SI-9254 UnrolledBuffer appends in wrong position

Fixed two bugs in insertion (insertAll of Unrolled):

1. Incorrect recursion leading to an inability to insert past the first chunk
2. Incorect repositioning of `lastptr` leading to strange `append` behavior after early insertion

Added tests checking that both of these things now work.

Also added a comment that "waterlineDelim" is misnamed.  But we can't fix it now--it's part of the public API.  (Shouldn't be, but it is.)

1 files changed, 7 insertions, 5 deletions

diff --git a/src/library/scala/collection/mutable/UnrolledBuffer.scala b/src/library/scala/collection/mutable/UnrolledBuffer.scala
index 693c47d86e..1fda318e51 100644
--- a/src/library/scala/collection/mutable/UnrolledBuffer.scala
+++ b/src/library/scala/collection/mutable/UnrolledBuffer.scala
@@ -208,7 +208,7 @@ object UnrolledBuffer extends ClassTagTraversableFactory[UnrolledBuffer] {
   def newBuilder[T](implicit t: ClassTag[T]): Builder[T, UnrolledBuffer[T]] = new UnrolledBuffer[T]
 
   val waterline = 50
-  val waterlineDelim = 100
+  val waterlineDelim = 100    // TODO -- fix this name!  It's a denominator, not a delimiter.  (But it's part of the API so we can't just change it.)
   private[collection] val unrolledlength = 32
 
   /** Unrolled buffer node.
@@ -319,13 +319,15 @@ object UnrolledBuffer extends ClassTagTraversableFactory[UnrolledBuffer] {
 	for (elem <- t) curr = curr append elem
 	curr.next = newnextnode
 
-	// try to merge the last node of this with the newnextnode
+	// try to merge the last node of this with the newnextnode and fix tail pointer if needed
 	if (curr.tryMergeWithNext()) buffer.lastPtr = curr
+	else if (newnextnode.next eq null) buffer.lastPtr = newnextnode
       }
-      else if (idx == size) {
+      else if (idx == size || (next eq null)) {
 	var curr = this
 	for (elem <- t) curr = curr append elem
-      } else insertAll(idx - size, t, buffer)
+      }
+      else next.insertAll(idx - size, t, buffer)
     }
     private def nullout(from: Int, until: Int) {
       var idx = from
@@ -344,7 +346,7 @@ object UnrolledBuffer extends ClassTagTraversableFactory[UnrolledBuffer] {
       tryMergeWithNext()
     }
 
-    override def toString = array.take(size).mkString("Unrolled[" + array.length + "](", ", ", ")") + " -> " + (if (next ne null) next.toString else "")
+    override def toString = array.take(size).mkString("Unrolled@%08x".format(System.identityHashCode(this)) + "[" + size + "/" + array.length + "](", ", ", ")") + " -> " + (if (next ne null) next.toString else "")
   }
 
 }