Also print unique ids for symbols with meaningless names

Author: odersky

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -850,8 +850,6 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         nameString(sym.owner.name)
       else if (sym.is(ModuleClass))
         nameString(sym.name.stripModuleClassSuffix)
-      else if (hasMeaninglessName(sym))
-        simpleNameString(sym.owner)
       else
         nameString(sym)
     (keywordText(kindString(sym)) ~~ {

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

@@ -40,10 +40,11 @@ class CompleteJavaEnums extends MiniPhase with InfoTransformer { thisPhase =>
       addConstrParams(sym.info)
     else tp
 
-  /** Is `sym` a Scala enum class that derives from `java.lang.Enum`?
+  /** Is `sym` a Scala enum class that derives (directly) from `java.lang.Enum`?
    */
   private def derivesFromJavaEnum(sym: Symbol)(implicit ctx: Context) =
-    sym.is(Enum, butNot = Case) && sym.derivesFrom(defn.JavaEnumClass)
+    sym.is(Enum, butNot = Case) &&
+    sym.info.parents.exists(p => p.typeSymbol == defn.JavaEnumClass)
 
   /** Add constructor parameters `$name: String` and `$ordinal: Int` to the end of
    *  the last parameter list of (method- or poly-) type `tp`.