When calling a macro with a generic type parameter from a method with another generic type parameter, the macro is evaluated with the generic type instead of waiting until a concrete type is used. This raises a compile error in Scala 2:

def factory[A](deriver: Deriver[TC])(implicit schema: Schema[A]): TC[A] =
  Derive.derive[TC](deriver)

In Scala 3 this can be avoided using inline.

Adding a typeclass Factory allows to implement a factory method without having to create a macro calling deriveImpl in Scala 2.