Fix SI-4813 - Clone doesn't work on LinkedList.

* Added extensive test for clone across all standard mutable collections
* Fixed clone implementations when needed so they work.

6 files changed, 40 insertions, 6 deletions

diff --git a/src/library/scala/collection/mutable/ArrayBuffer.scala b/src/library/scala/collection/mutable/ArrayBuffer.scala
index 3034fc2bce..d5308c3b1a 100644
--- a/src/library/scala/collection/mutable/ArrayBuffer.scala
+++ b/src/library/scala/collection/mutable/ArrayBuffer.scala
@@ -169,12 +169,6 @@ class ArrayBuffer[A](override protected val initialSize: Int)
     result
   }
 
-  /** Return a clone of this buffer.
-   *
-   *  @return an `ArrayBuffer` with the same elements.
-   */
-  override def clone(): ArrayBuffer[A] = new ArrayBuffer[A] ++= this
-
   def result: ArrayBuffer[A] = this
 
   /** Defines the prefix of the string representation.
diff --git a/src/library/scala/collection/mutable/ArraySeq.scala b/src/library/scala/collection/mutable/ArraySeq.scala
index d0eaee348b..60baf7b35b 100644
--- a/src/library/scala/collection/mutable/ArraySeq.scala
+++ b/src/library/scala/collection/mutable/ArraySeq.scala
@@ -89,6 +89,13 @@ extends AbstractSeq[A]
     Array.copy(array, 0, xs, start, len1)
   }
 
+  override def clone(): ArraySeq[A] = {
+    val cloned = array.clone.asInstanceOf[Array[AnyRef]]
+    new ArraySeq[A](length) {
+      override val array = cloned
+    }
+  }
+
 }
 
 /** $factoryInfo
diff --git a/src/library/scala/collection/mutable/BufferLike.scala b/src/library/scala/collection/mutable/BufferLike.scala
index 3274fe6194..e77c1256a0 100644
--- a/src/library/scala/collection/mutable/BufferLike.scala
+++ b/src/library/scala/collection/mutable/BufferLike.scala
@@ -252,4 +252,14 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
    */
   @migration("`--` creates a new buffer. Use `--=` to remove an element from this buffer and return that buffer itself.", "2.8.0")
   override def --(xs: GenTraversableOnce[A]): This = clone() --= xs.seq
+
+  /** Return a clone of this buffer.
+   *
+   *  @return a `Buffer` with the same elements.
+   */
+  override def clone(): This = {
+    val bf = newBuilder
+    bf ++= this
+    bf.result.asInstanceOf[This]
+  }
 }
diff --git a/src/library/scala/collection/mutable/LinkedListLike.scala b/src/library/scala/collection/mutable/LinkedListLike.scala
index 07a8501ca4..59004a3de6 100644
--- a/src/library/scala/collection/mutable/LinkedListLike.scala
+++ b/src/library/scala/collection/mutable/LinkedListLike.scala
@@ -180,4 +180,14 @@ trait LinkedListLike[A, This <: Seq[A] with LinkedListLike[A, This]] extends Seq
       these = these.next
     }
   }
+
+  /** Return a clone of this list.
+   *
+   *  @return a `LinkedList` with the same elements.
+   */
+  override def clone(): This = {
+    val bf = newBuilder
+    bf ++= this
+    bf.result
+  }
 }
diff --git a/src/library/scala/collection/mutable/MutableList.scala b/src/library/scala/collection/mutable/MutableList.scala
index c9e44ac165..6fa1f4872a 100644
--- a/src/library/scala/collection/mutable/MutableList.scala
+++ b/src/library/scala/collection/mutable/MutableList.scala
@@ -140,6 +140,13 @@ extends AbstractSeq[A]
   }
 
   def result = this
+
+  override def clone(): MutableList[A]  = {
+    val bf = newBuilder
+    bf ++= seq
+    bf.result
+  }
+
 }
 
 
diff --git a/src/library/scala/collection/mutable/Queue.scala b/src/library/scala/collection/mutable/Queue.scala
index 21c3a84699..fc7e76125e 100644
--- a/src/library/scala/collection/mutable/Queue.scala
+++ b/src/library/scala/collection/mutable/Queue.scala
@@ -177,6 +177,12 @@ extends MutableList[A]
     tl.len = len - 1
     tl
   }
+
+  override def clone(): Queue[A] = {
+    val bf = newBuilder
+    bf ++= seq
+    bf.result
+  }
 }