src/test/ui/traits/traits-assoc-type-in-supertrait-bad.rs

// Test case where an associated type is referenced from within the
// supertrait definition, and the impl makes the wrong
// associations. Issue #20220.

use std::vec::IntoIter;

pub trait Foo: Iterator<Item=<Self as Foo>::Key> {
    type Key;
}

impl Foo for IntoIter<i32> { //~ ERROR type mismatch
    type Key = u32;
}

fn main() {
}