error: expected identifier, found keyword `async`
  --> $DIR/method-call-pos.rs:4:11
   |
LL |     <_ as async Fn()>(|| async {});
   |           ^^^^^ expected identifier, found keyword

error: expected one of `(`, `::`, `<`, or `>`, found `Fn`
  --> $DIR/method-call-pos.rs:4:17
   |
LL |     <_ as async Fn()>(|| async {});
   |                 ^^ expected one of `(`, `::`, `<`, or `>`

error: aborting due to 2 previous errors