error: lifetime may not live long enough
  --> $DIR/regions-variance-covariant-use-contravariant.rs:23:12
   |
LL | fn use_<'short,'long>(c: Covariant<'long>,
   |         ------ ----- lifetime `'long` defined here
   |         |
   |         lifetime `'short` defined here
...
LL |     let _: Covariant<'short> = c;
   |            ^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
   |
   = help: consider adding the following bound: `'short: 'long`

error: aborting due to previous error