error[E0277]: `()` is not a future --> $DIR/async-error-span.rs:10:20 | LL | fn get_future() -> impl Future { | ^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not a future | = help: the trait `Future` is not implemented for `()` = note: () must be a future or must implement `IntoFuture` to be awaited error[E0698]: type inside `async fn` body must be known in this context --> $DIR/async-error-span.rs:16:9 | LL | let a; | ^ cannot infer type | note: the type is part of the `async fn` body because of this `await` --> $DIR/async-error-span.rs:19:18 | LL | get_future().await; | ^^^^^ error: aborting due to 2 previous errors Some errors have detailed explanations: E0277, E0698. For more information about an error, try `rustc --explain E0277`.