error[E0308]: mismatched types --> $DIR/issue-102392.rs:2:5 | LL | fn g(f: for<'a> fn(fn(&str, &'a str))) -> bool { | ---- expected `bool` because of return type LL | f | ^ expected `bool`, found fn pointer | = note: expected type `bool` found fn pointer `for<'a> fn(for<'b> fn(&'b str, &'a str))` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0308`.