Project: Scala

Revision: 16033

Author: odersky

Date: 05 Sep 2008 09:07:08

Diff at Trac: https://lampsvn.epfl.ch/trac/scala/changeset/16033

• /scala/trunk/src/compiler/scala/tools/nsc/symtab/Types.scala

  ......	@@ -377,6 +377,10 @@
  377	377	def implicitMembers: List[Symbol] =
  378	378	findMember(nme.ANYNAME, BRIDGE, IMPLICIT, false)(NoSymbol).alternatives
  379	379
  	380	/** A list of all deferred symbols of this type (defined or inherited) */
  	381	def deferredMembers: List[Symbol] =
  	382	findMember(nme.ANYNAME, BRIDGE, DEFERRED, false)(NoSymbol).alternatives
  	383
  380	384	/** The member with given name,
  381	385	* an OverloadedSymbol if several exist, NoSymbol if none exist */
  382	386	def member(name: Name): Symbol = findMember(name, BRIDGE, 0, false)(NoSymbol)
  ......	@@ -849,7 +853,7 @@
  849	853	abstract class SingletonType extends SubType with SimpleTypeProxy {
  850	854	def supertype = underlying
  851	855	override def isTrivial = false
  852		override def isStable = !underlying.isVolatile
  	856	override def isStable = true
  853	857	override def isVolatile = underlying.isVolatile
  854	858	override def widen: Type = underlying.widen
  855	859	override def baseTypeSeq: BaseTypeSeq = {
  ......	@@ -970,6 +974,8 @@
  970	974	assert(underlyingCache ne this, this)
  971	975	underlyingCache
  972	976	}
  	977
  	978	override def isStable = !underlying.isVolatile
  973	979	/*
  974	980	override def narrow: Type = {
  975	981	if (phase.erasedTypes) this
  ......	@@ -1159,12 +1165,28 @@
  1159	1165	decls))
  1160	1166	else super.normalize
  1161	1167
  1162		override def isVolatile = false // for now; this should really be:
  1163		/*
  1164		!parents.isEmpty &&
  1165		(!parents.tail.isEmpty || !decls.isEmpty) &&
  1166		(parents exists (_.typeSymbol.isAbstractType))
  1167		*/
  	1168	/** A refined type P1 with ... with Pn { decls } is volatile if
  	1169	* one of the parent types Pi is an abstract type, and either decls
  	1170	* or a following parent Pj, j > i, contributes an abstract member.
  	1171	* A type contributes an abstract member if it has an abstract member which
  	1172	* is also a member of the whole refined type. A scope `decls' contributes
  	1173	* an abstract member if it has an abstract definition which is also
  	1174	* a member of the whole type.
  	1175	*/
  	1176	override def isVolatile = {
  	1177	def isVisible(m: Symbol) =
  	1178	this.nonPrivateMember(m.name).alternatives contains m
  	1179	def contributesAbstractMembers(p: Type) =
  	1180	p.deferredMembers exists isVisible
  	1181
  	1182	parents dropWhile (! _.typeSymbol.isAbstractType) match {
  	1183	case _ :: ps =>
  	1184	(ps exists contributesAbstractMembers) ||
  	1185	(decls.elements exists (m => m.isDeferred && isVisible(m)))
  	1186	case _ =>
  	1187	false
  	1188	}
  	1189	}
  1168	1190
  1169	1191	override def kind = "RefinedType"
  1170	1192	}
  ......	@@ -2671,7 +2693,8 @@
  2671	2693	if (!(pre1.isStable ||
  2672	2694	pre1.typeSymbol.isPackageClass ||
  2673	2695	pre1.typeSymbol.isModuleClass && pre1.typeSymbol.isStatic)) {
  2674		// throw new MalformedType("non-stable type "+pre1+" replacing a stable reference "+tp)
  	2696	if (pre1.isVolatile)
  	2697	throw new MalformedType("non-stable type "+pre1+" replacing a stable reference "+tp)
  2675	2698	stabilize(pre1, sym)
  2676	2699	} else {
  2677	2700	pre1

• /scala/trunk/test/files/neg/null-unsoundness.check

  ......	@@ -0,0 +1,5 @@
  	1	null-unsoundness.scala:8: error: stable identifier required, but A.this.x found.
  	2	Note that value x is not stable because its type, A.this.D with A.this.A, is volatile.
  	3	var y: x.T = new C("abc")
  	4	^
  	5	one error found

• /scala/trunk/test/files/neg/null-unsoundness.scala

  ......	@@ -0,0 +1,15 @@
  	1	class B
  	2	class C(x: String) extends B
  	3
  	4	class A {
  	5	type A >: Null
  	6	class D { type T >: C <: B }
  	7	val x: D with A = null
  	8	var y: x.T = new C("abc")
  	9	}
  	10	object Test extends A with Application {
  	11	class C { type T = Int; val x = 1 }
  	12	type A = C
  	13	y = 42
  	14	}
  	15