31 lines
913 B
Rust
31 lines
913 B
Rust
// Copyright 2012 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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struct boxed_int {
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f: &int,
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}
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fn get(bi: &r/boxed_int) -> &r/int {
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bi.f
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}
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fn with(bi: &r/boxed_int) {
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// Here, the upcast is allowed because the `boxed_int` type is
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// contravariant with respect to `&r`. See also
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// compile-fail/regions-infer-invariance-due-to-mutability.rs
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let bi: &blk/boxed_int/&blk = bi;
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assert *get(bi) == 22;
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}
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fn main() {
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let g = 22;
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let foo = boxed_int { f: &g };
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with(&foo);
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} |