Issue #3680: Reference cycles created through a dict, set or deque iterator did not get collected.

3 files changed, 48 insertions, 4 deletions

diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 0f0d098..4e2de3d 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -1,7 +1,8 @@
 from collections import deque
 import unittest
 from test import test_support, seq_tests
-from weakref import proxy
+import gc
+import weakref
 import copy
 import cPickle as pickle
 import random
@@ -418,6 +419,22 @@ class TestBasic(unittest.TestCase):
             d.append(1)
             gc.collect()
 
+    def test_container_iterator(self):
+        # Bug # XXX: tp_traverse was not implemented for deque iterator objects
+        class C(object):
+            pass
+        for i in range(2):
+            obj = C()
+            ref = weakref.ref(obj)
+            if i == 0:
+                container = deque([obj, 1])
+            else:
+                container = reversed(deque([obj, 1]))
+            obj.x = iter(container)
+            del obj, container
+            gc.collect()
+            self.assert_(ref() is None, "Cycle was not collected")
+
 class TestVariousIteratorArgs(unittest.TestCase):
 
     def test_constructor(self):
@@ -528,7 +545,7 @@ class TestSubclass(unittest.TestCase):
 
     def test_weakref(self):
         d = deque('gallahad')
-        p = proxy(d)
+        p = weakref.proxy(d)
         self.assertEqual(str(p), str(d))
         d = None
         self.assertRaises(ReferenceError, str, p)
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index f715657..14d62f5 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -2,6 +2,7 @@ import unittest
 from test import test_support
 
 import UserDict, random, string
+import gc, weakref
 
 
 class DictTest(unittest.TestCase):
@@ -554,6 +555,19 @@ class DictTest(unittest.TestCase):
             pass
         d = {}
 
+    def test_container_iterator(self):
+        # Bug # XXX: tp_traverse was not implemented for dictiter objects
+        class C(object):
+            pass
+        iterators = (dict.iteritems, dict.itervalues, dict.iterkeys)
+        for i in iterators:
+            obj = C()
+            ref = weakref.ref(obj)
+            container = {obj: 1}
+            obj.x = i(container)
+            del obj, container
+            gc.collect()
+            self.assert_(ref() is None, "Cycle was not collected")
 
 
 from test import mapping_tests
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index d38a675..8d05712 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -1,6 +1,7 @@
 import unittest
 from test import test_support
-from weakref import proxy
+import gc
+import weakref
 import operator
 import copy
 import pickle
@@ -322,6 +323,18 @@ class TestJointOps(unittest.TestCase):
         self.assertEqual(sum(elem.hash_count for elem in d), n)
         self.assertEqual(d3, dict.fromkeys(d, 123))
 
+    def test_container_iterator(self):
+        # Bug # XXX: tp_traverse was not implemented for set iterator object
+        class C(object):
+            pass
+        obj = C()
+        ref = weakref.ref(obj)
+        container = set([obj, 1])
+        obj.x = iter(container)
+        del obj, container
+        gc.collect()
+        self.assert_(ref() is None, "Cycle was not collected")
+
 class TestSet(TestJointOps):
     thetype = set
 
@@ -538,7 +551,7 @@ class TestSet(TestJointOps):
 
     def test_weakref(self):
         s = self.thetype('gallahad')
-        p = proxy(s)
+        p = weakref.proxy(s)
         self.assertEqual(str(p), str(s))
         s = None
         self.assertRaises(ReferenceError, str, p)