From 296b7061ccef8600c011140fa6fd64afec244ed0 Mon Sep 17 00:00:00 2001
From: Paul Phillips <paulp@improving.org>
Date: Thu, 5 Apr 2012 15:50:10 -0700
Subject: A boatload of work on Symbols and Flags.

Finally my dream of orderliness is within sight.

It's all pretty self-explanatory.  More polymorphism, more immutable
identity, more invariants.
---
 .../scala/reflect/internal/Definitions.scala       |  14 +-
 src/compiler/scala/reflect/internal/Flags.scala    |  80 +-
 src/compiler/scala/reflect/internal/HasFlags.scala | 109 +--
 .../scala/reflect/internal/Importers.scala         |  10 +-
 .../scala/reflect/internal/SymbolCreations.scala   | 106 +++
 .../scala/reflect/internal/SymbolFlags.scala       | 237 ++++++
 .../scala/reflect/internal/SymbolTable.scala       |   9 +
 src/compiler/scala/reflect/internal/Symbols.scala  | 852 +++++++++++----------
 .../scala/reflect/internal/TreePrinters.scala      |   2 +-
 .../reflect/internal/pickling/UnPickler.scala      |  27 +-
 .../reflect/runtime/SynchronizedSymbols.scala      |  47 +-
 src/compiler/scala/tools/nsc/Global.scala          |   4 -
 src/compiler/scala/tools/nsc/ast/Reifiers.scala    |   2 +-
 src/compiler/scala/tools/nsc/ast/TreeInfo.scala    |   2 +-
 .../scala/tools/nsc/ast/parser/Parsers.scala       |  13 +-
 .../scala/tools/nsc/backend/icode/TypeKinds.scala  |   2 +-
 .../scala/tools/nsc/transform/AddInterfaces.scala  |  11 +-
 .../scala/tools/nsc/transform/ExplicitOuter.scala  |   2 +-
 .../scala/tools/nsc/transform/Flatten.scala        |   2 +-
 .../tools/nsc/typechecker/ContextErrors.scala      |   2 +-
 .../scala/tools/nsc/typechecker/Infer.scala        |   2 +-
 .../scala/tools/nsc/typechecker/Namers.scala       |   8 +-
 .../tools/nsc/typechecker/NamesDefaults.scala      |   4 +-
 .../scala/tools/nsc/typechecker/RefChecks.scala    |   4 +-
 .../scala/tools/nsc/typechecker/Typers.scala       |   6 +-
 25 files changed, 970 insertions(+), 587 deletions(-)
 create mode 100644 src/compiler/scala/reflect/internal/SymbolCreations.scala
 create mode 100644 src/compiler/scala/reflect/internal/SymbolFlags.scala

(limited to 'src/compiler')

diff --git a/src/compiler/scala/reflect/internal/Definitions.scala b/src/compiler/scala/reflect/internal/Definitions.scala
index 8ea3cd511a..0224f9158e 100644
--- a/src/compiler/scala/reflect/internal/Definitions.scala
+++ b/src/compiler/scala/reflect/internal/Definitions.scala
@@ -138,6 +138,12 @@ trait Definitions extends reflect.api.StandardDefinitions {
     // symbols related to packages
     var emptypackagescope: Scope = null //debug
 
+    // TODO - having these as objects means they elude the attempt to
+    // add synchronization in SynchronizedSymbols.  But we should either
+    // flip on object overrides or find some other accomodation, because
+    // lazy vals are unnecessarily expensive relative to objects and it
+    // is very beneficial for a handful of bootstrap symbols to have
+    // first class identities
     sealed trait WellKnownSymbol extends Symbol {
       this initFlags TopLevelCreationFlags
     }
@@ -148,7 +154,7 @@ trait Definitions extends reflect.api.StandardDefinitions {
     }
     // This is the package _root_.  The actual root cannot be referenced at
     // the source level, but _root_ is essentially a function => <root>.
-    final object RootPackage extends ModuleSymbol(NoSymbol, NoPosition, nme.ROOTPKG) with RootSymbol {
+    final object RootPackage extends PackageSymbol(NoSymbol, NoPosition, nme.ROOTPKG) with RootSymbol {
       this setInfo NullaryMethodType(RootClass.tpe)
       RootClass.sourceModule = this
 
@@ -160,7 +166,7 @@ trait Definitions extends reflect.api.StandardDefinitions {
     // although it is probable that some symbols are created as direct children
     // of NoSymbol to ensure they will not be stumbled upon.  (We should designate
     // a better encapsulated place for that.)
-    final object RootClass extends ModuleClassSymbol(NoSymbol, NoPosition, tpnme.ROOT) with RootSymbol {
+    final object RootClass extends PackageClassSymbol(NoSymbol, NoPosition, tpnme.ROOT) with RootSymbol {
       this setInfo rootLoader
 
       override def isRoot            = true
@@ -170,10 +176,10 @@ trait Definitions extends reflect.api.StandardDefinitions {
       override def ownerOfNewSymbols = EmptyPackageClass
     }
     // The empty package, which holds all top level types without given packages.
-    final object EmptyPackage extends ModuleSymbol(RootClass, NoPosition, nme.EMPTY_PACKAGE_NAME) with WellKnownSymbol {
+    final object EmptyPackage extends PackageSymbol(RootClass, NoPosition, nme.EMPTY_PACKAGE_NAME) with WellKnownSymbol {
       override def isEmptyPackage = true
     }
-    final object EmptyPackageClass extends ModuleClassSymbol(RootClass, NoPosition, tpnme.EMPTY_PACKAGE_NAME) with WellKnownSymbol {
+    final object EmptyPackageClass extends PackageClassSymbol(RootClass, NoPosition, tpnme.EMPTY_PACKAGE_NAME) with WellKnownSymbol {
       override def isEffectiveRoot     = true
       override def isEmptyPackageClass = true
     }
diff --git a/src/compiler/scala/reflect/internal/Flags.scala b/src/compiler/scala/reflect/internal/Flags.scala
index ce1c8d0908..38f9ec6669 100644
--- a/src/compiler/scala/reflect/internal/Flags.scala
+++ b/src/compiler/scala/reflect/internal/Flags.scala
@@ -174,6 +174,9 @@ class Flags extends ModifierFlags {
   final val LateShift     = 47L
   final val AntiShift     = 56L
 
+  // Flags which sketchily share the same slot
+  val OverloadedFlagsMask = 0L | BYNAMEPARAM | CONTRAVARIANT | DEFAULTPARAM | EXISTENTIAL | IMPLCLASS
+
   // ------- late flags (set by a transformer phase) ---------------------------------
   //
   // Summary of when these are claimed to be first used.
@@ -206,12 +209,24 @@ class Flags extends ModifierFlags {
 
   // ------- masks -----------------------------------------------------------------------
 
+  /** To be a little clearer to people who aren't habitual bit twiddlers.
+   */
+  final val AllFlags = -1L
+
   /** These flags can be set when class or module symbol is first created.
    *  They are the only flags to survive a call to resetFlags().
    */
   final val TopLevelCreationFlags: Long =
     MODULE | PACKAGE | FINAL | JAVA
 
+  // TODO - there's no call to slap four flags onto every package.
+  final val PackageFlags: Long = TopLevelCreationFlags
+
+  // FINAL not included here due to possibility of object overriding.
+  // In fact, FINAL should not be attached regardless.  We should be able
+  // to reconstruct whether an object was marked final in source.
+  final val ModuleFlags: Long = MODULE
+
   /** These modifiers can be set explicitly in source programs.  This is
    *  used only as the basis for the default flag mask (which ones to display
    *  when printing a normal message.)
@@ -220,15 +235,15 @@ class Flags extends ModifierFlags {
     PRIVATE | PROTECTED | ABSTRACT | FINAL | SEALED |
     OVERRIDE | CASE | IMPLICIT | ABSOVERRIDE | LAZY
 
-  /** These modifiers appear in TreePrinter output. */
-  final val PrintableFlags: Long =
-    ExplicitFlags | LOCAL | SYNTHETIC | STABLE | CASEACCESSOR | MACRO |
-    ACCESSOR | SUPERACCESSOR | PARAMACCESSOR | BRIDGE | STATIC | VBRIDGE | SPECIALIZED | SYNCHRONIZED
-
   /** The two bridge flags */
   final val BridgeFlags = BRIDGE | VBRIDGE
   final val BridgeAndPrivateFlags = BridgeFlags | PRIVATE
 
+  /** These modifiers appear in TreePrinter output. */
+  final val PrintableFlags: Long =
+    ExplicitFlags | BridgeFlags | LOCAL | SYNTHETIC | STABLE | CASEACCESSOR | MACRO |
+    ACCESSOR | SUPERACCESSOR | PARAMACCESSOR | STATIC | SPECIALIZED | SYNCHRONIZED
+
   /** When a symbol for a field is created, only these flags survive
    *  from Modifiers.  Others which may be applied at creation time are:
    *  PRIVATE, LOCAL.
@@ -264,7 +279,7 @@ class Flags extends ModifierFlags {
   final val ConstrFlags: Long         = JAVA
 
   /** Module flags inherited by their module-class */
-  final val ModuleToClassFlags: Long = AccessFlags | MODULE | PACKAGE | CASE | SYNTHETIC | JAVA | FINAL
+  final val ModuleToClassFlags: Long = AccessFlags | TopLevelCreationFlags | CASE | SYNTHETIC
 
   def getterFlags(fieldFlags: Long): Long = ACCESSOR + (
     if ((fieldFlags & MUTABLE) != 0) fieldFlags & ~MUTABLE & ~PRESUPER
@@ -407,26 +422,43 @@ class Flags extends ModifierFlags {
     case _ => ""
   }
 
-  def flagsToString(flags: Long, privateWithin: String): String = {
-    var f = flags
-    val pw =
-      if (privateWithin == "") {
-        if ((flags & PrivateLocal) == PrivateLocal) {
-          f &= ~PrivateLocal
-          "private[this]"
-        } else if ((flags & ProtectedLocal) == ProtectedLocal) {
-          f &= ~ProtectedLocal
-          "protected[this]"
-        } else {
-          ""
+  def accessString(flags: Long, privateWithin: String)= (
+    if (privateWithin == "") {
+      if ((flags & PrivateLocal) == PrivateLocal) "private[this]"
+      else if ((flags & ProtectedLocal) == ProtectedLocal) "protected[this]"
+      else if ((flags & PRIVATE) != 0) "private"
+      else if ((flags & PROTECTED) != 0) "protected"
+      else ""
+    }
+    else if ((flags & PROTECTED) != 0) "protected[" + privateWithin + "]"
+    else "private[" + privateWithin + "]"
+  )
+  def nonAccessString(flags0: Long)(flagStringFn: Long => String): String = {
+    val flags = flags0 & ~AccessFlags
+    // Fast path for common case
+    if (flags == 0L) "" else {
+      var sb: StringBuilder = null
+      var i = 0
+      while (i <= MaxBitPosition) {
+        val mask = rawFlagPickledOrder(i)
+        if ((flags & mask) != 0L) {
+          val s = flagStringFn(mask)
+          if (s.length > 0) {
+            if (sb eq null) sb = new StringBuilder append s
+            else if (sb.length == 0) sb append s
+            else sb append " " append s
+          }
         }
-      } else if ((f & PROTECTED) != 0L) {
-        f &= ~PROTECTED
-        "protected[" + privateWithin + "]"
-      } else {
-        "private[" + privateWithin + "]"
+        i += 1
       }
-    List(flagsToString(f), pw) filterNot (_ == "") mkString " "
+      if (sb eq null) "" else sb.toString
+    }
+  }
+
+  def flagsToString(flags: Long, privateWithin: String): String = {
+    val access = accessString(flags, privateWithin)
+    val nonAccess = flagsToString(flags & ~AccessFlags)
+    List(nonAccess, access) filterNot (_ == "") mkString " "
   }
 
   // List of the raw flags, in pickled order
diff --git a/src/compiler/scala/reflect/internal/HasFlags.scala b/src/compiler/scala/reflect/internal/HasFlags.scala
index 8affd66cd5..2f574b6bfa 100644
--- a/src/compiler/scala/reflect/internal/HasFlags.scala
+++ b/src/compiler/scala/reflect/internal/HasFlags.scala
@@ -1,76 +1,6 @@
 package scala.reflect
 package internal
 
-/** ISSUE #1: Flag names vs. Test method names
- *
- *  The following methods from Symbol have a name of
- *  the form isFoo where FOO is the name of a flag, but where the method
- *  body tests for more than whether the flag is set.
- *
- *  There are two possibilities with such methods.  Either the extra
- *  tests are strictly to partition among overloaded flags (which is
- *  the case we can live with in the short term, if each such flag's
- *  partitioning assumptions are documented) or they aren't.
- *
- *  The second case implies that "x hasFlag FOO" and "x.isFoo" have
- *  different semantics, and this we can't live with, because even if
- *  we're smart enough to avoid being tripped up by that, the next guy isn't.
- *
- *  No extreme measures necessary, only renaming isFoo to something
- *  which hews more closely to its implementation.  (Or renaming the flag.)
- *
-    // Defined in the compiler Symbol
-    //
-    final def isLabel = isMethod && !hasAccessorFlag && hasFlag(LABEL)
-    final def isLocal: Boolean = owner.isTerm
-    final def isModuleVar: Boolean = isVariable && hasFlag(MODULEVAR)
-    final def isStable =
-      isTerm &&
-      !hasTraitFlag &&
-      (!hasFlag(METHOD | BYNAMEPARAM) || hasFlag(STABLE)) &&
-      !(tpe.isVolatile && !hasAnnotation(uncheckedStableClass))
-    final def isStatic: Boolean =
-      hasFlag(STATIC) || isRoot || owner.isStaticOwner
-    override final def isTrait: Boolean =
-      isClass && hasFlag(TRAIT | notDEFERRED)     // A virtual class becomes a trait (part of DEVIRTUALIZE)
-
-    // Defined in the library Symbol
-    //
-          def isTrait: Boolean = isClass && hasFlag(TRAIT) // refined later for virtual classes.
-    final def isContravariant = isType && hasFlag(CONTRAVARIANT)
-    final def isCovariant = isType && hasFlag(COVARIANT)
-    final def isMethod = isTerm && hasFlag(METHOD)
-    final def isModule = isTerm && hasFlag(MODULE)
-    final def isPackage = isModule && hasFlag(PACKAGE)
- *
- */
-
-/** ISSUE #2: Implicit flag relationships must be made explicit.
- *
- *  For instance, every time the MODULE flag is set, the FINAL flag is
- *  set along with it:
- *
-   .setFlag(FINAL | MODULE | PACKAGE | JAVA)
-   .setFlag(FINAL | MODULE | PACKAGE | JAVA).setInfo(rootLoader)
-   new ModuleSymbol(this, pos, name).setFlag(MODULE | FINAL)
-   new ModuleSymbol(this, pos, name).setFlag(MODULE | FINAL)
-   val m = new ModuleSymbol(this, pos, name).setFlag(MODULE | FINAL)
-   setFlag(module.getFlag(ModuleToClassFlags) | MODULE | FINAL)
-   sourceModule.flags = MODULE | FINAL
-
- * However the same is not true of when the MODULE flag is cleared:
-
-    sym.resetFlag(MODULE)
-    .setFlag(sym.flags | STABLE).resetFlag(MODULE)
-    sym.resetFlag(MODULE | FINAL | CASE)
-
- *  It's not relevant whether this example poses any issues: we must
- *  not tolerate these uncertainties.  If the flags are to move together
- *  then both setting and clearing have to be encapsulated.  If there
- *  is a useful and used distinction between the various permutations
- *  of on and off, then it must be documented.  It's the only way!
- */
-
 import Flags._
 
 /** Common code utilized by Modifiers (which carry the flags associated
@@ -165,26 +95,20 @@ trait HasFlags {
   // which must have been a bug.
   def isPublic = hasNoFlags(PRIVATE | PROTECTED) && !hasAccessBoundary
 
-  // Renamed the Modifiers impl from isArgument.
-  def isParameter = hasFlag(PARAM)
-
   // Removed isClass qualification since the flag isn't overloaded and
   // sym.isClass is enforced in Namers#validate.
   def isSealed = hasFlag(SEALED)
 
   // Removed !isClass qualification since the flag isn't overloaded.
-  def isDeferred = hasFlag(DEFERRED )
+  def isDeferred = hasFlag(DEFERRED)
 
   // Dropped isTerm condition because flag isn't overloaded.
   def isAbstractOverride = hasFlag(ABSOVERRIDE)
   def isAnyOverride = hasFlag(OVERRIDE | ABSOVERRIDE)
-  def isDefaultInit = hasFlag(DEFAULTINIT)
 
   // Disambiguating: DEFAULTPARAM, TRAIT
   def hasDefault     = hasAllFlags(DEFAULTPARAM | PARAM)
   def isTrait        = hasFlag(TRAIT) && !hasFlag(PARAM)
-  def hasTraitFlag   = hasFlag(TRAIT)
-  def hasDefaultFlag = hasFlag(DEFAULTPARAM)
 
   // Straightforwardly named accessors already being used differently.
   // These names are most likely temporary.
@@ -193,16 +117,9 @@ trait HasFlags {
   def hasLocalFlag         = hasFlag(LOCAL)
   def hasModuleFlag        = hasFlag(MODULE)
   def hasPackageFlag       = hasFlag(PACKAGE)
-  def hasPreSuperFlag      = hasFlag(PRESUPER)
   def hasStableFlag        = hasFlag(STABLE)
   def hasStaticFlag        = hasFlag(STATIC)
 
-   // Disambiguating: BYNAMEPARAM, CAPTURED, COVARIANT.
-  def isByNameParam      = hasAllFlags(BYNAMEPARAM | PARAM)
-  // Nope, these aren't going to fly:
-  // def isCapturedVariable = hasAllFlags(CAPTURED | MUTABLE)
-  // def isCovariant        = hasFlag(COVARIANT) && hasNoFlags(PARAM | MUTABLE)
-
   // Disambiguating: LABEL, CONTRAVARIANT, INCONSTRUCTOR
   def isLabel = hasAllFlags(LABEL | METHOD) && !hasAccessorFlag
   // Cannot effectively disambiguate the others at this level.
@@ -212,23 +129,13 @@ trait HasFlags {
   // Name
   def isJavaDefined = hasFlag(JAVA)
 
-  // Keeping some potentially ambiguous names around so as not to break
-  // the rest of the world
+  // Backward compat section
+  @deprecated( "Use isTrait", "2.10.0")
+  def hasTraitFlag = hasFlag(TRAIT)
+  @deprecated("Use hasDefault", "2.10.0")
+  def hasDefaultFlag = hasFlag(DEFAULTPARAM)
   @deprecated("", "2.9.0")
   def isAbstract = hasFlag(ABSTRACT)
-  // Problematic:
-  // ABSTRACT and DEFERRED too easy to confuse, and
-  // ABSTRACT + OVERRIDE ==> ABSOVERRIDE adds to it.
-  //
-  // final def isAbstractClass = isClass && hasFlag(ABSTRACT)
-  // def isAbstractType = false  // to be overridden
-
-  // Question:
-  // Which name? All other flags are isFlag so it's probably a mistake to
-  // vary from that, but isAccessor does sound like it includes the other
-  // *ACCESSOR flags. Perhaps something like isSimpleAccessor.
-  //
-  // def isAccessor      = hasFlag(ACCESSOR )
-  // final def isGetterOrSetter = hasAccessorFlag
+  @deprecated("Use isValueParameter or isTypeParameter", "2.10.0")
+  def isParameter = hasFlag(PARAM)
 }
-
diff --git a/src/compiler/scala/reflect/internal/Importers.scala b/src/compiler/scala/reflect/internal/Importers.scala
index 04381937d1..5dcff804a8 100644
--- a/src/compiler/scala/reflect/internal/Importers.scala
+++ b/src/compiler/scala/reflect/internal/Importers.scala
@@ -63,7 +63,7 @@ trait Importers { self: SymbolTable =>
             }
             myowner.newTypeSkolemSymbol(myname.toTypeName, origin, mypos, myflags)
           case x: from.ModuleClassSymbol =>
-            val mysym = myowner.newModuleClassSymbol(myname.toTypeName, mypos, myflags)
+            val mysym = myowner.newModuleClass(myname.toTypeName, mypos, myflags)
             symMap(x) = mysym
             mysym.sourceModule = importSymbol(x.sourceModule)
             mysym
@@ -109,14 +109,18 @@ trait Importers { self: SymbolTable =>
           val owner = sym.owner
           var scope = if (owner.isClass && !owner.isRefinementClass) owner.info else from.NoType
           var existing = scope.decl(name)
-          if (sym.isPackageClass || sym.isModuleClass) existing = existing.moduleClass
+          if (sym.isModuleClass)
+            existing = existing.moduleClass
+
           if (!existing.exists) scope = from.NoType
 
           val myname = importName(name)
           val myowner = importSymbol(owner)
           val myscope = if (scope != from.NoType && !(myowner hasFlag Flags.LOCKED)) myowner.info else NoType
           var myexisting = if (myscope != NoType) myowner.info.decl(myname) else NoSymbol // cannot load myexisting in general case, because it creates cycles for methods
-          if (sym.isPackageClass || sym.isModuleClass) myexisting = importSymbol(sym.sourceModule).moduleClass
+          if (sym.isModuleClass)
+            myexisting = importSymbol(sym.sourceModule).moduleClass
+
           if (!sym.isOverloaded && myexisting.isOverloaded) {
             myexisting =
               if (sym.isMethod) {
diff --git a/src/compiler/scala/reflect/internal/SymbolCreations.scala b/src/compiler/scala/reflect/internal/SymbolCreations.scala
new file mode 100644
index 0000000000..62fee9d7f3
--- /dev/null
+++ b/src/compiler/scala/reflect/internal/SymbolCreations.scala
@@ -0,0 +1,106 @@
+ /* NSC -- new Scala compiler
+ * Copyright 2005-2011 LAMP/EPFL
+ * @author  Paul Phillips
+ */
+
+package scala.reflect
+package internal
+
+import scala.collection.{ mutable, immutable }
+import scala.collection.mutable.ListBuffer
+import util.Statistics._
+import Flags._
+import api.Modifier
+import scala.tools.util.StringOps.{ ojoin }
+
+trait SymbolCreations {
+  self: SymbolTable =>
+
+  import definitions._
+
+  /** Symbol creation interface, possibly better moved somewhere else.
+   *  It'd be nice if we had virtual classes, but since we
+   *  don't: these methods insulate the direct instantiation of the symbols
+   *  (which may be overridden, e.g. in SynchronizedSymbols) from the
+   *  enforcement of preconditions and choice of symbol constructor based
+   *  on flags, which are (or should be) final so they can be reasoned about
+   *  without lots of surprises.
+   */
+  trait SymbolCreatorInterface {
+    // Fallbacks; more precise creators should normally be called.
+    protected def createTypeSymbol(name: TypeName, pos: Position, newFlags: Long): TypeSymbol
+    protected def createTermSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol
+
+    // I believe all but rogue TypeSymbols are one of: ClassSymbol, AbstractTypeSymbol, AliasTypeSymbol, or TypeSkolem.
+    protected def createAbstractTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AbstractTypeSymbol
+    protected def createAliasTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AliasTypeSymbol
+    protected def createTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position, newFlags: Long): TypeSkolem
+    protected def createClassSymbol(name: TypeName, pos: Position, newFlags: Long): ClassSymbol
+
+    // More specific ClassSymbols.
+    // TODO - AnonymousClassSymbol.
+    // TODO maybe - PackageObjects, but that one cost me a lot of time when I tried it before
+    // because it broke reification some way I couldn't see.
+    protected def createModuleClassSymbol(name: TypeName, pos: Position, newFlags: Long): ModuleClassSymbol
+    protected def createPackageClassSymbol(name: TypeName, pos: Position, newFlags: Long): PackageClassSymbol
+    protected def createRefinementClassSymbol(pos: Position, newFlags: Long): RefinementClassSymbol
+
+    // Distinguished term categories include methods, modules, packages, package objects,
+    // value parameters, and values (including vals, vars, and lazy vals.)
+    protected def createMethodSymbol(name: TermName, pos: Position, newFlags: Long): MethodSymbol
+    protected def createModuleSymbol(name: TermName, pos: Position, newFlags: Long): ModuleSymbol
+    protected def createPackageSymbol(name: TermName, pos: Position, newFlags: Long): PackageSymbol
+
+    // TODO
+    // protected def createValueParameterSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol
+    // protected def createValueMemberSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol
+  }
+
+  trait SymbolCreator extends SymbolCreatorInterface {
+    self: Symbol =>
+
+    /*** Predictable symbol creation.
+     *
+     *   newTermSymbol, newClassSymbol, and newNonClassSymbol all create symbols based
+     *   only on the flags (for reconstruction after reification.) It would be nice to
+     *   combine the last two into newTypeSymbol, but this requires some flag which allows us
+     *   to distinguish classes and type aliases, which as yet does not exist.
+     *
+     *   The fundamental flags used to determine which Symbol subclass to instantiate are:
+     *     METHOD, PACKAGE, MODULE, PARAM, DEFERRED.
+     */
+    final def newTermSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): TermSymbol = {
+      if ((newFlags & METHOD) != 0)
+        createMethodSymbol(name, pos, newFlags)
+      else if ((newFlags & PACKAGE) != 0)
+        createPackageSymbol(name, pos, newFlags | PackageFlags)
+      else if ((newFlags & MODULE) != 0)
+        createModuleSymbol(name, pos, newFlags)
+      else if ((newFlags & PARAM) != 0)
+        createValueParameterSymbol(name, pos, newFlags)
+      else
+        createValueMemberSymbol(name, pos, newFlags)
+    }
+
+    final def newClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ClassSymbol = {
+      if (name == tpnme.REFINE_CLASS_NAME)
+        createRefinementClassSymbol(pos, newFlags)
+      else if ((newFlags & PACKAGE) != 0)
+        createPackageClassSymbol(name, pos, newFlags | PackageFlags)
+      else if ((newFlags & MODULE) != 0)
+        createModuleClassSymbol(name, pos, newFlags)
+      else
+        createClassSymbol(name, pos, newFlags)
+    }
+
+    final def newNonClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): TypeSymbol = {
+      if ((newFlags & DEFERRED) != 0)
+        createAbstractTypeSymbol(name, pos, newFlags)
+      else
+        createAliasTypeSymbol(name, pos, newFlags)
+    }
+
+    def newTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): TypeSymbol =
+      newNonClassSymbol(name, pos, newFlags)
+  }
+}
diff --git a/src/compiler/scala/reflect/internal/SymbolFlags.scala b/src/compiler/scala/reflect/internal/SymbolFlags.scala
new file mode 100644
index 0000000000..0b49ee2505
--- /dev/null
+++ b/src/compiler/scala/reflect/internal/SymbolFlags.scala
@@ -0,0 +1,237 @@
+ /* NSC -- new Scala compiler
+ * Copyright 2005-2011 LAMP/EPFL
+ * @author  Paul Phillips
+ */
+
+package scala.reflect
+package internal
+
+import scala.collection.{ mutable, immutable }
+import scala.collection.mutable.ListBuffer
+import util.Statistics._
+import Flags._
+import api.Modifier
+import scala.tools.util.StringOps.{ ojoin }
+
+trait SymbolFlags {
+  self: SymbolTable =>
+
+  import definitions._
+
+  /** Not mixed in under normal conditions; a powerful debugging aid.
+   */
+  trait FlagVerifier extends SymbolFlagLogic {
+    this: Symbol =>
+
+    private def assert0(cond: Boolean, message: => Any) {
+      if (!cond) {
+        Console.err.println("[flag verification failure]\n%s\n%s\n".format(atPhaseStackMessage, message))
+        (new Throwable).getStackTrace.take(13).drop(3).foreach(println)
+        println("")
+      }
+    }
+
+    protected def verifyChange(isAdd: Boolean, mask: Long, before: Long) {
+      val after   = if (isAdd) before | mask else before & ~mask
+      val added   = after & ~before
+      val removed = before & ~after
+      val ignored = mask & ~added & ~removed
+      val error = (
+           (added & OverloadedFlagsMask) != 0 || (removed & OverloadedFlagsMask) != 0
+        // || (ignored != 0)
+      )
+      val addString    = if (added == 0) "" else "+(" + flagsToString(added) + ")"
+      val removeString = if (removed == 0) "" else "-(" + flagsToString(removed) + ")"
+      val changeString = if (added == 0 && removed == 0) "no change" else addString + " " + removeString
+
+      if (error) {
+        val templ = (
+          """|  symbol: %s %s in %s
+             |    call: %s(%s)
+             |   flags: %s
+             |  result: %s""".stripMargin
+        )
+
+        assert0(false, templ.format(
+          shortSymbolClass,
+          name.decode,
+          owner,
+          if (isAdd) "+" else "-",
+          flagsToString(mask),
+          flagsToString(before),
+          changeString
+        ))
+      }
+    }
+
+    protected def verifyFlags(what: String) {
+      assert0(this hasAllFlags alwaysHasFlags, symbolCreationString + "\n  always=%s, what=%s\n".format(flagsToString(alwaysHasFlags), what))
+      if (this hasFlag neverHasFlags) {
+        val hasRaw = (rawflags & neverHasFlags) != 0
+        assert0(!hasRaw, symbolCreationString + "\n   never=%s, what=%s".format(flagsToString(neverHasFlags), what))
+      }
+    }
+    override def initFlags(mask: Long): this.type = {
+      super.initFlags(mask)
+      verifyFlags("initFlags(" + flagsToString(mask) + ")")
+      this
+    }
+    override def setFlag(mask: Long): this.type = {
+      verifyChange(true, mask, rawflags)
+      super.setFlag(mask)
+      verifyFlags("setFlag(" + flagsToString(mask) + ")")
+      this
+    }
+    override def resetFlag(mask: Long): this.type = {
+      verifyChange(false, mask, rawflags)
+      super.resetFlag(mask)
+      verifyFlags("resetFlag(" + flagsToString(mask) + ")")
+      this
+    }
+    override def flags_=(fs: Long) {
+      if ((fs & ~rawflags) != 0)
+        verifyChange(true, fs & ~rawflags, rawflags)
+      if ((rawflags & ~fs) != 0)
+        verifyChange(false, rawflags & ~fs, rawflags)
+
+      super.flags_=(fs)
+      verifyFlags("flags_=(" + flagsToString(fs) + ")")
+    }
+  }
+
+  /** A distinguishing flag is one which the mixing class must always
+   *  have, and which no other symbol class is allowed to have.
+   */
+  trait DistinguishingFlag extends SymbolFlagLogic {
+    this: Symbol =>
+
+    def distinguishingFlag: Long
+    override protected def alwaysHasFlags = super.alwaysHasFlags | distinguishingFlag
+    override protected def neverHasFlags  = super.neverHasFlags & ~distinguishingFlag
+  }
+
+  trait SymbolFlagLogic {
+    this: Symbol =>
+
+    protected def alwaysHasFlags: Long = 0L
+    protected def neverHasFlags: Long = METHOD | MODULE
+
+    def flagStringFn(flag: Long): String = {
+      val res = flag match {
+        // "<bynameparam/captured/covariant>"
+        case BYNAMEPARAM =>
+          if (this.isValueParameter) "<bynameparam>"
+          else if (this.isTypeParameter) "<covariant>"
+          else "<captured>"
+        // "<contravariant/inconstructor/label>"
+        case CONTRAVARIANT =>
+          if (this.isLabel) "<label>"
+          else if (this.isTypeParameter) "<contravariant>"
+          else "<inconstructor>"
+        // "<defaultparam/trait>"
+        case DEFAULTPARAM =>
+          if (this.isTerm && (this hasFlag PARAM)) "<defaultparam>"
+          else "<trait>"
+        // "<existential/mixedin>"
+        case EXISTENTIAL =>
+          if (this.isType) "<existential>"
+          else "<mixedin>"
+        // "<implclass/presuper>"
+        case IMPLCLASS  =>
+          if (this.isClass) "<implclass>"
+          else "<presuper>"
+        case _ => ""
+      }
+      if (res == "") Flags.flagToString(flag)
+      else res + ":overloaded-flag"
+    }
+
+    private def calculateFlagString(basis: Long): String = {
+      val nonAccess = nonAccessString(basis)(flagStringFn)
+      val access    = Flags.accessString(basis, pwString)
+
+      ojoin(nonAccess, access)
+    }
+
+    def flagString(mask: Long): String    = calculateFlagString(flags & mask)
+    def flagString: String                = flagString(defaultFlagMask)
+    def rawFlagString(mask: Long): String = calculateFlagString(rawflags & mask)
+    def rawFlagString: String             = rawFlagString(defaultFlagMask)
+    def flaggedString(mask: Long): String = flagString(mask)
+    def flaggedString: String             = flaggedString(defaultFlagMask)
+
+    def accessString      = calculateFlagString(flags & AccessFlags)
+    def debugFlagString   = flaggedString(AllFlags)
+    def defaultFlagString = flaggedString(defaultFlagMask)
+
+    def hasFlagsToString(mask: Long) = flagString(mask)
+
+    /** String representation of symbol's variance */
+    def varianceString: String =
+      if (variance == 1) "+"
+      else if (variance == -1) "-"
+      else ""
+
+    def defaultFlagMask =
+      if (settings.debug.value && !isAbstractType) AllFlags
+      else if (owner.isRefinementClass) ExplicitFlags & ~OVERRIDE
+      else ExplicitFlags
+
+    // make the error message more googlable
+    def flagsExplanationString =
+      if (isGADTSkolem) " (this is a GADT skolem)"
+      else ""
+
+    private def pwString = if (hasAccessBoundary) privateWithin.toString else ""
+    private var _rawflags: FlagsType = 0L
+    protected def rawflags_=(x: FlagsType) { _rawflags = x }
+    def rawflags = _rawflags
+
+    final def flags: Long = {
+      val fs = rawflags & phase.flagMask
+      (fs | ((fs & LateFlags) >>> LateShift)) & ~(fs >>> AntiShift)
+    }
+    def flags_=(fs: Long) = rawflags = fs
+
+    /** Set the symbol's flags to the given value, asserting
+     *  that the previous value was 0.
+     */
+    def initFlags(mask: Long): this.type = {
+      assert(rawflags == 0L, symbolCreationString)
+      rawflags = mask
+      this
+    }
+    def reinitFlags(mask: Long): this.type = {
+      rawflags = mask
+      this
+    }
+    def setFlag(mask: Long): this.type   = { rawflags |= mask ; this }
+    def resetFlag(mask: Long): this.type = { rawflags &= ~mask ; this }
+    def resetFlags() { rawflags &= (TopLevelCreationFlags | alwaysHasFlags) }
+
+    def getFlag(mask: Long): Long
+    def hasFlag(mask: Long): Boolean
+    def hasAllFlags(mask: Long): Boolean
+
+    /** If the given flag is set on this symbol, also set the corresponding
+     *  notFLAG.  For instance if flag is PRIVATE, the notPRIVATE flag will
+     *  be set if PRIVATE is currently set.
+     */
+    final def setNotFlag(flag: Int) = if (hasFlag(flag)) setFlag((flag: @annotation.switch) match {
+      case PRIVATE   => notPRIVATE
+      case PROTECTED => notPROTECTED
+      case OVERRIDE  => notOVERRIDE
+      case _         => abort("setNotFlag on invalid flag: " + flag)
+    })
+
+    protected def shortSymbolClass = getClass.getName.split('.').last.stripPrefix("Symbols$")
+    def symbolCreationString: String = (
+      "%s%25s | %-40s | %s".format(
+        if (settings.uniqid.value) "%06d | ".format(id) else "",
+        shortSymbolClass,
+        name.decode + " in " + owner,
+        rawFlagString
+      )
+    )
+  }
+}
diff --git a/src/compiler/scala/reflect/internal/SymbolTable.scala b/src/compiler/scala/reflect/internal/SymbolTable.scala
index 256c1a6ced..daaf0dff26 100644
--- a/src/compiler/scala/reflect/internal/SymbolTable.scala
+++ b/src/compiler/scala/reflect/internal/SymbolTable.scala
@@ -13,7 +13,9 @@ import scala.tools.nsc.util.WeakHashSet
 abstract class SymbolTable extends api.Universe
                               with Collections
                               with Names
+                              with SymbolCreations
                               with Symbols
+                              with SymbolFlags
                               with Types
                               with Kinds
                               with ExistentialsAndSkolems
@@ -62,6 +64,8 @@ abstract class SymbolTable extends api.Universe
     result
   }
 
+  /** Dump each symbol to stdout after shutdown.
+   */
   final val traceSymbolActivity = sys.props contains "scalac.debug.syms"
   object traceSymbols extends {
     val global: SymbolTable.this.type = SymbolTable.this
@@ -98,6 +102,11 @@ abstract class SymbolTable extends api.Universe
   final def atPhaseStack: List[Phase] = phStack
   final def phase: Phase = ph
 
+  def atPhaseStackMessage = atPhaseStack match {
+    case Nil    => ""
+    case ps     => ps.reverseMap("->" + _).mkString("(", " ", ")")
+  }
+
   final def phase_=(p: Phase) {
     //System.out.println("setting phase to " + p)
     assert((p ne null) && p != NoPhase, p)
diff --git a/src/compiler/scala/reflect/internal/Symbols.scala b/src/compiler/scala/reflect/internal/Symbols.scala
index 5c43047046..cfab069588 100644
--- a/src/compiler/scala/reflect/internal/Symbols.scala
+++ b/src/compiler/scala/reflect/internal/Symbols.scala
@@ -55,11 +55,14 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
    */
   val originalOwner = perRunCaches.newMap[Symbol, Symbol]()
 
-  abstract class AbsSymbolImpl extends AbsSymbol { this: Symbol =>
-    def newNestedSymbol(name: Name, pos: Position, newFlags: Long) = name match {
+  abstract class AbsSymbolImpl extends AbsSymbol {
+    this: Symbol =>
+
+    def newNestedSymbol(name: Name, pos: Position, newFlags: Long, isClass: Boolean): Symbol = name match {
       case n: TermName => newTermSymbol(n, pos, newFlags)
-      case n: TypeName => newTypeSymbol(n, pos, newFlags)
+      case n: TypeName => if (isClass) newClassSymbol(n, pos, newFlags) else newNonClassSymbol(n, pos, newFlags)
     }
+
     def enclosingClass: Symbol            = enclClass
     def enclosingMethod: Symbol           = enclMethod
     def thisPrefix: Type                  = thisType
@@ -79,6 +82,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
   abstract class Symbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: Name)
           extends AbsSymbolImpl
              with HasFlags
+             with SymbolFlagLogic
+             with SymbolCreator
+             // with FlagVerifier
              with Annotatable[Symbol] {
 
     type FlagsType          = Long
@@ -87,13 +93,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     private[this] var _rawowner = initOwner // Syncnote: need not be protected, as only assignment happens in owner_=, which is not exposed to api
     private[this] var _rawname  = initName
-    private[this] var _rawflags = 0L
 
     def rawowner = _rawowner
     def rawname = _rawname
-    def rawflags = _rawflags
-
-    protected def rawflags_=(x: FlagsType) { _rawflags = x }
 
     private var rawpos = initPos
 
@@ -135,7 +137,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def newLocalDummy(pos: Position) =
       newTermSymbol(nme.localDummyName(this), pos) setInfo NoType
     final def newMethod(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): MethodSymbol =
-      newMethodSymbol(name, pos, METHOD | newFlags)
+      createMethodSymbol(name, pos, METHOD | newFlags)
     final def newLabel(name: TermName, pos: Position = NoPosition): MethodSymbol =
       newMethod(name, pos, LABEL)
 
@@ -146,73 +148,39 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** Static constructor with info set. */
     def newStaticConstructor(pos: Position) =
       newConstructor(pos, STATIC) setInfo UnitClass.tpe
+
     /** Instance constructor with info set. */
     def newClassConstructor(pos: Position) =
       newConstructor(pos) setInfo MethodType(Nil, this.tpe)
 
-    // Top-level objects can be automatically marked final, but others
-    // must be explicitly marked final if overridable objects are enabled.
-    private def ModuleFlags = (
-      if (isPackage || !settings.overrideObjects.value) MODULE | FINAL
-      else MODULE
-    )
     def newLinkedModule(clazz: Symbol, newFlags: Long = 0L): ModuleSymbol = {
-      val m = newModuleSymbol(clazz.name.toTermName, clazz.pos, ModuleFlags | newFlags)
+      val m = newModuleSymbol(clazz.name.toTermName, clazz.pos, MODULE | newFlags)
       connectModuleToClass(m, clazz.asInstanceOf[ClassSymbol])
     }
     final def newModule(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleSymbol = {
-      val m     = newModuleSymbol(name, pos, newFlags | ModuleFlags)
-      val clazz = newModuleClassSymbol(name.toTypeName, pos, (m getFlag ModuleToClassFlags) | MODULE)
+      val m     = newModuleSymbol(name, pos, newFlags | MODULE)
+      val clazz = newModuleClass(name.toTypeName, pos, m getFlag ModuleToClassFlags)
       connectModuleToClass(m, clazz)
     }
 
     final def newPackage(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleSymbol = {
       assert(name == nme.ROOT || isPackageClass, this)
-      newModule(name, pos, JAVA | PACKAGE | newFlags)
+      newModule(name, pos, PackageFlags | newFlags)
     }
+
     final def newThisSym(pos: Position) =
       newTermSymbol(nme.this_, pos, SYNTHETIC)
     final def newImport(pos: Position) =
       newTermSymbol(nme.IMPORT, pos)
 
-    /** Direct symbol factories.
-     *  For internal use; these are unlikely to be what you want.
-     */
-    def newTermSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): TermSymbol =
-      new TermSymbol(this, pos, name) initFlags newFlags
+    final def newModuleSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleSymbol =
+      newTermSymbol(name, pos, newFlags).asInstanceOf[ModuleSymbol]
 
-    def newAbstractTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): AbstractTypeSymbol =
-      new AbstractTypeSymbol(this, pos, name) initFlags newFlags
+    final def newModuleClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleClassSymbol =
+      newClassSymbol(name, pos, newFlags).asInstanceOf[ModuleClassSymbol]
 
-    def newAliasTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): AliasTypeSymbol =
-      new AliasTypeSymbol(this, pos, name) initFlags newFlags
-
-    def newModuleSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleSymbol =
-      new ModuleSymbol(this, pos, name) initFlags newFlags
-
-    def newMethodSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): MethodSymbol =
-      new MethodSymbol(this, pos, name) initFlags newFlags
-
-    def newClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ClassSymbol =
-      new ClassSymbol(this, pos, name) initFlags newFlags
-
-    def newModuleClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleClassSymbol =
-      new ModuleClassSymbol(this, pos, name) initFlags newFlags
-
-    /** Derive whether it is an abstract type from the flags; after creation
-     *  the DEFERRED flag will be ignored.
-     */
-    def newTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): TypeSymbol =
-      if ((newFlags & DEFERRED) == 0L)
-        newAliasTypeSymbol(name, pos, newFlags)
-      else
-        newAbstractTypeSymbol(name, pos, newFlags)
-
-    def newTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position = NoPosition, newFlags: Long = 0L): TypeSkolem =
-      if ((newFlags & DEFERRED) == 0L)
-        new TypeSkolem(this, pos, name, origin) initFlags newFlags
-      else
-        new TypeSkolem(this, pos, name, origin) with AbstractTypeMixin initFlags newFlags
+    final def newTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position = NoPosition, newFlags: Long = 0L): TypeSkolem =
+      createTypeSkolemSymbol(name, origin, pos, newFlags)
 
     /** @param pre   type relative to which alternatives are seen.
      *  for instance:
@@ -243,18 +211,23 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** Symbol of a type definition  type T = ...
      */
     final def newAliasType(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): Symbol =
-      newAliasTypeSymbol(name, pos, newFlags)
+      createAliasTypeSymbol(name, pos, newFlags)
 
     /** Symbol of an abstract type  type T >: ... <: ...
      */
     final def newAbstractType(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): Symbol =
-      newAbstractTypeSymbol(name, pos, DEFERRED | newFlags)
+      createAbstractTypeSymbol(name, pos, DEFERRED | newFlags)
 
     /** Symbol of a type parameter
      */
     final def newTypeParameter(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L) =
       newAbstractType(name, pos, PARAM | newFlags)
 
+    /** Symbol of an existential type T forSome { ... }
+     */
+    final def newExistential(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): Symbol =
+      newAbstractType(name, pos, EXISTENTIAL | newFlags)
+
     /** Synthetic value parameters when parameter symbols are not available
      */
     final def newSyntheticValueParamss(argtypess: List[List[Type]]): List[List[Symbol]] = {
@@ -280,10 +253,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def newGADTSkolem(name: TypeName, origin: Symbol, info: Type): TypeSkolem =
       newTypeSkolemSymbol(name, origin, origin.pos, origin.flags & ~(EXISTENTIAL | PARAM) | CASEACCESSOR | SYNTHETIC) setInfo info
 
-
-    final def newExistential(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): Symbol =
-      newAbstractType(name, pos, EXISTENTIAL | newFlags)
-
     final def freshExistential(suffix: String): Symbol =
       newExistential(freshExistentialName(suffix), pos)
 
@@ -318,8 +287,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def newErrorClass(name: TypeName) =
       newClassWithInfo(name, Nil, new ErrorScope(this), pos, SYNTHETIC | IS_ERROR)
 
-    final def newModuleClass(name: TypeName, pos: Position = NoPosition) =
-      newModuleClassSymbol(name, pos)
+    final def newModuleClass(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L) =
+      newModuleClassSymbol(name, pos, newFlags | MODULE)
 
     final def newAnonymousClass(pos: Position) =
       newClassSymbol(tpnme.ANON_CLASS_NAME, pos)
@@ -333,8 +302,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** Refinement types P { val x: String; type T <: Number }
      *  also have symbols, they are refinementClasses
      */
-    final def newRefinementClass(pos: Position) =
-      newClass(tpnme.REFINE_CLASS_NAME, pos)
+    final def newRefinementClass(pos: Position) = createRefinementClassSymbol(pos, 0L)
 
     /** Create a new getter for current symbol (which must be a field)
      */
@@ -410,7 +378,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       if ((rawflags & LOCKED) != 0L) {
 //        activeLocks -= 1
 //        lockedSyms -= this
-        _rawflags = rawflags & ~LOCKED
+        rawflags &= ~LOCKED
         if (settings.Yrecursion.value != 0)
           recursionTable -= this
       }
@@ -418,42 +386,84 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
 // ----- tests ----------------------------------------------------------------------
 
-    def isTerm         = false  // to be overridden
-    def isType         = false  // to be overridden
-    def isClass        = false  // to be overridden
-    def isBottomClass  = false  // to be overridden
-    def isAliasType    = false  // to be overridden
-    def isAbstractType = false  // to be overridden
-    private[scala] def isSkolem = false // to be overridden
-
-    /** Is this symbol a type but not a class? */
-    def isNonClassType = false // to be overridden
-
-    override final def isTrait     = isClass && hasFlag(TRAIT)
-    final def isAbstractClass      = isClass && hasFlag(ABSTRACT)
-    final def isBridge             = hasFlag(BRIDGE)
-    final def isContravariant      = isType && hasFlag(CONTRAVARIANT)
-    final def isConcreteClass      = isClass && !hasFlag(ABSTRACT | TRAIT)
-    final def isCovariant          = isType && hasFlag(COVARIANT)
-    final def isEarlyInitialized   = isTerm && hasFlag(PRESUPER)
-    final def isExistentiallyBound = isType && hasFlag(EXISTENTIAL)
-    final def isImplClass          = isClass && hasFlag(IMPLCLASS)
-    final def isLazyAccessor       = isLazy && lazyAccessor != NoSymbol
-    final def isMethod             = isTerm && hasFlag(METHOD)
-    final def isModule             = isTerm && hasFlag(MODULE)
-    final def isModuleClass        = isClass && hasFlag(MODULE)
-    final def isNumericValueClass  = definitions.isNumericValueClass(this)
-    final def isOverloaded         = hasFlag(OVERLOADED)
-    final def isOverridableMember  = !(isClass || isEffectivelyFinal) && owner.isClass
-    final def isRefinementClass    = isClass && name == tpnme.REFINE_CLASS_NAME
-    final def isSourceMethod       = isMethod && !hasFlag(STABLE) // exclude all accessors!!!
-    final def isTypeParameter      = isType && isParameter && !isSkolem
-    final def isPrimitiveValueClass = definitions.isPrimitiveValueClass(this)
-    final def isVarargsMethod      = isMethod && hasFlag(VARARGS)
-
-    /** Package tests */
-    final def isPackage           = isModule && hasFlag(PACKAGE)
-    final def isPackageClass      = isClass && hasFlag(PACKAGE)
+    /** All symbols are one of three categories: TermSymbol, TypeSymbol, or NoSymbol.
+     *  There is only one NoSymbol.
+     */
+    def isTerm = false
+    def isType = false
+
+    /** TypeSymbols fall into four named direct subclasses:
+     *   - ClassSymbol
+     *   - AliasTypeSymbol
+     *   - AbstractTypeSymbol
+     *   - TypeSkolem
+     */
+    def isClass        = false
+    def isAliasType    = false
+    def isAbstractType = false
+    def isSkolem       = false
+
+    /** A Type, but not a Class. */
+    def isNonClassType = false
+
+    /** The bottom classes are Nothing and Null, found in Definitions. */
+    def isBottomClass  = false
+
+    /** These are all tests for varieties of ClassSymbol, which has these subclasses:
+     *  - ModuleClassSymbol
+     *  - RefinementClassSymbol
+     *  - PackageClassSymbol (extends ModuleClassSymbol)
+     */
+    def isAbstractClass         = false
+    def isAnonOrRefinementClass = false
+    def isAnonymousClass        = false
+    def isConcreteClass         = false
+    def isImplClass             = false   // the implementation class of a trait
+    def isModuleClass           = false
+    def isNumericValueClass     = false
+    def isPrimitiveValueClass   = false
+    def isRefinementClass       = false
+    override def isTrait = false
+
+    /** Qualities of Types, always false for TermSymbols.
+     */
+    def isContravariant         = false
+    def isCovariant             = false
+    def isExistentialSkolem     = false
+    def isExistentiallyBound    = false
+    def isExistentialQuantified = false
+    def isGADTSkolem            = false
+    def isTypeParameter         = false
+    def isTypeParameterOrSkolem = false
+    def isTypeSkolem            = false
+
+    /** Qualities of Terms, always false for TypeSymbols.
+     */
+    override def hasDefault  = false
+    def isBridge             = false
+    def isEarlyInitialized   = false
+    def isModule             = false
+    def isOverloaded         = false
+    def isValueParameter     = false
+
+    /** Qualities of MethodSymbols, always false for TypeSymbols
+     *  and other TermSymbols.
+     */
+    def isCaseAccessorMethod = false
+    def isLiftedMethod       = false
+    def isMacro              = false
+    def isMethod             = false
+    def isSourceMethod       = false
+    def isVarargsMethod      = false
+
+    /** Package/package object tests */
+    def isPackage              = false
+    def isPackageClass         = false
+    def isPackageObject        = false
+    def isPackageObjectClass   = false
+
+    def isPackageObjectOrClass = isPackageObject || isPackageObjectClass
+    def isModuleOrModuleClass  = isModule || isModuleClass
 
     /** Overridden in custom objects in Definitions */
     def isRoot              = false
@@ -466,22 +476,30 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      */
     def isEffectiveRoot = false
 
-    /** For RootClass, EmptyPackageClass.  For all other symbols, itself.
+    /** For RootClass, this is EmptyPackageClass.  For all other symbols,
+     *  the symbol itself.
      */
     def ownerOfNewSymbols = this
 
+    final def isLazyAccessor       = isLazy && lazyAccessor != NoSymbol
+    final def isOverridableMember  = !(isClass || isEffectivelyFinal) && owner.isClass
+
     /** Does this symbol denote a wrapper created by the repl? */
     final def isInterpreterWrapper = (
-      (isModule || isModuleClass)
+         (this hasFlag MODULE)
       && owner.isPackageClass
       && nme.isReplWrapperName(name)
     )
+    @inline final override def getFlag(mask: Long): Long = flags & mask
+    /** Does symbol have ANY flag in `mask` set? */
+    @inline final override def hasFlag(mask: Long): Boolean = (flags & mask) != 0
+    /** Does symbol have ALL the flags in `mask` set? */
+    @inline final override def hasAllFlags(mask: Long): Boolean = (flags & mask) == mask
 
     /** Term symbols with the exception of static parts of Java classes and packages.
      */
-    final def isValue = isTerm && !(isModule && hasFlag(PACKAGE | JAVA))
-
-    final def isVariable  = isTerm && isMutable && !isMethod
+    final def isValue    = isTerm && !(isModule && hasFlag(PACKAGE | JAVA))
+    final def isVariable = isTerm && isMutable && !isMethod
 
     // interesting only for lambda lift. Captured variables are accessed from inner lambdas.
     final def isCapturedVariable  = isVariable && hasFlag(CAPTURED)
@@ -493,9 +511,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     final def hasGetter = isTerm && nme.isLocalName(name)
 
-    final def isValueParameter = isTerm && hasFlag(PARAM)
-    final def isLocalDummy = isTerm && nme.isLocalDummyName(name)
     final def isInitializedToDefault = !isType && hasAllFlags(DEFAULTINIT | ACCESSOR)
+    final def isLocalDummy = isTerm && nme.isLocalDummyName(name)
     final def isClassConstructor = isTerm && (name == nme.CONSTRUCTOR)
     final def isMixinConstructor = isTerm && (name == nme.MIXIN_CONSTRUCTOR)
     final def isConstructor = isTerm && nme.isConstructorName(name)
@@ -503,17 +520,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def isThisSym = isTerm && owner.thisSym == this
     final def isError = hasFlag(IS_ERROR)
     final def isErroneous = isError || isInitialized && tpe.isErroneous
-    final def isTypeParameterOrSkolem = isType && hasFlag(PARAM)
-    final def isHigherOrderTypeParameter = (this ne NoSymbol) && owner.isTypeParameterOrSkolem
-    final def isTypeSkolem            = isSkolem && hasFlag(PARAM)
-    // a type symbol bound by an existential type, for instance the T in
-    // List[T] forSome { type T }
-    final def isExistentialSkolem     = isExistentiallyBound && isSkolem
-    final def isExistentialQuantified = isExistentiallyBound && !isSkolem
-    final def isGADTSkolem            = isSkolem && hasFlag(CASEACCESSOR | SYNTHETIC)
+
+    def isHigherOrderTypeParameter = owner.isTypeParameterOrSkolem
 
     // class C extends D( { class E { ... } ... } ). Here, E is a class local to a constructor
-    final def isClassLocalToConstructor = isClass && hasFlag(INCONSTRUCTOR)
+    def isClassLocalToConstructor = false
 
     final def isDerivedValueClass =
       isClass && info.firstParent.typeSymbol == AnyValClass && !isPrimitiveValueClass
@@ -521,29 +532,27 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def isMethodWithExtension =
       isMethod && owner.isDerivedValueClass && !isParamAccessor && !isConstructor && !hasFlag(SUPERACCESSOR)
 
-    final def isAnonymousClass             = isClass && (name containsName tpnme.ANON_CLASS_NAME)
-    final def isAnonymousFunction          = isSynthetic && (name containsName tpnme.ANON_FUN_NAME)
-    final def isAnonOrRefinementClass      = isAnonymousClass || isRefinementClass
-
-    // A package object or its module class
-    final def isPackageObjectOrClass = (this ne NoSymbol) && owner.isPackageClass && (name == nme.PACKAGE || name == tpnme.PACKAGE)
-    final def isPackageObject        = (this ne NoSymbol) && owner.isPackageClass && name == nme.PACKAGE
-    final def isPackageObjectClass   = (this ne NoSymbol) && owner.isPackageClass && name == tpnme.PACKAGE
-
+    final def isAnonymousFunction = isSynthetic && (name containsName tpnme.ANON_FUN_NAME)
     final def isDefinedInPackage  = effectiveOwner.isPackageClass
-    final def isJavaInterface = isJavaDefined && isTrait
-    final def needsFlatClasses = phase.flatClasses && rawowner != NoSymbol && !rawowner.isPackageClass
+    final def isJavaInterface     = isJavaDefined && isTrait
+    final def needsFlatClasses    = phase.flatClasses && rawowner != NoSymbol && !rawowner.isPackageClass
+
+    /** change name by appending $$<fully-qualified-name-of-class `base`>
+     *  Do the same for any accessed symbols or setters/getters.
+     *  Implementation in TermSymbol.
+     */
+    def expandName(base: Symbol) { }
 
     // In java.lang, Predef, or scala package/package object
     def isInDefaultNamespace = UnqualifiedOwners(effectiveOwner)
 
     /** The owner, skipping package objects.
      */
-    def effectiveOwner = if (owner.isPackageObjectClass) owner.skipPackageObject else owner
+    def effectiveOwner = owner.skipPackageObject
 
     /** If this is a package object or its implementing class, its owner: otherwise this.
      */
-    final def skipPackageObject: Symbol = if (isPackageObjectOrClass) owner else this
+    def skipPackageObject: Symbol = if (this.isPackageObjectOrClass) owner else this
 
     /** If this is a constructor, its owner: otherwise this.
      */
@@ -622,15 +631,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     // def isVirtualClass = hasFlag(DEFERRED) && isClass
     // def isVirtualTrait = hasFlag(DEFERRED) && isTrait
-    def isLiftedMethod = isMethod && hasFlag(LIFTED)
+    // def isLiftedMethod = hasAllFlags(METHOD | LIFTED)
     def isCaseClass    = isClass && isCase
 
-    // unfortunately having the CASEACCESSOR flag does not actually mean you
-    // are a case accessor (you can also be a field.)
-    def isCaseAccessorMethod = isMethod && isCaseAccessor
-
-    def isMacro = isMethod && hasFlag(MACRO)
-
     /** Does this symbol denote the primary constructor of its enclosing class? */
     final def isPrimaryConstructor =
       isConstructor && owner.primaryConstructor == this
@@ -675,10 +678,12 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def isStaticOwner: Boolean =
       isPackageClass || isModuleClass && isStatic
 
+    def isTopLevelModule = hasFlag(MODULE) && owner.isPackageClass
+
     /** Is this symbol effectively final? I.e, it cannot be overridden */
     final def isEffectivelyFinal: Boolean = (
-         isFinal
-      || hasModuleFlag && !settings.overrideObjects.value
+         (this hasFlag FINAL | PACKAGE)
+      || isModuleOrModuleClass && (owner.isPackageClass || !settings.overrideObjects.value)
       || isTerm && (
              isPrivate
           || isLocal
@@ -693,7 +698,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     final def isConstant: Boolean = isStable && isConstantType(tpe.resultType)
 
     /** Is this class nested in another class or module (not a package)? */
-    def isNestedClass = isClass && !owner.isPackageClass
+    def isNestedClass = false
 
     /** Is this class locally defined?
      *  A class is local, if
@@ -701,9 +706,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *   - its owner is a value
      *   - it is defined within a local class
      */
-    final def isLocalClass: Boolean =
-      isClass && (isAnonOrRefinementClass || isLocal ||
-                  !owner.isPackageClass && owner.isLocalClass)
+    def isLocalClass = false
+
+    def isStableClass = false
 
 /* code for fixing nested objects
     override final def isModuleClass: Boolean =
@@ -738,26 +743,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     // Does not always work if the rawInfo is a SourcefileLoader, see comment
     // in "def coreClassesFirst" in Global.
-    final def exists: Boolean =
-      this != NoSymbol && (!owner.isPackageClass || { rawInfo.load(this); rawInfo != NoType })
+    def exists = !owner.isPackageClass || { rawInfo.load(this); rawInfo != NoType }
 
     final def isInitialized: Boolean =
       validTo != NoPeriod
 
-    final def isStableClass: Boolean = {
-      def hasNoAbstractTypeMember(clazz: Symbol): Boolean =
-        (clazz hasFlag STABLE) || {
-          var e = clazz.info.decls.elems
-          while ((e ne null) && !(e.sym.isAbstractType && info.member(e.sym.name) == e.sym))
-            e = e.next
-          e == null
-        }
-      def checkStable() =
-        (info.baseClasses forall hasNoAbstractTypeMember) && { setFlag(STABLE); true }
-      isClass && (hasFlag(STABLE) || checkStable())
-    }
-
-
     /** The variance of this symbol as an integer */
     final def variance: Int =
       if (isCovariant) 1
@@ -788,6 +778,10 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 // ------ owner attribute --------------------------------------------------------------
 
     def owner: Symbol = rawowner
+    // TODO - don't allow the owner to be changed without checking invariants, at least
+    // when under some flag. Define per-phase invariants for owner/owned relationships,
+    // e.g. after flatten all classes are owned by package classes, there are lots and
+    // lots of these to be declared (or more realistically, discovered.)
     def owner_=(owner: Symbol) {
       // don't keep the original owner in presentation compiler runs
       // (the map will grow indefinitely, and the only use case is the
@@ -805,11 +799,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def ownerChain: List[Symbol] = this :: owner.ownerChain
     def originalOwnerChain: List[Symbol] = this :: originalOwner.getOrElse(this, rawowner).originalOwnerChain
 
-    def enclClassChain: List[Symbol] = {
-      if ((this eq NoSymbol) || isPackageClass) Nil
-      else if (isClass) this :: owner.enclClassChain
-      else owner.enclClassChain
-    }
+    // Non-classes skip self and return rest of owner chain; overridden in ClassSymbol.
+    def enclClassChain: List[Symbol] = owner.enclClassChain
 
     def ownersIterator: Iterator[Symbol] = new Iterator[Symbol] {
       private var current = Symbol.this
@@ -817,21 +808,21 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       def next = { val r = current; current = current.owner; r }
     }
 
-    /** same as ownerChain contains sym, but more efficient, and
-     *  with a twist for refinement classes. A refinement class
-     *  has a transowner X if an of its parents has transowner X.
+    /** Same as `ownerChain contains sym` but more efficient, and
+     *  with a twist for refinement classes (see RefinementClassSymbol.)
      */
     def hasTransOwner(sym: Symbol): Boolean = {
       var o = this
       while ((o ne sym) && (o ne NoSymbol)) o = o.owner
-      (o eq sym) ||
-      isRefinementClass && (info.parents exists (_.typeSymbol.hasTransOwner(sym)))
+      (o eq sym)
     }
 
 // ------ name attribute --------------------------------------------------------------
 
     def name: Name = rawname
 
+    // TODO - don't allow names to be renamed in this unstructured a fashion.
+    // Rename as little as possible.  Enforce invariants on all renames.
     def name_=(name: Name) {
       if (name != rawname) {
         if (owner.isClass) {
@@ -903,43 +894,50 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      */
     final def fullName: String = fullName('.')
 
-// ------ flags attribute --------------------------------------------------------------
+    /**
+     *  Symbol creation implementations.
+     */
+    protected def createTypeSymbol(name: TypeName, pos: Position, newFlags: Long): TypeSymbol =
+      new TypeSymbol(this, pos, name) { } initFlags newFlags
 
-    final def flags: Long = {
-      val fs = rawflags & phase.flagMask
-      (fs | ((fs & LateFlags) >>> LateShift)) & ~(fs >>> AntiShift)
-    }
-    def flags_=(fs: Long) = _rawflags = fs
+    protected def createAbstractTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AbstractTypeSymbol =
+      new AbstractTypeSymbol(this, pos, name) initFlags newFlags
 
-    /** Set the symbol's flags to the given value, asserting
-     *  that the previous value was 0.
-     */
-    def initFlags(mask: Long): this.type = {
-      assert(rawflags == 0L, this)
-      _rawflags = mask
-      this
-    }
-    def setFlag(mask: Long): this.type = { _rawflags = rawflags | mask ; this }
-    def resetFlag(mask: Long): this.type = { _rawflags = rawflags & ~mask ; this }
-    final def getFlag(mask: Long): Long = flags & mask
-    final def resetFlags() { _rawflags = rawflags & TopLevelCreationFlags }
+    protected def createAliasTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AliasTypeSymbol =
+      new AliasTypeSymbol(this, pos, name) initFlags newFlags
 
-    /** Does symbol have ANY flag in `mask` set? */
-    final def hasFlag(mask: Long): Boolean = (flags & mask) != 0L
+    protected def createTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position, newFlags: Long): TypeSkolem =
+      new TypeSkolem(this, pos, name, origin) initFlags newFlags
 
-    /** Does symbol have ALL the flags in `mask` set? */
-    final def hasAllFlags(mask: Long): Boolean = (flags & mask) == mask
+    protected def createClassSymbol(name: TypeName, pos: Position, newFlags: Long): ClassSymbol =
+      new ClassSymbol(this, pos, name) initFlags newFlags
 
-    /** If the given flag is set on this symbol, also set the corresponding
-     *  notFLAG.  For instance if flag is PRIVATE, the notPRIVATE flag will
-     *  be set if PRIVATE is currently set.
-     */
-    final def setNotFlag(flag: Int) = if (hasFlag(flag)) setFlag((flag: @annotation.switch) match {
-      case PRIVATE   => notPRIVATE
-      case PROTECTED => notPROTECTED
-      case OVERRIDE  => notOVERRIDE
-      case _         => abort("setNotFlag on invalid flag: " + flag)
-    })
+    protected def createModuleClassSymbol(name: TypeName, pos: Position, newFlags: Long): ModuleClassSymbol =
+      new ModuleClassSymbol(this, pos, name) initFlags newFlags
+
+    protected def createPackageClassSymbol(name: TypeName, pos: Position, newFlags: Long): PackageClassSymbol =
+      new PackageClassSymbol(this, pos, name) initFlags newFlags
+
+    protected def createRefinementClassSymbol(pos: Position, newFlags: Long): RefinementClassSymbol =
+      new RefinementClassSymbol(this, pos) initFlags newFlags
+
+    protected def createTermSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol =
+      new TermSymbol(this, pos, name) initFlags newFlags
+
+    protected def createMethodSymbol(name: TermName, pos: Position, newFlags: Long): MethodSymbol =
+      new MethodSymbol(this, pos, name) initFlags newFlags
+
+    protected def createModuleSymbol(name: TermName, pos: Position, newFlags: Long): ModuleSymbol =
+      new ModuleSymbol(this, pos, name) initFlags newFlags
+
+    protected def createPackageSymbol(name: TermName, pos: Position, newFlags: Long): PackageSymbol =
+      new PackageSymbol(this, pos, name) initFlags newFlags
+
+    protected def createValueParameterSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol =
+      new TermSymbol(this, pos, name) initFlags newFlags
+
+    protected def createValueMemberSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol =
+      new TermSymbol(this, pos, name) initFlags newFlags
 
     /** The class or term up to which this symbol is accessible,
      *  or RootClass if it is public.  As java protected statics are
@@ -1008,7 +1006,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
             throw CyclicReference(this, tp)
           }
         } else {
-          _rawflags |= LOCKED
+          rawflags |= LOCKED
 //          activeLocks += 1
  //         lockedSyms += this
         }
@@ -1200,9 +1198,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       var ph = phase
       while (ph.prev.keepsTypeParams)
         ph = ph.prev
-      //
-      // if (ph ne phase)
-      //   debuglog("checking unsafeTypeParams(" + this + ") at: " + phase + " reading at: " + ph)
 
       ph
     }
@@ -1234,7 +1229,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** The value parameter sections of this symbol.
      */
     def paramss: List[List[Symbol]] = info.paramss
-    def hasParamWhich(cond: Symbol => Boolean) = paramss exists (_ exists cond)
+    def hasParamWhich(cond: Symbol => Boolean) = mexists(paramss)(cond)
 
     /** The least proper supertype of a class; includes all parent types
      *  and refinement where needed. You need to compute that in a situation like this:
@@ -1432,7 +1427,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     /** Internal method to clone a symbol's implementation with the given flags and no info. */
     def cloneSymbolImpl(owner: Symbol, newFlags: Long): Symbol
-    def cloneSymbolImpl(owner: Symbol): Symbol = cloneSymbolImpl(owner, 0L)
 
 // ------ access to related symbols --------------------------------------------------
 
@@ -1443,14 +1437,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def enclMethod: Symbol = if (isSourceMethod) this else owner.enclMethod
 
     /** The primary constructor of a class. */
-    def primaryConstructor: Symbol = {
-      var c = info.decl(
-        if (isTrait || isImplClass) nme.MIXIN_CONSTRUCTOR
-        else nme.CONSTRUCTOR)
-      c = if (c hasFlag OVERLOADED) c.alternatives.head else c
-      //assert(c != NoSymbol)
-      c
-    }
+    def primaryConstructor: Symbol = NoSymbol
 
     /** The self symbol (a TermSymbol) of a class with explicit self type, or else the
      *  symbol itself (a TypeSymbol).
@@ -1507,6 +1494,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *  is not updated when a module is cloned), or NoSymbol if this is not a ModuleClass.
      */
     def sourceModule: Symbol = NoSymbol
+    // if (isModuleClass) companionModule else NoSymbol
+    // NoSymbol
 
     /** The implementation class of a trait.  If available it will be the
      *  symbol with the same owner, and the name of this symbol with $class
@@ -1560,13 +1549,12 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     /** The package class containing this symbol, or NoSymbol if there
      *  is not one. */
-    def enclosingPackageClass: Symbol =
-      if (this == NoSymbol) this else {
-        var packSym = this.owner
-        while (packSym != NoSymbol && !packSym.isPackageClass)
-          packSym = packSym.owner
-        packSym
-      }
+    def enclosingPackageClass: Symbol = {
+      var packSym = this.owner
+      while (packSym != NoSymbol && !packSym.isPackageClass)
+        packSym = packSym.owner
+      packSym
+    }
 
     /** The package containing this symbol, or NoSymbol if there
      *  is not one. */
@@ -1677,21 +1665,12 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *  Note: does not work for classes owned by methods, see Namers.companionClassOf
      *
      *  object Foo  .  companionClass -->  class Foo
+     *
+     *  !!! linkedClassOfClass depends on companionClass on the module class getting
+     *  to the class.  As presently implemented this potentially returns class for
+     *  any symbol except NoSymbol.
      */
-    final def companionClass: Symbol = {
-      if (this != NoSymbol)
-        flatOwnerInfo.decl(name.toTypeName).suchThat(_ isCoDefinedWith this)
-      else NoSymbol
-    }
-
-    /** A helper method that factors the common code used the discover a
-     *  companion module of a class. If a companion module exists, its symbol is
-     *  returned, otherwise, `NoSymbol` is returned. The method assumes that
-     *  `this` symbol has already been checked to be a class (using `isClass`).
-     */
-    private final def companionModule0: Symbol =
-      flatOwnerInfo.decl(name.toTermName).suchThat(
-        sym => sym.hasFlag(MODULE) && (sym isCoDefinedWith this) && !sym.isMethod)
+    def companionClass: Symbol = flatOwnerInfo.decl(name.toTypeName).suchThat(_ isCoDefinedWith this)
 
     /** For a class: the module or case class factory with the same name in the same package.
      *  For all others: NoSymbol
@@ -1699,9 +1678,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *
      *  class Foo  .  companionModule -->  object Foo
      */
-    final def companionModule: Symbol =
-      if (isClass && !isRefinementClass) companionModule0
-      else NoSymbol
+    def companionModule: Symbol = NoSymbol
 
     /** For a module: its linked class
      *  For a plain class: its linked module or case factory.
@@ -1709,18 +1686,14 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *
      *  class Foo  <-- companionSymbol -->  object Foo
      */
-    final def companionSymbol: Symbol =
-      if (isTerm) companionClass
-      else if (isClass) companionModule0
-      else NoSymbol
+    def companionSymbol: Symbol = NoSymbol
 
     /** For a module class: its linked class
      *   For a plain class: the module class of its linked module.
      *
      *  class Foo  <-- linkedClassOfClass -->  class Foo$
      */
-    final def linkedClassOfClass: Symbol =
-      if (isModuleClass) companionClass else companionModule.moduleClass
+    def linkedClassOfClass: Symbol = NoSymbol
 
     /**
      * Returns the rawInfo of the owner. If the current phase has flat classes,
@@ -1733,7 +1706,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      * symbol B in the decls of p. So to find a linked symbol ("object B" or "class B")
      * we need to apply flatten to B first. Fixes #2470.
      */
-    private final def flatOwnerInfo: Type = {
+    protected final def flatOwnerInfo: Type = {
       if (needsFlatClasses)
         info
       owner.rawInfo
@@ -1912,23 +1885,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       case p :: _ => p
       case _      => NoSymbol
     }
-
-    /** change name by appending $$<fully-qualified-name-of-class `base`>
-     *  Do the same for any accessed symbols or setters/getters
-     */
-    def expandName(base: Symbol) {
-      if (this.isTerm && this != NoSymbol && !hasFlag(EXPANDEDNAME)) {
-        setFlag(EXPANDEDNAME)
-        if (hasAccessorFlag && !isDeferred) {
-          accessed.expandName(base)
-        } else if (hasGetter) {
-          getter(owner).expandName(base)
-          setter(owner).expandName(base)
-        }
-        name = nme.expandedName(name.toTermName, base)
-        if (isType) name = name
-      }
-    }
 /* code for fixing nested objects
     def expandModuleClassName() {
       name = newTypeName(name.toString + "$")
@@ -1953,7 +1909,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      */
     def sealedDescendants: Set[Symbol] = children.flatMap(_.sealedDescendants) + this
 
-    def orElse[T](alt: => Symbol): Symbol = if (this ne NoSymbol) this else alt
+    @inline final def orElse[T](alt: => Symbol): Symbol = if (this ne NoSymbol) this else alt
 
 // ------ toString -------------------------------------------------------------------
 
@@ -2115,31 +2071,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     def infosString = infos.toString
     def debugLocationString = fullLocationString + " " + debugFlagString
-    def debugFlagString = hasFlagsToString(-1L)
-    def hasFlagsToString(mask: Long): String = flagsToString(
-      flags & mask,
-      if (hasAccessBoundary) privateWithin.toString else ""
-    )
-
-    /** String representation of symbol's variance */
-    def varianceString: String =
-      if (variance == 1) "+"
-      else if (variance == -1) "-"
-      else ""
-
-    def defaultFlagMask =
-      if (isAbstractType) ExplicitFlags
-      else if (settings.debug.value) -1L
-      else if (owner.isRefinementClass) ExplicitFlags & ~OVERRIDE
-      else ExplicitFlags
-
-    // make the error message more googlable
-    def flagsExplanationString =
-      if (isGADTSkolem) " (this is a GADT skolem)"
-      else ""
 
-    def accessString = hasFlagsToString(PRIVATE | PROTECTED | LOCAL)
-    def defaultFlagString = hasFlagsToString(defaultFlagMask)
     private def defStringCompose(infoString: String) = compose(
       defaultFlagString,
       keyString,
@@ -2171,12 +2103,24 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
   /** A class for term symbols */
   class TermSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TermName)
   extends Symbol(initOwner, initPos, initName) {
-    final override def isTerm = true
+    private[this] var _referenced: Symbol = NoSymbol
+    privateWithin = NoSymbol
 
+    final override def isTerm = true
     override def name: TermName = rawname.toTermName
-    privateWithin = NoSymbol
+    override def companionSymbol: Symbol = companionClass
+    override def moduleClass = if (isModule) referenced else NoSymbol
 
-    private[this] var _referenced: Symbol = NoSymbol
+    override def hasDefault         = this hasFlag DEFAULTPARAM // overloaded with TRAIT
+    override def isBridge           = this hasFlag BRIDGE
+    override def isEarlyInitialized = this hasFlag PRESUPER
+    override def isMethod           = this hasFlag METHOD
+    override def isModule           = this hasFlag MODULE
+    override def isOverloaded       = this hasFlag OVERLOADED
+    override def isPackage          = this hasFlag PACKAGE
+    override def isValueParameter   = this hasFlag PARAM
+
+    override def isPackageObject  = isModule && (name == nme.PACKAGE)
 
     def referenced: Symbol = _referenced
     def referenced_=(x: Symbol) { _referenced = x }
@@ -2210,11 +2154,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       if (name endsWith nme.OUTER) initialize.referenced
       else NoSymbol
 
-    override def moduleClass: Symbol =
-      if (hasFlag(MODULE)) referenced else NoSymbol
-
     def setModuleClass(clazz: Symbol): TermSymbol = {
-      assert(hasFlag(MODULE), this)
+      assert(isModule, this)
       referenced = clazz
       this
     }
@@ -2230,6 +2171,23 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       referenced
     }
 
+    /** change name by appending $$<fully-qualified-name-of-class `base`>
+     *  Do the same for any accessed symbols or setters/getters
+     */
+    override def expandName(base: Symbol) {
+      if (!hasFlag(EXPANDEDNAME)) {
+        setFlag(EXPANDEDNAME)
+        if (hasAccessorFlag && !isDeferred) {
+          accessed.expandName(base)
+        }
+        else if (hasGetter) {
+          getter(owner).expandName(base)
+          setter(owner).expandName(base)
+        }
+        name = nme.expandedName(name.toTermName, base)
+      }
+    }
+
     protected def doCookJavaRawInfo() {
       def cook(sym: Symbol) {
         require(sym.isJavaDefined, sym)
@@ -2263,9 +2221,16 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
   /** A class for module symbols */
   class ModuleSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TermName)
-  extends TermSymbol(initOwner, initPos, initName) {
+  extends TermSymbol(initOwner, initPos, initName) with DistinguishingFlag {
+    def distinguishingFlag = MODULE
+
     private var flatname: TermName = null
 
+    override def isModule = true
+    override def moduleClass = referenced
+    override def companionClass =
+      flatOwnerInfo.decl(name.toTypeName).suchThat(_ isCoDefinedWith this)
+
     override def owner = (
       if (!isMethod && needsFlatClasses) rawowner.owner
       else rawowner
@@ -2279,21 +2244,38 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       }
       else rawname.toTermName
     )
+  }
 
-    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): Symbol =
-      owner.newModuleSymbol(name, pos, newFlags).copyAttrsFrom(this)
+  class PackageSymbol protected[Symbols] (owner0: Symbol, pos0: Position, name0: TermName)
+  extends ModuleSymbol(owner0, pos0, name0) with DistinguishingFlag {
+    override def distinguishingFlag = super.distinguishingFlag | PACKAGE
+    override def isPackage = true
   }
 
   /** A class for method symbols */
   class MethodSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TermName)
-  extends TermSymbol(initOwner, initPos, initName) {
-    private var mtpePeriod = NoPeriod
-    private var mtpePre: Type = _
-    private var mtpeResult: Type = _
-    private var mtpeInfo: Type = _
-
-    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): Symbol =
-      owner.newMethodSymbol(name, pos, newFlags).copyAttrsFrom(this)
+  extends TermSymbol(initOwner, initPos, initName) with DistinguishingFlag {
+    def distinguishingFlag = METHOD
+    // MethodSymbols pick up MODULE when trait-owned object accessors are cloned
+    // during mixin composition.
+    override protected def neverHasFlags = super.neverHasFlags & ~MODULE
+
+    private[this] var mtpePeriod       = NoPeriod
+    private[this] var mtpePre: Type    = _
+    private[this] var mtpeResult: Type = _
+    private[this] var mtpeInfo: Type   = _
+
+    override def isMethod        = true
+    override def isMacro         = this hasFlag MACRO
+    override def isVarargsMethod = this hasFlag VARARGS
+    override def isLiftedMethod  = this hasFlag LIFTED
+    // TODO - this seems a strange definition for "isSourceMethod", given that
+    // it does not make any specific effort to exclude synthetics.  Figure out what
+    // this method is really for and what logic makes sense.
+    override def isSourceMethod  = !(this hasFlag STABLE)  // exclude all accessors
+    // unfortunately having the CASEACCESSOR flag does not actually mean you
+    // are a case accessor (you can also be a field.)
+    override def isCaseAccessorMethod = isCaseAccessor
 
     def typeAsMemberOf(pre: Type): Type = {
       if (mtpePeriod == currentPeriod) {
@@ -2313,38 +2295,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
   class AliasTypeSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName)
   extends TypeSymbol(initOwner, initPos, initName) {
-    // Temporary programmatic help tracking down who might do such a thing
-    override def setFlag(mask: Long): this.type = {
-      if (isSetting(DEFERRED, mask)) {
-        println("Setting DEFERRED on alias at")
-        (new Throwable).printStackTrace
-      }
-      super.setFlag(mask)
-    }
     final override def isAliasType = true
-    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): AliasTypeSymbol =
-      owner.newAliasTypeSymbol(name, pos, newFlags)
-  }
-
-  class AbstractTypeSymbol(initOwner: Symbol, initPos: Position, initName: TypeName)
-  extends TypeSymbol(initOwner, initPos, initName) with AbstractTypeMixin {
-    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): AbstractTypeSymbol =
-      owner.newAbstractTypeSymbol(name, pos, newFlags)
   }
 
-  /** Might be mixed into TypeSymbol or TypeSkolem.
-   */
-  trait AbstractTypeMixin extends TypeSymbol {
-    override def resetFlag(mask: Long): this.type = {
-      // Temporary programmatic help tracking down who might do such a thing
-      if (settings.debug.value) {
-        if (isClearing(DEFERRED, mask)) {
-          println("Clearing DEFERRED on abstract type at")
-          (new Throwable).printStackTrace
-        }
-      }
-      super.resetFlag(mask)
-    }
+  class AbstractTypeSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName)
+  extends TypeSymbol(initOwner, initPos, initName) {
     final override def isAbstractType = true
     override def existentialBound = this.info
   }
@@ -2352,33 +2307,36 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
   /** A class of type symbols. Alias and abstract types are direct instances
    *  of this class. Classes are instances of a subclass.
    */
-  abstract class TypeSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName) extends Symbol(initOwner, initPos, initName) {
+  abstract class TypeSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName)
+  extends Symbol(initOwner, initPos, initName) {
     privateWithin = NoSymbol
+
+    final override def isType   = true
+    override def isNonClassType = true
+
     private var tyconCache: Type = null
     private var tyconRunId = NoRunId
     private var tpeCache: Type = _
     private var tpePeriod = NoPeriod
 
+    override def isAbstractType          = this hasFlag DEFERRED
+    override def isContravariant         = this hasFlag CONTRAVARIANT
+    override def isCovariant             = this hasFlag COVARIANT
+    override def isExistentialQuantified = isExistentiallyBound && !isSkolem
+    override def isExistentiallyBound    = this hasFlag EXISTENTIAL
+    override def isTypeParameter         = isTypeParameterOrSkolem && !isSkolem
+    override def isTypeParameterOrSkolem = this hasFlag PARAM
+
     /** Overridden in subclasses for which it makes sense.
      */
     def existentialBound: Type = abort("unexpected type: "+this.getClass+ " "+debugLocationString)
 
+    // a type symbol bound by an existential type, for instance the T in
+    // List[T] forSome { type T }
+
     override def name: TypeName = super.name.toTypeName
-    final override def isType = true
-    override def isNonClassType = true
-    override def isAbstractType = {
-      if (settings.debug.value) {
-        if (isDeferred) {
-          println("TypeSymbol claims to be abstract type: " + this.getClass + " " + debugFlagString + " at ")
-          (new Throwable).printStackTrace
-        }
-      }
-      isDeferred
-    }
-    private def newTypeRef(targs: List[Type]) = {
-      val pre = if (hasFlag(PARAM | EXISTENTIAL)) NoPrefix else owner.thisType
-      typeRef(pre, this, targs)
-    }
+    private def newPrefix = if (this hasFlag EXISTENTIAL | PARAM) NoPrefix else owner.thisType
+    private def newTypeRef(targs: List[Type]) = typeRef(newPrefix, this, targs)
 
     /** Let's say you have a type definition
      *
@@ -2471,8 +2429,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       }
     }
 
+    /** Default implementation. */
     def cloneSymbolImpl(owner: Symbol, newFlags: Long): Symbol =
-      owner.newTypeSymbol(name, pos, newFlags)
+      owner.newNonClassSymbol(name, pos, newFlags)
 
     incCounter(typeSymbolCount)
   }
@@ -2492,12 +2451,19 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
    */
   class TypeSkolem protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName, origin: AnyRef)
   extends TypeSymbol(initOwner, initPos, initName) {
-
     /** The skolemization level in place when the skolem was constructed */
     val level = skolemizationLevel
 
     final override def isSkolem = true
 
+    override def isGADTSkolem        = this hasFlag CASEACCESSOR | SYNTHETIC
+    override def isTypeSkolem        = this hasFlag PARAM
+    override def isExistentialSkolem = this hasFlag EXISTENTIAL
+    override def isAbstractType      = this hasFlag DEFERRED
+
+    override def isExistentialQuantified = false
+    override def existentialBound = if (isAbstractType) this.info else super.existentialBound
+
     /** If typeskolem comes from a type parameter, that parameter, otherwise skolem itself */
     override def deSkolemize = origin match {
       case s: Symbol => s
@@ -2521,17 +2487,92 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
   /** A class for class symbols */
   class ClassSymbol protected[Symbols] (initOwner: Symbol, initPos: Position, initName: TypeName)
   extends TypeSymbol(initOwner, initPos, initName) {
-    private[this] var flatname: TypeName = null
-    private[this] var source: AbstractFileType = null
-    private[this] var thissym: Symbol = this
+    private[this] var flatname: TypeName       = _
+    private[this] var source: AbstractFileType = _
+    private[this] var thissym: Symbol          = this
+
+    private[this] var thisTypeCache: Type      = _
+    private[this] var thisTypePeriod           = NoPeriod
+    private[this] var typeOfThisCache: Type    = _
+    private[this] var typeOfThisPeriod         = NoPeriod
+
+    override protected def alwaysHasFlags: Long = 0L
+    override protected def neverHasFlags: Long = 0L
 
     final override def isClass = true
     final override def isNonClassType = false
     final override def isAbstractType = false
     final override def isAliasType = false
 
+    override def isAbstractClass           = this hasFlag ABSTRACT
+    override def isClassLocalToConstructor = this hasFlag INCONSTRUCTOR
+    override def isImplClass               = this hasFlag IMPLCLASS
+    override def isModuleClass             = this hasFlag MODULE
+    override def isPackageClass            = this hasFlag PACKAGE
+    override def isTrait                   = this hasFlag TRAIT
+
+    override def isConcreteClass      = !(this hasFlag ABSTRACT | TRAIT)
+    override def isPackageObjectClass = isModuleClass && (name == tpnme.PACKAGE)
+
+    def isTraitOrImplClass   = this hasFlag TRAIT | IMPLCLASS
+    def isNonImplModuleClass = isModuleClass && !isImplClass
+
+    override def isAnonymousClass        = name containsName tpnme.ANON_CLASS_NAME
+    override def isAnonOrRefinementClass = isAnonymousClass || isRefinementClass
+    override def isNestedClass           = !owner.isPackageClass
+    override def isNumericValueClass     = definitions.isNumericValueClass(this)
+    override def isPrimitiveValueClass   = definitions.isPrimitiveValueClass(this)
+
+    /** Is this class locally defined?
+     *  A class is local, if
+     *   - it is anonymous, or
+     *   - its owner is a value
+     *   - it is defined within a local class
+     */
+    override def isLocalClass = (
+         isAnonOrRefinementClass
+      || isLocal
+      || !owner.isPackageClass && owner.isLocalClass
+    )
+    override def isStableClass = (this hasFlag STABLE) || checkStable()
+
+    private def checkStable() = {
+      def hasNoAbstractTypeMember(clazz: Symbol): Boolean =
+        (clazz hasFlag STABLE) || {
+          var e = clazz.info.decls.elems
+          while ((e ne null) && !(e.sym.isAbstractType && info.member(e.sym.name) == e.sym))
+            e = e.next
+          e == null
+        }
+      (info.baseClasses forall hasNoAbstractTypeMember) && {
+        setFlag(STABLE)
+        true
+      }
+    }
+
+    override def enclClassChain = this :: owner.enclClassChain
+
+    /** A helper method that factors the common code used the discover a
+     *  companion module of a class. If a companion module exists, its symbol is
+     *  returned, otherwise, `NoSymbol` is returned.
+     */
+    protected final def companionModule0: Symbol =
+      flatOwnerInfo.decl(name.toTermName).suchThat(
+        sym => sym.hasFlag(MODULE) && (sym isCoDefinedWith this) && !sym.isMethod)
+
+    override def companionModule    = companionModule0
+    override def companionSymbol    = companionModule0
+    override def linkedClassOfClass = companionModule.moduleClass
+
     override def existentialBound = GenPolyType(this.typeParams, TypeBounds.upper(this.classBound))
 
+    def primaryConstructorName = if (isTraitOrImplClass) nme.MIXIN_CONSTRUCTOR else nme.CONSTRUCTOR
+
+    override def primaryConstructor = {
+      val c = info decl primaryConstructorName
+      if (c.isOverloaded) c.alternatives.head else c
+    }
+
     override def sourceFile =
       if (owner.isPackageClass) source
       else super.sourceFile
@@ -2542,12 +2583,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       thissym = this
     }
 
-    private var thisTypeCache: Type = _
-    private var thisTypePeriod = NoPeriod
-
-    private var typeOfThisCache: Type = _
-    private var typeOfThisPeriod = NoPeriod
-
     /** the type this.type in this class */
     override def thisType: Type = {
       val period = thisTypePeriod
@@ -2558,8 +2593,24 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       thisTypeCache
     }
 
+    /** the self type of an object foo is foo.type, not class<foo>.this.type
+     */
+    override def typeOfThis: Type = {
+      if (isNonImplModuleClass && owner != NoSymbol) {
+        val period = typeOfThisPeriod
+        if (period != currentPeriod) {
+          typeOfThisPeriod = currentPeriod
+          if (!isValid(period))
+            typeOfThisCache = singleType(owner.thisType, sourceModule)
+        }
+        typeOfThisCache
+      }
+      else thisSym.tpe
+    }
+
     override def owner: Symbol =
       if (needsFlatClasses) rawowner.owner else rawowner
+
     override def name: TypeName = (
       if (needsFlatClasses) {
         if (flatname eq null)
@@ -2573,27 +2624,12 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** A symbol carrying the self type of the class as its type */
     override def thisSym: Symbol = thissym
 
-    /** the self type of an object foo is foo.type, not class<foo>.this.type
-     */
-    override def typeOfThis: Type = {
-      if (getFlag(MODULE | IMPLCLASS) == MODULE.toLong && owner != NoSymbol) {
-        val period = typeOfThisPeriod
-        if (period != currentPeriod) {
-          typeOfThisPeriod = currentPeriod
-          if (!isValid(period))
-            typeOfThisCache = singleType(owner.thisType, sourceModule)
-        }
-        typeOfThisCache
-      }
-      else thisSym.tpe
-    }
-
     /** Sets the self type of the class */
     override def typeOfThis_=(tp: Type) {
       thissym = newThisSym(pos).setInfo(tp)
     }
 
-    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): Symbol = {
+    override def cloneSymbolImpl(owner: Symbol, newFlags: Long): ClassSymbol = {
       val clone = owner.newClassSymbol(name, pos, newFlags)
       if (thisSym != this) {
         clone.typeOfThis = typeOfThis
@@ -2602,12 +2638,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       clone
     }
 
-    override def sourceModule =
-      if (isModuleClass) companionModule else NoSymbol
+    // Must have this line.
+    override def sourceModule = if (isModuleClass) companionModule else NoSymbol
 
     override def firstParamAccessor =
-      info.decls.find(m => (m hasFlag PARAMACCESSOR) && m.isMethod) getOrElse NoSymbol
-
+      info.decls.find(_ hasAllFlags PARAMACCESSOR | METHOD) getOrElse NoSymbol
 
     private[this] var childSet: Set[Symbol] = Set()
     override def children = childSet
@@ -2621,12 +2656,17 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
    *  plain class symbols!
    */
   class ModuleClassSymbol protected[Symbols] (owner: Symbol, pos: Position, name: TypeName)
-  extends ClassSymbol(owner, pos, name) {
+  extends ClassSymbol(owner, pos, name) with DistinguishingFlag {
+    def distinguishingFlag = MODULE
+
     private var module: Symbol = null
-    private var implicitMembersCacheValue: List[Symbol] = List()
+    private var implicitMembersCacheValue: List[Symbol] = Nil
     private var implicitMembersCacheKey1: Type = NoType
     private var implicitMembersCacheKey2: ScopeEntry = null
 
+    override def isModuleClass = true
+    override def linkedClassOfClass = companionClass
+
     def implicitMembers: List[Symbol] = {
       val tp = info
       if ((implicitMembersCacheKey1 ne tp) || (implicitMembersCacheKey2 ne tp.decls.elems)) {
@@ -2644,6 +2684,35 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     override def sourceModule_=(module: Symbol) { this.module = module }
   }
 
+  class PackageClassSymbol protected[Symbols] (owner0: Symbol, pos0: Position, name0: TypeName)
+  extends ModuleClassSymbol(owner0, pos0, name0) with DistinguishingFlag {
+    override def distinguishingFlag = super.distinguishingFlag | PACKAGE
+    override def sourceModule = companionModule
+    override def enclClassChain = Nil
+    override def isPackageClass = true
+  }
+
+  class RefinementClassSymbol protected[Symbols] (owner0: Symbol, pos0: Position)
+  extends ClassSymbol(owner0, pos0, tpnme.REFINE_CLASS_NAME) {
+    override def name_=(name: Name) {
+      assert(false, "Cannot set name of RefinementClassSymbol to " + name)
+      super.name_=(name)
+    }
+    override def isRefinementClass       = true
+    override def isAnonOrRefinementClass = true
+    override def isLocalClass            = true
+    override def hasMeaninglessName      = true
+    override def companionModule: Symbol = NoSymbol
+
+    /** The mentioned twist.  A refinement class has transowner X
+     *  if any of its parents has transowner X.
+     */
+    override def hasTransOwner(sym: Symbol) = (
+         super.hasTransOwner(sym)
+      || info.parents.exists(_.typeSymbol hasTransOwner sym)
+    )
+  }
+
   class FreeVar(name0: TermName, val value: Any) extends TermSymbol(NoSymbol, NoPosition, name0) {
     override def hashCode = if (value == null) 0 else value.hashCode
     override def equals(other: Any): Boolean = other match {
@@ -2663,12 +2732,20 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       unlock()
       validTo = currentPeriod
     }
+    override def defaultFlagMask = AllFlags
+    override def exists = false
+    override def isHigherOrderTypeParameter = false
+    override def companionClass = NoSymbol
+    override def companionModule = NoSymbol
+    override def companionSymbol = NoSymbol
     override def isSubClass(that: Symbol) = false
     override def filter(cond: Symbol => Boolean) = this
     override def defString: String = toString
     override def locationString: String = ""
+    override def enclClassChain = Nil
     override def enclClass: Symbol = this
     override def enclosingTopLevelClass: Symbol = this
+    override def enclosingPackageClass: Symbol = this
     override def enclMethod: Symbol = this
     override def sourceFile: AbstractFileType = null
     override def ownerChain: List[Symbol] = List()
@@ -2689,9 +2766,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       abort("no-symbol does not have a type constructor (this may indicate scalac cannot find fundamental classes)")
   }
 
-  protected def makeNoSymbol = new NoSymbol
+  protected def makeNoSymbol: NoSymbol = new NoSymbol
 
-  lazy val NoSymbol = makeNoSymbol
+  lazy val NoSymbol: NoSymbol = makeNoSymbol
 
   /** Derives a new list of symbols from the given list by mapping the given
    *  list across the given function.  Then fixes the info of all the new symbols
@@ -2779,7 +2856,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
   /** A class for type histories */
   private sealed case class TypeHistory(var validFrom: Period, info: Type, prev: TypeHistory) {
     assert((prev eq null) || phaseId(validFrom) > phaseId(prev.validFrom), this)
-    assert(validFrom != NoPeriod)
+    assert(validFrom != NoPeriod, this)
+
     override def toString() =
       "TypeHistory(" + phaseOf(validFrom)+":"+runId(validFrom) + "," + info + "," + prev + ")"
     
diff --git a/src/compiler/scala/reflect/internal/TreePrinters.scala b/src/compiler/scala/reflect/internal/TreePrinters.scala
index 8ed0ee6357..7a084304a8 100644
--- a/src/compiler/scala/reflect/internal/TreePrinters.scala
+++ b/src/compiler/scala/reflect/internal/TreePrinters.scala
@@ -175,7 +175,7 @@ trait TreePrinters extends api.TreePrinters { self: SymbolTable =>
           printAnnotations(tree)
           printModifiers(tree, mods)
           val word =
-            if (mods.hasTraitFlag) "trait"
+            if (mods.isTrait) "trait"
             else if (ifSym(tree, _.isModuleClass)) "object"
             else "class"
 
diff --git a/src/compiler/scala/reflect/internal/pickling/UnPickler.scala b/src/compiler/scala/reflect/internal/pickling/UnPickler.scala
index f1ec64bda9..f89aa9bf5c 100644
--- a/src/compiler/scala/reflect/internal/pickling/UnPickler.scala
+++ b/src/compiler/scala/reflect/internal/pickling/UnPickler.scala
@@ -257,12 +257,11 @@ abstract class UnPickler /*extends reflect.generic.UnPickler*/ {
         }
 
       def isModuleFlag = (flags & MODULE) != 0L
-      def isMethodFlag = (flags & METHOD) != 0L
       def isClassRoot  = (name == classRoot.name) && (owner == classRoot.owner)
       def isModuleRoot = (name == moduleRoot.name) && (owner == moduleRoot.owner)
+      def pflags       = flags & PickledFlags
 
       def finishSym(sym: Symbol): Symbol = {
-        sym.flags         = flags & PickledFlags
         sym.privateWithin = privateWithin
         sym.info = (
           if (atEnd) {
@@ -282,27 +281,27 @@ abstract class UnPickler /*extends reflect.generic.UnPickler*/ {
       }
 
       finishSym(tag match {
-        case TYPEsym  => owner.newAbstractType(name.toTypeName)
-        case ALIASsym => owner.newAliasType(name.toTypeName)
+        case TYPEsym  | ALIASsym =>
+          owner.newNonClassSymbol(name.toTypeName, NoPosition, pflags)
         case CLASSsym =>
-          val sym = (isClassRoot, isModuleFlag) match {
-            case (true, true)   => moduleRoot.moduleClass
-            case (true, false)  => classRoot
-            case (false, true)  => owner.newModuleClass(name.toTypeName)
-            case (false, false) => owner.newClass(name.toTypeName)
-          }
+          val sym = (
+            if (isClassRoot) {
+              if (isModuleFlag) moduleRoot.moduleClass setFlag pflags
+              else classRoot setFlag pflags
+            }
+            else owner.newClassSymbol(name.toTypeName, NoPosition, pflags)
+          )
           if (!atEnd)
             sym.typeOfThis = newLazyTypeRef(readNat())
 
           sym
         case MODULEsym =>
           val clazz = at(inforef, () => readType()).typeSymbol // after the NMT_TRANSITION period, we can leave off the () => ... ()
-          if (isModuleRoot) moduleRoot
-          else owner.newLinkedModule(clazz)
+          if (isModuleRoot) moduleRoot setFlag pflags
+          else owner.newLinkedModule(clazz, pflags)
         case VALsym =>
           if (isModuleRoot) { assert(false); NoSymbol }
-          else if (isMethodFlag) owner.newMethod(name.toTermName)
-          else owner.newValue(name.toTermName)
+          else owner.newTermSymbol(name.toTermName, NoPosition, pflags)
 
         case _ =>
           errorBadSignature("bad symbol tag: " + tag)
diff --git a/src/compiler/scala/reflect/runtime/SynchronizedSymbols.scala b/src/compiler/scala/reflect/runtime/SynchronizedSymbols.scala
index 3f2fa30be2..85f7b56920 100644
--- a/src/compiler/scala/reflect/runtime/SynchronizedSymbols.scala
+++ b/src/compiler/scala/reflect/runtime/SynchronizedSymbols.scala
@@ -17,7 +17,7 @@ trait SynchronizedSymbols extends internal.Symbols { self: SymbolTable =>
   override def newFreeVar(name: TermName, tpe: Type, value: Any, newFlags: Long = 0L): FreeVar =
     new FreeVar(name, value) with SynchronizedTermSymbol initFlags newFlags setInfo tpe
 
-  override protected def makeNoSymbol = new NoSymbol with SynchronizedSymbol
+  override protected def makeNoSymbol: NoSymbol = new NoSymbol with SynchronizedSymbol
 
   trait SynchronizedSymbol extends Symbol {
 
@@ -55,32 +55,45 @@ trait SynchronizedSymbols extends internal.Symbols { self: SymbolTable =>
 
 // ------ creators -------------------------------------------------------------------
 
-    override def newTermSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): TermSymbol =
-      new TermSymbol(this, pos, name) with SynchronizedTermSymbol initFlags newFlags
+    override protected def createTypeSymbol(name: TypeName, pos: Position, newFlags: Long): TypeSymbol =
+      new TypeSymbol(this, pos, name) with SynchronizedTypeSymbol initFlags newFlags
 
-    override def newAbstractTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): AbstractTypeSymbol =
+    override protected def createAbstractTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AbstractTypeSymbol =
       new AbstractTypeSymbol(this, pos, name) with SynchronizedTypeSymbol initFlags newFlags
 
-    override def newAliasTypeSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): AliasTypeSymbol =
+    override protected def createAliasTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AliasTypeSymbol =
       new AliasTypeSymbol(this, pos, name) with SynchronizedTypeSymbol initFlags newFlags
 
-    override def newModuleSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleSymbol =
-      new ModuleSymbol(this, pos, name) with SynchronizedTermSymbol initFlags newFlags
-
-    override def newMethodSymbol(name: TermName, pos: Position = NoPosition, newFlags: Long = 0L): MethodSymbol =
-      new MethodSymbol(this, pos, name) with SynchronizedMethodSymbol initFlags newFlags
+    override protected def createTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position, newFlags: Long): TypeSkolem =
+      new TypeSkolem(this, pos, name, origin) with SynchronizedTypeSymbol initFlags newFlags
 
-    override def newClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ClassSymbol =
+    override protected def createClassSymbol(name: TypeName, pos: Position, newFlags: Long): ClassSymbol =
       new ClassSymbol(this, pos, name) with SynchronizedClassSymbol initFlags newFlags
 
-    override def newModuleClassSymbol(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): ModuleClassSymbol =
+    override protected def createModuleClassSymbol(name: TypeName, pos: Position, newFlags: Long): ModuleClassSymbol =
       new ModuleClassSymbol(this, pos, name) with SynchronizedModuleClassSymbol initFlags newFlags
 
-    override def newTypeSkolemSymbol(name: TypeName, origin: AnyRef, pos: Position = NoPosition, newFlags: Long = 0L): TypeSkolem =
-      if ((newFlags & DEFERRED) == 0L)
-        new TypeSkolem(this, pos, name, origin) with SynchronizedTypeSymbol initFlags newFlags
-      else
-        new TypeSkolem(this, pos, name, origin) with AbstractTypeMixin with SynchronizedTypeSymbol initFlags newFlags
+    override protected def createPackageClassSymbol(name: TypeName, pos: Position, newFlags: Long): PackageClassSymbol =
+      new PackageClassSymbol(this, pos, name) with SynchronizedModuleClassSymbol initFlags newFlags
+
+    override protected def createRefinementClassSymbol(pos: Position, newFlags: Long): RefinementClassSymbol =
+      new RefinementClassSymbol(this, pos) with SynchronizedClassSymbol initFlags newFlags
+
+    override protected def createTermSymbol(name: TermName, pos: Position, newFlags: Long): TermSymbol =
+      new TermSymbol(this, pos, name) with SynchronizedTermSymbol initFlags newFlags
+
+    override protected def createMethodSymbol(name: TermName, pos: Position, newFlags: Long): MethodSymbol =
+      new MethodSymbol(this, pos, name) with SynchronizedMethodSymbol initFlags newFlags
+
+    override protected def createModuleSymbol(name: TermName, pos: Position, newFlags: Long): ModuleSymbol =
+      new ModuleSymbol(this, pos, name) with SynchronizedTermSymbol initFlags newFlags
+
+    override protected def createPackageSymbol(name: TermName, pos: Position, newFlags: Long): PackageSymbol =
+      new PackageSymbol(this, pos, name) with SynchronizedTermSymbol initFlags newFlags
+
+    // TODO
+    // override protected def createValueParameterSymbol(name: TermName, pos: Position, newFlags: Long)
+    // override protected def createValueMemberSymbol(name: TermName, pos: Position, newFlags: Long)
   }
 
 // ------- subclasses ---------------------------------------------------------------------
diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 6a30dc2a0f..8df687eca9 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -220,10 +220,6 @@ class Global(var currentSettings: Settings, var reporter: Reporter) extends Symb
        (settings.log.isSetByUser)
     && ((settings.log containsPhase globalPhase) || (settings.log containsPhase phase))
   )
-  def atPhaseStackMessage = atPhaseStack match {
-    case Nil    => ""
-    case ps     => ps.reverseMap("->" + _).mkString("(", " ", ")")
-  }
   // Over 200 closure objects are eliminated by inlining this.
   @inline final def log(msg: => AnyRef) {
     if (shouldLogAtThisPhase)
diff --git a/src/compiler/scala/tools/nsc/ast/Reifiers.scala b/src/compiler/scala/tools/nsc/ast/Reifiers.scala
index 7ece8bbd31..04468a096d 100644
--- a/src/compiler/scala/tools/nsc/ast/Reifiers.scala
+++ b/src/compiler/scala/tools/nsc/ast/Reifiers.scala
@@ -199,7 +199,7 @@ trait Reifiers { self: Global =>
         ValDef(NoMods, localName(sym), TypeTree(),
           Apply(
             Select(reify(sym.owner), "newNestedSymbol"),
-            List(reify(sym.name), reify(sym.pos), Literal(Constant(sym.flags)))
+            List(reify(sym.name), reify(sym.pos), Literal(Constant(sym.flags)), Literal(Constant(sym.isClass)))
           )
         )
       }
diff --git a/src/compiler/scala/tools/nsc/ast/TreeInfo.scala b/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
index 9f361e5bcc..569cb4977b 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
@@ -44,7 +44,7 @@ abstract class TreeInfo extends reflect.internal.TreeInfo {
   }
 
   def isInterface(mods: HasFlags, body: List[Tree]) =
-    mods.hasTraitFlag && (body forall isInterfaceMember)
+    mods.isTrait && (body forall isInterfaceMember)
 
   def isAllowedInUniversalTrait(stat: Tree): Boolean = stat match {
     case _: ValDef => false
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 45325b4694..fa2fc54ac0 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -2600,7 +2600,6 @@ self =>
       in.nextToken
       val nameOffset = in.offset
       val name = identForType()
-      def isTrait = mods.hasTraitFlag
 
       atPos(start, if (name == tpnme.ERROR) start else nameOffset) {
         savingClassContextBounds {
@@ -2608,16 +2607,16 @@ self =>
           val tparams = typeParamClauseOpt(name, contextBoundBuf)
           classContextBounds = contextBoundBuf.toList
           val tstart = in.offset :: classContextBounds.map(_.pos.startOrPoint) min;
-          if (!classContextBounds.isEmpty && isTrait) {
+          if (!classContextBounds.isEmpty && mods.isTrait) {
             syntaxError("traits cannot have type parameters with context bounds `: ...' nor view bounds `<% ...'", false)
             classContextBounds = List()
           }
           val constrAnnots = constructorAnnotations()
           val (constrMods, vparamss) =
-            if (isTrait) (Modifiers(Flags.TRAIT), List())
+            if (mods.isTrait) (Modifiers(Flags.TRAIT), List())
             else (accessModifierOpt(), paramClauses(name, classContextBounds, mods.isCase))
           var mods1 = mods
-          if (isTrait) {
+          if (mods.isTrait) {
             if (settings.YvirtClasses && in.token == SUBTYPE) mods1 |= Flags.DEFERRED
           } else if (in.token == SUBTYPE) {
             syntaxError("classes are not allowed to be virtual", false)
@@ -2709,7 +2708,7 @@ self =>
     }
 
     def isInterface(mods: Modifiers, body: List[Tree]): Boolean =
-      mods.hasTraitFlag && (body forall treeInfo.isInterfaceMember)
+      mods.isTrait && (body forall treeInfo.isInterfaceMember)
 
     /** {{{
      *  ClassTemplateOpt ::= `extends' ClassTemplate | [[`extends'] TemplateBody]
@@ -2719,9 +2718,9 @@ self =>
      */
     def templateOpt(mods: Modifiers, name: Name, constrMods: Modifiers, vparamss: List[List[ValDef]], tstart: Int): Template = {
       val (parents0, argss, self, body) = (
-        if (in.token == EXTENDS || in.token == SUBTYPE && mods.hasTraitFlag) {
+        if (in.token == EXTENDS || in.token == SUBTYPE && mods.isTrait) {
           in.nextToken()
-          template(mods.hasTraitFlag)
+          template(mods.isTrait)
         }
         else {
           newLineOptWhenFollowedBy(LBRACE)
diff --git a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
index 2ff0c1926c..7ad7cadd92 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
@@ -142,7 +142,7 @@ trait TypeKinds { self: ICodes =>
     def lub0(tk1: TypeKind, tk2: TypeKind): Type = beforeUncurry {
       import definitions._
       val tp = global.lub(List(tk1.toType, tk2.toType))
-      val (front, rest) = tp.parents span (_.typeSymbol.hasTraitFlag)
+      val (front, rest) = tp.parents span (_.typeSymbol.isTrait)
 
       if (front.isEmpty || rest.isEmpty || rest.head.typeSymbol == ObjectClass) tp
       else rest.head
diff --git a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
index 39e2cbe694..dde166d64b 100644
--- a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
+++ b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
@@ -43,11 +43,7 @@ abstract class AddInterfaces extends InfoTransform { self: Erasure =>
    */
   private def isInterfaceMember(sym: Symbol) = (
     sym.isType || {
-      // !!! Shouldn't the following code be equivalent to leaving
-      // out the "sym.info" call and starting with "sym.initialize.isMethod" ?
-      // Because, it is not, which I found a little disturbing.  The compiler
-      // fails to bootstrap with an error somewhere.
-      sym.info    // initialize to set lateMETHOD flag if necessary
+      sym.info  // initialize to set lateMETHOD flag if necessary
 
       (     sym.isMethod
         && !sym.isLabel
@@ -71,6 +67,7 @@ abstract class AddInterfaces extends InfoTransform { self: Erasure =>
   /** Return the implementation class of a trait; create a new one of one does not yet exist */
   def implClass(iface: Symbol): Symbol = {
     iface.info
+    def implClassFlags = iface.flags & ~(INTERFACE | lateINTERFACE) | IMPLCLASS
 
     implClassMap.getOrElse(iface, {
       atPhase(implClassPhase) {
@@ -101,7 +98,7 @@ abstract class AddInterfaces extends InfoTransform { self: Erasure =>
           else log("not unlinking existing " + impl + " as the impl class is not visible on the classpath.")
         }
         if (impl == NoSymbol) {
-          impl = iface.cloneSymbolImpl(iface.owner)
+          impl = iface.cloneSymbolImpl(iface.owner, implClassFlags)
           impl.name = implName
           impl.sourceFile = iface.sourceFile
           if (iface.owner.isClass)
@@ -109,7 +106,7 @@ abstract class AddInterfaces extends InfoTransform { self: Erasure =>
         }
         if (currentRun.compiles(iface)) currentRun.symSource(impl) = iface.sourceFile
         impl setPos iface.pos
-        impl.flags = iface.flags & ~(INTERFACE | lateINTERFACE) | IMPLCLASS
+        impl.flags = implClassFlags
         impl setInfo new LazyImplClassType(iface)
         implClassMap(iface) = impl
         debuglog(
diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index 595c1486b6..16c7c3c3ff 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -93,7 +93,7 @@ abstract class ExplicitOuter extends InfoTransform
   }
   def newOuterAccessor(clazz: Symbol) = {
     val accFlags = SYNTHETIC | METHOD | STABLE | ( if (clazz.isTrait) DEFERRED else 0 )
-    val sym      = clazz.newMethodSymbol(nme.OUTER, clazz.pos, accFlags)
+    val sym      = clazz.newMethod(nme.OUTER, clazz.pos, accFlags)
     val restpe   = if (clazz.isTrait) clazz.outerClass.tpe else clazz.outerClass.thisType
 
     sym expandName clazz
diff --git a/src/compiler/scala/tools/nsc/transform/Flatten.scala b/src/compiler/scala/tools/nsc/transform/Flatten.scala
index 8856024a30..ac76862094 100644
--- a/src/compiler/scala/tools/nsc/transform/Flatten.scala
+++ b/src/compiler/scala/tools/nsc/transform/Flatten.scala
@@ -108,7 +108,7 @@ abstract class Flatten extends InfoTransform {
       tree match {
         case PackageDef(_, _) =>
           liftedDefs(tree.symbol.moduleClass) = new ListBuffer
-        case Template(_, _, _) if tree.symbol.owner.hasPackageFlag =>
+        case Template(_, _, _) if tree.symbol.isDefinedInPackage =>
           liftedDefs(tree.symbol.owner) = new ListBuffer
         case _ =>
       }
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index 49ddb985dc..ff0bdf7580 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -661,7 +661,7 @@ trait ContextErrors {
       }
 
       private def ambiguousErrorMsgPos(pos: Position, pre: Type, sym1: Symbol, sym2: Symbol, rest: String) =
-        if (sym1.hasDefaultFlag && sym2.hasDefaultFlag && sym1.enclClass == sym2.enclClass) {
+        if (sym1.hasDefault && sym2.hasDefault && sym1.enclClass == sym2.enclClass) {
           val methodName = nme.defaultGetterToMethod(sym1.name)
           (sym1.enclClass.pos,
            "in "+ sym1.enclClass +", multiple overloaded alternatives of " + methodName +
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index dba31f7bca..ebf8e3fc9a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -699,7 +699,7 @@ trait Infer {
               case NamedType(name, _) => Some(name)
               case _ => None
             })._1
-            if (missing forall (_.hasDefaultFlag)) {
+            if (missing forall (_.hasDefault)) {
               // add defaults as named arguments
               val argtpes1 = argtpes0 ::: (missing map (p => NamedType(p.name, p.tpe)))
               isApplicable(undetparams, ftpe, argtpes1, pt)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 1b505d1e5d..7ea78a81d5 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -529,7 +529,7 @@ trait Namers extends MethodSynthesis {
     def enterCopyMethodOrGetter(tree: Tree, tparams: List[TypeDef]): Symbol = {
       val sym          = tree.symbol
       val lazyType     = completerOf(tree, tparams)
-      def completeCopyFirst = sym.isSynthetic && (!sym.hasDefaultFlag || sym.owner.info.member(nme.copy).isSynthetic)
+      def completeCopyFirst = sym.isSynthetic && (!sym.hasDefault || sym.owner.info.member(nme.copy).isSynthetic)
       def completeCopyMethod(clazz: Symbol) {
         // the 'copy' method of case classes needs a special type completer to make
         // bug0054.scala (and others) work. the copy method has to take exactly the same
@@ -1045,7 +1045,7 @@ trait Namers extends MethodSynthesis {
           }
         )
         // #2382: return type of default getters are always @uncheckedVariance
-        if (meth.hasDefaultFlag)
+        if (meth.hasDefault)
           rt.withAnnotation(AnnotationInfo(uncheckedVarianceClass.tpe, List(), List()))
         else rt
       })
@@ -1095,8 +1095,8 @@ trait Namers extends MethodSynthesis {
         for (vparam <- vparams) {
           val sym = vparam.symbol
           // true if the corresponding parameter of the base class has a default argument
-          val baseHasDefault = overrides && baseParams.head.hasDefaultFlag
-          if (sym.hasDefaultFlag) {
+          val baseHasDefault = overrides && baseParams.head.hasDefault
+          if (sym.hasDefault) {
             // generate a default getter for that argument
             val oflag = if (baseHasDefault) OVERRIDE else 0
             val name = nme.defaultGetterName(meth.name, posCounter)
diff --git a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
index c621497618..2573678f8c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
@@ -377,7 +377,7 @@ trait NamesDefaults { self: Analyzer =>
                   pos: util.Position, context: Context): (List[Tree], List[Symbol]) = {
     if (givenArgs.length < params.length) {
       val (missing, positional) = missingParams(givenArgs, params)
-      if (missing forall (_.hasDefaultFlag)) {
+      if (missing forall (_.hasDefault)) {
         val defaultArgs = missing flatMap (p => {
           val defGetter = defaultGetter(p, context)
           // TODO #3649 can create spurious errors when companion object is gone (because it becomes unlinked from scope)
@@ -399,7 +399,7 @@ trait NamesDefaults { self: Analyzer =>
           }
         })
         (givenArgs ::: defaultArgs, Nil)
-      } else (givenArgs, missing filterNot (_.hasDefaultFlag))
+      } else (givenArgs, missing filterNot (_.hasDefault))
     } else (givenArgs, Nil)
   }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 54b711cebc..5a7c015f09 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -123,7 +123,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
 
       defaultMethodNames.distinct foreach { name =>
         val methods      = clazz.info.findMember(name, 0L, METHOD, false).alternatives
-        val haveDefaults = methods filter (sym => sym.hasParamWhich(_.hasDefaultFlag) && !nme.isProtectedAccessorName(sym.name))
+        val haveDefaults = methods filter (sym => sym.hasParamWhich(_.hasDefault) && !nme.isProtectedAccessorName(sym.name))
 
         if (haveDefaults.lengthCompare(1) > 0) {
           val owners = haveDefaults map (_.owner)
@@ -381,7 +381,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             overrideError("cannot be used here - class definitions cannot be overridden");
           } else if (!other.isDeferred && member.isClass) {
             overrideError("cannot be used here - classes can only override abstract types");
-          } else if (other.isFinal) { // (1.2)
+          } else if (other.isEffectivelyFinal) { // (1.2)
             overrideError("cannot override final member");
             // synthetic exclusion needed for (at least) default getters.
           } else if (!other.isDeferred && !member.isAnyOverride && !member.isSynthetic) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 36c81b09cd..76e1d40af9 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1922,7 +1922,7 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
         rhs1 = checkDead(rhs1)
 
       if (!isPastTyper && meth.owner.isClass &&
-          meth.paramss.exists(ps => ps.exists(_.hasDefaultFlag) && isRepeatedParamType(ps.last.tpe)))
+          meth.paramss.exists(ps => ps.exists(_.hasDefault) && isRepeatedParamType(ps.last.tpe)))
         StarWithDefaultError(meth)
 
       if (!isPastTyper) {
@@ -2492,7 +2492,7 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
                     (e.sym.isType || inBlock || (e.sym.tpe matches e1.sym.tpe) || e.sym.isMacro && e1.sym.isMacro))
                   // default getters are defined twice when multiple overloads have defaults. an
                   // error for this is issued in RefChecks.checkDefaultsInOverloaded
-                  if (!e.sym.isErroneous && !e1.sym.isErroneous && !e.sym.hasDefaultFlag &&
+                  if (!e.sym.isErroneous && !e1.sym.isErroneous && !e.sym.hasDefault &&
                       !e.sym.hasAnnotation(BridgeClass) && !e1.sym.hasAnnotation(BridgeClass)) {
                     log("Double definition detected:\n  " +
                       ((e.sym.getClass, e.sym.info, e.sym.ownerChain)) + "\n  " +
@@ -3106,7 +3106,7 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
             for (sym <- names) {
               // make sure the flags are up to date before erroring (jvm/t3415 fails otherwise)
               sym.initialize
-              if (!sym.hasAnnotation(AnnotationDefaultAttr) && !sym.hasDefaultFlag)
+              if (!sym.hasAnnotation(AnnotationDefaultAttr) && !sym.hasDefault)
                 reportAnnotationError(AnnotationMissingArgError(ann, annType, sym))
             }
 
-- 
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