw identifiers in struct patterns - the compiler will now correctly suggest `r#move: _` instead of the invalid `move: _`.

qaijuang improved the single-use lifetimes lint to properly account for lifetime bounds, so lifetimes like `'b` in `<'a, 'b: 'a>` won't be incorrectly flagged as single-use.

In a notable rollback, folkertdev reverted the recent change allowing `global_asm!` in statement positions. The feature was merged without proper FCP process and contained implementation bugs that violated existing code assumptions.

Additional improvements included onehr's fix for the `impl_trait_redundant_captures` lint to remove adjacent plus signs, preventing syntax errors in suggestions, and xizheyin's work preventing compatible variant suggestions inside macros.

JonathanBrouwer and jhpratt coordinated rollup merges that bundled several of these fixes together efficiently.

Looking ahead: The parser improvements for `mut` restrictions continue progressing toward full implementation, and the development team will need to address the proper process for reintroducing `global_asm!` statement support.

That's your Rust briefing. Back tomorrow with more updates from the rust-lang repository.