error[E0499]: cannot borrow `*f` as mutable more than once at a time --> $DIR/moves-based-on-type-no-recursive-stack-closure.rs:20:27 | LL | (f.c)(f, true); | ----- ^ second mutable borrow occurs here | | | first mutable borrow occurs here | first borrow later used by call error[E0382]: borrow of moved value: `f` --> $DIR/moves-based-on-type-no-recursive-stack-closure.rs:32:5 | LL | fn conspirator(mut f: F) where F: FnMut(&mut R, bool) { | ----- move occurs because `f` has type `F`, which does not implement the `Copy` trait LL | let mut r = R {c: Box::new(f)}; | - value moved here LL | f(&mut r, false) | ^ value borrowed here after move | help: consider further restricting this bound | LL | fn conspirator(mut f: F) where F: FnMut(&mut R, bool) + Copy { | ^^^^^^ error: aborting due to 2 previous errors Some errors have detailed explanations: E0382, E0499. For more information about an error, try `rustc --explain E0382`.