1 error[E0596]: cannot borrow `f` as mutable, as it is not declared as mutable
2 --> $DIR/issue-84044-drop-non-mut.rs:5:10
5 | ^^^^^^ cannot borrow as mutable
7 help: consider changing this to be mutable
9 LL | let mut f = || {};
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0596`.