error[E0597]: `new_string` does not live long enough
  --> tests/compile_fail/with_referential_mut_from_outer.rs:13:47
   |
13 |         selfie.with_referential_mut(|s| *s = &new_string);
   |                                     --- ------^^^^^^^^^^
   |                                     |   |     |
   |                                     |   |     borrowed value does not live long enough
   |                                     |   assignment requires that `new_string` is borrowed for `'static`
   |                                     value captured here
14 |     }
   |     - `new_string` dropped here while still borrowed