31 lines
1.1 KiB
Rust
31 lines
1.1 KiB
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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// Ensure that you cannot use generic types to return a region outside
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// of its bound. Here, in the `return_it()` fn, we call with() but
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// with R bound to &isize from the return_it. Meanwhile, with()
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// provides a value that is only good within its own stack frame. This
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// used to successfully compile because we failed to account for the
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// fact that fn(x: &isize) rebound the region &.
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fn with<R, F>(f: F) -> R where F: FnOnce(&isize) -> R {
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f(&3)
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}
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fn return_it<'a>() -> &'a isize {
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with(|o| o)
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//~^ ERROR cannot infer
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}
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fn main() {
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let x = return_it();
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println!("foo={}", *x);
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}
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