error[E0277]: the trait bound `{async block@$DIR/issue-55872-3.rs:15:9: 15:17}: Copy` is not satisfied --> $DIR/issue-55872-3.rs:13:20 | LL | fn foo() -> Self::E { | ^^^^^^^ the trait `Copy` is not implemented for `{async block@$DIR/issue-55872-3.rs:15:9: 15:17}` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.