53 lines
1.9 KiB
Rust
53 lines
1.9 KiB
Rust
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// Copyright 2018 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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// This is testing an attempt to corrupt the discriminant of the match
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// arm in a guard, followed by an attempt to continue matching on that
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// corrupted discriminant in the remaining match arms.
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//
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// Basically this is testing that our new NLL feature of emitting a
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// fake read on each match arm is catching cases like this.
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//
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// This case is interesting because it includes a guard that
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// diverges, and therefore a single final fake-read at the very end
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// after the final match arm would not suffice.
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//
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// It is also interesting because the access to the corrupted data
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// occurs in the pattern-match itself, and not in the guard
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// expression.
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#![feature(nll)]
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struct ForceFnOnce;
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fn main() {
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let mut x = &mut Some(&2);
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let force_fn_once = ForceFnOnce;
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match x {
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&mut None => panic!("unreachable"),
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&mut Some(&_)
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if {
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// ForceFnOnce needed to exploit #27282
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(|| { *x = None; drop(force_fn_once); })();
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//~^ ERROR closure requires unique access to `x` but it is already borrowed [E0500]
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false
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} => {}
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// this segfaults if we corrupted the discriminant, because
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// the compiler gets to *assume* that it cannot be the `None`
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// case, even though that was the effect of the guard.
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&mut Some(&2)
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if {
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panic!()
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} => {}
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_ => panic!("unreachable"),
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}
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}
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