38 lines
1.0 KiB
Rust
38 lines
1.0 KiB
Rust
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use std::ops::Deref;
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struct DerefWithHelper<H, T> {
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helper: H
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}
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trait Helper<T> {
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fn helper_borrow<'a>(&'a self) -> &'a T;
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}
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impl<T> Helper<T> for Option<T> {
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fn helper_borrow<'a>(&'a self) -> &'a T {
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self.as_ref().unwrap()
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}
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}
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impl<T, H: Helper<T>> Deref<T> for DerefWithHelper<H, T> {
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fn deref<'a>(&'a self) -> &'a T {
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self.helper.helper_borrow()
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}
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}
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// Test cross-crate autoderef + vtable.
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pub fn check<T: Eq>(x: T, y: T) -> bool {
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let d: DerefWithHelper<Option<T>, T> = DerefWithHelper { helper: Some(x) };
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d.eq(&y)
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}
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