error[E0310]: the associated type `<Self as MyTrait>::{opaque#0}` may not live long enough
  --> $DIR/async-and-ret-ref.rs:7:5
   |
LL |     async fn foo() -> &'static impl T;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |     |
   |     the associated type `<Self as MyTrait>::{opaque#0}` must be valid for the static lifetime...
   |     ...so that the reference type `&'static impl T` does not outlive the data it points at
   |
   = help: consider adding an explicit lifetime bound `<Self as MyTrait>::{opaque#0}: 'static`...

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0310`.