Migrate build to @odersky's suggestion of convertTo.

* Move method into TraversableOnce from Iterator and Traversable to make the build pass.
* Udpate IDE tests with new collection methods.
* Rewire default toXYZ methods to use convertTo.

5 files changed, 19 insertions, 16 deletions

diff --git a/src/library/scala/collection/GenTraversableOnce.scala b/src/library/scala/collection/GenTraversableOnce.scala
index 46be27f1cd..37f726c8fb 100644
--- a/src/library/scala/collection/GenTraversableOnce.scala
+++ b/src/library/scala/collection/GenTraversableOnce.scala
@@ -565,10 +565,10 @@ trait GenTraversableOnce[+A] extends Any {
    *  @tparam Col  The collection type to build.
    *  @return a new collection containing all elements of this $coll.
    *  
-   *  @usecase def build[Col[_]]: Col[A]
+   *  @usecase def convertTo[Col[_]]: Col[A]
    *    @inheritdoc
    *    $willNotTerminateInf
    *    @return a new collection containing all elements of this $coll.
    */
-  def build[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV]
+  def convertTo[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV]
 }
diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
index 6b96c8dba5..5f369de3b7 100644
--- a/src/library/scala/collection/Iterator.scala
+++ b/src/library/scala/collection/Iterator.scala
@@ -1140,13 +1140,6 @@ trait Iterator[+A] extends TraversableOnce[A] {
   def toStream: Stream[A] =
     if (self.hasNext) Stream.cons(self.next, self.toStream)
     else Stream.empty[A]
-
-  def toVector: Vector[A] = build[Vector]
-  def build[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV] = {
-    val b = cbf()
-    while(hasNext) b += next
-    b.result
-  }
   
 
   /** Converts this iterator to a string.
diff --git a/src/library/scala/collection/TraversableLike.scala b/src/library/scala/collection/TraversableLike.scala
index e2e9195f4d..e5861f5760 100644
--- a/src/library/scala/collection/TraversableLike.scala
+++ b/src/library/scala/collection/TraversableLike.scala
@@ -616,8 +616,8 @@ trait TraversableLike[+A, +Repr] extends Any
   def toTraversable: Traversable[A] = thisCollection
   def toIterator: Iterator[A] = toStream.iterator
   def toStream: Stream[A] = toBuffer.toStream
-  def toVector: Vector[A] = build[Vector]
-  def build[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV] = {
+  // Override to provide size hint.
+  override def convertTo[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV] = {
     val b = cbf()
     b.sizeHint(this)
     b ++= thisCollection
diff --git a/src/library/scala/collection/TraversableOnce.scala b/src/library/scala/collection/TraversableOnce.scala
index 386ce2d95a..8dc6184d88 100644
--- a/src/library/scala/collection/TraversableOnce.scala
+++ b/src/library/scala/collection/TraversableOnce.scala
@@ -9,6 +9,7 @@
 package scala.collection
 
 import mutable.{ Buffer, Builder, ListBuffer, ArrayBuffer }
+import generic.CanBuildFrom
 import annotation.unchecked.{ uncheckedVariance => uV }
 import language.{implicitConversions, higherKinds}
 import reflect.ClassTag
@@ -239,17 +240,25 @@ trait TraversableOnce[+A] extends Any with GenTraversableOnce[A] {
 
   def toTraversable: Traversable[A]
 
-  def toList: List[A] = (new ListBuffer[A] ++= seq).toList
+  def toList: List[A] = convertTo[List]
 
   def toIterable: Iterable[A] = toStream
 
   def toSeq: Seq[A] = toStream
 
-  def toIndexedSeq: immutable.IndexedSeq[A] = immutable.IndexedSeq() ++ seq
+  def toIndexedSeq: immutable.IndexedSeq[A] = convertTo[immutable.IndexedSeq]
 
-  def toBuffer[B >: A]: mutable.Buffer[B] = new ArrayBuffer[B] ++= seq
+  def toBuffer[B >: A]: mutable.Buffer[B] = convertTo[ArrayBuffer].asInstanceOf[mutable.Buffer[B]]
 
-  def toSet[B >: A]: immutable.Set[B] = immutable.Set() ++ seq
+  def toSet[B >: A]: immutable.Set[B] = convertTo[immutable.Set].asInstanceOf[immutable.Set[B]]
+
+  def toVector: Vector[A] = convertTo[Vector]
+
+  def convertTo[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV] = {
+    val b = cbf()
+    b ++= seq
+    b.result
+  }
 
   def toMap[T, U](implicit ev: A <:< (T, U)): immutable.Map[T, U] = {
     val b = immutable.Map.newBuilder[T, U]
diff --git a/src/library/scala/collection/parallel/ParIterableLike.scala b/src/library/scala/collection/parallel/ParIterableLike.scala
index 20d0a65a4c..a7ec833193 100644
--- a/src/library/scala/collection/parallel/ParIterableLike.scala
+++ b/src/library/scala/collection/parallel/ParIterableLike.scala
@@ -851,9 +851,10 @@ self: ParIterableLike[T, Repr, Sequential] =>
 
   override def toMap[K, V](implicit ev: T <:< (K, V)): immutable.ParMap[K, V] = toParMap[K, V, immutable.ParMap[K, V]](() => immutable.ParMap.newCombiner[K, V])
 
+  // TODO(@alex22): make these better
   override def toVector: Vector[T] = seq.toVector
 
-  override def build[Col[_]](implicit cbf: CanBuildFrom[Nothing, T, Col[T @uncheckedVariance]]): Col[T @uncheckedVariance] = seq.build[Col]
+  override def convertTo[Col[_]](implicit cbf: CanBuildFrom[Nothing, T, Col[T @uncheckedVariance]]): Col[T @uncheckedVariance] = seq.convertTo[Col]
   
 
   /* tasks */