Burned by a last minute adjustment, I lost the ...

Burned by a last minute adjustment, I lost the downward counting
direction. It is a seriously fiddly process to adjust Range and I don't
recommend it to anyone. Closes #3529 over again. Review by prokopec.

2 files changed, 6 insertions, 1 deletions

diff --git a/src/library/scala/collection/immutable/Range.scala b/src/library/scala/collection/immutable/Range.scala
index 930b007389..68b50fd09f 100644
--- a/src/library/scala/collection/immutable/Range.scala
+++ b/src/library/scala/collection/immutable/Range.scala
@@ -120,7 +120,10 @@ class Range(val start: Int, val end: Int, val step: Int) extends IndexedSeq[Int]
    *  @return   a new range consisting of all the elements of this range except `n` first elements.
    */
   final override def drop(n: Int): Range =
-    if (n >= length) copy(end + 1, end, step)
+    if (n >= length) {
+      if (step > 0) copy(end + 1, end, step)
+      else copy(end - 1, end, step)
+    }
     else copy(locationAfterN(n), end, step)
 
   /** Creates a new range containing all the elements of this range except the last one.
diff --git a/test/files/run/bug3529.scala b/test/files/run/bug3529.scala
index 4d83bcfa22..bb82424bf6 100644
--- a/test/files/run/bug3529.scala
+++ b/test/files/run/bug3529.scala
@@ -3,6 +3,8 @@ object Test {
     assert(1 to 10 drop 10 isEmpty)
     assert(1 until 10 drop 9 isEmpty)
     assert(1 to 10 by 2 drop 5 isEmpty)
+    assert(10 to 1 by -1 drop 10 isEmpty)
+    assert((10 to 1 by -1 drop 9) == Seq(1))
 
     assert((1 to 10 drop 9) == Seq(10))
     assert((1 until 10 drop 9) == Nil)