error[E0401]: can't use generic parameters from outer item
  --> $DIR/issue-5997-enum.rs:2:16
   |
LL | fn f<Z>() -> bool {
   |      - type parameter from outer item
LL |     enum E { V(Z) }
   |           -    ^ use of generic parameter from outer item
   |           |
   |           help: try introducing a local generic parameter here: `<Z>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0401`.