diff options
Diffstat (limited to 'src/library/scala/collection/generic/GenSetFactory.scala')
-rw-r--r-- | src/library/scala/collection/generic/GenSetFactory.scala | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/src/library/scala/collection/generic/GenSetFactory.scala b/src/library/scala/collection/generic/GenSetFactory.scala index 800f66eb53..65404a4991 100644 --- a/src/library/scala/collection/generic/GenSetFactory.scala +++ b/src/library/scala/collection/generic/GenSetFactory.scala @@ -40,7 +40,11 @@ abstract class GenSetFactory[CC[X] <: GenSet[X] with GenSetLike[X, CC[X]]] /** $setCanBuildFromInfo */ def setCanBuildFrom[A] = new CanBuildFrom[CC[_], A, CC[A]] { - def apply(from: CC[_]) = newBuilder[A] + def apply(from: CC[_]) = from match { + // When building from an existing Set, try to preserve its type: + case from: Set[_] => from.genericBuilder.asInstanceOf[Builder[A, CC[A]]] + case _ => newBuilder[A] + } def apply() = newBuilder[A] } } |