Fixes SI-5328. Iterator.patched failed when from=0.

It turns out iterator.patched forgot to drop replacement values if they were at the beginning.
This is because the index was advancing before checking to see if replaced elements should be
dropped.   Moved this behavior to the beginning of next.

3 files changed, 10 insertions, 1 deletions

diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
index e9a7906527..7d5cd9989c 100644
--- a/src/library/scala/collection/Iterator.scala
+++ b/src/library/scala/collection/Iterator.scala
@@ -1079,11 +1079,12 @@ trait Iterator[+A] extends TraversableOnce[A] {
       if (i < from) origElems.hasNext
       else patchElems.hasNext || origElems.hasNext
     def next(): B = {
+      // We have to do this *first* just in case from = 0.
+      if (i == from) origElems = origElems drop replaced
       val result: B =
         if (i < from || !patchElems.hasNext) origElems.next()
         else patchElems.next()
       i += 1
-      if (i == from) origElems = origElems drop replaced
       result
     }
   }
diff --git a/test/files/run/t5328.check b/test/files/run/t5328.check
new file mode 100644
index 0000000000..77a43968c5
--- /dev/null
+++ b/test/files/run/t5328.check
@@ -0,0 +1,3 @@
+2
+1,2,8
+1,8,3
diff --git a/test/files/run/t5328.scala b/test/files/run/t5328.scala
new file mode 100644
index 0000000000..12adf45b84
--- /dev/null
+++ b/test/files/run/t5328.scala
@@ -0,0 +1,5 @@
+object Test extends App {
+  println(Vector(1).view.updated(0,2).toList mkString ",")
+  println(Seq(1,2,3).view.updated(2,8).toList mkString ",")
+  println(List(1,2,3).view.updated(1,8).toList mkString ",")
+}