From 54b26beb2c9a82fc5a1b3a66f11ed763bfad39be Mon Sep 17 00:00:00 2001
From: Paul Phillips <paulp@improving.org>
Date: Mon, 4 Jul 2011 04:55:04 +0000
Subject: Discovered another impressive source of unneces...

Discovered another impressive source of unnecessary garbage is every
collection creating a new GenericCanBuildFrom for every map ever
performed. They can all use the same one: they all have the same
implementation. It looks like tiark had already figured this out and
done it for Vector: I followed with the other fifty. I really haven't
the least idea who to have review most things. No review.
---
 src/library/scala/collection/GenIterable.scala                   | 2 +-
 src/library/scala/collection/GenSeq.scala                        | 2 +-
 src/library/scala/collection/GenSet.scala                        | 2 +-
 src/library/scala/collection/GenTraversable.scala                | 2 +-
 src/library/scala/collection/IndexedSeq.scala                    | 2 +-
 src/library/scala/collection/Iterable.scala                      | 2 +-
 src/library/scala/collection/LinearSeq.scala                     | 2 +-
 src/library/scala/collection/Seq.scala                           | 2 +-
 src/library/scala/collection/Traversable.scala                   | 2 +-
 src/library/scala/collection/generic/GenTraversableFactory.scala | 6 ++++++
 .../scala/collection/immutable/GenIterable.scala.disabled        | 2 +-
 src/library/scala/collection/immutable/GenSeq.scala.disabled     | 2 +-
 src/library/scala/collection/immutable/GenSet.scala.disabled     | 2 +-
 .../scala/collection/immutable/GenTraversable.scala.disabled     | 2 +-
 src/library/scala/collection/immutable/IndexedSeq.scala          | 2 +-
 src/library/scala/collection/immutable/Iterable.scala            | 2 +-
 src/library/scala/collection/immutable/LinearSeq.scala           | 2 +-
 src/library/scala/collection/immutable/List.scala                | 3 ++-
 src/library/scala/collection/immutable/Queue.scala               | 2 +-
 src/library/scala/collection/immutable/Seq.scala                 | 2 +-
 src/library/scala/collection/immutable/Stack.scala               | 2 +-
 src/library/scala/collection/immutable/Traversable.scala         | 2 +-
 src/library/scala/collection/immutable/Vector.scala              | 9 +--------
 src/library/scala/collection/mutable/ArrayBuffer.scala           | 2 +-
 src/library/scala/collection/mutable/ArraySeq.scala              | 2 +-
 src/library/scala/collection/mutable/ArrayStack.scala            | 2 +-
 src/library/scala/collection/mutable/Buffer.scala                | 2 +-
 src/library/scala/collection/mutable/DoubleLinkedList.scala      | 2 +-
 src/library/scala/collection/mutable/GenIterable.scala.disabled  | 2 +-
 src/library/scala/collection/mutable/GenSeq.scala.disabled       | 2 +-
 src/library/scala/collection/mutable/GenSet.scala.disabled       | 2 +-
 .../scala/collection/mutable/GenTraversable.scala.disabled       | 2 +-
 src/library/scala/collection/mutable/IndexedSeq.scala            | 2 +-
 src/library/scala/collection/mutable/Iterable.scala              | 2 +-
 src/library/scala/collection/mutable/LinearSeq.scala             | 2 +-
 src/library/scala/collection/mutable/LinkedList.scala            | 2 +-
 src/library/scala/collection/mutable/ListBuffer.scala            | 2 +-
 src/library/scala/collection/mutable/MutableList.scala           | 2 +-
 src/library/scala/collection/mutable/Queue.scala                 | 2 +-
 src/library/scala/collection/mutable/ResizableArray.scala        | 2 +-
 src/library/scala/collection/mutable/Seq.scala                   | 2 +-
 src/library/scala/collection/mutable/Stack.scala                 | 2 +-
 src/library/scala/collection/mutable/Traversable.scala           | 2 +-
 43 files changed, 49 insertions(+), 49 deletions(-)

diff --git a/src/library/scala/collection/GenIterable.scala b/src/library/scala/collection/GenIterable.scala
index 9d25f21c38..6631a4cdd8 100644
--- a/src/library/scala/collection/GenIterable.scala
+++ b/src/library/scala/collection/GenIterable.scala
@@ -30,7 +30,7 @@ extends GenIterableLike[A, GenIterable[A]]
 
 
 object GenIterable extends GenTraversableFactory[GenIterable] {
-  implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A] = Iterable.newBuilder
 }
 
diff --git a/src/library/scala/collection/GenSeq.scala b/src/library/scala/collection/GenSeq.scala
index 9a7ee9890e..20aa850223 100644
--- a/src/library/scala/collection/GenSeq.scala
+++ b/src/library/scala/collection/GenSeq.scala
@@ -31,6 +31,6 @@ extends GenSeqLike[A, GenSeq[A]]
 
 
 object GenSeq extends GenTraversableFactory[GenSeq] {
-  implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A] = Seq.newBuilder
 }
diff --git a/src/library/scala/collection/GenSet.scala b/src/library/scala/collection/GenSet.scala
index fdf6d1edb2..aa158876b3 100644
--- a/src/library/scala/collection/GenSet.scala
+++ b/src/library/scala/collection/GenSet.scala
@@ -31,7 +31,7 @@ extends GenSetLike[A, GenSet[A]]
 
 
 object GenSet extends GenTraversableFactory[GenSet] {
-  implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A] = Set.newBuilder
 }
 
diff --git a/src/library/scala/collection/GenTraversable.scala b/src/library/scala/collection/GenTraversable.scala
index 8e6ab50f1a..dac3fa9f08 100644
--- a/src/library/scala/collection/GenTraversable.scala
+++ b/src/library/scala/collection/GenTraversable.scala
@@ -32,7 +32,7 @@ extends GenTraversableLike[A, GenTraversable[A]]
 
 
 object GenTraversable extends GenTraversableFactory[GenTraversable] {
-  implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A] = Traversable.newBuilder
 }
 
diff --git a/src/library/scala/collection/IndexedSeq.scala b/src/library/scala/collection/IndexedSeq.scala
index d7a68d38b2..13c48ec144 100644
--- a/src/library/scala/collection/IndexedSeq.scala
+++ b/src/library/scala/collection/IndexedSeq.scala
@@ -28,7 +28,7 @@ trait IndexedSeq[+A] extends Seq[A]
  *  @define Coll IndexedSeq
  */
 object IndexedSeq extends SeqFactory[IndexedSeq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, IndexedSeq[A]] = immutable.IndexedSeq.newBuilder[A]
 }
 
diff --git a/src/library/scala/collection/Iterable.scala b/src/library/scala/collection/Iterable.scala
index 03a8302116..0381da0841 100644
--- a/src/library/scala/collection/Iterable.scala
+++ b/src/library/scala/collection/Iterable.scala
@@ -45,7 +45,7 @@ trait Iterable[+A] extends Traversable[A]
 object Iterable extends TraversableFactory[Iterable] {
 
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, Iterable[A]] = immutable.Iterable.newBuilder[A]
 
diff --git a/src/library/scala/collection/LinearSeq.scala b/src/library/scala/collection/LinearSeq.scala
index f1fa91907f..dfa0a0ed68 100644
--- a/src/library/scala/collection/LinearSeq.scala
+++ b/src/library/scala/collection/LinearSeq.scala
@@ -28,6 +28,6 @@ trait LinearSeq[+A] extends Seq[A]
  *  @define Coll LinearSeq
  */
 object LinearSeq extends SeqFactory[LinearSeq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, LinearSeq[A]] = immutable.LinearSeq.newBuilder[A]
 }
diff --git a/src/library/scala/collection/Seq.scala b/src/library/scala/collection/Seq.scala
index abcc0b5780..2fbbaee355 100644
--- a/src/library/scala/collection/Seq.scala
+++ b/src/library/scala/collection/Seq.scala
@@ -36,7 +36,7 @@ object Seq extends SeqFactory[Seq] {
   private[collection] val hashSeed = "Seq".hashCode
 
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, Seq[A]] = immutable.Seq.newBuilder[A]
 
diff --git a/src/library/scala/collection/Traversable.scala b/src/library/scala/collection/Traversable.scala
index 71c5839d43..3cdc4cbf82 100644
--- a/src/library/scala/collection/Traversable.scala
+++ b/src/library/scala/collection/Traversable.scala
@@ -103,7 +103,7 @@ object Traversable extends TraversableFactory[Traversable] { self =>
   private[collection] val breaks: Breaks = new Breaks
 
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, Traversable[A]] = immutable.Traversable.newBuilder[A]
 }
diff --git a/src/library/scala/collection/generic/GenTraversableFactory.scala b/src/library/scala/collection/generic/GenTraversableFactory.scala
index c2718e5ee2..66eb57657b 100644
--- a/src/library/scala/collection/generic/GenTraversableFactory.scala
+++ b/src/library/scala/collection/generic/GenTraversableFactory.scala
@@ -36,6 +36,12 @@ package generic
 abstract class GenTraversableFactory[CC[X] <: GenTraversable[X] with GenericTraversableTemplate[X, CC]]
   extends GenericCompanion[CC] {
 
+  // A default implementation of GenericCanBuildFrom which can be cast
+  // to whatever is desired.
+  private[collection] object ReusableCBF extends GenericCanBuildFrom[Nothing] {
+    override def apply() = newBuilder[Nothing]
+  }
+
   /** A generic implementation of the `CanBuildFrom` trait, which forwards
    *  all calls to `apply(from)` to the `genericBuilder` method of
    *  $coll `from`, and which forwards all calls of `apply()` to the
diff --git a/src/library/scala/collection/immutable/GenIterable.scala.disabled b/src/library/scala/collection/immutable/GenIterable.scala.disabled
index 252c721271..858abd27aa 100644
--- a/src/library/scala/collection/immutable/GenIterable.scala.disabled
+++ b/src/library/scala/collection/immutable/GenIterable.scala.disabled
@@ -31,7 +31,7 @@ trait GenIterable[+A] extends GenTraversable[A]
 
 
 // object GenIterable extends TraversableFactory[GenIterable] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenIterable[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenIterable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenIterable[A]] = Iterable.newBuilder
 // }
 
diff --git a/src/library/scala/collection/immutable/GenSeq.scala.disabled b/src/library/scala/collection/immutable/GenSeq.scala.disabled
index 36aff8f8e6..5b59418b9f 100644
--- a/src/library/scala/collection/immutable/GenSeq.scala.disabled
+++ b/src/library/scala/collection/immutable/GenSeq.scala.disabled
@@ -39,7 +39,7 @@ trait GenSeq[+A] extends GenIterable[A]
 
 
 // object GenSeq extends SeqFactory[GenSeq] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSeq[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenSeq[A]] = Seq.newBuilder
 // }
 
diff --git a/src/library/scala/collection/immutable/GenSet.scala.disabled b/src/library/scala/collection/immutable/GenSet.scala.disabled
index 3cca6ba66e..dc921b5245 100644
--- a/src/library/scala/collection/immutable/GenSet.scala.disabled
+++ b/src/library/scala/collection/immutable/GenSet.scala.disabled
@@ -38,6 +38,6 @@ trait GenSet[A] extends GenIterable[A]
 
 
 // object GenSet extends TraversableFactory[GenSet] {
-//   implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A] = Set.newBuilder
 // }
diff --git a/src/library/scala/collection/immutable/GenTraversable.scala.disabled b/src/library/scala/collection/immutable/GenTraversable.scala.disabled
index 2ee9bd9d8c..4a5cf12ebe 100644
--- a/src/library/scala/collection/immutable/GenTraversable.scala.disabled
+++ b/src/library/scala/collection/immutable/GenTraversable.scala.disabled
@@ -34,7 +34,7 @@ trait GenTraversable[+A] extends scala.collection.GenTraversable[A]
 
 
 // object GenTraversable extends TraversableFactory[GenTraversable] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenTraversable[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenTraversable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenTraversable[A]] = Traversable.newBuilder
 // }
 
diff --git a/src/library/scala/collection/immutable/IndexedSeq.scala b/src/library/scala/collection/immutable/IndexedSeq.scala
index 9945f6f0e7..2b06c950fa 100644
--- a/src/library/scala/collection/immutable/IndexedSeq.scala
+++ b/src/library/scala/collection/immutable/IndexedSeq.scala
@@ -35,6 +35,6 @@ object IndexedSeq extends SeqFactory[IndexedSeq] {
     def length = buf.length
     def apply(idx: Int) = buf.apply(idx)
   }
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, IndexedSeq[A]] = Vector.newBuilder[A]
 }
diff --git a/src/library/scala/collection/immutable/Iterable.scala b/src/library/scala/collection/immutable/Iterable.scala
index 81579ef3b7..d5fca2bdff 100644
--- a/src/library/scala/collection/immutable/Iterable.scala
+++ b/src/library/scala/collection/immutable/Iterable.scala
@@ -38,6 +38,6 @@ trait Iterable[+A] extends Traversable[A]
  *  @define coll immutable iterable collection
  */
 object Iterable extends TraversableFactory[Iterable] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Iterable[A]] = new mutable.ListBuffer
 }
diff --git a/src/library/scala/collection/immutable/LinearSeq.scala b/src/library/scala/collection/immutable/LinearSeq.scala
index ab8b63238d..e2e2d97588 100644
--- a/src/library/scala/collection/immutable/LinearSeq.scala
+++ b/src/library/scala/collection/immutable/LinearSeq.scala
@@ -31,6 +31,6 @@ trait LinearSeq[+A] extends Seq[A]
  *  @define Coll immutable.LinearSeq
  */
 object LinearSeq extends SeqFactory[LinearSeq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, LinearSeq[A]] = new mutable.ListBuffer
 }
diff --git a/src/library/scala/collection/immutable/List.scala b/src/library/scala/collection/immutable/List.scala
index 563f14eac6..1781e7ba36 100644
--- a/src/library/scala/collection/immutable/List.scala
+++ b/src/library/scala/collection/immutable/List.scala
@@ -426,7 +426,8 @@ object List extends SeqFactory[List] {
   import scala.collection.{Iterable, Seq, IndexedSeq}
 
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, List[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, List[A]] =
+    ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, List[A]] = new ListBuffer[A]
 
diff --git a/src/library/scala/collection/immutable/Queue.scala b/src/library/scala/collection/immutable/Queue.scala
index bf5dc6816a..e09e4b7196 100644
--- a/src/library/scala/collection/immutable/Queue.scala
+++ b/src/library/scala/collection/immutable/Queue.scala
@@ -144,7 +144,7 @@ class Queue[+A] protected(protected val in: List[A], protected val out: List[A])
  */
 object Queue extends SeqFactory[Queue] {
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Queue[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Queue[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Queue[A]] = new ListBuffer[A] mapResult (x => new Queue[A](Nil, x.toList))
   override def empty[A]: Queue[A] = EmptyQueue.asInstanceOf[Queue[A]]
   override def apply[A](xs: A*): Queue[A] = new Queue[A](Nil, xs.toList)
diff --git a/src/library/scala/collection/immutable/Seq.scala b/src/library/scala/collection/immutable/Seq.scala
index 11e56df354..882ca12612 100644
--- a/src/library/scala/collection/immutable/Seq.scala
+++ b/src/library/scala/collection/immutable/Seq.scala
@@ -41,6 +41,6 @@ trait Seq[+A] extends Iterable[A]
  */
 object Seq extends SeqFactory[Seq] {
   /** genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Seq[A]] = new mutable.ListBuffer
 }
diff --git a/src/library/scala/collection/immutable/Stack.scala b/src/library/scala/collection/immutable/Stack.scala
index 329f12190f..adbe34ed09 100644
--- a/src/library/scala/collection/immutable/Stack.scala
+++ b/src/library/scala/collection/immutable/Stack.scala
@@ -20,7 +20,7 @@ import mutable.{ ArrayBuffer, Builder }
  */
 object Stack extends SeqFactory[Stack] {
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Stack[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Stack[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Stack[A]] = new ArrayBuffer[A] mapResult (buf => new Stack(buf.toList))
 
   @deprecated("Use Stack.empty instead", "2.8.0")
diff --git a/src/library/scala/collection/immutable/Traversable.scala b/src/library/scala/collection/immutable/Traversable.scala
index 80839db31c..7830b38d69 100644
--- a/src/library/scala/collection/immutable/Traversable.scala
+++ b/src/library/scala/collection/immutable/Traversable.scala
@@ -33,6 +33,6 @@ trait Traversable[+A] extends scala.collection.Traversable[A]
  *  @define Coll immutable.Traversable
  */
 object Traversable extends TraversableFactory[Traversable] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Traversable[A]] = new mutable.ListBuffer
 }
diff --git a/src/library/scala/collection/immutable/Vector.scala b/src/library/scala/collection/immutable/Vector.scala
index ab44585902..5adbcbb524 100644
--- a/src/library/scala/collection/immutable/Vector.scala
+++ b/src/library/scala/collection/immutable/Vector.scala
@@ -6,30 +6,23 @@
 **                          |/                                          **
 \*                                                                      */
 
-
 package scala.collection
 package immutable
 
 import scala.annotation.unchecked.uncheckedVariance
 import compat.Platform
-
 import scala.collection.generic._
 import scala.collection.mutable.Builder
 import scala.collection.parallel.immutable.ParVector
 
-
 object Vector extends SeqFactory[Vector] {
-  private[immutable] val BF = new GenericCanBuildFrom[Nothing] {
-    override def apply() = newBuilder[Nothing]
-  }
   @inline implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Vector[A]] =
-    BF.asInstanceOf[CanBuildFrom[Coll, A, Vector[A]]]
+    ReusableCBF.asInstanceOf[CanBuildFrom[Coll, A, Vector[A]]]
   def newBuilder[A]: Builder[A, Vector[A]] = new VectorBuilder[A]
   private[immutable] val NIL = new Vector[Nothing](0, 0, 0)
   @inline override def empty[A]: Vector[A] = NIL
 }
 
-
 // in principle, most members should be private. however, access privileges must
 // be carefully chosen to not prevent method inlining
 
diff --git a/src/library/scala/collection/mutable/ArrayBuffer.scala b/src/library/scala/collection/mutable/ArrayBuffer.scala
index 7edbad6518..46499eb326 100644
--- a/src/library/scala/collection/mutable/ArrayBuffer.scala
+++ b/src/library/scala/collection/mutable/ArrayBuffer.scala
@@ -187,7 +187,7 @@ class ArrayBuffer[A](override protected val initialSize: Int)
  */
 object ArrayBuffer extends SeqFactory[ArrayBuffer] {
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArrayBuffer[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArrayBuffer[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, ArrayBuffer[A]] = new ArrayBuffer[A]
 }
 
diff --git a/src/library/scala/collection/mutable/ArraySeq.scala b/src/library/scala/collection/mutable/ArraySeq.scala
index 4b0b4779e9..0d6aac3549 100644
--- a/src/library/scala/collection/mutable/ArraySeq.scala
+++ b/src/library/scala/collection/mutable/ArraySeq.scala
@@ -94,7 +94,7 @@ extends IndexedSeq[A]
  */
 object ArraySeq extends SeqFactory[ArraySeq] {
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArraySeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArraySeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, ArraySeq[A]] =
     new ArrayBuffer[A] mapResult { buf =>
       val result = new ArraySeq[A](buf.length)
diff --git a/src/library/scala/collection/mutable/ArrayStack.scala b/src/library/scala/collection/mutable/ArrayStack.scala
index ce4fe30630..d31627f55a 100644
--- a/src/library/scala/collection/mutable/ArrayStack.scala
+++ b/src/library/scala/collection/mutable/ArrayStack.scala
@@ -22,7 +22,7 @@ import generic._
  *  @define Coll ArrayStack
  */
 object ArrayStack extends SeqFactory[ArrayStack] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArrayStack[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ArrayStack[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, ArrayStack[A]] = new ArrayStack[A]
   def empty: ArrayStack[Nothing] = new ArrayStack()
   def apply[A: ClassManifest](elems: A*): ArrayStack[A] = {
diff --git a/src/library/scala/collection/mutable/Buffer.scala b/src/library/scala/collection/mutable/Buffer.scala
index fa2615e035..4ced60c44d 100644
--- a/src/library/scala/collection/mutable/Buffer.scala
+++ b/src/library/scala/collection/mutable/Buffer.scala
@@ -40,7 +40,7 @@ trait Buffer[A] extends Seq[A]
  *  @define Coll Buffer
  */
 object Buffer extends SeqFactory[Buffer] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Buffer[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Buffer[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Buffer[A]] = new ArrayBuffer
 }
 
diff --git a/src/library/scala/collection/mutable/DoubleLinkedList.scala b/src/library/scala/collection/mutable/DoubleLinkedList.scala
index 2d630c3756..24c2306e30 100644
--- a/src/library/scala/collection/mutable/DoubleLinkedList.scala
+++ b/src/library/scala/collection/mutable/DoubleLinkedList.scala
@@ -67,7 +67,7 @@ class DoubleLinkedList[A]() extends LinearSeq[A]
  */
 object DoubleLinkedList extends SeqFactory[DoubleLinkedList] {
   /** $genericCanBuildFromInfo */
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, DoubleLinkedList[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, DoubleLinkedList[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, DoubleLinkedList[A]] =
     new Builder[A, DoubleLinkedList[A]] {
diff --git a/src/library/scala/collection/mutable/GenIterable.scala.disabled b/src/library/scala/collection/mutable/GenIterable.scala.disabled
index 7fd6a8ca2c..e09981bc9b 100644
--- a/src/library/scala/collection/mutable/GenIterable.scala.disabled
+++ b/src/library/scala/collection/mutable/GenIterable.scala.disabled
@@ -30,7 +30,7 @@ trait GenIterable[A] extends GenTraversable[A]
 
 
 // object GenIterable extends TraversableFactory[GenIterable] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenIterable[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenIterable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenIterable[A]] = Iterable.newBuilder
 // }
 
diff --git a/src/library/scala/collection/mutable/GenSeq.scala.disabled b/src/library/scala/collection/mutable/GenSeq.scala.disabled
index 376a2ceb8b..85e4065183 100644
--- a/src/library/scala/collection/mutable/GenSeq.scala.disabled
+++ b/src/library/scala/collection/mutable/GenSeq.scala.disabled
@@ -38,7 +38,7 @@ trait GenSeq[A] extends GenIterable[A]
 
 
 // object GenSeq extends SeqFactory[GenSeq] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSeq[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenSeq[A]] = Seq.newBuilder
 // }
 
diff --git a/src/library/scala/collection/mutable/GenSet.scala.disabled b/src/library/scala/collection/mutable/GenSet.scala.disabled
index 7416577a6a..ac11e634e8 100644
--- a/src/library/scala/collection/mutable/GenSet.scala.disabled
+++ b/src/library/scala/collection/mutable/GenSet.scala.disabled
@@ -39,7 +39,7 @@ trait GenSet[A] extends GenIterable[A]
 
 
 // object GenSet extends TraversableFactory[GenSet] {
-//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSet[A]] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, GenSet[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A]: Builder[A, GenSet[A]] = Set.newBuilder
 // }
 
diff --git a/src/library/scala/collection/mutable/GenTraversable.scala.disabled b/src/library/scala/collection/mutable/GenTraversable.scala.disabled
index 1ad9bfa9ca..e78e758c12 100644
--- a/src/library/scala/collection/mutable/GenTraversable.scala.disabled
+++ b/src/library/scala/collection/mutable/GenTraversable.scala.disabled
@@ -32,7 +32,7 @@ trait GenTraversable[A] extends scala.collection.GenTraversable[A]
 }
 
 // object GenTraversable extends TraversableFactory[GenTraversable] {
-//   implicit def canBuildFrom[A] = new GenericCanBuildFrom[A]
+//   implicit def canBuildFrom[A] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 //   def newBuilder[A] = Traversable.newBuilder
 // }
 
diff --git a/src/library/scala/collection/mutable/IndexedSeq.scala b/src/library/scala/collection/mutable/IndexedSeq.scala
index 1d7b54214a..e55cf0429f 100644
--- a/src/library/scala/collection/mutable/IndexedSeq.scala
+++ b/src/library/scala/collection/mutable/IndexedSeq.scala
@@ -31,6 +31,6 @@ trait IndexedSeq[A] extends Seq[A]
  *  @define Coll mutable.IndexedSeq
  */
 object IndexedSeq extends SeqFactory[IndexedSeq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, IndexedSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, IndexedSeq[A]] = new ArrayBuffer[A]
 }
diff --git a/src/library/scala/collection/mutable/Iterable.scala b/src/library/scala/collection/mutable/Iterable.scala
index 1a5e58b504..f20179a2d9 100644
--- a/src/library/scala/collection/mutable/Iterable.scala
+++ b/src/library/scala/collection/mutable/Iterable.scala
@@ -32,7 +32,7 @@ trait Iterable[A] extends Traversable[A]
  *  @define Coll mutable.Iterable
  */
 object Iterable extends TraversableFactory[Iterable] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Iterable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Iterable[A]] = new ArrayBuffer
 }
 
diff --git a/src/library/scala/collection/mutable/LinearSeq.scala b/src/library/scala/collection/mutable/LinearSeq.scala
index 2fdca6bed9..0994c9e885 100644
--- a/src/library/scala/collection/mutable/LinearSeq.scala
+++ b/src/library/scala/collection/mutable/LinearSeq.scala
@@ -33,6 +33,6 @@ trait LinearSeq[A] extends Seq[A]
  *  @define Coll mutable.LinearSeq
  */
 object LinearSeq extends SeqFactory[LinearSeq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinearSeq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, LinearSeq[A]] = new MutableList[A]
 }
diff --git a/src/library/scala/collection/mutable/LinkedList.scala b/src/library/scala/collection/mutable/LinkedList.scala
index b701a42596..bfb2db2b34 100644
--- a/src/library/scala/collection/mutable/LinkedList.scala
+++ b/src/library/scala/collection/mutable/LinkedList.scala
@@ -61,7 +61,7 @@ class LinkedList[A]() extends LinearSeq[A]
  */
 object LinkedList extends SeqFactory[LinkedList] {
   override def empty[A]: LinkedList[A] = new LinkedList[A]
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinkedList[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, LinkedList[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, LinkedList[A]] =
     (new MutableList) mapResult ((l: MutableList[A]) => l.toLinkedList)
diff --git a/src/library/scala/collection/mutable/ListBuffer.scala b/src/library/scala/collection/mutable/ListBuffer.scala
index f1271627c1..69b15d7a6f 100644
--- a/src/library/scala/collection/mutable/ListBuffer.scala
+++ b/src/library/scala/collection/mutable/ListBuffer.scala
@@ -379,6 +379,6 @@ final class ListBuffer[A]
  *  @define coll list buffer
  */
 object ListBuffer extends SeqFactory[ListBuffer] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ListBuffer[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ListBuffer[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, ListBuffer[A]] = new GrowingBuilder(new ListBuffer[A])
 }
diff --git a/src/library/scala/collection/mutable/MutableList.scala b/src/library/scala/collection/mutable/MutableList.scala
index c931513da9..3eb60698cd 100644
--- a/src/library/scala/collection/mutable/MutableList.scala
+++ b/src/library/scala/collection/mutable/MutableList.scala
@@ -143,7 +143,7 @@ extends LinearSeq[A]
 
 
 object MutableList extends SeqFactory[MutableList] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, MutableList[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, MutableList[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, MutableList[A]] = new MutableList[A]
 }
diff --git a/src/library/scala/collection/mutable/Queue.scala b/src/library/scala/collection/mutable/Queue.scala
index cf0d2bdfe0..e1723241f5 100644
--- a/src/library/scala/collection/mutable/Queue.scala
+++ b/src/library/scala/collection/mutable/Queue.scala
@@ -168,7 +168,7 @@ extends MutableList[A]
 
 
 object Queue extends SeqFactory[Queue] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Queue[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Queue[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
 
   def newBuilder[A]: Builder[A, Queue[A]] = new MutableList[A] mapResult { _.toQueue }
 }
diff --git a/src/library/scala/collection/mutable/ResizableArray.scala b/src/library/scala/collection/mutable/ResizableArray.scala
index d5398f0e0e..d57e6477b3 100644
--- a/src/library/scala/collection/mutable/ResizableArray.scala
+++ b/src/library/scala/collection/mutable/ResizableArray.scala
@@ -117,6 +117,6 @@ trait ResizableArray[A] extends IndexedSeq[A]
 }
 
 object ResizableArray extends SeqFactory[ResizableArray] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ResizableArray[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ResizableArray[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, ResizableArray[A]] = new ArrayBuffer[A]
 }
diff --git a/src/library/scala/collection/mutable/Seq.scala b/src/library/scala/collection/mutable/Seq.scala
index 42b4ac5c15..d876824ec2 100644
--- a/src/library/scala/collection/mutable/Seq.scala
+++ b/src/library/scala/collection/mutable/Seq.scala
@@ -39,6 +39,6 @@ trait Seq[A] extends Iterable[A]
  *  @define Coll mutable.Seq
  */
 object Seq extends SeqFactory[Seq] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Seq[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Seq[A]] = new ArrayBuffer
 }
diff --git a/src/library/scala/collection/mutable/Stack.scala b/src/library/scala/collection/mutable/Stack.scala
index 89a02ad2ab..63503d77de 100644
--- a/src/library/scala/collection/mutable/Stack.scala
+++ b/src/library/scala/collection/mutable/Stack.scala
@@ -33,7 +33,7 @@ object Stack extends SeqFactory[Stack] {
     }
   }
 
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Stack[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Stack[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Stack[A]] = new StackBuilder[A]
   val empty: Stack[Nothing] = new Stack(Nil)
 }
diff --git a/src/library/scala/collection/mutable/Traversable.scala b/src/library/scala/collection/mutable/Traversable.scala
index b711e0b4db..04b67c0bad 100644
--- a/src/library/scala/collection/mutable/Traversable.scala
+++ b/src/library/scala/collection/mutable/Traversable.scala
@@ -32,7 +32,7 @@ trait Traversable[A] extends scala.collection.Traversable[A]
  *  @define Coll mutable.Traversable
  */
 object Traversable extends TraversableFactory[Traversable] {
-  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = new GenericCanBuildFrom[A]
+  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Traversable[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
   def newBuilder[A]: Builder[A, Traversable[A]] = new ArrayBuffer
 }
 
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