error[E0594]: cannot assign to `x`, as it is not declared as mutable --> $DIR/cannot-mutate-captured-non-mut-var.rs:13:25 | LL | let x = 1; | - help: consider changing this to be mutable: `mut x` LL | to_fn_once(move|| { x = 2; }); | ^^^^^ cannot assign error[E0596]: cannot borrow `s` as mutable, as it is not declared as mutable --> $DIR/cannot-mutate-captured-non-mut-var.rs:18:25 | LL | let s = std::io::stdin(); | - help: consider changing this to be mutable: `mut s` LL | to_fn_once(move|| { s.read_to_end(&mut Vec::new()); }); | ^ cannot borrow as mutable error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0596`.