error[E0597]: `root` does not live long enough
 --> tests/compile_fail/hold_borrow_to_long_mut.rs:7:17
  |
7 |         let a = root.add(0);
  |                 ^^^^^^^^^^^ borrowed value does not live long enough
8 |         a.borrow_mut_untraced(&mut owner)
  |         --------------------------------- borrow later used here
9 |     };
  |     - `root` dropped here while still borrowed