error[E0277]: the trait bound `{gen closure@$DIR/iter-macro-not-async-closure-simplified.rs:21:21: 21:28}: AsyncFnOnce()` is not satisfied --> $DIR/iter-macro-not-async-closure-simplified.rs:27:21 | LL | call_async_once(f); | --------------- ^ the trait `AsyncFnOnce()` is not implemented for `{gen closure@$DIR/iter-macro-not-async-closure-simplified.rs:21:21: 21:28}` | | | required by a bound introduced by this call | note: required by a bound in `call_async_once` --> $DIR/iter-macro-not-async-closure-simplified.rs:18:28 | LL | fn call_async_once(_: impl AsyncFnOnce()) {} | ^^^^^^^^^^^^^ required by this bound in `call_async_once` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.