| // This test serves to document the change in semantics introduced by |
| // rust-lang/rust#138961. |
| // |
| // Previously, the closure would capture the entirety of x, and access *(*x).0 |
| // when called. Now, the closure only captures *(*x).0, which means that |
| // a &*(*x).0 reborrow happens when the closure is constructed. |
| // |
| // Hence, if one of the references is dangling, this constitutes newly introduced UB |
| // in the case where the closure doesn't get called. This isn't a big deal, |
| // because while opsem only now considers this to be UB, the unsafe code |
| // guidelines have long recommended against any handling of dangling references. |
| |
| fn main() { |
| // the inner references are dangling |
| let x: &(&u32, &u32) = unsafe { |
| let a = 21; |
| let b = 37; |
| let ra = &* &raw const a; |
| let rb = &* &raw const b; |
| &(ra, rb) |
| }; |
| |
| let _ = || { //~ ERROR: encountered a dangling reference |
| match x { |
| (&_y, _) => {}, |
| } |
| }; |
| } |
