A total rewrite of "runtimeClass", discarding t...

A total rewrite of "runtimeClass", discarding the user-space approach in
favor of simply fixing getClass.

  def f1 = 5.getClass                       // Class[Int]
  def f2 = (5: AnyVal).getClass             // Class[_ <: AnyVal]
  def f3 = (5: java.lang.Integer).getClass  // Class[_ <: java.lang.Integer]

  class A
  class B extends A

  def f1 = (new B: Any).getClass().newInstance()      // Any
  def f2 = (new B: AnyRef).getClass().newInstance()   // AnyRef
  def f3 = (new B: A).getClass().newInstance()        // A
  def f4 = (new B: B).getClass().newInstance()        // B

But that's not all!

  def f0[T >: B] = (new B: T).getClass().newInstance()

  def f5 = f0[Any]        // Any
  def f6 = f0[AnyRef]     // AnyRef
  def f7 = f0[A]          // A
  def f8 = f0[B]          // B

Closes #490, #896, #4696. Review by moors. (Note: I think this is pretty
good, but picky review requested.)

1 files changed, 16 insertions, 0 deletions

diff --git a/src/library/scala/runtime/ScalaRunTime.scala b/src/library/scala/runtime/ScalaRunTime.scala
index 7a8224298b..031f15f10a 100644
--- a/src/library/scala/runtime/ScalaRunTime.scala
+++ b/src/library/scala/runtime/ScalaRunTime.scala
@@ -32,6 +32,22 @@ object ScalaRunTime {
 
   def isValueClass(clazz: Class[_]) = clazz.isPrimitive()
 
+  /** Return the class object representing an unboxed value type,
+   *  e.g. classOf[int], not classOf[java.lang.Integer].  The compiler
+   *  rewrites expressions like 5.getClass to come here.
+   */
+  def anyValClass[T <: AnyVal](value: T): Class[T] = (value match {
+    case x: Byte    => java.lang.Byte.TYPE
+    case x: Short   => java.lang.Short.TYPE
+    case x: Char    => java.lang.Character.TYPE
+    case x: Int     => java.lang.Integer.TYPE
+    case x: Long    => java.lang.Long.TYPE
+    case x: Float   => java.lang.Float.TYPE
+    case x: Double  => java.lang.Double.TYPE
+    case x: Boolean => java.lang.Boolean.TYPE
+    case x: Unit    => java.lang.Void.TYPE
+  }).asInstanceOf[Class[T]]
+
   /** Retrieve generic array element */
   def array_apply(xs: AnyRef, idx: Int): Any = xs match {
     case x: Array[AnyRef]  => x(idx).asInstanceOf[Any]