Fixed #2183.

3 files changed, 8 insertions, 3 deletions

diff --git a/src/library/scala/collection/generic/MutableSetTemplate.scala b/src/library/scala/collection/generic/MutableSetTemplate.scala
index 1f29838174..d79c737e66 100644
--- a/src/library/scala/collection/generic/MutableSetTemplate.scala
+++ b/src/library/scala/collection/generic/MutableSetTemplate.scala
@@ -41,7 +41,7 @@ trait MutableSetTemplate[A, +This <: MutableSetTemplate[A, This] with mutable.Se
      with Builder[A, This]
      with Growable[A]
      with Shrinkable[A]
-     with Cloneable[This]
+     with Cloneable[mutable.Set[A]]
 { self =>
 
   /** A common implementation of <code>newBuilder</code> for all mutable sets
@@ -103,7 +103,7 @@ trait MutableSetTemplate[A, +This <: MutableSetTemplate[A, This] with mutable.Se
    */
   def clear() { foreach(-=) }
 
-  override def clone(): This = empty ++= thisCollection
+  override def clone(): mutable.Set[A] = empty ++= thisCollection
 
   def result: This = thisCollection
 
diff --git a/src/library/scala/collection/mutable/HashSet.scala b/src/library/scala/collection/mutable/HashSet.scala
index 12b7398db1..b150c75773 100644
--- a/src/library/scala/collection/mutable/HashSet.scala
+++ b/src/library/scala/collection/mutable/HashSet.scala
@@ -48,7 +48,7 @@ class HashSet[A] extends Set[A]
     }
   }
 
-  override def clone(): HashSet[A] = new HashSet[A] ++= this
+  override def clone(): Set[A] = new HashSet[A] ++= this
 }
 
 /** Factory object for `HashSet` class */
diff --git a/test/files/pos/t2183.scala b/test/files/pos/t2183.scala
new file mode 100644
index 0000000000..1243568b63
--- /dev/null
+++ b/test/files/pos/t2183.scala
@@ -0,0 +1,5 @@
+import scala.collection.mutable._
+
+object Test {
+  val m = new HashSet[String] with SynchronizedSet[String]
+}