1 error[E0599]: no method named `f` found for fn pointer `fn(&u8)` in the current scope
2 --> $DIR/issue-57362-1.rs:20:7
5 | ^ method not found in `fn(&u8)`
7 = note: `a` is a function, perhaps you wish to call it
8 = help: items from traits can only be used if the trait is implemented and in scope
9 note: `Trait` defines an item `f`, perhaps you need to implement it
10 --> $DIR/issue-57362-1.rs:8:1
15 error: aborting due to previous error
17 For more information about this error, try `rustc --explain E0599`.