40 lines
1.3 KiB
Rust
40 lines
1.3 KiB
Rust
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// Copyright 2015 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 attempts to use the unsafe attribute are feature-gated.
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// Example adapted from RFC 1238 text (just left out the feature gate).
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// https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md#example-of-the-unguarded-escape-hatch
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// #![feature(dropck_parametricity)]
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use std::cell::Cell;
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struct Concrete<'a>(u32, Cell<Option<&'a Concrete<'a>>>);
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struct Foo<T> { data: Vec<T> }
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impl<T> Drop for Foo<T> {
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#[unsafe_destructor_blind_to_params] // This is the UGEH attribute
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//~^ ERROR unsafe_destructor_blind_to_params has unstable semantics
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fn drop(&mut self) { }
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}
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fn main() {
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let mut foo = Foo { data: Vec::new() };
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foo.data.push(Concrete(0, Cell::new(None)));
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foo.data.push(Concrete(0, Cell::new(None)));
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foo.data[0].1.set(Some(&foo.data[1]));
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foo.data[1].1.set(Some(&foo.data[0]));
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}
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