Can't define an enum with higher kinded types

[halcat0x15a]

I get an error in Dotty 0.6.0-RC1.

scala> enum class Hoge[F[_]]
1 |enum class Hoge[F[_]]
  |^
  |Type argument F$1 has not the same kind as its bound

I guessed that it failed to derive an Eq instance.

[halcat0x15a]

I think that will be fixed if #3970 is implemented.

[smarter]

The error comes from an incorrectly generated implicit instance of Eq:

  final module class Hoge$() extends Object() { this: Hoge.type => 
    implicit def eqInstance[F$1 <: [_$1] => Any, F$2 <: [_$1] => Any](
      implicit evidence$1: Eq[F$1, F$2]
    ): Eq[Hoge[F$1], Hoge[F$2]] = Eq
  }

Eq[F$1, F$2] does not typecheck since F$1 and F$2 are type constructors. Maybe replacing this by Eq[F$1[_], F$2[_]] is good enough, not sure.