error[E0308]: mismatched types --> $DIR/issue-113354.rs:3:24 | LL | let _ = || { while Some(_) = Some(1) { } }; | ^^^^^^^^^^^^^^^^^ expected `bool`, found `()` | help: consider adding `let` | LL | let _ = || { while let Some(_) = Some(1) { } }; | +++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0308`.