Async support cannot handle generators as arguments or returns from non-async functions

[JustusAdam]

For instance

bla.map(|..| async { .. }).unwrap().await

Or another example from Hyperswitch

pub async fn time_future<F, R>(future: F) -> (R, time::Duration)
where
    F: futures::Future<Output = R>,
{
    let start = time::Instant::now();
    let result = future.await;
    let time_spent = start.elapsed();
    (result, time_spent)
}