GenCodec.materialize fails for Type Members and works for Type Parameters

[bgrochal]

Please consider the following Type Parameter hierarchy:

sealed trait A[X] {
  def foo: X
}

object A {
  final case class First[Type : GenCodec](foo: Type) extends A[Type]
  object First {
    implicit def genCodec[Type : GenCodec]: GenCodec[First[Type]] = GenCodec.materialize
  }

  implicit def genCodec[T : GenCodec]: GenCodec[A[T]] = GenCodec.materialize
}

The code above compiles and works nicely. However, after turning the Type Parameter into the Type Member:

sealed trait A {
  type X
  def foo: X
}

object A {
  final case class First[Type : GenCodec](foo: Type) extends A { type X = Type }
  object First {
    implicit def genCodec[Type : GenCodec]: GenCodec[First[Type]] = GenCodec.materialize
  }

  implicit def genCodec[T : GenCodec]: GenCodec[A { type X = T }] = GenCodec.materialize
}

the compiler claims that Cannot automatically derive GenCodec for com.avsystem.yanush.components.shared.search.model.A{type X = T}.

[ghik]

Fixed in 1.28.0