From d526f8bd74a3a6b878dda77bf19beb60dbc28f81 Mon Sep 17 00:00:00 2001
From: Jason Zaugg <jzaugg@gmail.com>
Date: Sat, 8 Dec 2012 09:30:42 +0100
Subject: SI-6690 Release reference to last dequeued element.

Avoids leaks in MutableList and its more better known child,
mutable.Queue, when the last element is dequeued or when we
take the tail of a one element collection.

Refactors copy/pasted code between the two implementations of
tail.
---
 test/files/run/t6690.scala | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 test/files/run/t6690.scala

(limited to 'test/files/run/t6690.scala')

diff --git a/test/files/run/t6690.scala b/test/files/run/t6690.scala
new file mode 100644
index 0000000000..43ede967a0
--- /dev/null
+++ b/test/files/run/t6690.scala
@@ -0,0 +1,62 @@
+import scala.collection.mutable
+
+object Test extends App {
+  def last0(ml: mutable.MutableList[Int]) =
+    ml.asInstanceOf[{def last0: mutable.LinkedList[Int]}].last0
+
+  def first0(ml: mutable.MutableList[Int]) =
+    ml.asInstanceOf[{def first0: mutable.LinkedList[Int]}].first0
+
+  val f = mutable.Queue[Int]()
+  def check(desc: String) {
+    assert(f.length == 0, s"$desc: non empty: $f")
+    assert(last0(f).isEmpty, s"$desc: last0 leak: ${last0(f)}")
+    assert(first0(f).isEmpty, s"$desc: first0 leak: ${last0(f)}")
+  }
+
+  f.enqueue(1)
+  f.dequeue()
+  check("dequeue 1")
+
+  f.enqueue(1)
+  f.enqueue(2)
+  f.dequeue()
+  assert(last0(f).toList == List(2), last0(f))
+  f.dequeue()
+  check("dequeue 2")
+
+  f.enqueue(1)
+  f.dequeueAll(_ => false)
+  f.dequeueAll(_ => true)
+  check("dequeueAll")
+
+  f.enqueue(1)
+  f.dequeueFirst(_ => true)
+  check("dequeueFirst")
+
+  {
+    f.enqueue(1)
+    val tail = f.tail
+    assert(last0(tail).isEmpty, last0(tail))
+    assert(first0(tail).isEmpty, first0(tail))
+  }
+
+  {
+    val ml = mutable.MutableList[Int]()
+    1 +=: ml
+    val tail = ml.tail
+    assert(last0(tail).isEmpty, last0(tail))
+    assert(first0(tail).isEmpty, first0(tail))
+  }
+
+  {
+    val ml = mutable.MutableList[Int]()
+    1 +=: ml
+    ml += 2
+    val tail = ml.tail
+    assert(last0(tail).toList == List(2), last0(tail))
+    assert(first0(tail) == last0(tail).toList, first0(tail))
+    assert(last0(tail.tail).toList == Nil, last0(tail.tail).toList)
+    assert(first0(tail.tail) == Nil, first0(tail.tail))
+  }
+}
-- 
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