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