Unclear ambiguity on nested Associated Types

[icorderi]

Given the following code:

pub trait Bar { }

pub trait Foo {
    type BarType: Bar;
}

pub trait Houston {
    type FooType: Foo;

    fn we_have_a(&self, problem: &Self::FooType::BarType); // does not compile
}

we get:

src/foo.rs:10:35: 10:57 error: ambiguous associated type; specify the type using the syntax `<<Self as foo::Houston>::FooType as Trait>::BarType` [E0223]
src/foo.rs:10     fn we_have_a(&self, problem: &Self::FooType::BarType);

This works, but it's not clear why the compiler consideres it an ambiguity:

pub trait Houston {
    type FooType: Foo;

    fn works(&self, looks_fishy: &<Self::FooType as Foo>::BarType); // compiles
}

[malbarbo]

@arielb1 Is this limitation difficult to overcome?

[Mark-Simulacrum]

Closing this in favor of #38078 because it has more discussion.