10 files changed, 31 insertions, 22 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index dad422a4a9..a2ab678e36 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -908,15 +908,14 @@ abstract class Erasure extends AddInterfaces
               SelectFromArray(qual, name, erasure(qual.tpe)).copyAttrs(fn),
               args)
 
-        case Apply(fn @ Select(qual, _), Nil) if (fn.symbol == Any_## || fn.symbol == Object_##) =>
+        case Apply(fn @ Select(qual, _), Nil) if fn.symbol == Any_## || fn.symbol == Object_## =>
           // This is unattractive, but without it we crash here on ().## because after
           // erasure the ScalaRunTime.hash overload goes from Unit => Int to BoxedUnit => Int.
           // This must be because some earlier transformation is being skipped on ##, but so
-          // far I don't know what.  We also crash on null.## but unless we want to implement
-          // my good idea that null.## works (like null == "abc" works) we have to NPE.
+          // far I don't know what.  For null we now define null.## == 0.
           val arg = qual.tpe.typeSymbolDirect match {
-            case UnitClass  => BLOCK(qual, REF(BoxedUnit_UNIT))       // ({ expr; UNIT }).##
-            case NullClass  => Typed(qual, TypeTree(ObjectClass.tpe)) // (null: Object).##
+            case UnitClass  => BLOCK(qual, REF(BoxedUnit_UNIT))   // ({ expr; UNIT }).##
+            case NullClass  => LIT(0)                             // (null: Object).##
             case _          => qual
           }
           Apply(gen.mkAttributedRef(scalaRuntimeHash), List(arg))
diff --git a/src/library/scala/collection/immutable/HashMap.scala b/src/library/scala/collection/immutable/HashMap.scala
index e0f15f67da..d44791c2eb 100644
--- a/src/library/scala/collection/immutable/HashMap.scala
+++ b/src/library/scala/collection/immutable/HashMap.scala
@@ -59,7 +59,7 @@ class HashMap[A, +B] extends Map[A,B] with MapLike[A, B, HashMap[A, B]] with Par
   def - (key: A): HashMap[A, B] =
     removed0(key, computeHash(key), 0)
 
-  protected def elemHashCode(key: A) = if (key == null) 0 else key.##
+  protected def elemHashCode(key: A) = key.##
 
   protected final def improve(hcode: Int) = {
     var h: Int = hcode + ~(hcode << 9)
diff --git a/src/library/scala/collection/immutable/HashSet.scala b/src/library/scala/collection/immutable/HashSet.scala
index c47186b27b..7d31f20e14 100644
--- a/src/library/scala/collection/immutable/HashSet.scala
+++ b/src/library/scala/collection/immutable/HashSet.scala
@@ -60,7 +60,7 @@ class HashSet[A] extends Set[A]
 
   def par = ParHashSet.fromTrie(this)
 
-  protected def elemHashCode(key: A) = if (key == null) 0 else key.##
+  protected def elemHashCode(key: A) = key.##
 
   protected final def improve(hcode: Int) = {
     var h: Int = hcode + ~(hcode << 9)
diff --git a/src/library/scala/collection/mutable/HashTable.scala b/src/library/scala/collection/mutable/HashTable.scala
index 00c7588967..420670d755 100644
--- a/src/library/scala/collection/mutable/HashTable.scala
+++ b/src/library/scala/collection/mutable/HashTable.scala
@@ -363,7 +363,7 @@ private[collection] object HashTable {
     // so that:
     protected final def sizeMapBucketSize = 1 << sizeMapBucketBitSize
 
-    protected def elemHashCode(key: KeyType) = if (key == null) 0 else key.##
+    protected def elemHashCode(key: KeyType) = key.##
 
     protected final def improve(hcode: Int) = {
       /* Murmur hash
diff --git a/src/library/scala/reflect/generic/Constants.scala b/src/library/scala/reflect/generic/Constants.scala
index 861a4a9eab..88a213481d 100755
--- a/src/library/scala/reflect/generic/Constants.scala
+++ b/src/library/scala/reflect/generic/Constants.scala
@@ -233,7 +233,6 @@ trait Constants {
     def typeValue: Type     = value.asInstanceOf[Type]
     def symbolValue: Symbol = value.asInstanceOf[Symbol]
 
-    override def hashCode: Int =
-      if (value == null) 0 else value.## * 41 + 17
+    override def hashCode: Int = value.## * 41 + 17
   }
 }
diff --git a/src/library/scala/runtime/ScalaRunTime.scala b/src/library/scala/runtime/ScalaRunTime.scala
index 548875bb6c..8ca461d799 100644
--- a/src/library/scala/runtime/ScalaRunTime.scala
+++ b/src/library/scala/runtime/ScalaRunTime.scala
@@ -167,7 +167,7 @@ object ScalaRunTime {
     var i = 0
     while (i < arr) {
       val elem = x.productElement(i)
-      h = extendHash(h, if (elem == null) 0 else elem.##, c, k)
+      h = extendHash(h, elem.##, c, k)
       c = nextMagicA(c)
       k = nextMagicB(k)
       i += 1
@@ -195,7 +195,8 @@ object ScalaRunTime {
   // must not call ## themselves.
 
   @inline def hash(x: Any): Int =
-    if (x.isInstanceOf[java.lang.Number]) BoxesRunTime.hashFromNumber(x.asInstanceOf[java.lang.Number])
+    if (x == null) 0
+    else if (x.isInstanceOf[java.lang.Number]) BoxesRunTime.hashFromNumber(x.asInstanceOf[java.lang.Number])
     else x.hashCode
 
   @inline def hash(dv: Double): Int = {
diff --git a/src/library/scala/xml/Equality.scala b/src/library/scala/xml/Equality.scala
index 22c1552bbb..1e7cd482ed 100644
--- a/src/library/scala/xml/Equality.scala
+++ b/src/library/scala/xml/Equality.scala
@@ -74,8 +74,6 @@ trait Equality extends scala.Equals {
   def strict_==(other: Equality): Boolean
   def strict_!=(other: Equality) = !strict_==(other)
 
-  private def hashOf(x: Any) = if (x == null) 1 else x.##
-
   /** We insist we're only equal to other xml.Equality implementors,
    *  which heads off a lot of inconsistency up front.
    */
@@ -90,10 +88,7 @@ trait Equality extends scala.Equals {
    *  are final since clearly individual classes cannot be trusted
    *  to maintain a semblance of order.
    */
-  override def hashCode() = basisForHashCode match {
-    case Nil      => 0
-    case x :: xs  => hashOf(x) * 41 + (xs map hashOf).foldLeft(0)(_ * 7 + _)
-  }
+  override def hashCode()         = basisForHashCode.##
   override def equals(other: Any) = doComparison(other, false)
   final def xml_==(other: Any)    = doComparison(other, true)
   final def xml_!=(other: Any)    = !xml_==(other)
diff --git a/src/library/scala/xml/Utility.scala b/src/library/scala/xml/Utility.scala
index 995563e9ac..3f1c5fb81b 100644
--- a/src/library/scala/xml/Utility.scala
+++ b/src/library/scala/xml/Utility.scala
@@ -263,7 +263,7 @@ object Utility extends AnyRef with parsing.TokenTests
    * @param children
    */
   def hashCode(pre: String, label: String, attribHashCode: Int, scpeHash: Int, children: Seq[Node]) = {
-    val h = new util.MurmurHash[Node]( if (pre ne null) pre.## else 0 )
+    val h = new util.MurmurHash[Node](pre.##)
     h.append(label.##)
     h.append(attribHashCode)
     h.append(scpeHash)
diff --git a/src/swing/scala/swing/Publisher.scala b/src/swing/scala/swing/Publisher.scala
index 6042dce943..ebab00463a 100644
--- a/src/swing/scala/swing/Publisher.scala
+++ b/src/swing/scala/swing/Publisher.scala
@@ -78,9 +78,9 @@ import scala.ref._
 private[swing] trait SingleRefCollection[+A <: AnyRef] extends Iterable[A] { self =>
 
   trait Ref[+A <: AnyRef] extends Reference[A] {
-    override def hashCode() = {
-      val v = get
-      if (v == None) 0 else v.get.##
+    override def hashCode() = get match {
+      case Some(x)  => x.##
+      case _        => 0
     }
     override def equals(that: Any) = that match {
       case that: ReferenceWrapper[_] =>
diff --git a/test/files/run/null-hash.scala b/test/files/run/null-hash.scala
new file mode 100644
index 0000000000..9b1f28b083
--- /dev/null
+++ b/test/files/run/null-hash.scala
@@ -0,0 +1,15 @@
+object Test {
+  def f1 = List(5, 10, null: String).##
+  def f2(x: Any) = x.##
+  def f3 = ((55, "abc", null: List[Int])).##
+
+  def main(args: Array[String]): Unit = {
+    f1
+    f2(null)
+    f2(null: String)
+    f3
+    null.##
+    (null: Any).##
+    (null: String).##
+  }
+}