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https://github.com/rust-lang/rust
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103 lines
3 KiB
Rust
103 lines
3 KiB
Rust
//@ run-pass
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#![allow(unreachable_code)]
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// More thorough regression test for Issues #30018 and #30822. This
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// attempts to explore different ways that array element construction
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// (for both scratch arrays and non-scratch ones) interacts with
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// breaks in the control-flow, in terms of the order of evaluation of
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// the destructors (which may change; see RFC Issue 744) and the
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// number of times that the destructor evaluates for each value (which
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// should never exceed 1; this latter case is what #30822 is about).
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use std::cell::RefCell;
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struct D<'a>(&'a RefCell<Vec<i32>>, i32);
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impl<'a> Drop for D<'a> {
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fn drop(&mut self) {
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println!("Dropping D({})", self.1);
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(self.0).borrow_mut().push(self.1);
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}
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}
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fn main() {
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println!("Start");
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break_during_elem();
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break_after_whole();
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println!("Finis");
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}
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fn break_during_elem() {
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let log = &RefCell::new(Vec::new());
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// CASE 1: Fixed-size array itself is stored in _r slot.
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loop {
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let _r = [D(log, 10),
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D(log, 11),
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{ D(log, 12); break; },
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D(log, 13)];
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}
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assert_eq!(&log.borrow()[..], &[12, 11, 10]);
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log.borrow_mut().clear();
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// CASE 2: Slice (borrow of array) is stored in _r slot.
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// This is the case that is actually being reported in #30018.
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loop {
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let _r = &[D(log, 20),
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D(log, 21),
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{ D(log, 22); break; },
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D(log, 23)];
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}
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assert_eq!(&log.borrow()[..], &[22, 21, 20]);
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log.borrow_mut().clear();
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// CASE 3: (Borrow of) slice-index of array is stored in _r slot.
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loop {
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let _r = &[D(log, 30),
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D(log, 31),
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{ D(log, 32); break; },
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D(log, 33)][..];
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}
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assert_eq!(&log.borrow()[..], &[32, 31, 30]);
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log.borrow_mut().clear();
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}
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// The purpose of these functions is to test what happens when we
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// panic after an array has been constructed in its entirety.
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//
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// It is meant to act as proof that we still need to continue
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// scheduling the destruction of an array even after we've scheduling
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// drop for its elements during construction; the latter is tested by
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// `fn break_during_elem()`.
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fn break_after_whole() {
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let log = &RefCell::new(Vec::new());
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// CASE 1: Fixed-size array itself is stored in _r slot.
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loop {
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let _r = [D(log, 10),
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D(log, 11),
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D(log, 12)];
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break;
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}
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assert_eq!(&log.borrow()[..], &[10, 11, 12]);
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log.borrow_mut().clear();
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// CASE 2: Slice (borrow of array) is stored in _r slot.
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loop {
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let _r = &[D(log, 20),
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D(log, 21),
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D(log, 22)];
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break;
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}
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assert_eq!(&log.borrow()[..], &[20, 21, 22]);
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log.borrow_mut().clear();
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// CASE 3: (Borrow of) slice-index of array is stored in _r slot.
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loop {
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let _r = &[D(log, 30),
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D(log, 31),
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D(log, 32)][..];
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break;
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}
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assert_eq!(&log.borrow()[..], &[30, 31, 32]);
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log.borrow_mut().clear();
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}
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