error: lifetime may not live long enough
 --> tests/ui/contravariant.rs:7:5
  |
6 | fn require_covariant<'a>(phantom: ContravariantPhantom<&'static str>) -> ContravariantPhantom<&'a str> {
  |                      -- lifetime `'a` defined here
7 |     phantom
  |     ^^^^^^^ returning this value requires that `'a` must outlive `'static`