existential-associated-type.rs

// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(existential_type)]
// compile-pass

trait Bar {}
struct Dummy;
impl Bar for Dummy {}

trait Foo {
    type Assoc: Bar;
    fn foo() -> Self::Assoc;
    fn bar() -> Self::Assoc;
}

existential type Helper: Bar;

impl Foo for i32 {
    type Assoc = Helper;
    fn foo() -> Helper {
        Dummy
    }
    fn bar() -> Helper {
        Dummy
    }
}

fn main() {}