error[E0596]: cannot borrow `callback` as mutable, as it is not declared as mutable --> $DIR/issue-80313-mutation-in-move-closure.rs:6:5 | LL | let callback = move || { | -------- help: consider changing this to be mutable: `mut callback` LL | my_var = true; | ------ calling `callback` requires mutable binding due to possible mutation of `my_var` LL | }; LL | callback(); | ^^^^^^^^ cannot borrow as mutable error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.