error[E0597]: `a` does not live long enough
  --> $DIR/cast_generated_lifetime.rs:13:30
   |
13 |         let r = WithLifetime(&a);
   |                              ^^ borrowed value does not live long enough
...
16 |     }
   |     - `a` dropped here while still borrowed
...
19 |     do_stuff(invalid);
   |              ------- borrow later used here