error: variable does not need to be mutable --> $DIR/unused-mut-warning-captured-var.rs:4:9 | LL | let mut x = 1; | ----^ | | | help: remove this `mut` | note: lint level defined here --> $DIR/unused-mut-warning-captured-var.rs:1:11 | LL | #![forbid(unused_mut)] | ^^^^^^^^^^ error: aborting due to previous error