use m.Builder over plain Builder

Author: Martijn Hoekstra

compat/src/main/scala-2.11_2.12/scala/collection/compat/CompatImpl.scala

@@ -14,14 +14,13 @@ package scala.collection.compat
 
 import scala.reflect.ClassTag
 import scala.collection.generic.CanBuildFrom
-import scala.collection.mutable.Builder
 import scala.collection.{immutable => i, mutable => m}
 
 /* builder optimized for a single ++= call, which returns identity on result if possible
  * and defers to the underlying builder if not.
  */
-private final class IdentityPreservingBuilder[A, CC[X] <: TraversableOnce[X]](that: Builder[A, CC[A]])(implicit ct: ClassTag[CC[A]])
-    extends Builder[A, CC[A]] {
+private final class IdentityPreservingBuilder[A, CC[X] <: TraversableOnce[X]](that: m.Builder[A, CC[A]])(implicit ct: ClassTag[CC[A]])
+    extends m.Builder[A, CC[A]] {
 
   //invariant: ruined => (collection == null)
   var collection: CC[A] = null.asInstanceOf[CC[A]]
@@ -62,9 +61,9 @@ private final class IdentityPreservingBuilder[A, CC[X] <: TraversableOnce[X]](th
 }
 
 private[compat] object CompatImpl {
-  def simpleCBF[A, C](f: => Builder[A, C]): CanBuildFrom[Any, A, C] = new CanBuildFrom[Any, A, C] {
-    def apply(from: Any): Builder[A, C] = apply()
-    def apply(): Builder[A, C]          = f
+  def simpleCBF[A, C](f: => m.Builder[A, C]): CanBuildFrom[Any, A, C] = new CanBuildFrom[Any, A, C] {
+    def apply(from: Any): m.Builder[A, C] = apply()
+    def apply(): m.Builder[A, C]          = f
   }
 
   type ImmutableBitSetCC[X] = ({ type L[_] = i.BitSet })#L[X]