Positive coverage: prove_wf / aliases

1 test exercised this rule:

Source location: tests/coherence_overlap.rs:307

#[test]
fn is_local_unknowable_trait_ref() {
    FormalityTest::new(crates![crate core {
        trait Project {
            type Assoc: [];
        }

        impl<T> Project for T {
            type Assoc = T;
        }

        trait Foo<U> { }
    },
    crate foo {
        struct LocalType {}

        trait Overlap<U> {}
        impl<T, U> Overlap<U> for T
        where
            <T as Project>::Assoc: Foo<U> {}
        impl<T> Overlap<LocalType> for () {}
    }])
    .skip_execute()
    .ok()
}