error[E0308]: mismatched types --> $DIR/regions-lifetime-bounds-on-fns.rs:20:43 | LL | let _: fn(&mut &isize, &mut &isize) = a; | ^ one type is more general than the other | = note: expected fn pointer `for<'r, 's, 't0, 't1> fn(&'r mut &'s isize, &'t0 mut &'t1 isize)` found fn item `for<'r, 's> fn(&'r mut &isize, &'s mut &isize) {a::<'_, '_>}` error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.