prevent leaks with simple cases

Author: bishabosha

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

@@ -16,7 +16,6 @@ import dotty.tools.dotc.ast.Trees._
 import SymUtils._
 
 import annotation.threadUnsafe
-import collection.mutable
 
 object CompleteJavaEnums {
   val name: String = "completeJavaEnums"
@@ -116,13 +115,13 @@ class CompleteJavaEnums extends MiniPhase with InfoTransformer { thisPhase =>
     && (((cls.owner.name eq nme.DOLLAR_NEW) && cls.owner.isAllOf(Private|Synthetic)) || cls.owner.isAllOf(EnumCase))
     && cls.owner.owner.linkedClass.derivesFromJavaEnum
 
-  @threadUnsafe
-  private lazy val enumCaseOrdinals: mutable.Map[Symbol, Int] = mutable.AnyRefMap.empty
+  private val enumCaseOrdinals: MutableSymbolMap[Int] = newMutableSymbolMap
 
   private def registerEnumClass(cls: Symbol)(using Context): Unit =
     cls.children.zipWithIndex.foreach(enumCaseOrdinals.put)
 
-  private def ordinalFor(enumCase: Symbol): Int = enumCaseOrdinals.remove(enumCase).get
+  private def ordinalFor(enumCase: Symbol): Int =
+    enumCaseOrdinals.remove(enumCase).get
 
   /** 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.
@@ -145,17 +144,20 @@ class CompleteJavaEnums extends MiniPhase with InfoTransformer { thisPhase =>
    *          "same as before"
    *       }
    */
-  override def transformTemplate(templ: Template)(using Context): Template = {
+  override def transformTemplate(templ: Template)(using Context): Tree = {
     val cls = templ.symbol.owner
     if cls.derivesFromJavaEnum then
-      registerEnumClass(cls)
+      registerEnumClass(cls) // invariant: class is visited before cases: see tests/pos/enum-companion-first.scala
       val (params, rest) = decomposeTemplateBody(templ.body)
       val addedDefs = addedParams(cls, isLocal=true, ParamAccessor)
       val addedSyms = addedDefs.map(_.symbol.entered)
       val addedForwarders = addedEnumForwarders(cls)
       cpy.Template(templ)(
         parents = addEnumConstrArgs(defn.JavaEnumClass, templ.parents, addedSyms.map(ref)),
         body = params ++ addedDefs ++ addedForwarders ++ rest)
+    else if cls.linkedClass.derivesFromJavaEnum then
+      enumCaseOrdinals.clear() // remove simple cases // invariant: companion is visited after cases
+      templ
     else if isJavaEnumValueImpl(cls) then
       def creatorParamRef(name: TermName) =
         ref(cls.owner.paramSymss.head.find(_.name == name).get)

tests/pos/enum-companion-first.scala

@@ -0,0 +1,9 @@
+object Planet:
+  final val G = 6.67300E-11
+
+enum Planet(mass: Double, radius: Double) extends java.lang.Enum[Planet]:
+  def surfaceGravity = Planet.G * mass / (radius * radius)
+  def surfaceWeight(otherMass: Double) =  otherMass * surfaceGravity
+
+  case Mercury extends Planet(3.303e+23, 2.4397e6)
+  case Venus   extends Planet(4.869e+24, 6.0518e6)