error: type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias --> $DIR/issue-55872-2.rs:14:9 | LL | async {} | ^^^^^^^^ error: type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias --> $DIR/issue-55872-2.rs:14:9 | LL | async {} | ^^^^^^^^ error: aborting due to 2 previous errors