error: borrow of moved value --> $DIR/borrowck-pat-by-move-and-ref-inverse-promotion.rs:6:9 | LL | let a @ ref b = U; | ^ ----- value borrowed here after move | | | value moved into `a` here | move occurs because `a` has type `U` which does not implement the `Copy` trait | help: borrow this binding in the pattern to avoid moving the value | LL | let ref a @ ref b = U; | +++ error: aborting due to 1 previous error