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Auto merge of #38600 - arielb1:dead-drop, r=eddyb
clear discriminant drop flag at the bottom of a drop ladder Fixes #38437. Beta-nominating because serious I-wrong. r? @eddyb
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// Copyright 2016 The Rust Project Developers. See the COPYRIGHT | ||
// file at the top-level directory of this distribution and at | ||
// http://rust-lang.org/COPYRIGHT. | ||
// | ||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
// option. This file may not be copied, modified, or distributed | ||
// except according to those terms. | ||
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// Check that drop elaboration clears the "master" discriminant | ||
// drop flag even if it protects no fields. | ||
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struct Good(usize); | ||
impl Drop for Good { | ||
#[inline(never)] | ||
fn drop(&mut self) { | ||
println!("dropping Good({})", self.0); | ||
} | ||
} | ||
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struct Void; | ||
impl Drop for Void { | ||
#[inline(never)] | ||
fn drop(&mut self) { | ||
panic!("Suddenly, a Void appears."); | ||
} | ||
} | ||
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enum E { | ||
Never(Void), | ||
Fine(Good) | ||
} | ||
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fn main() { | ||
let mut go = true; | ||
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loop { | ||
let next; | ||
match go { | ||
true => next = E::Fine(Good(123)), | ||
false => return, | ||
} | ||
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match next { | ||
E::Never(_) => return, | ||
E::Fine(_good) => go = false, | ||
} | ||
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// `next` is dropped and StorageDead'd here. We must reset the | ||
// discriminant's drop flag to avoid random variants being | ||
// dropped. | ||
} | ||
} |