error: variable does not need to be mutable --> $DIR/unused-mut-issue-50343.rs:7:33 | LL | vec![(42, 22)].iter().map(|(mut x, _y)| ()).count(); | ----^ | | | help: remove this `mut` | note: the lint level is defined here --> $DIR/unused-mut-issue-50343.rs:3:9 | LL | #![deny(unused_mut)] | ^^^^^^^^^^ error: aborting due to previous error