Simplify type bounds.

I started out looking to limit the noise from empty type
bounds, i.e. the endless repetition of

  class A[T >: _root_.scala.Nothing <: _root_.scala.Any]

This led me to be reminded of all the unnecessary and
in fact damaging overreaches which are performed during parsing.
Why should a type parameter for which no bounds are
specified be immediately encoded with this giant tree:

  TypeBounds(
    Select(Select(Ident(nme.ROOTPKG), tpnme.scala_), tpnme.Nothing),
    Select(Select(Ident(nme.ROOTPKG), tpnme.scala_), tpnme.Any)
  )

...which must then be manually recognized as empty type bounds?
Truly, this is madness.

 - It deftly eliminates the possibility of recognizing
   whether the user wrote "class A[T]" or "class A[T >: Nothing]"
   or "class A[T <: Any]" or specified both bounds. The fact
   that these work out the same internally does not imply the
   information should be exterminated even before parsing completes.
 - It burdens everyone who must recognize type bounds trees,
   such as this author
 - It is far less efficient than the obvious encoding
 - It offers literally no advantage whatsoever

Encode empty type bounds as

  TypeBounds(EmptyTree, EmptyTree)

What could be simpler.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/files/run/reify_ann3.check b/test/files/run/reify_ann3.check
index 8caceb2696..d4cf660758 100644
--- a/test/files/run/reify_ann3.check
+++ b/test/files/run/reify_ann3.check
@@ -1,5 +1,5 @@
 {
-  class Tree[A >: Nothing <: Any, B >: Nothing <: Any] extends AnyRef {
+  class Tree[A, B] extends AnyRef {
     @new inline @getter() final <paramaccessor> val key: A = _;
     def <init>(key: A) = {
       super.<init>();