Fix for wrong results from groupBy on views.

2 files changed, 12 insertions, 1 deletions

diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
index 23e967aea0..36fe6251df 100644
--- a/src/library/scala/collection/TraversableViewLike.scala
+++ b/src/library/scala/collection/TraversableViewLike.scala
@@ -169,7 +169,7 @@ trait TraversableViewLike[+A,
     newForced(thisSeq.scanRight(z)(op)).asInstanceOf[That]
 
   override def groupBy[K](f: A => K): immutable.Map[K, This] =
-    thisSeq.groupBy(f).mapValues(xs => newForced(thisSeq))
+    thisSeq groupBy f mapValues (xs => newForced(xs))
 
   override def toString = viewToString
 }
diff --git a/test/files/run/bug4660.scala b/test/files/run/bug4660.scala
new file mode 100644
index 0000000000..e57bb4bf25
--- /dev/null
+++ b/test/files/run/bug4660.scala
@@ -0,0 +1,11 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val traversable = 1 to 20 map (_.toString)
+    def normalize(m: Map[Char, Traversable[String]]) = m.map { case (k,v) => (k, v.toList) }
+
+    val groupedFromView   = (traversable view).groupBy(_(0))
+    val groupedFromStrict = traversable.groupBy(_(0))
+
+    assert(normalize(groupedFromView) == normalize(groupedFromStrict))
+  }
+}