fn id(
f: &dyn Fn(u32),
) -> &dyn Fn(
&dyn Fn(
&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(u32))))))))),
),
) {
f
//~^ ERROR mismatched types
}
fn main() {}