Merge branch '2.11.x' into topic/merge-2.11.x-to-2.12.x-20160210

Conflicts:
	src/library/scala/collection/Iterator.scala
	|
	`-- trivial conflicts only. Parens were added to the
	    next() calls in 2.12.x, while in the meantime
	    `{Concat,Join}Iterator` were optimized in 2.11.x

1 files changed, 28 insertions, 0 deletions

diff --git a/test/junit/scala/collection/IteratorTest.scala b/test/junit/scala/collection/IteratorTest.scala
index b0639ef365..4df29e36c0 100644
--- a/test/junit/scala/collection/IteratorTest.scala
+++ b/test/junit/scala/collection/IteratorTest.scala
@@ -186,4 +186,32 @@ class IteratorTest {
     assertEquals(1, y.next)
     assertFalse(x.hasNext)   // was true, after advancing underlying iterator
   }
+  // SI-9623
+  @Test def noExcessiveHasNextInJoinIterator: Unit = {
+    var counter = 0
+    val exp = List(1,2,3,1,2,3)
+    def it: Iterator[Int] = new Iterator[Int] {
+      val parent = List(1,2,3).iterator
+      def next(): Int = parent.next
+      def hasNext: Boolean = { counter += 1; parent.hasNext }
+    }
+    // Iterate separately
+    val res = new mutable.ArrayBuffer[Int]
+    it.foreach(res += _)
+    it.foreach(res += _)
+    assertSameElements(exp, res)
+    assertEquals(8, counter)
+    // JoinIterator
+    counter = 0
+    res.clear
+    (it ++ it).foreach(res += _)
+    assertSameElements(exp, res)
+    assertEquals(8, counter) // was 17
+    // ConcatIterator
+    counter = 0
+    res.clear
+    (Iterator.empty ++ it ++ it).foreach(res += _)
+    assertSameElements(exp, res)
+    assertEquals(8, counter) // was 14
+  }
 }