// edition: 2021 #![feature(unsized_fn_params, unsized_locals)] //~^ WARN the feature `unsized_locals` is incomplete use std::future::Future; async fn bug(mut f: dyn Future + Unpin) -> T { //~^ ERROR the size for values of type `(dyn Future + Unpin + 'static)` cannot be known at compilation time (&mut f).await } fn main() {}