Fixes #3422. No review necessary.

2 files changed, 19 insertions, 1 deletions

diff --git a/src/library/scala/collection/TraversableLike.scala b/src/library/scala/collection/TraversableLike.scala
index e688664bed..50259a1ee8 100644
--- a/src/library/scala/collection/TraversableLike.scala
+++ b/src/library/scala/collection/TraversableLike.scala
@@ -338,7 +338,7 @@ trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr] with Traversable
       }
       bldr += elem
     }
-    m mapValues (_.result)
+    m map { case (k, b) => (k, b.result) }
   }
 
   /** Tests whether a predicate holds for all elements of this $coll.
diff --git a/test/files/run/groupby.scala b/test/files/run/groupby.scala
new file mode 100644
index 0000000000..895410e34d
--- /dev/null
+++ b/test/files/run/groupby.scala
@@ -0,0 +1,18 @@
+
+
+
+// Fixes #3422
+object Test {
+
+  def main(args: Array[String]) {
+    val arr = Array.range(0,10)
+    val map = arr groupBy (_%2)
+    val v1 = map(0)
+    val v2 = map(0)
+    // this should hold, of course, assuming also that group by returns a regular
+    // map implementation, and does nothing fancy - and it should default just a
+    // hash map by default.
+    assert(v1 eq v2)
+  }
+
+}