| // Copyright 2015 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(specialization)] |
| |
| // Make sure we can't project defaulted associated types |
| |
| trait Foo { |
| type Assoc; |
| } |
| |
| impl<T> Foo for T { |
| default type Assoc = (); |
| } |
| |
| impl Foo for u8 { |
| type Assoc = String; |
| } |
| |
| fn generic<T>() -> <T as Foo>::Assoc { |
| // `T` could be some downstream crate type that specializes (or, |
| // for that matter, `u8`). |
| |
| () //~ ERROR mismatched types |
| } |
| |
| fn monomorphic() -> () { |
| // Even though we know that `()` is not specialized in a |
| // downstream crate, typeck refuses to project here. |
| |
| generic::<()>() //~ ERROR mismatched types |
| } |
| |
| fn main() { |
| // No error here, we CAN project from `u8`, as there is no `default` |
| // in that impl. |
| let s: String = generic::<u8>(); |
| println!("{}", s); // bad news if this all compiles |
| } |