906c06a2f6
In MIR construction, operands need to live exactly until they are used, which is during the (sub)expression that made the call to `as_operand`. Before this PR, operands lived until the end of the temporary scope, which was sometimes unnecessarily longer and sometimes too short. Fixes #38669.
56 lines
1.7 KiB
Rust
56 lines
1.7 KiB
Rust
// Copyright 2017 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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use std::cell::RefCell;
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use std::panic;
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pub struct DropLogger<'a> {
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id: usize,
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log: &'a panic::AssertUnwindSafe<RefCell<Vec<usize>>>
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}
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impl<'a> Drop for DropLogger<'a> {
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fn drop(&mut self) {
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self.log.0.borrow_mut().push(self.id);
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}
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}
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struct InjectedFailure;
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#[allow(unreachable_code)]
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fn main() {
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let log = panic::AssertUnwindSafe(RefCell::new(vec![]));
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let d = |id| DropLogger { id: id, log: &log };
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let get = || -> Vec<_> {
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let mut m = log.0.borrow_mut();
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let n = m.drain(..);
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n.collect()
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};
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{
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let _x = (d(0), &d(1), d(2), &d(3));
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// all borrows are extended - nothing has been dropped yet
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assert_eq!(get(), vec![]);
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}
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// in a let-statement, extended lvalues are dropped
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// *after* the let result (tho they have the same scope
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// as far as scope-based borrowck goes).
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assert_eq!(get(), vec![0, 2, 3, 1]);
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let _ = std::panic::catch_unwind(|| {
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(d(4), &d(5), d(6), &d(7), panic!(InjectedFailure));
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});
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// here, the temporaries (5/7) live until the end of the
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// containing statement, which is destroyed after the operands
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// (4/6) on a panic.
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assert_eq!(get(), vec![6, 4, 7, 5]);
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}
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