Attempted to resolve the improbable mess surrou...

Attempted to resolve the improbable mess surrounding implicit
conversions from Unit. Modified test case which relied on the supposedly
verboten behavior; verbotenized () => AnyRef; added new test case which
fails if verboten behavior should ever return.

3 files changed, 11 insertions, 19 deletions

diff --git a/src/library/scala/Ordering.scala b/src/library/scala/Ordering.scala
index c772e0d3fe..38f9ffa9b4 100644
--- a/src/library/scala/Ordering.scala
+++ b/src/library/scala/Ordering.scala
@@ -100,20 +100,14 @@ object Ordering
 {
   def apply[T](implicit ord : Ordering[T]) = ord
 
-  def ordered[A <: Ordered[A]] : Ordering[A] = new Ordering[A]{
+  def ordered[A <: Ordered[A]] : Ordering[A] = new Ordering[A] {
     def compare(x : A, y : A) = x.compare(y);
   }
 
   trait UnitOrdering extends Ordering[Unit] {
     def compare(x : Unit, y : Unit) = 0;
   }
-  // XXX For the time being this is non-implicit so there remains
-  // only one default implicit conversion Unit => AnyRef (the other
-  // being any2stringadd in Predef.) See
-  //    test/files/neg/structural.scala
-  // for an example of code which is influenced by the next line.
-  // implicit object Unit extends UnitOrdering
-  object Unit extends UnitOrdering
+  implicit object Unit extends UnitOrdering
 
   trait BooleanOrdering extends Ordering[Boolean] {
     def compare(x : Boolean, y : Boolean) = (x, y) match {
diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala
index 49af94b716..565aa363e8 100644
--- a/src/library/scala/Predef.scala
+++ b/src/library/scala/Predef.scala
@@ -190,8 +190,7 @@ object Predef {
   implicit def floatWrapper(x: Float)   = new runtime.RichFloat(x)
   implicit def doubleWrapper(x: Double) = new runtime.RichDouble(x)
 
-  implicit def booleanWrapper(x: Boolean)  = new runtime.RichBoolean(x)
-  implicit def unitWrapper(x: Boolean)  = new runtime.RichUnit
+  implicit def booleanWrapper(x: Boolean) = new runtime.RichBoolean(x)
 
   implicit def stringWrapper(x: String) = new runtime.RichString(x)
 
@@ -203,12 +202,6 @@ object Predef {
   implicit def orderingToOrdered[T](x: T)(implicit ord: Ordering[T]): Ordered[T] =
     new Ordered[T] { def compare(that: T): Int = ord.compare(x, that) }
 
-  /** Temporarily leaving this conversion to Ordered - see Ordering.scala for reasoning */
-  implicit def unit2ordered(x: Unit): Ordered[Unit] = new Ordered[Unit] with Proxy {
-    def self: Any = x
-    def compare(y: Unit): Int = 0
-  }
-
   implicit def byte2short(x: Byte): Short = x.toShort
   implicit def byte2int(x: Byte): Int = x.toInt
   implicit def byte2long(x: Byte): Long = x.toLong
diff --git a/src/library/scala/runtime/RichUnit.scala b/src/library/scala/runtime/RichUnit.scala
index 7738d0634a..4072e81dc7 100644
--- a/src/library/scala/runtime/RichUnit.scala
+++ b/src/library/scala/runtime/RichUnit.scala
@@ -6,13 +6,18 @@
 **                          |/                                          **
 \*                                                                      */
 
-// $Id: RichInt.scala 14532 2008-04-07 12:23:22Z washburn $
+// $Id: RichUnit.scala 14532 2008-04-07 12:23:22Z washburn $
 
 
 package scala.runtime
 
 /** This class exists only as a dummy subclass so that there are two ambiguous
  *  implicit conversions from Unit to some subclass to Object.
- *  It's important that this class should NOT inherit from Ordered
+ *  It's important that this class should NOT inherit from Ordered.
+ *
+ *  Note - in reality the ambiguity is successfully introduced by any2stringadd
+ *  and orderingToOrdered, and adding an implicit from () => RichUnit actually
+ *  resolves the ambiguity by being more specific, and succeeds! So this class
+ *  is probably useless, and unitWrapper has been removed from Predef.
  */
-final class RichUnit {}
+final class RichUnit {}
\ No newline at end of file