New ICE from modified example code: Uninferred types/regions in _

[kyleheadley]

I tried to instantiate the types in #36839 with a Vec and received the original ICE.

playground

pub trait Foo {
    type Bar;
}

pub trait Broken {
    type Assoc;
    fn broken(&self)->Vec<<Self::Assoc as Foo>::Bar> where Self::Assoc: Foo;
}

impl<T> Broken for T {
    type Assoc = ();
    fn broken(&self)->Vec<<Self::Assoc as Foo>::Bar> where Self::Assoc: Foo {
        Vec::new()
    }
}

fn main() { 
    let _m: &Broken<Assoc=()> = &();
}

What's the expected behavior here? A compiler error on trait impl or a compiler error if the fn is called?

[estebank]

No longer reproducible.