warning: elided lifetime has a name
  --> $DIR/issue-63388-1.rs:12:10
   |
LL |     async fn do_sth<'a>(
   |                     -- lifetime `'a` declared here
LL |         &'a self, foo: &dyn Foo
LL |     ) -> &dyn Foo
   |          ^ this elided lifetime gets resolved as `'a`
   |
   = note: `#[warn(elided_named_lifetimes)]` on by default

error[E0621]: explicit lifetime required in the type of `foo`
  --> $DIR/issue-63388-1.rs:14:9
   |
LL |         &'a self, foo: &dyn Foo
   |                        -------- help: add explicit lifetime `'a` to the type of `foo`: `&'a (dyn Foo + 'a)`
...
LL |         foo
   |         ^^^ lifetime `'a` required

error: aborting due to 1 previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0621`.