One more attempt to be sound and at the same ti...

One more attempt to be sound and at the same time let the plugin build
go through.

7 files changed, 16 insertions, 35 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/Definitions.scala b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
index cd24f34097..3e9230ca68 100644
--- a/src/compiler/scala/tools/nsc/symtab/Definitions.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
@@ -44,7 +44,7 @@ trait Definitions {
     var NullClass: Symbol = _
     var NothingClass: Symbol = _
     var SingletonClass: Symbol = _
-    lazy val UncheckedStableClass = getClass("scala.UncheckedStable")
+    lazy val uncheckedStableClass = getClass("scala.uncheckedStable")
 
     lazy val ClassClass: Symbol = getClass(sn.Class)
     lazy val StringClass: Symbol = getClass(sn.String)
diff --git a/src/compiler/scala/tools/nsc/symtab/Symbols.scala b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
index 7d0bd9476d..5ef82e4db7 100644
--- a/src/compiler/scala/tools/nsc/symtab/Symbols.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
@@ -312,7 +312,10 @@ trait Symbols {
 
     /** Does this symbol denote a stable value? */
     final def isStable =
-      isTerm && !hasFlag(MUTABLE) && (!hasFlag(METHOD | BYNAMEPARAM) || hasFlag(STABLE)) && !tpe.isVolatile
+      isTerm &&
+      !hasFlag(MUTABLE) &&
+      (!hasFlag(METHOD | BYNAMEPARAM) || hasFlag(STABLE)) &&
+      !(tpe.isVolatile && getAttributes(uncheckedStableClass).isEmpty)
 
     def isDeferred =
       hasFlag(DEFERRED) && !isClass
diff --git a/src/compiler/scala/tools/nsc/symtab/Types.scala b/src/compiler/scala/tools/nsc/symtab/Types.scala
index 2d83924226..342d931eeb 100644
--- a/src/compiler/scala/tools/nsc/symtab/Types.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Types.scala
@@ -975,7 +975,6 @@ trait Types {
       underlyingCache
     }
 
-    override def isStable = !underlying.isVolatile
 /*
     override def narrow: Type = {
       if (phase.erasedTypes) this
@@ -1180,21 +1179,17 @@ trait Types {
       def contributesAbstractMembers(p: Type) =
         p.deferredMembers exists isVisible
 
-      ((parents exists (_.isVolatile)) ||
-       (parents dropWhile (! _.typeSymbol.isAbstractType) match {
+      (parents exists (_.isVolatile)) ||
+      (parents dropWhile (! _.typeSymbol.isAbstractType) match {
         case ps @ (_ :: ps1) =>
           (ps ne parents) ||
           (ps1 exists contributesAbstractMembers) ||
           (decls.elements exists (m => m.isDeferred && isVisible(m)))
         case _ =>
           false
-       })) &&
-      !(typeSymbol isNonBottomSubClass UncheckedStableClass) // escape hatch!
+       })
     }
 
-    override def isStable =
-      (parents exists (_.isStable)) && !isVolatile
-
     override def kind = "RefinedType"
   }
 
@@ -1381,9 +1376,8 @@ trait Types {
 
     override def isStable: Boolean = {
       sym == SingletonClass ||
-      sym == UncheckedStableClass ||
       sym.isAliasType && normalize.isStable ||
-      sym.isAbstractType && bounds.hi.isStable
+      sym.isAbstractType && (bounds.hi.typeSymbol isSubClass SingletonClass)
     }
 
     override def isVolatile: Boolean =
@@ -2622,8 +2616,6 @@ A type's typeSymbol should never be inspected directly.
   }
 
   def singletonBounds(hi: Type) = {
-    if (hi.isVolatile)
-      throw new MalformedType("cannot abstract over singleton with volatile type "+hi)
     mkTypeBounds(NothingClass.tpe, intersectionType(List(hi, SingletonClass.tpe)))
   }
 
@@ -2702,8 +2694,6 @@ A type's typeSymbol should never be inspected directly.
               if (!(pre1.isStable ||
                     pre1.typeSymbol.isPackageClass ||
                     pre1.typeSymbol.isModuleClass && pre1.typeSymbol.isStatic)) {
-                if (pre1.isVolatile)
-                  throw new MalformedType("non-stable type "+pre1+" replacing a stable reference "+tp)
                 stabilize(pre1, sym)
               } else {
                 pre1
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 592d95fd2e..798a0f91af 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2240,6 +2240,9 @@ trait Typers { self: Analyzer =>
         if (wc.symbol == NoSymbol) { namer.enterSym(wc); wc.symbol setFlag EXISTENTIAL }
         else context.scope enter wc.symbol
       val whereClauses1 = typedStats(tree.whereClauses, context.owner)
+      for (vd @ ValDef(_, _, _, _) <- tree.whereClauses)
+        if (vd.symbol.tpe.isVolatile)
+          error(vd.pos, "illegal abstraction from value with volatile type "+vd.symbol.tpe)
       val tpt1 = typedType(tree.tpt, mode)
       val (typeParams, tpe) = existentialTransform(tree.whereClauses map (_.symbol), tpt1.tpe)
       //println(tpe + ": " + tpe.getClass )
@@ -3424,7 +3427,7 @@ trait Typers { self: Analyzer =>
     /** Types a higher-kinded type tree -- pt denotes the expected kind*/
     def typedHigherKindedType(tree: Tree, mode: Int, pt: Type): Tree =
       if (pt.typeParams.isEmpty) typedType(tree, mode) // kind is known and it's *
-      else typed(tree, HKmode, pt)//!!!
+      else typed(tree, HKmode, pt)
 
     def typedHigherKindedType(tree: Tree, mode: Int): Tree =
       typed(tree, HKmode, WildcardType)
diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala
index ce3b05771c..f1bff1f990 100644
--- a/src/library/scala/Predef.scala
+++ b/src/library/scala/Predef.scala
@@ -114,9 +114,6 @@ object Predef {
 
   // tupling ------------------------------------------------------------
 
-  def uncheckedStable[A](x: A): A with UncheckedStable =
-    x.asInstanceOf[A with UncheckedStable]
-
   type Pair[+A, +B] = Tuple2[A, B]
   object Pair {
     def apply[A, B](x: A, y: B) = Tuple2(x, y)
diff --git a/src/library/scala/_$Stable.scala b/src/library/scala/_$Stable.scala
deleted file mode 100644
index d98cbaec7b..0000000000
--- a/src/library/scala/_$Stable.scala
+++ /dev/null
@@ -1,13 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2002-2007, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-package scala
-
-/** A marker thread for types that are assumed to be stable
- *  todo: internalize in Definitions
- */
-trait _$Stable {}
diff --git a/src/library/scala/UncheckedStable.scala b/src/library/scala/uncheckedStable.scala
index fab43b48a7..8d423c10bc 100755
--- a/src/library/scala/UncheckedStable.scala
+++ b/src/library/scala/uncheckedStable.scala
@@ -7,6 +7,7 @@
 \*                                                                      */
 package scala
 
-/** A marker class for types that are assumed to be stable
+/** An annotation for values that are assumed to be stable even though their
+ *  types are volatile.
  */
-abstract final class UncheckedStable {}
+final class uncheckedStable extends StaticAnnotation {}