diff options
Diffstat (limited to 'src/test/ui/nll/issue-27282-mutate-before-diverging-arm-1.rs')
-rw-r--r-- | src/test/ui/nll/issue-27282-mutate-before-diverging-arm-1.rs | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/src/test/ui/nll/issue-27282-mutate-before-diverging-arm-1.rs b/src/test/ui/nll/issue-27282-mutate-before-diverging-arm-1.rs new file mode 100644 index 000000000..d17d6f07f --- /dev/null +++ b/src/test/ui/nll/issue-27282-mutate-before-diverging-arm-1.rs @@ -0,0 +1,31 @@ +// This is testing an attempt to corrupt the discriminant of the match +// arm in a guard, followed by an attempt to continue matching on that +// corrupted discriminant in the remaining match arms. +// +// Basically this is testing that our new NLL feature of emitting a +// fake read on each match arm is catching cases like this. +// +// This case is interesting because it includes a guard that +// diverges, and therefore a single final fake-read at the very end +// after the final match arm would not suffice. + +struct ForceFnOnce; + +fn main() { + let mut x = &mut Some(&2); + let force_fn_once = ForceFnOnce; + match x { + &mut None => panic!("unreachable"), + &mut Some(&_) if { + // ForceFnOnce needed to exploit #27282 + (|| { *x = None; drop(force_fn_once); })(); + //~^ ERROR cannot mutably borrow `x` in match guard [E0510] + false + } => {} + &mut Some(&a) if { // this binds to garbage if we've corrupted discriminant + println!("{}", a); + panic!() + } => {} + _ => panic!("unreachable"), + } +} |