error[E0597]: `x` does not live long enough
  --> tests/lifetime-fail/fail.rs:7:17
   |
6  |         let x = 17;
   |             - binding `x` declared here
7  |         let y = &x;
   |                 ^^ borrowed value does not live long enough
8  |         tagged = TaggedNan::new_pointer(y);
9  |     }
   |     - `x` dropped here while still borrowed
10 |     tagged.extract();
   |     ------ borrow later used here