| // 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 a borrow of **x is untracked, because **x is |
| // immutable. However, for matches we care that **x refers to the same value |
| // until we have chosen a match arm. |
| |
| struct ForceFnOnce; |
| fn main() { |
| let mut x = &mut &Some(&2); |
| let force_fn_once = ForceFnOnce; |
| match **x { |
| None => panic!("unreachable"), |
| Some(&_) if { |
| // ForceFnOnce needed to exploit #27282 |
| (|| { *x = &None; drop(force_fn_once); })(); |
| //~^ ERROR cannot mutably borrow `x` in match guard [E0510] |
| false |
| } => {} |
| Some(&a) if { // this binds to garbage if we've corrupted discriminant |
| println!("{}", a); |
| panic!() |
| } => {} |
| _ => panic!("unreachable"), |
| } |
| } |
