pub trait Trait<'a> {
    type Item;
}

impl<'a> Trait<'a> for () {
    type Item = ();
}

pub fn foo<T, F>(_: T, _: F)
where
    T: for<'a> Trait<'a>,
    F: for<'a> FnMut(<T as Trait<'a>>::Item),
{
}

fn main() {
    foo((), drop)
    //~^ ERROR type mismatch in function arguments
    //~| ERROR size for values of type `<() as Trait<'_>>::Item` cannot be known at compilation time
}