error[E0277]: `()` is not a future --> $DIR/async-error-span.rs:7:20 | 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[E0282]: type annotations needed --> $DIR/async-error-span.rs:13:9 | LL | let a; | ^ | help: consider giving `a` an explicit type | LL | let a: /* Type */; | ++++++++++++ error: aborting due to 2 previous errors Some errors have detailed explanations: E0277, E0282. For more information about an error, try `rustc --explain E0277`.