Merge remote-tracking branch 'origin/2.12.x' into backport/sbt-bump

Author: retronym

library/src/scala/collection/immutable/HashMap.scala

@@ -139,6 +139,21 @@ sealed class HashMap[A, +B] extends AbstractMap[A, B]
 
   override def par = ParHashMap.fromTrie(this)
 
+  /* Override to avoid tuple allocation in foreach */
+  private[collection] class HashMapKeys extends ImmutableDefaultKeySet {
+    override def foreach[U](f: A => U) = foreachEntry((key, _) => f(key))
+    override lazy val hashCode = super.hashCode()
+  }
+  override def keySet: immutable.Set[A] = new HashMapKeys
+
+  /** The implementation class of the iterable returned by `values`.
+   */
+  private[collection] class HashMapValues extends DefaultValuesIterable {
+    override def foreach[U](f: B => U) = foreachEntry((_, value) => f(value))
+  }
+  override def values: scala.collection.Iterable[B] = new HashMapValues
+
+
 }
 
 /** $factoryInfo

library/src/scala/collection/immutable/TreeMap.scala

@@ -215,4 +215,11 @@ final class TreeMap[A, +B] private (tree: RB.Tree[A, B])(implicit val ordering:
     }
   }
 
+  override def keySet: SortedSet[A] = new DefaultKeySortedSet {
+    override def foreach[U](f: A => U): Unit = RB.foreachEntry(tree, {(key: A, _: B) => f(key)})
+  }
+
+  override def values: scala.Iterable[B] = new DefaultValuesIterable {
+    override def foreach[U](f: B => U): Unit = RB.foreachEntry(tree, {(_: A, value: B) => f(value)})
+  }
 }

library/src/scala/collection/mutable/ListBuffer.scala

@@ -306,13 +306,18 @@ final class ListBuffer[A]
   def result: List[A] = toList
 
   /** Converts this buffer to a list. Takes constant time. The buffer is
-   *  copied lazily, the first time it is mutated.
+   *  copied lazily the first time it is mutated.
    */
   override def toList: List[A] = {
     exported = !isEmpty
     start
   }
 
+  // scala/bug#11869
+  override def toSeq: collection.Seq[A] = toList
+  override def toIterable: collection.Iterable[A] = toList
+  override def toStream: immutable.Stream[A] = toList.toStream // mind the laziness
+
 // New methods in ListBuffer
 
   /** Prepends the elements of this buffer to a given list