| // Copyright 2014 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. |
| |
| use std::ops::Deref; |
| |
| struct DerefWithHelper<H, T> { |
| pub helper: H, |
| pub value: Option<T> |
| } |
| |
| trait Helper<T> { |
| fn helper_borrow(&self) -> &T; |
| } |
| |
| impl<T> Helper<T> for Option<T> { |
| fn helper_borrow(&self) -> &T { |
| self.as_ref().unwrap() |
| } |
| } |
| |
| impl<T, H: Helper<T>> Deref for DerefWithHelper<H, T> { |
| type Target = T; |
| |
| fn deref(&self) -> &T { |
| self.helper.helper_borrow() |
| } |
| } |
| |
| // Test cross-crate autoderef + vtable. |
| pub fn check<T: PartialEq>(x: T, y: T) -> bool { |
| let d: DerefWithHelper<Option<T>, T> = DerefWithHelper { helper: Some(x), value: None }; |
| d.eq(&y) |
| } |