expected-seems-good.rs

trait X {
    type G;
    fn make_g() -> Self::G;
}

impl<'a> X for fn(&'a ()) {
    type G = &'a ();

    fn make_g() -> Self::G {
        &()
    }
}

// Always an error, but the message is bad
fn higher_ranked_region_has_lost_its_binder() {
    let x = <fn (&())>::make_g();
}

// error: implementation of `X` is not general enough
//   --> src/main.rs:44:13
//    |
// 44 |     let x = <fn (&())>::make_g();
//    |             ^^^^^^^^^^^^^^^^^^
//    |
//    = note: `for<'r> fn(&'r ())` must implement `X`
//    = note: but `fn(&'0 ())` only implements `X` for the lifetime `'0`