1error[E0277]: expected a `Fn<(isize,)>` closure, found `S` 2 --> $DIR/unboxed-closures-fnmut-as-fn.rs:28:21 3 | 4LL | let x = call_it(&S, 22); 5 | ------- ^^ expected an `Fn<(isize,)>` closure, found `S` 6 | | 7 | required by a bound introduced by this call 8 | 9 = help: the trait `Fn<(isize,)>` is not implemented for `S` 10note: required by a bound in `call_it` 11 --> $DIR/unboxed-closures-fnmut-as-fn.rs:23:14 12 | 13LL | fn call_it<F:Fn(isize)->isize>(f: &F, x: isize) -> isize { 14 | ^^^^^^^^^^^^^^^^ required by this bound in `call_it` 15 16error: aborting due to previous error 17 18For more information about this error, try `rustc --explain E0277`. 19