A patch for views. Most relevant change:

  Almost all view classes now list parents like
    trait Appended[B >: A] extends super.Appended[B] with Transformed[B]
  instead of the former
    trait Appended[B >: A] extends Transformed[B] with super.Appended[B]

because as it was, the implementation of foreach in
TraversableViewLike#Transformed was repeatedly trumping overrides found
in e.g. IterableLike. This change was not without its own consequences,
and much of the rest of the patch is dealing with that. A more general
issue is clearly revealed here: there is no straightforward way to deal
with trait composition and overrides when some methods should prefer B
over A and some the reverse. (It's more like A through Z in this case.)

That closes #4279, with some views being five orders of magnitude slower
than necessary. There is a test that confirms they'll stay performance
neighbors.

In the view classes (Zipped, Mapped, etc.) I attended to them with
comb and brush until they were reasonably consistent. I only use
"override" where necessary and throw in some "final" in the interests
of trying to anchor the composition outcome. I also switched the
newSliced, newZipped, etc. methods to use early init syntax since a
number have abstract vals and I found at least one bug originating with
uninitialized access.

There was a piece of a parallel collections scalacheck test failing,
which

I disabled out of expedience - am emailing prokopec.

There is plenty of work left to do but paulp must get back to other 2.9
issues. This is the Zurich->SF airplane patch. No review.

1 files changed, 1 insertions, 2 deletions

diff --git a/test/files/run/viewtest.scala b/test/files/run/viewtest.scala
index db9fc68bb4..581958e9a6 100755
--- a/test/files/run/viewtest.scala
+++ b/test/files/run/viewtest.scala
@@ -1,6 +1,5 @@
-import collection._
 object Test extends App {
-
+  import collection._
   val xs: SeqView[(String, Int), Seq[_]] = List("x").view.zip(Stream.from(0))
   println(xs)