Merge pull request #584 from smarter/fix/isUnbox

Fix null unboxing of primitives (fixes #582)

Author: DarkDimius

src/dotty/tools/dotc/transform/Erasure.scala

@@ -119,7 +119,7 @@ object Erasure extends TypeTestsCasts{
   object Boxing {
 
     def isUnbox(sym: Symbol)(implicit ctx: Context) =
-      sym.name == nme.unbox && (defn.ScalaBoxedClasses contains sym.owner.linkedClass)
+      sym.name == nme.unbox && (defn.ScalaValueClasses contains sym.owner.linkedClass)
 
     def isBox(sym: Symbol)(implicit ctx: Context) =
       sym.name == nme.box && (defn.ScalaValueClasses contains sym.owner.linkedClass)

tests/pos/nullAsInstanceOf.scala

@@ -0,0 +1,23 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val u = null.asInstanceOf[Unit]
+    val b = null.asInstanceOf[Byte]
+    val c = null.asInstanceOf[Char]
+    val s = null.asInstanceOf[Short]
+    val i = null.asInstanceOf[Int]
+    val l = null.asInstanceOf[Long]
+    val f = null.asInstanceOf[Float]
+    val d = null.asInstanceOf[Double]
+    val str = null.asInstanceOf[String]
+
+    println(u)
+    println(b)
+    println(c)
+    println(s)
+    println(i)
+    println(l)
+    println(f)
+    println(d)
+    println(str)
+  }
+}