tests/ui/nll/issue-57642-higher-ranked-subtype.rs


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// Regression test for issue #57642
// Tests that we reject a bad higher-ranked subtype

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

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

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

trait Y {
    type F;
    fn make_f() -> Self::F;
}

impl<T> Y for fn(T) {
    type F = fn(T);

    fn make_f() -> Self::F {
        |_| {}
    }
}

fn higher_ranked_region_has_lost_its_binder() {
    let x = <fn (&())>::make_g(); //~ ERROR the function
}

fn magical() {
    let x = <fn (&())>::make_f(); //~ ERROR no function
}

fn main() {}