From c29405dfe1a24419ce4ce10500b5e8d05c581bee Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Fri, 19 Apr 2013 15:01:46 -0700 Subject: 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. --- test/files/run/reify_ann2a.check | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'test/files/run/reify_ann2a.check') diff --git a/test/files/run/reify_ann2a.check b/test/files/run/reify_ann2a.check index ccbcb4c31e..a26fa42045 100644 --- a/test/files/run/reify_ann2a.check +++ b/test/files/run/reify_ann2a.check @@ -6,7 +6,7 @@ () } }; - @new ann(List.apply("1a")) @new ann(List.apply("1b")) class C[@new ann(List.apply("2a")) @new ann(List.apply("2b")) T >: Nothing <: Any] extends AnyRef { + @new ann(List.apply("1a")) @new ann(List.apply("1b")) class C[@new ann(List.apply("2a")) @new ann(List.apply("2b")) T] extends AnyRef { @new ann(List.apply("3a")) @new ann(List.apply("3b")) private[this] val x: T @ann(List.apply("4a")) @ann(List.apply("4b")) = _; def (@new ann(List.apply("3a")) @new ann(List.apply("3b")) x: T @ann(List.apply("4a")) @ann(List.apply("4b"))) = { super.(); -- cgit v1.2.3