Fix typeclass derivation now that case classes extend Serializable

Author: smarter

tests/neg/typeclass-derivation2.scala

@@ -170,7 +170,7 @@ object Pair {
   }
 }
 
-sealed trait Either[+L, +R] extends Product // derives Eq, Pickler, Show
+sealed trait Either[+L, +R] extends Product with Serializable // derives Eq, Pickler, Show
 case class Left[L](x: L) extends Either[L, Nothing]
 case class Right[R](x: R) extends Either[Nothing, R]
 
@@ -275,4 +275,4 @@ object Test extends App {
     |
     |But no implicit values were found that match type Show[Pair[Int]].
 */
-}
+}

tests/run/typeclass-derivation2.scala

@@ -179,7 +179,7 @@ object Pair {
   implicit def derived$Show[T: Show]: Show[Pair[T]] = Show.derived
 }
 
-sealed trait Either[+L, +R] extends Product // derives Eq, Pickler, Show
+sealed trait Either[+L, +R] extends Product with Serializable // derives Eq, Pickler, Show
 case class Left[L](x: L) extends Either[L, Nothing]
 case class Right[R](x: R) extends Either[Nothing, R]
 
@@ -486,4 +486,4 @@ object Test extends App {
   val zs1 = copy(zs)
   showPrintln(zs1)
   assert(eql(zs, zs1))
-}
+}

tests/run/typeclass-derivation2a.scala

@@ -179,7 +179,7 @@ object Pair {
   implicit def derived$Show[T: Show]: Show[Pair[T]] = Show.derived
 }
 
-sealed trait Either[+L, +R] extends Product // derives Eq, Pickler, Show
+sealed trait Either[+L, +R] extends Product with Serializable // derives Eq, Pickler, Show
 case class Left[L](x: L) extends Either[L, Nothing]
 case class Right[R](x: R) extends Either[Nothing, R]
 

tests/run/typeclass-derivation3.scala

@@ -16,7 +16,7 @@ object datatypes {
   case class Pair[T](x: T, y: T) derives Eq, Pickler, Show
 
   // another ADT
-  sealed trait Either[+L, +R] extends Product derives Eq, Pickler, Show
+  sealed trait Either[+L, +R] extends Product with Serializable derives Eq, Pickler, Show
   case class Left[L](x: L) extends Either[L, Nothing]
   case class Right[R](x: R) extends Either[Nothing, R]
 }
@@ -311,4 +311,4 @@ object Test extends App {
   val zss1 = pklList.unpickle(buf)
   assert(eql(zss, zss1))
   showPrintln(zss1)
-}
+}