mirror of https://github.com/rust-lang/rust
31 lines
1.1 KiB
Rust
31 lines
1.1 KiB
Rust
// 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 a borrow of **x is untracked, because **x is
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// immutable. However, for matches we care that **x refers to the same value
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// until we have chosen a match arm.
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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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None => panic!("unreachable"),
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Some(&_) 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 cannot mutably borrow `x` in match guard [E0510]
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false
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} => {}
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Some(&a) if { // this binds to garbage if we've corrupted discriminant
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println!("{}", a);
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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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