src/test/run-pass/specialization/specialization-translate-projections.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Ensure that provided items are inherited properly even when impls vary in
  12 // type parameters *and* rely on projections.
  13
  14 #![feature(specialization)]
  15
  16 use std::convert::Into;
  17
  18 trait Trait {
  19     fn to_u8(&self) -> u8;
  20 }
  21 trait WithAssoc {
  22     type Item;
  23     fn to_item(&self) -> Self::Item;
  24 }
  25
  26 impl<T, U> Trait for T where T: WithAssoc<Item=U>, U: Into<u8> {
  27     fn to_u8(&self) -> u8 {
  28         self.to_item().into()
  29     }
  30 }
  31
  32 impl WithAssoc for u8 {
  33     type Item = u8;
  34     fn to_item(&self) -> u8 { *self }
  35 }
  36
  37 impl Trait for u8 {}
  38
  39 fn main() {
  40     assert!(3u8.to_u8() == 3u8);
  41 }