error[E0277]: the trait bound `A: Copy` is not satisfied
  --> $DIR/wf-enum-fields.rs:12:17
   |
LL | struct IsCopy<T:Copy> {
   |                 ---- required by this bound in `IsCopy`
...
LL |     SomeVariant(IsCopy<A>)
   |                 ^^^^^^^^^ the trait `Copy` is not implemented for `A`
   |
help: consider restricting type parameter `A`
   |
LL | enum SomeEnum<A: std::marker::Copy> {
   |                +++++++++++++++++++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.