#![feature(coerce_unsized)]
use std::ops::CoerceUnsized;
struct Foo<T: ?Sized> { //~ ERROR `T` is never used
a: i32,
}
impl<T, U> CoerceUnsized<Foo<U>> for Foo<T> //~ ERROR E0374
where T: CoerceUnsized<U> {}
fn main() {}