Traits with where clauses that themselves reference associated types

[nikomatsakis]

Based on a read of the implementation, I believe situations like this are incorrectly handled:

trait Foo {
    type Out;
}

trait Bar<T: Foo> {
}

The problem is that Bar needs a synthetic parameter to play the role of T::Out, but the current code only adds synthetic parameters to things other than traits (since, in a trait, we add the parameters for the associated types defined within the trait itself). We also do not add synthetic parameters for bounds appearing on structs etc.

[nikomatsakis]

I don't think this is really relevant to the current implementation.