Re-use Enum flag for Scala enums

Author: odersky

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -132,7 +132,7 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
     case class Inline() extends Mod(Flags.Inline)
 
-    case class Enum() extends Mod(Flags.EmptyFlags)
+    case class Enum() extends Mod(Flags.Enum)
   }
 
   /** Modifiers and annotations for definitions
@@ -191,8 +191,10 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
       mods.exists(mod => cls.isAssignableFrom(mod.getClass))
     }
 
-    def isEnumCase = hasMod[Mod.Enum] && is(Case)
-    def isEnumClass = hasMod[Mod.Enum] && !is(Case)
+    private def isEnum = hasMod[Mod.Enum] || is(Enum, butNot = JavaDefined)
+
+    def isEnumCase = isEnum && is(Case)
+    def isEnumClass = isEnum && !is(Case)
   }
 
   @sharable val EmptyModifiers: Modifiers = new Modifiers()

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

@@ -563,6 +563,9 @@ object Flags {
   /** An inline parameter */
   final val InlineParam = allOf(Inline, Param)
 
+  /** An enum case */
+  final val EnumCase = allOf(Enum, Case)
+
   /** A term parameter or parameter accessor */
   final val TermParamOrAccessor = Param | ParamAccessor