false positive unused_parens causes syntax error around labled loops with ifs #143256
Description
Using the following flags
--force-warn unused_parens
this code:
fn foo() { let _x = || 'outer: loop { let inner = 'inner: loop { let i = Default::default(); if (break 'outer i) { loop { break 'inner 5i8; }; } else if true { break 'inner 6; } break 7; }; break inner < 8; }; }caused the following diagnostics:
Checking _snippet_0 v0.1.0 (/tmp/icemaker_global_tempdir.IbV1PR0WiGNQ/icemaker_clippyfix_tempdir.vZHbFsvN0OT0/_snippet_0) warning: unnecessary parentheses around `if` condition --> src/lib.rs:5:16 | 5 | if (break 'outer i) { | ^ ^ | = note: requested on the command line with `--force-warn unused-parens` help: remove these parentheses | 5 - if (break 'outer i) { 5 + if break 'outer i { | warning: `_snippet_0` (lib) generated 1 warning (run `cargo clippy --fix --lib -p _snippet_0` to apply 1 suggestion) Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.11s However after applying these diagnostics, the resulting code:
fn foo() { let _x = || 'outer: loop { let inner = 'inner: loop { let i = Default::default(); if break 'outer i { loop { break 'inner 5i8; }; } else if true { break 'inner 6; } break 7; }; break inner < 8; }; }no longer compiled:
Checking _snippet_0 v0.1.0 (/tmp/icemaker_global_tempdir.IbV1PR0WiGNQ/icemaker_clippyfix_tempdir.vZHbFsvN0OT0/_snippet_0) error: expected identifier, found keyword `loop` --> src/lib.rs:6:17 | 5 | if break 'outer i { | - while parsing this struct 6 | loop { break 'inner 5i8; }; | ^^^^ expected identifier, found keyword | help: escape `loop` to use it as an identifier | 6 | r#loop { break 'inner 5i8; }; | ++ error: this `if` expression is missing a block after the condition --> src/lib.rs:5:13 | 5 | if break 'outer i { | ^^ | help: add a block here --> src/lib.rs:7:14 | 7 | } else if true { | ^ error[E0574]: expected struct, variant or union type, found local variable `i` --> src/lib.rs:5:29 | 5 | if break 'outer i { | ^ not a struct, variant or union type For more information about this error, try `rustc --explain E0574`. error: could not compile `_snippet_0` (lib test) due to 3 previous errors warning: build failed, waiting for other jobs to finish... error: could not compile `_snippet_0` (lib) due to 3 previous errors Version:
rustc 1.90.0-nightly (ed2d75978 2025-06-29) binary: rustc commit-hash: ed2d759783dc9de134bbb3f01085b1e6dbf539f3 commit-date: 2025-06-29 host: x86_64-unknown-linux-gnu release: 1.90.0-nightly LLVM version: 20.1.7