src/test/run-pass/auxiliary/overloaded_autoderef_xc.rs

   1 // Copyright 2014 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 use std::ops::Deref;
  12
  13 struct DerefWithHelper<H, T> {
  14     pub helper: H,
  15     pub value: Option<T>
  16 }
  17
  18 trait Helper<T> {
  19     fn helper_borrow(&self) -> &T;
  20 }
  21
  22 impl<T> Helper<T> for Option<T> {
  23     fn helper_borrow(&self) -> &T {
  24         self.as_ref().unwrap()
  25     }
  26 }
  27
  28 impl<T, H: Helper<T>> Deref for DerefWithHelper<H, T> {
  29     type Target = T;
  30
  31     fn deref(&self) -> &T {
  32         self.helper.helper_borrow()
  33     }
  34 }
  35
  36 // Test cross-crate autoderef + vtable.
  37 pub fn check<T: PartialEq>(x: T, y: T) -> bool {
  38     let d: DerefWithHelper<Option<T>, T> = DerefWithHelper { helper: Some(x), value: None };
  39     d.eq(&y)
  40 }