45 lines
1.3 KiB
Rust
45 lines
1.3 KiB
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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// Test that we are able to handle the relationships between free
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// regions bound in a closure callback.
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#[derive(Copy, Clone)]
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struct MyCx<'short, 'long: 'short> {
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short: &'short u32,
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long: &'long u32,
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}
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impl<'short, 'long> MyCx<'short, 'long> {
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fn short(self) -> &'short u32 { self.short }
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fn long(self) -> &'long u32 { self.long }
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fn set_short(&mut self, v: &'short u32) { self.short = v; }
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}
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fn with<F, R>(op: F) -> R
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where
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F: for<'short, 'long> FnOnce(MyCx<'short, 'long>) -> R,
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{
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op(MyCx {
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short: &22,
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long: &22,
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})
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}
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fn main() {
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with(|mut cx| {
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// For this to type-check, we need to be able to deduce that
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// the lifetime of `l` can be `'short`, even though it has
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// input from `'long`.
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let l = if true { cx.long() } else { cx.short() };
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cx.set_short(l);
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});
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}
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