Specialized associated type doesn't have impls that it should have

[ivan770]

I tried this code:

#![feature(specialization)]

trait One {
    type Output;
}

impl<T> One for T {
    default type Output = i32;
}

impl One for f32 {
    type Output = f32;
}

trait Two {
    type Output;
}

impl Two for i32 {
    type Output = String;
}

impl Two for f32 {
    type Output = Vec<()>;
}

type Whatever<T> = <<T as One>::Output as Two>::Output;

fn main() {
    let t: Whatever<Vec<i32>> = String::from("123");
}

I expected to see this happen: It compiles, as it does with Chalk

Instead, this happened: It doesn't compile

[ivan770]

@rustbot label +T-compiler +F-specialization +A-traits +requires-nightly

[ivan770]

Slightly minimized:

#![feature(specialization)]

trait One {
    type Output;
}

impl<T> One for T {
    default type Output = i32;
}

trait Two {
    type Output;
}

impl Two for i32 {
    type Output = String;
}

type Whatever<T> = <<T as One>::Output as Two>::Output;

fn main() {
    let t: Whatever<Vec<i32>> = String::from("123");
}