29 files changed, 228 insertions, 184 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 66b264a4ce..e8d72fb88d 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -231,7 +231,7 @@ class Global(val settings: Settings, val reporter: Reporter) extends SymbolTable
     val global: Global.this.type = Global.this;
   }
 
-  object mixin extends Mixin {
+  object mixer extends Mixin {
     val global: Global.this.type = Global.this;
   }
 
@@ -274,7 +274,7 @@ class Global(val settings: Settings, val reporter: Reporter) extends SymbolTable
     lambdaLift,
     constructors,
     flatten,
-    mixin,
+    mixer,
     genicode,
     genJVM,
     sampleTransform);
diff --git a/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala b/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
index 9e4821a734..20c7ce05dd 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
@@ -317,8 +317,8 @@ abstract class TreeBrowsers {
       case Apply(fun, args) =>
         Pair("Apply", EMPTY);
 
-      case Super(qualif, mixin) =>
-        Pair("Super", qualif.toString() + ", mixin: " + mixin.toString());
+      case Super(qualif, mix) =>
+        Pair("Super", qualif.toString() + ", mix: " + mix.toString());
 
       case This(qualifier) =>
         Pair("This", qualifier);
@@ -458,7 +458,7 @@ abstract class TreeBrowsers {
       case Apply(fun, args) =>
         List(fun) ::: args;
 
-      case Super(qualif, mixin) =>
+      case Super(qualif, mix) =>
         Nil;
 
       case This(qualif) =>
diff --git a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
index 206fa58061..4d13548a08 100644
--- a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
@@ -82,17 +82,20 @@ abstract class TreePrinters {
     def printModifiers(tree: Tree, mods: Modifiers): unit = {
       if (tree.symbol == NoSymbol)
         printFlags(mods.flags, mods.privateWithin)
-      else if (tree.symbol.privateWithin == null)
+      else if (tree.symbol.privateWithin == NoSymbol ||
+               tree.symbol.privateWithin == tree.symbol.owner)
         printFlags(tree.symbol.flags, nme.EMPTY.toTypeName)
       else
         printFlags(tree.symbol.flags, tree.symbol.privateWithin.name)
     }
 
     def printFlags(flags: long, privateWithin: Name): unit = {
-      val mask = if (settings.debug.value) -1 else PrintableFlags;
-      val suffixes: List[Pair[long, String]] =
-        if (privateWithin.isEmpty) List() else List(Pair(PRIVATE, privateWithin.toString()));
-      val s = flagsToString(flags & mask, suffixes);
+      var mask = if (settings.debug.value) -1 else PrintableFlags;
+      if (!privateWithin.isEmpty) {
+        print("private["+privateWithin+"] ");
+        mask = mask & ~PRIVATE
+      }
+      val s = flagsToString(flags & mask);
       if (s.length() != 0) print(s + " ")
     }
 
@@ -106,7 +109,7 @@ abstract class TreePrinters {
 
         case ClassDef(mods, name, tparams, tp, impl) =>
           printModifiers(tree, mods);
-	  print((if (mods.hasFlag(TRAIT)) "trait " else "class ") + symName(tree, name));
+	  print("class " + symName(tree, name));
           printTypeParams(tparams);
           printOpt(": ", tp); print(" extends "); print(impl);
 
@@ -221,11 +224,11 @@ abstract class TreePrinters {
         case Apply(fun, vargs) =>
           print(fun); printRow(vargs, "(", ", ", ")");
 
-        case Super(qual, mixin) =>
+        case Super(qual, mix) =>
           if (!qual.isEmpty || tree.symbol != NoSymbol) print(symName(tree, qual) + ".");
           print("super");
-          if (!mixin.isEmpty)
-	    print("[" + mixin + "]")
+          if (!mix.isEmpty)
+	    print("[" + mix + "]")
 
         case This(qual) =>
           if (!qual.isEmpty) print(symName(tree, qual) + ".");
diff --git a/src/compiler/scala/tools/nsc/ast/Trees.scala b/src/compiler/scala/tools/nsc/ast/Trees.scala
index 92b147c947..48f6cbbd7b 100644
--- a/src/compiler/scala/tools/nsc/ast/Trees.scala
+++ b/src/compiler/scala/tools/nsc/ast/Trees.scala
@@ -19,7 +19,7 @@ import symtab.Flags._;
   case class Modifiers(flags: int, privateWithin: Name) {
     def isPrivate   = ((flags & PRIVATE  ) != 0);
     def isProtected = ((flags & PROTECTED) != 0);
-    def isVariable  = ((flags &   MUTABLE) != 0);
+    def isVariable  = ((flags & MUTABLE  ) != 0);
     def isPublic    = !isPrivate && !isProtected;
     def hasFlag(flag: int) = (flags & flag) != 0;
     def | (flag: int): Modifiers = {
@@ -452,10 +452,10 @@ import symtab.Flags._;
   }
 
   /** Super reference */
-  case class Super(qual: Name, mixin: Name)
+  case class Super(qual: Name, mix: Name)
        extends TermTree with SymTree;
 
-  def Super(sym: Symbol, mixin: Name): Tree = Super(sym.name, mixin) setSymbol sym;
+  def Super(sym: Symbol, mix: Name): Tree = Super(sym.name, mix) setSymbol sym;
 
   /** Self reference */
   case class This(qual: Name)
@@ -590,7 +590,7 @@ import symtab.Flags._;
   case Typed(expr, tpt) =>                                         (eliminated by erasure)
   case TypeApply(fun, args) =>
   case Apply(fun, args) =>
-  case Super(qual, mixin) =>
+  case Super(qual, mix) =>
   case This(qual) =>
   case Select(qualifier, selector) =>
   case Ident(name) =>
@@ -633,7 +633,7 @@ import symtab.Flags._;
     def Typed(tree: Tree, expr: Tree, tpt: Tree): Typed;
     def TypeApply(tree: Tree, fun: Tree, args: List[Tree]): TypeApply;
     def Apply(tree: Tree, fun: Tree, args: List[Tree]): Apply;
-    def Super(tree: Tree, qual: Name, mixin: Name): Super;
+    def Super(tree: Tree, qual: Name, mix: Name): Super;
     def This(tree: Tree, qual: Name): This;
     def Select(tree: Tree, qualifier: Tree, selector: Name): Select;
     def Ident(tree: Tree, name: Name): Ident;
@@ -706,8 +706,8 @@ import symtab.Flags._;
       new TypeApply(fun, args).copyAttrs(tree);
     def Apply(tree: Tree, fun: Tree, args: List[Tree]) =
       new Apply(fun, args).copyAttrs(tree);
-    def Super(tree: Tree, qual: Name, mixin: Name) =
-      new Super(qual, mixin).copyAttrs(tree);
+    def Super(tree: Tree, qual: Name, mix: Name) =
+      new Super(qual, mix).copyAttrs(tree);
     def This(tree: Tree, qual: Name) =
       new This(qual).copyAttrs(tree);
     def Select(tree: Tree, qualifier: Tree, selector: Name) =
@@ -880,10 +880,10 @@ import symtab.Flags._;
       if ((fun0 == fun) && (args0 == args)) => t
       case _ => copy.Apply(tree, fun, args)
     }
-    def Super(tree: Tree, qual: Name, mixin: Name) = tree match {
-      case t @ Super(qual0, mixin0)
-      if ((qual0 == qual) && (mixin0 == mixin)) => t
-      case _ => copy.Super(tree, qual, mixin)
+    def Super(tree: Tree, qual: Name, mix: Name) = tree match {
+      case t @ Super(qual0, mix0)
+      if ((qual0 == qual) && (mix0 == mix)) => t
+      case _ => copy.Super(tree, qual, mix)
     }
     def This(tree: Tree, qual: Name) = tree match {
       case t @ This(qual0)
@@ -1012,8 +1012,8 @@ import symtab.Flags._;
         copy.TypeApply(tree, transform(fun), transformTrees(args))
       case Apply(fun, args) =>
         copy.Apply(tree, transform(fun), transformTrees(args))
-      case Super(qual, mixin) =>
-        copy.Super(tree, qual, mixin)
+      case Super(qual, mix) =>
+        copy.Super(tree, qual, mix)
       case This(qual) =>
         copy.This(tree, qual)
       case Select(qualifier, selector) =>
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 36f6d5890e..00c8cf99a5 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -133,12 +133,12 @@ import Tokens._;
 /////// TOKEN CLASSES //////////////////////////////////////////////////////
 
     def isModifier: boolean = in.token match {
-      case ABSTRACT | FINAL | SEALED | PRIVATE | PROTECTED | OVERRIDE | IMPLICIT => true
+      case ABSTRACT | FINAL | SEALED | MIXIN | PRIVATE | PROTECTED | OVERRIDE | IMPLICIT => true
       case _ => false
     }
 
     def isLocalModifier: boolean = in.token match {
-      case ABSTRACT | FINAL | SEALED => true
+      case ABSTRACT | FINAL | SEALED | MIXIN => true
       case _ => false
     }
 
@@ -1061,22 +1061,29 @@ import Tokens._;
 ////////// MODIFIERS ////////////////////////////////////////////////////////////
 
     /** Modifiers ::= {Modifier}
-     *  Modifier  ::= final
-     *             | private [ "[" Id "]" ]
-     *             | protected
-     *             | override
-     *             | abstract
+     *  Modifier  ::= LocalClassModifier
+     *             |  private [ "[" Id "]" ]
+     *             |  protected | override | implicit
      */
     def modifiers(): Modifiers = {
+      var privateWithin: Name = nme.EMPTY.toTypeName;
       def loop(mods: int): int = in.token match {
 	case ABSTRACT =>
           loop(addMod(mods, Flags.ABSTRACT))
+	case MIXIN =>
+          loop(addMod(mods, Flags.MIXIN))
 	case FINAL =>
           loop(addMod(mods, Flags.FINAL))
 	case SEALED =>
           loop(addMod(mods, Flags.SEALED))
 	case PRIVATE =>
-          loop(addMod(mods, Flags.PRIVATE))
+          val mods1 = addMod(mods, Flags.PRIVATE);
+          if (in.token == LBRACKET) {
+            in.nextToken();
+            privateWithin = ident().toTypeName;
+            accept(RBRACKET)
+          }
+          loop(mods1)
 	case PROTECTED =>
           loop(addMod(mods, Flags.PROTECTED))
 	case OVERRIDE =>
@@ -1089,17 +1096,18 @@ import Tokens._;
       var mods = loop(0);
       if ((mods & (Flags.ABSTRACT | Flags.OVERRIDE)) == (Flags.ABSTRACT | Flags.OVERRIDE))
         mods = mods & ~(Flags.ABSTRACT | Flags.OVERRIDE) | Flags.ABSOVERRIDE;
-      Modifiers(mods)
+      Modifiers(mods, privateWithin)
     }
 
     /** LocalClassModifiers ::= {LocalClassModifier}
-     *  LocalClassModifier  ::= final
-     *                       | private
+     *  LocalClassModifier  ::= abstract | mixin | final | sealed
      */
     def localClassModifiers(): Modifiers = {
       def loop(mods: int): int = in.token match {
 	case ABSTRACT =>
           loop(addMod(mods, Flags.ABSTRACT))
+	case MIXIN =>
+          loop(addMod(mods, Flags.MIXIN))
 	case FINAL =>
           loop(addMod(mods, Flags.FINAL))
 	case SEALED =>
@@ -1506,20 +1514,23 @@ import Tokens._;
       /**  TmplDef ::= ([case] class | trait) ClassDef
        *            | [case] object ObjectDef
        */
-      def tmplDef(mods: Modifiers): Tree = in.token match {
-        case TRAIT =>
-          classDef(mods | Flags.TRAIT | Flags.ABSTRACT);
-        case CLASS =>
-          classDef(mods);
-        case CASECLASS =>
-          classDef(mods | Flags.CASE);
-        case OBJECT =>
-          objectDef(mods);
-        case CASEOBJECT =>
-          objectDef(mods | Flags.CASE);
-        case _ =>
-          syntaxError("illegal start of definition", true);
+      def tmplDef(mods: Modifiers): Tree = {
+        val mods1 = if (mods.hasFlag(Flags.MIXIN)) mods | Flags.ABSTRACT else mods;
+        in.token match {
+          case TRAIT =>
+            classDef(mods1 | Flags.MIXIN | Flags.ABSTRACT);
+          case CLASS =>
+            classDef(mods1);
+          case CASECLASS =>
+            classDef(mods1 | Flags.CASE);
+          case OBJECT =>
+            objectDef(mods1);
+          case CASEOBJECT =>
+            objectDef(mods1 | Flags.CASE);
+          case _ =>
+            syntaxError("illegal start of definition", true);
 	  EmptyTree
+        }
       }
 
     /** ClassDef ::= ClassSig RequiresTypeOpt ClassTemplate
@@ -1534,7 +1545,7 @@ import Tokens._;
 	val vparamss = paramClauses(name, implicitViews.toList, mods.hasFlag(Flags.CASE));
 	val thistpe = requiresTypeOpt();
 	val template = classTemplate(mods, name, vparamss);
-	val mods1 = if (mods.hasFlag(Flags.TRAIT) && (template.body forall treeInfo.isInterfaceMember))
+	val mods1 = if (mods.hasFlag(Flags.MIXIN) && (template.body forall treeInfo.isInterfaceMember))
                       mods | Flags.INTERFACE
                     else mods;
 	ClassDef(mods1, name, tparams, thistpe, template)
@@ -1583,7 +1594,7 @@ import Tokens._;
 	var body =
 	  if (in.token == LBRACE) templateBody()
 	  else { acceptEmptyTemplateBody("`{' expected"); List() }
-	if (!mods.hasFlag(Flags.TRAIT)) Template(ps, vparamss, argss.toList, body)
+	if (!mods.hasFlag(Flags.MIXIN)) Template(ps, vparamss, argss.toList, body)
 	else Template(ps, body)
       }
 
@@ -1644,7 +1655,7 @@ import Tokens._;
                    isModifier) {
           val attrs = attributeClauses();
           (stats ++
-             joinAttributes(attrs, joinComment(List(tmplDef(modifiers() | traitAttribute(attrs))))))
+             joinAttributes(attrs, joinComment(List(tmplDef(modifiers() | mixinAttribute(attrs))))))
         } else if (in.token != SEMI && in.token != NEWLINE) {
           syntaxError("illegal start of class or object definition", true);
         }
@@ -1670,7 +1681,7 @@ import Tokens._;
         } else if (isDefIntro || isModifier || in.token == LBRACKET) {
           val attrs = attributeClauses();
           (stats ++
-             joinAttributes(attrs, joinComment(defOrDcl(modifiers() | traitAttribute(attrs)))))
+             joinAttributes(attrs, joinComment(defOrDcl(modifiers() | mixinAttribute(attrs)))))
         } else if (in.token != SEMI && in.token != NEWLINE) {
           syntaxError("illegal start of definition", true);
         }
@@ -1708,14 +1719,15 @@ import Tokens._;
       atPos(pos) { New(t, List(args)) }
     }
 
-    def traitAttribute(attrs: List[Tree]) = {
-      def isTraitAttribute(attr: Tree) = attr match {
-        case Apply(Select(New(Ident(name)), constr), List()) if (name.toString() == "_trait_") =>
+    def mixinAttribute(attrs: List[Tree]) = {
+      def isMixinAttribute(attr: Tree) = attr match {
+        case Apply(Select(New(Ident(name)), constr), List())
+        if (name.toString() == "_mixin_" || name.toString() == "_trait_") =>
 	  true
 	case _ =>
           false
       }
-      if (attrs exists isTraitAttribute) Flags.TRAIT else 0
+      if (attrs exists isMixinAttribute) Flags.MIXIN else 0
     }
 
     def joinAttributes(attrs: List[Tree], defs: List[Tree]): List[Tree] =
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
index 091a4faa05..717d4fd23a 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
@@ -768,7 +768,7 @@ import scala.tools.nsc.util.CharArrayReader
       enterKeyword(nme.IMPLICITkw, IMPLICIT)
       enterKeyword(nme.IMPORTkw, IMPORT)
       enterKeyword(nme.MATCHkw, MATCH)
-      enterKeyword(nme.REQUIRESkw, REQUIRES)
+      enterKeyword(nme.MIXINkw, MIXIN)
       enterKeyword(nme.NEWkw, NEW)
       enterKeyword(nme.NULLkw, NULL)
       enterKeyword(nme.OBJECTkw, OBJECT)
@@ -776,6 +776,7 @@ import scala.tools.nsc.util.CharArrayReader
       enterKeyword(nme.PACKAGEkw, PACKAGE)
       enterKeyword(nme.PRIVATEkw, PRIVATE)
       enterKeyword(nme.PROTECTEDkw, PROTECTED)
+      enterKeyword(nme.REQUIRESkw, REQUIRES)
       enterKeyword(nme.RETURNkw, RETURN)
       enterKeyword(nme.SEALEDkw, SEALED)
       enterKeyword(nme.SUPERkw, SUPER)
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala b/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
index b99ee08811..2f07497ede 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
@@ -67,6 +67,7 @@ object Tokens {
   final val RETURN = 57;
   final val MATCH = 58;
   final val REQUIRES = 59;
+  final val MIXIN = 60;
 
   /** special symbols */
   final val COMMA = 61;
diff --git a/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala b/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
index 6676c820bc..d6b81a84fe 100644
--- a/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
+++ b/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
@@ -15,7 +15,7 @@ import scala.collection.mutable.MutableList;
  * function is applied repeatedly to the first element in the
  * worklist, as long as the stack is not empty.
  *
- * The client class should mix-in this trait and initialize the
+ * The client class should mix-in this class and initialize the
  * worklist field and define the processElement method. Then call
  * the 'run' method providing a function that initializes the
  * worklist.
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Checkers.scala b/src/compiler/scala/tools/nsc/backend/icode/Checkers.scala
index be6aef6251..00741a1e0e 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Checkers.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Checkers.scala
@@ -419,7 +419,7 @@ abstract class Checkers {
                  stack.push(toTypeKind(method.info.resultType));
                }
 
-             case SuperCall(mixin) =>
+             case SuperCall(mix) =>
                checkStack(1 + method.info.paramTypes.length);
                checkMethodArgs(method);
                checkMethod(stack.pop, method);
diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index a7940cd66a..0e7c126f0d 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@@ -526,11 +526,11 @@ abstract class GenICode extends SubComponent  {
         // to call super constructors explicitly and/or use their 'returned' value.
         // therefore, we can ignore this fact, and generate code that leaves nothing
         // on the stack (contrary to what the type in the AST says).
-        case Apply(fun @ Select(Super(_, mixin), _), args) =>
+        case Apply(fun @ Select(Super(_, mix), _), args) =>
           if (settings.debug.value)
             log("Call to super: " + tree);
-          val invokeStyle = SuperCall(mixin);
-//            if (fun.symbol.isConstructor) Static(true) else SuperCall(mixin);
+          val invokeStyle = SuperCall(mix);
+//            if (fun.symbol.isConstructor) Static(true) else SuperCall(mix);
 
           ctx.bb.emit(THIS(ctx.clazz.symbol), tree.pos);
           val ctx1 = genLoadArguments(args, fun.symbol.info.paramTypes, ctx);
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala b/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
index 24eb1132f6..bb2b0c39eb 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
@@ -454,7 +454,7 @@ import scala.tools.nsc.util.Position;
         case Dynamic =>  "dynamic";
         case Static(false) => "static-class";
         case Static(true) =>  "static-instance";
-        case SuperCall(mixin) => "super(" + mixin + ")";
+        case SuperCall(mix) => "super(" + mix + ")";
       }
     }
 
@@ -466,8 +466,8 @@ import scala.tools.nsc.util.Position;
      */
     case class Static(onInstance: Boolean) extends InvokeStyle;
 
-    /** Call through super[mixin]. */
-    case class SuperCall(mixin: Name) extends InvokeStyle;
+    /** Call through super[mix]. */
+    case class SuperCall(mix: Name) extends InvokeStyle;
 
   }
 }
diff --git a/src/compiler/scala/tools/nsc/matching/CodeFactory.scala b/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
index 1d6882a0fa..d4678738ec 100644
--- a/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
+++ b/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
@@ -134,6 +134,7 @@ import scala.tools.nsc.util.Position;
   }
 
   // used by Equals
+  /*
   private def getCoerceToInt(left: Type): Symbol = {
     val sym = left.nonPrivateMember( nme.coerce );
     //assert sym != Symbol.NONE : Debug.show(left);
@@ -145,7 +146,7 @@ import scala.tools.nsc.util.Position;
       }
     }.get
   }
-
+  */
   // used by Equals
 /*
   private def getEqEq(left: Type, right: Type): Symbol = {
diff --git a/src/compiler/scala/tools/nsc/symtab/Definitions.scala b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
index b4f760220f..af2f8e55d8 100644
--- a/src/compiler/scala/tools/nsc/symtab/Definitions.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
@@ -80,7 +80,7 @@ import Flags._;
       def SeqFactory = getMember(ScalaRunTimeModule, "Seq");
     var RepeatedParamClass: Symbol = _;
     var ByNameParamClass: Symbol = _;
-    var TraitClass: Symbol = _;
+    //var TraitClass: Symbol = _;
 
     val MaxTupleArity = 9;
     val MaxFunctionArity = 9;
@@ -310,10 +310,10 @@ import Flags._;
       AnyRefClass = newAlias(ScalaPackageClass, "AnyRef", ObjectClass.typeConstructor);
 
       AllRefClass = newClass(ScalaPackageClass, "AllRef", List(AnyRefClass.typeConstructor))
-	.setFlag(ABSTRACT | TRAIT | FINAL);
+	.setFlag(ABSTRACT | MIXIN | FINAL);
 
       AllClass = newClass(ScalaPackageClass, "All", List(AnyClass.typeConstructor))
-	.setFlag(ABSTRACT | TRAIT | FINAL);
+	.setFlag(ABSTRACT | MIXIN | FINAL);
 
       StringClass = getClass("java.lang.String");
       ThrowableClass = getClass("java.lang.Throwable");
@@ -352,7 +352,7 @@ import Flags._;
         tparam => typeRef(SeqClass.typeConstructor.prefix, SeqClass, List(tparam.typeConstructor)));
       ByNameParamClass = newCovariantPolyClass(
         ScalaPackageClass, nme.BYNAME_PARAM_CLASS_NAME, tparam => AnyClass.typeConstructor);
-      TraitClass = getClass("scala._trait_");
+      //TraitClass = getClass("scala._trait_");
       TupleClass = new Array(MaxTupleArity + 1);
       for (val i <- List.range(1, MaxTupleArity + 1))
 	TupleClass(i) = getClass("scala.Tuple" + i);
diff --git a/src/compiler/scala/tools/nsc/symtab/Flags.scala b/src/compiler/scala/tools/nsc/symtab/Flags.scala
index 2627640d2e..39563cab29 100644
--- a/src/compiler/scala/tools/nsc/symtab/Flags.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Flags.scala
@@ -43,8 +43,8 @@ object Flags {
   final val STATIC        = 0x00800000;   // static field, method or class
 
   final val CASEACCESSOR  = 0x01000000;   // symbol is a case parameter (or its accessor)
-  final val TRAIT         = 0x02000000;   // symbol is a trait
-  final val BRIDGE        = 0x04000000;  // function is a bridge method. Set by Erasure
+  final val MIXIN         = 0x02000000;   // symbol is a mixin class
+  final val BRIDGE        = 0x04000000;   // function is a bridge method. Set by Erasure
   final val ACCESSOR      = 0x08000000;   // a value or variable accessor
 
   final val SUPERACCESSOR = 0x10000000;   // a super accessor
@@ -100,7 +100,7 @@ object Flags {
     MODULE | PACKAGE | FINAL | JAVA;
 
   final val ExplicitFlags =                // these modifiers can be set explicitly in source programs.
-    PRIVATE | PROTECTED | ABSTRACT | FINAL | SEALED | OVERRIDE | CASE | IMPLICIT | ABSOVERRIDE;
+    PRIVATE | PROTECTED | ABSTRACT | MIXIN | FINAL | SEALED | OVERRIDE | CASE | IMPLICIT | ABSOVERRIDE;
 
   final val PrintableFlags =               // these modifiers appear in TreePrinter output.
     (ExplicitFlags | LOCAL | SYNTHETIC | STABLE | CASEACCESSOR | ACCESSOR |
@@ -116,17 +116,9 @@ object Flags {
   /** Module flags inherited by their module-class */
   final val ModuleToClassFlags = AccessFlags | PACKAGE | CASE;
 
-  def flagsToString(flags: long, suffixes: List[Pair[long, String]]): String =
-    (for (val i <- List.range(0, 63)) yield {
-      var s = flagToString(flags & (1L << i));
-      suffixes.find(._1.==(i)) match {
-        case Some(Pair(i, suffix)) => s = s + "[" + suffix + "]"
-        case None =>
-      }
-      s
-    }).filter("" !=).mkString("", " ", "");
-
-  def flagsToString(flags: long): String = flagsToString(flags, List());
+  def flagsToString(flags: long): String =
+    (for (val i <- List.range(0, 63)) yield flagToString(flags & (1L << i)))
+      .filter("" !=).mkString("", " ", "");
 
   private def flagToString(flag: long): String = {
     if (flag == LABEL) "<label>"
@@ -153,7 +145,7 @@ object Flags {
 
       case DEFERRED      => "<deferred>"
       case METHOD        => "<method>"
-      case TRAIT         => "<trait>"
+      case MIXIN         => "mixin"
       case MODULE        => "<module>"
 
       case MUTABLE       => "<mutable>"
diff --git a/src/compiler/scala/tools/nsc/symtab/StdNames.scala b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
index d0bf3da3ac..a07933af4f 100644
--- a/src/compiler/scala/tools/nsc/symtab/StdNames.scala
+++ b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
@@ -28,6 +28,7 @@ import scala.tools.nsc.util.NameTransformer;
     val IMPLICITkw = newTermName("implicit");
     val IMPORTkw = newTermName("import");
     val MATCHkw = newTermName("match");
+    val MIXINkw = newTermName("mixin");
     val NEWkw = newTermName("new");
     val NULLkw = newTermName("null");
     val OBJECTkw = newTermName("object");
diff --git a/src/compiler/scala/tools/nsc/symtab/Symbols.scala b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
index f4d2bc38a1..2d7966add0 100644
--- a/src/compiler/scala/tools/nsc/symtab/Symbols.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
@@ -57,7 +57,7 @@ import Flags._;
 
     var attributes: List[AttrInfo] = List();
 
-    var privateWithin: Symbol = null;
+    var privateWithin: Symbol = NoSymbol;
 
 // Creators -------------------------------------------------------------------
 
@@ -156,7 +156,7 @@ import Flags._;
     final def isThisSym = isTerm && name == nme.this_;
     final def isThisSkolem = isTerm && deSkolemize != this;
     final def isError = hasFlag(IS_ERROR);
-    final def isTrait = isClass & hasFlag(TRAIT);
+    final def isMixin = isClass & hasFlag(MIXIN);
     final def isAliasType = isType && !isClass && !hasFlag(DEFERRED);
     final def isAbstractType = isType && !isClass && hasFlag(DEFERRED);
     final def isTypeParameterOrSkolem = isType && hasFlag(PARAM);
@@ -176,20 +176,19 @@ import Flags._;
     final def isStable =
       isTerm && !hasFlag(MUTABLE) && (!hasFlag(METHOD | BYNAMEPARAM) || hasFlag(STABLE));
 
-    /** Does this symbol denote the primary constructor
-     * of its enclosing class or trait? */
+    /** Does this symbol denote the primary constructor of its enclosing class? */
     final def isPrimaryConstructor =
       isConstructor && owner.primaryConstructor == this;
 
-    /** Is this symbol an implementation class for a trait ? */
+    /** Is this symbol an implementation class for a mixin? */
     final def isImplClass: boolean = isClass && hasFlag(IMPLCLASS);
 
     final def needsImplClass: boolean =
-      isTrait && (!hasFlag(INTERFACE) || hasFlag(lateINTERFACE)) && !isImplClass;
+      isMixin && (!hasFlag(INTERFACE) || hasFlag(lateINTERFACE)) && !isImplClass;
 
     final def isImplOnly: boolean = (
       hasFlag(PRIVATE) ||
-      (owner.isImplClass || owner.isTrait) &&
+      (owner.isImplClass || owner.isMixin) &&
       (hasFlag(notPRIVATE | LIFTED) && !hasFlag(ACCESSOR | SUPERACCESSOR) ||
        isConstructor)
     );
@@ -512,7 +511,7 @@ import Flags._;
 
     /** The primary constructor of a class */
     def primaryConstructor: Symbol = {
-      val c = info.decl(if (isTrait || isImplClass) nme.MIXIN_CONSTRUCTOR else nme.CONSTRUCTOR);
+      val c = info.decl(if (isMixin || isImplClass) nme.MIXIN_CONSTRUCTOR else nme.CONSTRUCTOR);
       if (c hasFlag OVERLOADED) c.alternatives.head else c
     }
 
@@ -686,8 +685,7 @@ import Flags._;
 
     /** String representation of symbol's definition key word */
     final def keyString: String =
-      if (isTrait)
-        if (hasFlag(JAVA)) "interface" else "trait"
+      if (isMixin && hasFlag(JAVA)) "interface"
       else if (isClass) "class"
       else if (isType && !hasFlag(PARAM)) "type"
       else if (isVariable) "var"
@@ -704,7 +702,6 @@ import Flags._;
       else if (isAnonymousClass) "<template>"
       else if (isRefinementClass) ""
       else if (isModuleClass) "singleton class"
-      else if (isTrait) "trait"
       else if (isClass) "class"
       else if (isType) "type"
       else if (isVariable) "variable"
@@ -754,10 +751,10 @@ import Flags._;
     /** String representation of symbol's definition following its name */
     final def infoString(tp: Type): String = {
       def typeParamsString: String = tp match {
-  case PolyType(tparams, _) if (tparams.length != 0) =>
-    (tparams map (.defString)).mkString("[", ",", "]")
-  case _ =>
-    ""
+        case PolyType(tparams, _) if (tparams.length != 0) =>
+          (tparams map (.defString)).mkString("[", ",", "]")
+        case _ =>
+          ""
       }
       if (isClass)
         typeParamsString + " extends " + tp.resultType
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
index 6b633f389f..e5803d18e5 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
@@ -392,7 +392,7 @@ abstract class ClassfileParser {
     if ((flags & JAVA_ACC_FINAL) != 0)
       res = res | FINAL;
     if ((flags & JAVA_ACC_INTERFACE) != 0)
-      res = res | TRAIT | INTERFACE | ABSTRACT;
+      res = res | MIXIN | INTERFACE | ABSTRACT;
     if ((flags & JAVA_ACC_SYNTHETIC) != 0)
       res = res | SYNTHETIC;
     if ((flags & JAVA_ACC_STATIC) != 0)
diff --git a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
index 016de25857..8e87e85200 100644
--- a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
+++ b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
@@ -84,9 +84,9 @@ abstract class AddInterfaces extends InfoTransform {
     override def complete(sym: Symbol): unit = {
       def implType(tp: Type): Type = tp match {
 	case ClassInfoType(parents, decls, _) =>
-	  //ClassInfoType(traitToImplClass(parents) ::: List(iface.tpe), implDecls(sym, decls), sym)
+	  //ClassInfoType(mixinToImplClass(parents) ::: List(iface.tpe), implDecls(sym, decls), sym)
 	  ClassInfoType(
-            ObjectClass.tpe :: (parents.tail map traitToImplClass) ::: List(iface.tpe),
+            ObjectClass.tpe :: (parents.tail map mixinToImplClass) ::: List(iface.tpe),
             implDecls(sym, decls),
             sym)
 	case PolyType(tparams, restpe) =>
@@ -98,14 +98,14 @@ abstract class AddInterfaces extends InfoTransform {
     override def load(clazz: Symbol): unit = complete(clazz)
   }
 
-  private def traitToImplClass(tp: Type): Type = tp match {
+  private def mixinToImplClass(tp: Type): Type = tp match {
     case TypeRef(pre, sym, args) if (sym.needsImplClass) =>
       typeRef(pre, implClass(sym), args)
     case _ =>
       tp
   }
 
-  def transformTraitInfo(tp: Type): Type = tp match {
+  def transformMixinInfo(tp: Type): Type = tp match {
     case ClassInfoType(parents, decls, clazz) =>
       if (clazz.needsImplClass) {
         clazz setFlag lateINTERFACE;
@@ -114,10 +114,10 @@ abstract class AddInterfaces extends InfoTransform {
       val parents1 =
         if (parents.isEmpty) List()
         else {
-          assert(!parents.head.symbol.isTrait || clazz == RepeatedParamClass, clazz);
+          assert(!parents.head.symbol.isMixin || clazz == RepeatedParamClass, clazz);
           if (clazz hasFlag INTERFACE) erasedTypeRef(ObjectClass) :: parents.tail
           else if (clazz.isImplClass || clazz == ArrayClass) parents
-	  else parents map traitToImplClass
+	  else parents map mixinToImplClass
         }
       val decls1 = if (clazz hasFlag INTERFACE) new Scope(decls.toList filter isInterfaceMember)
                    else decls;
@@ -186,7 +186,7 @@ abstract class AddInterfaces extends InfoTransform {
     buf.toList
   }
 
-  protected val traitTransformer = new Transformer {
+  protected val mixinTransformer = new Transformer {
     override def transformStats(stats: List[Tree], exprOwner: Symbol): List[Tree] =
       (super.transformStats(stats, exprOwner) :::
        super.transformStats(implClassDefs(stats), exprOwner));
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 8971d5787b..3555bee62b 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -122,7 +122,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
         }
       else erasure(tp)
     } else
-      transformTraitInfo(erasure(tp));
+      transformMixinInfo(erasure(tp));
 
 // -------- boxing/unboxing --------------------------------------------------------
 
@@ -498,7 +498,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
 */
 
     def addBridges(stats: List[Tree], base: Symbol): List[Tree] =
-      if (base.isTrait) stats
+      if (base.isMixin) stats
       else {
         val bridges = bridgeDefs(base);
         if (bridges.isEmpty) stats else stats ::: bridges
@@ -571,7 +571,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
     override def transform(tree: Tree): Tree = {
       val tree1 = preTransformer.transform(tree);
       atPhase(phase.next) {
-        val tree2 = traitTransformer.transform(tree1);
+        val tree2 = mixinTransformer.transform(tree1);
         if (settings.debug.value) log("tree after addinterfaces: \n" + tree2);
         newTyper(startContext.make(
 	  unit, tree, startContext.owner, startContext.scope, startContext.imports))
diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index 466ed4674c..45629ec4e0 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -33,13 +33,13 @@ abstract class ExplicitOuter extends InfoTransform {
   /** The type transformation method:
    *  1. Add an outer paramter to the formal parameters of a constructor or mixin constructor
    *     in a non-static class;
-   *  2. Add a mixin constructor $init$ to all traits except interfaces
+   *  2. Add a mixin constructor $init$ to all mixins except interfaces
    *  Leave all other types unchanged.
    */
   def transformInfo(sym: Symbol, tp: Type): Type = tp match {
     case MethodType(formals, restpe) =>
       //todo: needed?
-      if (sym.owner.isTrait && (sym hasFlag PROTECTED)) sym setFlag notPROTECTED;
+      if (sym.owner.isMixin && (sym hasFlag PROTECTED)) sym setFlag notPROTECTED;
       if (sym.isConstructor && !isStatic(sym.owner))
 	MethodType(formals ::: List(outerClass(sym.owner).toInterface.thisType), restpe)
       else tp;
@@ -49,7 +49,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	if (!isStatic(clazz)) {
 	  decls1 = new Scope(decls1.toList);
 	  val outerAcc = clazz.newMethod(clazz.pos, nme.OUTER);
-	  if ((clazz hasFlag TRAIT) || (decls.toList exists (.isClass)))
+	  if (clazz.isMixin || (decls.toList exists (.isClass)))
             outerAcc.expandName(clazz);
 	  decls1 enter (
 	    outerAcc setFlag (PARAMACCESSOR | ACCESSOR | STABLE)
@@ -58,7 +58,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	    setFlag (LOCAL | PRIVATE | PARAMACCESSOR | (outerAcc getFlag EXPANDEDNAME))
 	    setInfo outerClass(clazz).thisType);
 	}
-	if (clazz.isTrait) {
+	if (clazz.isMixin) {
 	  decls1 = new Scope(decls1.toList);
 	  decls1 enter makeMixinConstructor(clazz);
 	}
@@ -201,19 +201,19 @@ abstract class ExplicitOuter extends InfoTransform {
        *  to `tree'. `tree' which is assumed to be the body of a constructor of class `clazz'.
        */
       def addMixinConstructorCalls(tree: Tree, clazz: Symbol): Tree = {
-	def mixinConstructorCall(mixin: Symbol): Tree =
+	def mixinConstructorCall(mixinClass: Symbol): Tree =
 	  atPos(tree.pos) {
 	    Apply(
 	      localTyper.typedOperator {
-		Select(Super(clazz, mixin.name), mixin.primaryConstructor)
+		Select(Super(clazz, mixinClass.name), mixinClass.primaryConstructor)
 	      },
 	      List()) setType UnitClass.tpe; // don't type this with typed(...),
  	                                     // as constructor arguments might be missing
 	  }
 	val mixinConstructorCalls =
-	  for (val mixin <- clazz.info.parents.tail;
-               !(mixin.symbol hasFlag INTERFACE) && mixin.symbol != ScalaObjectClass) yield
-	    mixinConstructorCall(mixin.symbol);
+	  for (val mixinClass <- clazz.info.parents.tail;
+               !(mixinClass.symbol hasFlag INTERFACE) && mixinClass.symbol != ScalaObjectClass) yield
+	    mixinConstructorCall(mixinClass.symbol);
 	tree match {
 	  case Block(supercall :: stats, expr) =>
             assert(supercall match {
@@ -239,7 +239,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	    if (!(currentOwner hasFlag INTERFACE)) {
 	      if (!isStatic(currentOwner))
 		decls1 = decls1 ::: outerDefs(currentOwner); // (1)
-	      if (currentOwner.isTrait)
+	      if (currentOwner.isMixin)
 		decls1 = decls1 ::: List(mixinConstructorDef(currentOwner)) // (2)
 	    }
 	    localTyper = savedLocalTyper;
@@ -295,7 +295,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	val tree1 = super.transform(tree);
 	tree1 match {
           case DefDef(_, _, _, _, _, _) =>
-            if (sym.owner.isTrait && (sym hasFlag (ACCESSOR | SUPERACCESSOR)))
+            if (sym.owner.isMixin && (sym hasFlag (ACCESSOR | SUPERACCESSOR)))
               sym.makeNotPrivate(sym.owner); //(2)
             tree1
 	  case Select(qual, name) =>
diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index bcdd9b09b8..580365c713 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -101,17 +101,17 @@ abstract class Mixin extends InfoTransform {
 
   def addMixedinMembers(clazz: Symbol): unit = {
     if (!(clazz hasFlag MIXEDIN) && (clazz != ObjectClass)) {
-      assert(!clazz.isTrait, clazz);
+      assert(!clazz.isMixin, clazz);
       clazz setFlag MIXEDIN;
       assert(!clazz.info.parents.isEmpty, clazz);
       val superclazz = clazz.info.parents.head.symbol;
       addMixedinMembers(superclazz);
       //System.out.println("adding members of " + clazz.info.baseClasses.tail.takeWhile(superclazz !=) + " to " + clazz);//DEBUG
       val mixins = clazz.info.baseClasses.tail.takeWhile(superclazz !=);
-      def mixinMembers(mixin: Symbol, mmap: Symbol => Symbol): unit = {
-        if (mixin.isImplClass) {
-          addLateInterfaceMembers(mixin.toInterface);
-          for (val member <- mixin.info.decls.toList) {
+      def mixinMembers(mixinClass: Symbol, mmap: Symbol => Symbol): unit = {
+        if (mixinClass.isImplClass) {
+          addLateInterfaceMembers(mixinClass.toInterface);
+          for (val member <- mixinClass.info.decls.toList) {
             //System.out.println("adding forwarded method " + member + " " + mmap(member) + member.locationString + " to " + clazz + " " + clazz.info.member(member.name).alternatives);//DEBUG
             if (isForwarded(member) && !isStatic(member) &&
                 (clazz.info.findMember(member.name, 0, 0).alternatives contains mmap(member))) {
@@ -121,12 +121,12 @@ abstract class Mixin extends InfoTransform {
                   member1.asInstanceOf[TermSymbol] setAlias member;
                 }
           }
-        } else if (mixin.hasFlag(lateINTERFACE)) {
-          addLateInterfaceMembers(mixin);
-          val impl = implClass(mixin);
-          //System.out.println("late impl " + mixin + " " + impl);//DEBUG
-          if (!(mixins contains impl)) mixinMembers(impl, .overriddenSymbol(mixin));
-          for (val member <- mixin.info.decls.toList) {
+        } else if (mixinClass.hasFlag(lateINTERFACE)) {
+          addLateInterfaceMembers(mixinClass);
+          val impl = implClass(mixinClass);
+          //System.out.println("late impl " + mixinClass + " " + impl);//DEBUG
+          if (!(mixins contains impl)) mixinMembers(impl, .overriddenSymbol(mixinClass));
+          for (val member <- mixinClass.info.decls.toList) {
             if (member hasFlag ACCESSOR) {
               val member1 = addMember(
                 clazz,
@@ -146,7 +146,7 @@ abstract class Mixin extends InfoTransform {
             } else if (member hasFlag SUPERACCESSOR) {
               val member1 = addMember(clazz, member.cloneSymbol(clazz)) setPos clazz.pos;
               assert(member1.alias != NoSymbol, member1);
-              val alias1 = rebindSuper(clazz, member.alias, mixin);
+              val alias1 = rebindSuper(clazz, member.alias, mixinClass);
               member1.asInstanceOf[TermSymbol] setAlias alias1;
             } else if (member.isMethod && member.isModule && !(member hasFlag (LIFTED | BRIDGE))) {
               addMember(clazz, member.cloneSymbol(clazz))
@@ -156,8 +156,8 @@ abstract class Mixin extends InfoTransform {
           }
         }
       }
-//      for (val mixin <- mixins) if (mixin.hasFlag(lateINTERFACE)) addLateInterfaceMembers(mixin);
-      for (val mixin <- mixins) mixinMembers(mixin, identity);
+//      for (val mixinClass <- mixins) if (mixinClass.hasFlag(lateINTERFACE)) addLateInterfaceMembers(mixinClass);
+      for (val mixinClass <- mixins) mixinMembers(mixinClass, identity);
       if (settings.debug.value) log("new defs of " + clazz + " = " + clazz.info.decls);
     }
   }
@@ -216,7 +216,7 @@ abstract class Mixin extends InfoTransform {
         case Template(parents, body) =>
 	  localTyper = erasure.newTyper(rootContext.make(tree, currentOwner));
 	  atPhase(phase.next)(currentOwner.owner.info);//needed?
-          if (!currentOwner.isTrait) addMixedinMembers(currentOwner)
+          if (!currentOwner.isMixin) addMixedinMembers(currentOwner)
           else if (currentOwner hasFlag lateINTERFACE) addLateInterfaceMembers(currentOwner);
 	  tree
         case DefDef(mods, name, tparams, List(vparams), tpt, rhs) if currentOwner.isImplClass =>
@@ -300,7 +300,7 @@ abstract class Mixin extends InfoTransform {
 	if (sym hasFlag MIXEDIN) {
           if (clazz hasFlag lateINTERFACE) {
 	    addDefDef(sym, vparamss => EmptyTree)
-	  } else if (!clazz.isTrait) {
+	  } else if (!clazz.isMixin) {
 	    if (sym hasFlag ACCESSOR) {
               addDefDef(sym, vparams => {
 		val accessedRef = sym.tpe match {
@@ -325,7 +325,7 @@ abstract class Mixin extends InfoTransform {
 	}
       }
       val stats1 = add(stats, newDefs.toList);
-      if (clazz.isTrait) stats1 else stats1 map completeSuperAccessor;
+      if (clazz.isMixin) stats1 else stats1 map completeSuperAccessor;
     }
 
     private def postTransform(tree: Tree): Tree = {
diff --git a/src/compiler/scala/tools/nsc/transform/TailCalls.scala b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
index c6fa574228..c2681b2d3b 100644
--- a/src/compiler/scala/tools/nsc/transform/TailCalls.scala
+++ b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
@@ -228,7 +228,7 @@ abstract class TailCalls extends Transform
           else
             copy.Apply(tree, fun, transformTrees(args, mkContext(ctx, false)));
 
-        case Super(qual, mixin) =>
+        case Super(qual, mix) =>
           tree;
         case This(qual) =>
           tree;
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 6f9df75223..ce53aa40c2 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -40,7 +40,13 @@ trait Namers: Analyzer {
 
   class Namer(val context: Context) {
 
-    def setPrivate(sym: Symbol, mods: Modifiers): Symbol = sym;
+    val typer = newTyper(context);
+
+    def setPrivate(sym: Symbol, mods: Modifiers): Symbol = {
+      if (!mods.privateWithin.isEmpty)
+        sym.privateWithin = typer.qualifyingClassContext(EmptyTree, mods.privateWithin).owner;
+      sym
+    }
 
     def updatePosFlags(sym: Symbol, pos: int, flags: int): Symbol = {
       if (settings.debug.value) log("overwriting " + sym);
@@ -271,8 +277,6 @@ trait Namers: Analyzer {
 
 // --- Lazy Type Assignment --------------------------------------------------
 
-    val typer = newTyper(context);
-
     def typeCompleter(tree: Tree) = new TypeCompleter(tree) {
       override def complete(sym: Symbol): unit = {
         if (settings.debug.value) log("defining " + sym);
@@ -499,7 +503,7 @@ trait Namers: Analyzer {
      *   - `abstract' modifier only for classes
      *   - `override' modifier never for classes
      *   - `def' modifier never for parameters of case classes
-     *   - declarations only in traits or abstract classes
+     *   - declarations only in mixins or abstract classes
      */
     def validate(sym: Symbol): unit = {
       def checkNoConflict(flag1: int, flag2: int): unit =
@@ -512,13 +516,15 @@ trait Namers: Analyzer {
 	      Flags.flagsToString(flag1) + " and " + Flags.flagsToString(flag2));
       if (sym.hasFlag(IMPLICIT) && !sym.isTerm)
 	context.error(sym.pos, "`implicit' modifier can be used only for values, variables and methods");
+      if (sym.hasFlag(MIXIN) && !sym.isClass)
+	context.error(sym.pos, "`mixin' modifier can be used only for classes");
       if (sym.hasFlag(ABSTRACT) && !sym.isClass)
 	context.error(sym.pos, "`abstract' modifier can be used only for classes; " +
 	  "\nit should be omitted for abstract members");
       if (sym.hasFlag(OVERRIDE | ABSOVERRIDE) && sym.isClass)
 	context.error(sym.pos, "`override' modifier not allowed for classes");
-      if (sym.hasFlag(ABSOVERRIDE) && !sym.owner.isTrait)
-	context.error(sym.pos, "`abstract override' modifier only allowed for members of traits");
+      if (sym.hasFlag(ABSOVERRIDE) && !sym.owner.isMixin)
+	context.error(sym.pos, "`abstract override' modifier only allowed for members of mixin classes");
       if (sym.info.symbol == FunctionClass(0) &&
 	  sym.isValueParameter && sym.owner.isClass && sym.owner.hasFlag(CASE))
 	context.error(sym.pos, "pass-by-name arguments not allowed for case class parameters");
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index f6552d9fc5..d69b6d540c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -226,11 +226,11 @@ abstract class RefChecks extends InfoTransform {
 	}
 */
       // 2. Check that only abstract classes have deferred members
-      if (clazz.isClass && !clazz.isTrait) {
-	def abstractClassError(mustBeTrait: boolean, msg: String): unit = {
+      if (clazz.isClass && !clazz.isMixin) {
+	def abstractClassError(mustBeMixin: boolean, msg: String): unit = {
 	  unit.error(clazz.pos,
 	    (if (clazz.isAnonymousClass || clazz.isModuleClass) "object creation impossible"
-	     else if (mustBeTrait) clazz.toString() + " needs to be a trait"
+	     else if (mustBeMixin) clazz.toString() + " needs to be a mixin"
 	     else clazz.toString() + " needs to be abstract") + ", since " + msg);
 	  clazz.setFlag(ABSTRACT);
 	}
@@ -265,7 +265,7 @@ abstract class RefChecks extends InfoTransform {
   // Basetype Checking --------------------------------------------------------
 
     /** 1. Check that later type instances in the base-type sequence
-     *     are subtypes of earlier type instances of the same trait.
+     *     are subtypes of earlier type instances of the same mixin.
      *  2. Check that case classes do not inherit from case classes.
      *  3. Check that at most one base type is a case-class.
      */
@@ -460,12 +460,12 @@ abstract class RefChecks extends InfoTransform {
           val ddef =
 	    atPhase(phase.next) {
 	      localTyper.typed {
-                if (sym.owner.isTrait) newModuleAccessDcl(sym)
+                if (sym.owner.isMixin) newModuleAccessDcl(sym)
                 else newModuleAccessDef(sym, vdef.symbol)
               }
             }
 
-          if (sym.owner.isTrait) transformTrees(List(cdef, ddef))
+          if (sym.owner.isMixin) transformTrees(List(cdef, ddef))
           else transformTrees(List(cdef, vdef, ddef))
 	}
 
@@ -553,16 +553,16 @@ abstract class RefChecks extends InfoTransform {
 	  if (sym.isSourceMethod && sym.hasFlag(CASE))
 	    result = toConstructor
 	  else qual match {
-	    case Super(qualifier, mixin) =>
+	    case Super(qualifier, mix) =>
               val base = currentOwner.enclClass;
               if (sym hasFlag DEFERRED) {
 	        val member = sym.overridingSymbol(base);//???
-	        if (mixin != nme.EMPTY.toTypeName || member == NoSymbol ||
+	        if (mix != nme.EMPTY.toTypeName || member == NoSymbol ||
 		    !((member hasFlag ABSOVERRIDE) && member.isIncompleteIn(base)))
 		  unit.error(tree.pos, "symbol accessed from super may not be abstract");
               }
               //System.out.println("super: " + tree + " in " + base);//DEBUG
-              if (base.isTrait && sym.isTerm && mixin == nme.EMPTY.toTypeName) {
+              if (base.isMixin && sym.isTerm && mix == nme.EMPTY.toTypeName) {
                 val superAccName = nme.superName(sym.name);
 	        val superAcc = base.info.decl(superAccName) suchThat (.alias.==(sym));
 	        assert(superAcc != NoSymbol, "" + sym + " " + base + " " + superAccName);//debug
diff --git a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
index 4eb38f349b..7e0562d633 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
@@ -46,7 +46,7 @@ abstract class SuperAccessors extends transform.Transform {
       case Select(sup @ Super(_, mix), name) =>
 	val clazz = sup.symbol;
 	if (tree.isTerm && mix == nme.EMPTY.toTypeName &&
-	    (clazz.isTrait || clazz != currentOwner.enclClass || !validCurrentOwner)) {
+	    (clazz.isMixin || clazz != currentOwner.enclClass || !validCurrentOwner)) {
 	  val supername = nme.superName(tree.symbol.name);
 	  var superAcc = clazz.info.decl(supername).suchThat(.alias.==(tree.symbol));
 	  if (superAcc == NoSymbol) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 0814defc9e..551fb0bd6c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -3,7 +3,7 @@
  * @author  Martin Odersky
  */
 // $Id$
-//todo: rewrite or disallow new T where T is a trait (currently: <init> not a member of T)
+//todo: rewrite or disallow new T where T is a mixin (currently: <init> not a member of T)
 package scala.tools.nsc.typechecker
 
 import symtab.Flags._
@@ -237,6 +237,20 @@ import scala.collection.mutable.{HashMap, ListBuffer}
         })
     }
 
+    /** The qualifying class of a this or super with prefix `qual' */
+    def qualifyingClassContext(tree: Tree, qual: Name): Context = {
+      if (qual.isEmpty) {
+        if (context.enclClass.owner.isPackageClass)
+          error(tree.pos, ""+tree+" can be used only in a class, object, or template")
+        context.enclClass
+      } else {
+        var c = context.enclClass
+        while (c != NoContext && c.owner.name != qual) c = c.outer.enclClass
+        if (c == NoContext) error(tree.pos, ""+qual+" is not an enclosing class")
+	c
+      }
+    }
+
     /** Post-process an identifier or selection node, performing the following:
      *  (1) Check that non-function pattern expressions are stable
      *  (2) Check that packages and static modules are not used as values
@@ -469,8 +483,8 @@ import scala.collection.mutable.{HashMap, ListBuffer}
       else {
 	var supertpt = typedTypeConstructor(templ.parents.head)
 	var mixins = templ.parents.tail map typedType
-	// If first parent is trait, make it first mixin and add its superclass as first parent
-	while (supertpt.tpe.symbol != null && supertpt.tpe.symbol.initialize.isTrait) {
+	// If first parent is a mixin class, make it first mixin and add its superclass as first parent
+	while (supertpt.tpe.symbol != null && supertpt.tpe.symbol.initialize.isMixin) {
 	  mixins = typedType(supertpt) :: mixins
 	  supertpt = TypeTree(supertpt.tpe.parents.head) setPos supertpt.pos
 	}
@@ -501,7 +515,7 @@ import scala.collection.mutable.{HashMap, ListBuffer}
 
     /** Check that
      *  - all parents are class types,
-     *  - first parent cluss is not a trait; following classes are traits,
+     *  - first parent cluss is not a mixin; following classes are mixins,
      *  - final classes are not inherited,
      *  - sealed classes are only inherited by classes which are
      *    nested within definition of base class, or that occur within same
@@ -519,8 +533,8 @@ import scala.collection.mutable.{HashMap, ListBuffer}
 	  val psym = parent.tpe.symbol.initialize
 	  if (!psym.isClass)
 	    error(parent.pos, "class type expected")
-	  else if (!isFirst && !psym.isTrait)
-	    error(parent.pos, ""+psym+" is not a trait; cannot be used as mixin")
+	  else if (!isFirst && !psym.isMixin)
+	    error(parent.pos, ""+psym+" is not declared to be a mixin class")
 	  else if (psym.hasFlag(FINAL))
 	    error(parent.pos, "illegal inheritance from final class")
 	  else if (psym.isSealed && !phase.erasedTypes) {
@@ -944,20 +958,6 @@ import scala.collection.mutable.{HashMap, ListBuffer}
 	  errorTree(tree, ""+fun+" does not take parameters")
       }
 
-      /** The qualifying class of a this or super with prefix `qual' */
-      def qualifyingClassContext(qual: Name): Context = {
-        if (qual == nme.EMPTY.toTypeName) {
-          if (context.enclClass.owner.isPackageClass)
-            error(tree.pos, ""+tree+" can be used only in a class, object, or template")
-          context.enclClass
-        } else {
-          var c = context.enclClass
-          while (c != NoContext && c.owner.name != qual) c = c.outer.enclClass
-          if (c == NoContext) error(tree.pos, ""+qual+" is not an enclosing class")
-	  c
-        }
-      }
-
       /** Attribute a selection where `tree' is `qual.name'.
        *  `qual' is already attributed.
        */
@@ -1261,7 +1261,7 @@ import scala.collection.mutable.{HashMap, ListBuffer}
               .setPos(tpt1.pos)
               .setType(appliedType(tpt1.tpe, context.undetparams map (.tpe)))
           }
-	  if (tpt1.tpe.symbol.isTrait) error(tree.pos, "traits cannot be instantiated")
+	  if (tpt1.tpe.symbol.isMixin) error(tree.pos, "mixin classes cannot be instantiated")
           copy.New(tree, tpt1).setType(tpt1.tpe)
 
         case Typed(expr, tpt @ Ident(name)) if (name == nme.WILDCARD_STAR.toTypeName) =>
@@ -1314,13 +1314,13 @@ import scala.collection.mutable.{HashMap, ListBuffer}
             if (tree.symbol != NoSymbol) {
               Pair(tree.symbol, tree.symbol.thisType)
             } else {
-              val clazzContext = qualifyingClassContext(qual)
+              val clazzContext = qualifyingClassContext(tree, qual)
               Pair(clazzContext.owner, clazzContext.prefix)
             }
           if (clazz == NoSymbol) setError(tree)
           else {
 	    val owntype =
-	      if (mix == nme.EMPTY.toTypeName)
+	      if (mix.isEmpty)
                 if ((mode & SUPERCONSTRmode) != 0) clazz.info.parents.head
                 else intersectionType(clazz.info.parents)
               else {
@@ -1339,7 +1339,7 @@ import scala.collection.mutable.{HashMap, ListBuffer}
             if (tree.symbol != NoSymbol) {
               Pair(tree.symbol, tree.symbol.thisType)
             } else {
-              val clazzContext = qualifyingClassContext(qual)
+              val clazzContext = qualifyingClassContext(tree, qual)
               Pair(clazzContext.owner, clazzContext.prefix)
             }
           if (clazz == NoSymbol) setError(tree)
diff --git a/src/compiler/scala/tools/nsc/util/Set.scala b/src/compiler/scala/tools/nsc/util/Set.scala
index dab7898e39..cd6d8ceaae 100644
--- a/src/compiler/scala/tools/nsc/util/Set.scala
+++ b/src/compiler/scala/tools/nsc/util/Set.scala
@@ -5,7 +5,7 @@
 // $Id$
 package scala.tools.nsc.util;
 
-/** A common trait for lightweight sets.
+/** A common class for lightweight sets.
  */
 abstract class Set[T <: AnyRef] {
 
diff --git a/src/library/scala/NotDefinedError.scala b/src/library/scala/NotDefinedError.scala
new file mode 100755
index 0000000000..9c7d7695a8
--- /dev/null
+++ b/src/library/scala/NotDefinedError.scala
@@ -0,0 +1,12 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002, LAMP/EPFL                  **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+**                                                                      **
+** $Id: MatchError.scala 5390 2005-12-19 13:49:03Z dubochet $
+\*                                                                      */
+package scala;
+
+final class NotDefinedError(msg: String) extends Error("not defined: " + msg);
diff --git a/src/library/scala/_mixin_.scala b/src/library/scala/_mixin_.scala
new file mode 100644
index 0000000000..5d80167992
--- /dev/null
+++ b/src/library/scala/_mixin_.scala
@@ -0,0 +1,18 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2005, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+*/
+
+// $Id:_trait_.scala 5359 2005-12-16 16:33:49 +0100 (Fri, 16 Dec 2005) dubochet $
+
+package scala;
+
+/** Temporary class.
+ *  When this appears in the attribute list of an abstract class, the class
+ *  is assumed to be a mixin. Used to ensure that code that compiles under
+ *  (old) <code>scalac</code> can also compile under <code>nsc</code>.
+ */
+class _mixin_ extends Attribute {}