Merge pull request scala#787 from axel22/issue/5971

Fix SI-5971.

Author: jsuereth

src/library/scala/collection/IterableViewLike.scala

@@ -44,7 +44,7 @@ trait IterableViewLike[+A,
   }
 
   /** Explicit instantiation of the `Transformed` trait to reduce class file size in subclasses. */
-  private[collection] abstract class AbstractTransformed[+B] extends super[TraversableViewLike].Transformed[B] with Transformed[B]
+  private[collection] abstract class AbstractTransformed[+B] extends Iterable[B] with super[TraversableViewLike].Transformed[B] with Transformed[B]
 
   trait EmptyView extends Transformed[Nothing] with super[TraversableViewLike].EmptyView with super[GenIterableViewLike].EmptyView
 

src/library/scala/collection/SeqViewLike.scala

@@ -40,7 +40,7 @@ trait SeqViewLike[+A,
   }
 
   /** Explicit instantiation of the `Transformed` trait to reduce class file size in subclasses. */
-  private[collection] abstract class AbstractTransformed[+B] extends super[IterableViewLike].AbstractTransformed[B] with Transformed[B]
+  private[collection] abstract class AbstractTransformed[+B] extends Seq[B] with super[IterableViewLike].Transformed[B] with Transformed[B]
 
   trait EmptyView extends Transformed[Nothing] with super[IterableViewLike].EmptyView with super[GenSeqViewLike].EmptyView
 

src/library/scala/collection/TraversableViewLike.scala

@@ -117,7 +117,7 @@ trait TraversableViewLike[+A,
   }
 
   /** Explicit instantiation of the `Transformed` trait to reduce class file size in subclasses. */
-  private[collection] abstract class AbstractTransformed[+B] extends Transformed[B]
+  private[collection] abstract class AbstractTransformed[+B] extends Traversable[B] with Transformed[B]
 
   trait EmptyView extends Transformed[Nothing] with super.EmptyView
 

test/files/run/t5971.check

@@ -0,0 +1,4 @@
+r,b
+r
+a,b
+r,a,b

test/files/run/t5971.scala

@@ -0,0 +1,23 @@
+
+
+
+
+
+/** When using `AbstractTransformed` abstract inner class in views in order
+ *  to force generating bridges, one must take care to push the corresponding
+ *  collection trait (such as `Iterable` or `Seq`) as far as possible to the
+ *  left in the linearization order -- otherwise, overridden methods from these
+ *  traits can override the already overridden methods in view. This was the
+ *  case with `takeWhile`.
+ *  Mind blowing, I know.
+ */
+object Test {
+  
+  def main(args: Array[String]) {
+    println("bar".view.reverse.filter(_ > 'a').mkString(","))
+    println("bar".view.reverse.take(1).mkString(","))
+    println("bar".view.reverse.dropWhile(_ > 'a').mkString(","))
+    println("bar".view.reverse.takeWhile(_ => true).mkString(","))
+  }
+  
+}