| //@compile-flags: -Zmiri-tree-borrows |
| |
| // We invalidate a reference during a 2-phase borrow by doing a Foreign |
| // Write in between the initial reborrow and function entry. UB occurs |
| // on function entry when reborrow from a Disabled fails. |
| // This test would pass under Stacked Borrows, but Tree Borrows |
| // is more strict on 2-phase borrows. |
| |
| struct Foo(u64); |
| impl Foo { |
| fn add(&mut self, n: u64) -> u64 { |
| //~^ ERROR: /reborrow through .* is forbidden/ |
| self.0 + n |
| } |
| } |
| |
| pub fn main() { |
| let mut f = Foo(0); |
| let alias = &mut f.0 as *mut u64; |
| let res = f.add(unsafe { |
| // This is the access at fault, but it's not immediately apparent because |
| // the reference that got invalidated is not under a Protector. |
| *alias = 42; |
| 0 |
| }); |
| // `res` could be optimized to be `0`, since at the time the reference for the `self` argument |
| // is created, it has value `0`, and then later we add `0` to that. But turns out there is |
| // a sneaky alias that's used to change the value of `*self` before it is read... |
| assert_eq!(res, 42); |
| } |
