43 lines
1.0 KiB
Rust
43 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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// Uncovered during work on new scoping rules for safe destructors
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// as an important use case to support properly.
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pub struct E<'a> {
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pub f: &'a u8,
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}
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impl<'b> E<'b> {
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pub fn m(&self) -> &'b u8 { self.f }
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}
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pub struct P<'c> {
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pub g: &'c u8,
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}
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pub trait M {
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fn n(&self) -> u8;
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}
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impl<'d> M for P<'d> {
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fn n(&self) -> u8 { *self.g }
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}
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fn extension<'e>(x: &'e E<'e>) -> Box<M+'e> {
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loop {
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let p = P { g: x.m() };
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return Box::new(p) as Box<M+'e>;
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}
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}
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fn main() {
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let w = E { f: &10u8 };
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let o = extension(&w);
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assert_eq!(o.n(), 10u8);
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}
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