| error[E0204]: the trait `Copy` may not be implemented for this type | |
| --> $DIR/union-copy.rs:14:6 | |
| | | |
| LL | a: String | |
| | --------- this field does not implement `Copy` | |
| ... | |
| LL | impl Copy for W {} | |
| | ^^^^ | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0204`. |