Fix size update on `mutable.TreeMap#clear()`

The previous implementation has a major bug - although `clear()` sets the root node to `null`, the `size` attribute of the `Tree` was not updated. This effectively meant that even after a `map.clear()`, a call to `map.size` would still yield the old size of the map.

The scalacheck test suite was updated to contemplate this issue.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/library/scala/collection/mutable/TreeMap.scala b/src/library/scala/collection/mutable/TreeMap.scala
index 244cc18735..b96cef5bee 100644
--- a/src/library/scala/collection/mutable/TreeMap.scala
+++ b/src/library/scala/collection/mutable/TreeMap.scala
@@ -64,7 +64,7 @@ sealed class TreeMap[A, B] private (tree: RB.Tree[A, B])(implicit val ordering:
   def keysIteratorFrom(start: A) = RB.keysIterator(tree, Some(start))
   def valuesIteratorFrom(start: A) = RB.valuesIterator(tree, Some(start))
 
-  override def size = tree.size
+  override def size = RB.size(tree)
   override def isEmpty = RB.isEmpty(tree)
   override def contains(key: A) = RB.contains(tree, key)
 
@@ -78,7 +78,7 @@ sealed class TreeMap[A, B] private (tree: RB.Tree[A, B])(implicit val ordering:
 
   override def foreach[U](f: ((A, B)) => U): Unit = RB.foreach(tree, f)
   override def transform(f: (A, B) => B) = { RB.transform(tree, f); this }
-  override def clear(): Unit = tree.root = null
+  override def clear(): Unit = RB.clear(tree)
 
   override def stringPrefix = "TreeMap"