2fc3c69e54
Fix closure migration suggestion when the body is a macro. Fixes https://github.com/rust-lang/rust/issues/87955 Before: ``` warning: changes to closure capture in Rust 2021 will affect drop order --> src/main.rs:5:13 | 5 | let _ = || panic!(a.0); | ^^^^^^^^^^---^ | | | in Rust 2018, closure captures all of `a`, but in Rust 2021, it only captures `a.0` 6 | } | - in Rust 2018, `a` would be dropped here, but in Rust 2021, only `a.0` would be dropped here alongside the closure | help: add a dummy let to cause `a` to be fully captured | 20~ ($msg:expr $(,)?) => ({ let _ = &a; 21+ $crate::rt::begin_panic($msg) 22~ }), | ``` After: ``` warning: changes to closure capture in Rust 2021 will affect drop order --> src/main.rs:5:13 | 5 | let _ = || panic!(a.0); | ^^^^^^^^^^---^ | | | in Rust 2018, closure captures all of `a`, but in Rust 2021, it only captures `a.0` 6 | } | - in Rust 2018, `a` would be dropped here, but in Rust 2021, only `a.0` would be dropped here alongside the closure | help: add a dummy let to cause `a` to be fully captured | 5 | let _ = || { let _ = &a; panic!(a.0) }; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ```
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.