1 error[E0204]: the trait `Copy` may not be implemented for this type
2 --> $DIR/union-copy.rs:12:6
4 LL | a: std::mem::ManuallyDrop<String>
5 | --------------------------------- this field does not implement `Copy`
7 LL | impl Copy for W {}
10 error: aborting due to previous error
12 For more information about this error, try `rustc --explain E0204`.