supertrait expansion needs normalization

[nikomatsakis]

This example doesn't compile:

trait TheTrait : TheSuperTrait<<Self as TheTrait>::Item> {
    type Item;
}

trait TheSuperTrait<T> {
    fn get(&self) -> T;
}

impl TheTrait for i32 {
    type Item = u32;
}

impl TheSuperTrait<u32> for i32 {
    fn get(&self) -> u32 {
        *self as u32
    }
}

fn foo<T:TheTrait<Item=u32>>(t: &T) -> u32 {
    t.get()
}

fn main() {
    foo::<i32>(&22);
}

This is because we fail to normalize during supertrait expansion.

[huonw]

Is the example missing the definition of TheTrait?

[nikomatsakis]

I suppose it is. That's kind of important isn't it :)

[nikomatsakis]

Updated the example.

[apasel422]

This appears to compile with rustc 1.4.0-nightly (d50352419 2015-08-29).