Make Matchable a trait

Author: odersky

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -269,10 +269,10 @@ class Definitions {
    */
   @tu lazy val AnyClass: ClassSymbol = completeClass(enterCompleteClassSymbol(ScalaPackageClass, tpnme.Any, Abstract, Nil), ensureCtor = false)
   def AnyType: TypeRef = AnyClass.typeRef
-  @tu lazy val MatchableClass: ClassSymbol = completeClass(enterCompleteClassSymbol(ScalaPackageClass, tpnme.Matchable, Abstract, AnyType :: Nil), ensureCtor = false)
+  @tu lazy val MatchableClass: ClassSymbol = completeClass(enterCompleteClassSymbol(ScalaPackageClass, tpnme.Matchable, Trait, AnyType :: Nil), ensureCtor = false)
   def MatchableType: TypeRef = MatchableClass.typeRef
   @tu lazy val AnyValClass: ClassSymbol =
-    val res = completeClass(enterCompleteClassSymbol(ScalaPackageClass, tpnme.AnyVal, Abstract, List(MatchableType)))
+    val res = completeClass(enterCompleteClassSymbol(ScalaPackageClass, tpnme.AnyVal, Abstract, List(AnyType, MatchableType)))
     // Mark companion as absent, so that class does not get re-completed
     val companion = ScalaPackageVal.info.decl(nme.AnyVal).symbol
     companion.moduleClass.markAbsent()
@@ -312,7 +312,7 @@ class Definitions {
   @tu lazy val ObjectClass: ClassSymbol = {
     val cls = requiredClass("java.lang.Object")
     assert(!cls.isCompleted, "race for completing java.lang.Object")
-    cls.info = ClassInfo(cls.owner.thisType, cls, MatchableType :: Nil, newScope)
+    cls.info = ClassInfo(cls.owner.thisType, cls, List(AnyType, MatchableType), newScope)
     cls.setFlag(NoInits | JavaDefined)
 
     // The companion object doesn't really exist, so it needs to be marked as