29 lines
917 B
Rust
29 lines
917 B
Rust
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// Copyright 2016 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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trait Future: 'static {
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// The requirement for Self: Sized must prevent instantiation of
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// Future::forget in vtables, otherwise there's an infinite type
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// recursion through <Map<...> as Future>::forget.
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fn forget(self) where Self: Sized {
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Box::new(Map(self)) as Box<Future>;
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}
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}
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struct Map<A>(A);
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impl<A: Future> Future for Map<A> {}
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pub struct Promise;
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impl Future for Promise {}
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fn main() {
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Promise.forget();
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}
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