error[E0277]: the trait bound `U1: std::marker::Copy` is not satisfied
  --> $DIR/union-derive-clone.rs:3:10
   |
LL | #[derive(Clone)]
   |          ^^^^^ the trait `std::marker::Copy` is not implemented for `U1`
   |
   = note: required by `std::clone::AssertParamIsCopy`

error[E0599]: no method named `clone` found for type `U4<CloneNoCopy>` in the current scope
  --> $DIR/union-derive-clone.rs:30:15
   |
LL | union U4<T> {
   | ----------- method `clone` not found for this
...
LL |     let w = u.clone();
   |               ^^^^^
   |
   = note: the method `clone` exists but the following trait bounds were not satisfied:
           `U4<CloneNoCopy> : std::clone::Clone`
   = help: items from traits can only be used if the trait is implemented and in scope
   = note: the following trait defines an item `clone`, perhaps you need to implement it:
           candidate #1: `std::clone::Clone`

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0277, E0599.
For more information about an error, try `rustc --explain E0277`.