error[E0277]: the trait bound `U1: std::marker::Copy` is not satisfied
  --> $DIR/union-derive-clone.rs:5:10
   |
LL | #[derive(Clone)]
   |          ^^^^^ the trait `std::marker::Copy` is not implemented for `U1`
   | 
  ::: $SRC_DIR/libcore/clone.rs:LL:COL
   |
LL | pub struct AssertParamIsCopy<T: Copy + ?Sized> {
   |                                 ---- required by this bound in `std::clone::AssertParamIsCopy`
   |
   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no method named `clone` found for union `U5<CloneNoCopy>` in the current scope
  --> $DIR/union-derive-clone.rs:37:15
   |
LL | union U5<T> {
   | -----------
   | |
   | method `clone` not found for this
   | doesn't satisfy `U5<CloneNoCopy>: std::clone::Clone`
...
LL | struct CloneNoCopy;
   | ------------------- doesn't satisfy `CloneNoCopy: std::marker::Copy`
...
LL |     let w = u.clone();
   |               ^^^^^ method not found in `U5<CloneNoCopy>`
   | 
  ::: $SRC_DIR/libcore/clone.rs:LL:COL
   |
LL |     fn clone(&self) -> Self;
   |        -----
   |        |
   |        the method is available for `std::sync::Arc<U5<CloneNoCopy>>` here
   |        the method is available for `std::rc::Rc<U5<CloneNoCopy>>` here
   |
   = note: the method `clone` exists but the following trait bounds were not satisfied:
           `CloneNoCopy: std::marker::Copy`
           which is required by `U5<CloneNoCopy>: 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`.