// We must not allow this with our current setup as `T`
// is mentioned both in the tail of `Foo` and by another
// field.
struct Foo<T: ?Sized>(Box<T>, T);

fn main() {
    let x: Foo<[u8; 1]> = Foo(Box::new([2]), [3]);
    let y: &Foo<[u8]> = &x; //~ ERROR mismatched types
    assert_eq!(y.0.len(), 1);
}