Make enum cases static values

Author: anatoliykmetyuk

compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala

@@ -224,7 +224,7 @@ class BTypesFromSymbols[I <: BackendInterface](val int: I) extends BTypes {
       if (sym.isVarargsMethod) ACC_VARARGS else 0,
       if (sym.isSynchronized) ACC_SYNCHRONIZED else 0,
       if (sym.isDeprecated) asm.Opcodes.ACC_DEPRECATED else 0,
-      if (sym.isJavaEnum) asm.Opcodes.ACC_ENUM else 0
+      if (sym.isEnum) asm.Opcodes.ACC_ENUM else 0
     )
   }
 

compiler/src/dotty/tools/backend/jvm/BackendInterface.scala

@@ -512,7 +512,7 @@ abstract class BackendInterface extends BackendInterfaceDefinitions {
     def isJavaDefaultMethod: Boolean
     def isClassConstructor: Boolean
     def isSerializable: Boolean
-    def isJavaEnum: Boolean
+    def isEnum: Boolean
 
     /**
      * True for module classes of modules that are top-level or owned only by objects. Module classes

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -703,7 +703,7 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
     def shouldEmitForwarders: Boolean =
       (sym is Flags.Module) && sym.isStatic
     def isJavaEntryPoint: Boolean = CollectEntryPoints.isJavaEntryPoint(sym)
-    def isJavaEnum = sym.derivesFromJavaEnum
+    def isEnum = sym.is(Flags.Enum)
 
     def isClassConstructor: Boolean = toDenot(sym).isClassConstructor
     def isSerializable: Boolean = toDenot(sym).isSerializable

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

@@ -84,13 +84,13 @@ object DesugarEnums {
   /**  The following lists of definitions for an enum type E:
    *
    *   private val $values = new EnumValues[E]
+   *   def values = $values.values.toArray
    *   def valueOf($name: String) =
    *     try $values.fromName($name) catch
    *       {
    *         case ex$:NoSuchElementException =>
    *           throw new IllegalArgumentException("key not found: ".concat(name))
    *       }
-   *   def values = $values.values.toArray
    */
   private def enumScaffolding(implicit ctx: Context): List[Tree] = {
     val valuesDef =
@@ -286,7 +286,7 @@ object DesugarEnums {
       val toStringDef = toStringMethLit(name.toString)
       val impl1 = cpy.Template(impl)(body = List(ordinalDef, toStringDef) ++ registerCall)
         .withAttachment(ExtendsSingletonMirror, ())
-      val vdef = ValDef(name, TypeTree(), New(impl1)).withMods(mods | Final)
+      val vdef = ValDef(name, TypeTree(), New(impl1)).withMods(mods | EnumValue)
       flatTree(scaffolding ::: vdef :: Nil).withSpan(span)
     }
   }
@@ -302,7 +302,7 @@ object DesugarEnums {
     else {
       val (tag, scaffolding) = nextOrdinal(CaseKind.Simple)
       val creator = Apply(Ident(nme.DOLLAR_NEW), List(Literal(Constant(tag)), Literal(Constant(name.toString))))
-      val vdef = ValDef(name, enumClassRef, creator).withMods(mods | Final)
+      val vdef = ValDef(name, enumClassRef, creator).withMods(mods | EnumValue)
       flatTree(scaffolding ::: vdef :: Nil).withSpan(span)
     }
 }

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

@@ -693,6 +693,9 @@ object Flags {
   /** A Java enum value */
   final val JavaEnumValue: FlagConjunction = allOf(StableRealizable, JavaStatic, JavaDefined, Enum)
 
+  /** An enum value */
+  final val EnumValue: FlagConjunction = allOf(StableRealizable, JavaStatic, Enum)
+
   /** Labeled private[this] */
   final val PrivateLocal: FlagConjunction = allOf(Private, Local)
 

compiler/src/dotty/tools/dotc/transform/CompleteJavaEnums.scala

@@ -110,6 +110,13 @@ class CompleteJavaEnums extends MiniPhase with InfoTransformer { thisPhase =>
     else tree
   }
 
+  override def transformValDef(tree: ValDef)(implicit ctx: Context): ValDef = {
+    val sym = tree.symbol
+    if ((sym.is(EnumValue) || sym.name == nme.DOLLAR_VALUES) && sym.owner.linkedClass.derivesFromJavaEnum)
+      sym.addAnnotation(Annotations.Annotation(defn.ScalaStaticAnnot))
+    tree
+  }
+
   /** 1. If this is an enum class, add $name and $ordinal parameters to its
    *     parameter accessors and pass them on to the java.lang.Enum constructor.
    *