MagnoliaCompileCrash.scala

import language.experimental.macros
import language.implicitConversions
import magnolia._

trait MyTypeclass[T] {
  def f(t: T): String
}

object MyTypeclass {
  type Typeclass[T] = MyTypeclass[T]

  implicit def deriveOption[A](implicit ev: Typeclass[A]): Typeclass[Option[A]] = (t: Option[A]) => ???

  def combine[T](ctx: CaseClass[Typeclass, T]): Typeclass[T]    = (t: T) => ???
  def dispatch[T](ctx: SealedTrait[Typeclass, T]): Typeclass[T] = (t: T) => ???

  implicit def gen[T]: Typeclass[T] = macro Magnolia.gen[T]
}

object Test extends App {

  case class SomeClass(id: Option[Another])
  case class Another(b: String)

  MyTypeclass.gen[List[SomeClass]]
}