warning: unused coroutine that must be used
  --> $DIR/issue-52398.rs:17:5
   |
LL | /     move || {
LL | |         A.test(yield);
LL | |     };
   | |_____^
   |
   = note: coroutines are lazy and do nothing unless resumed
   = note: `#[warn(unused_must_use)]` on by default

warning: unused coroutine that must be used
  --> $DIR/issue-52398.rs:24:5
   |
LL | /     static move || {
LL | |         yield *y.borrow();
LL | |         return "Done";
LL | |     };
   | |_____^
   |
   = note: coroutines are lazy and do nothing unless resumed

warning: 2 warnings emitted