Issue #26494: Fixed crash on iterating exhausting iterators.

Affected classes are generic sequence iterators, iterators of bytearray,
list, tuple, set, frozenset, dict, OrderedDict and corresponding views.

9 files changed, 62 insertions, 1 deletions

diff --git a/Lib/test/seq_tests.py b/Lib/test/seq_tests.py
index f4673d4..f019e8d 100644
--- a/Lib/test/seq_tests.py
+++ b/Lib/test/seq_tests.py
@@ -4,6 +4,7 @@ Tests common to tuple, list and UserList.UserList
 
 import unittest
 import sys
+from test import test_support as support
 
 # Various iterables
 # This is used for checking the constructor (here and in test_deque.py)
@@ -402,3 +403,7 @@ class CommonTest(unittest.TestCase):
         self.assertEqual(a.index(0, -4*sys.maxint, 4*sys.maxint), 2)
         self.assertRaises(ValueError, a.index, 0, 4*sys.maxint,-4*sys.maxint)
         self.assertRaises(ValueError, a.index, 2, 0, -10)
+
+    def test_free_after_iterating(self):
+        support.check_free_after_iterating(self, iter, self.type2test)
+        support.check_free_after_iterating(self, reversed, self.type2test)
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 02fba38..82ad451 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -518,6 +518,10 @@ class BaseBytesTest(unittest.TestCase):
         self.assertRaisesRegexp(TypeError, r'\bendswith\b', b.endswith,
                                 x, None, None, None)
 
+    def test_free_after_iterating(self):
+        test.test_support.check_free_after_iterating(self, iter, self.type2test)
+        test.test_support.check_free_after_iterating(self, reversed, self.type2test)
+
 
 class ByteArrayTest(BaseBytesTest):
     type2test = bytearray
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 13ea02f..b4efa65 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -669,6 +669,10 @@ class TestSubclassWithKwargs(unittest.TestCase):
         # SF bug #1486663 -- this used to erroneously raise a TypeError
         SubclassWithKwargs(newarg=1)
 
+    def test_free_after_iterating(self):
+        # For now, bypass tests that require slicing
+        self.skipTest("Exhausted deque iterator doesn't free a deque")
+
 #==============================================================================
 
 libreftest = """
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 1c63fc0..4474c9b 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -681,6 +681,15 @@ class DictTest(unittest.TestCase):
         self._tracked(MyDict())
 
 
+    def test_free_after_iterating(self):
+        test_support.check_free_after_iterating(self, iter, dict)
+        test_support.check_free_after_iterating(self, lambda d: d.iterkeys(), dict)
+        test_support.check_free_after_iterating(self, lambda d: d.itervalues(), dict)
+        test_support.check_free_after_iterating(self, lambda d: d.iteritems(), dict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewkeys()), dict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewvalues()), dict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewitems()), dict)
+
 from test import mapping_tests
 
 class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py
index bd1b32d..4495fa1 100644
--- a/Lib/test/test_iter.py
+++ b/Lib/test/test_iter.py
@@ -2,7 +2,8 @@
 
 import unittest
 from test.test_support import run_unittest, TESTFN, unlink, have_unicode, \
-                              check_py3k_warnings, cpython_only
+                              check_py3k_warnings, cpython_only, \
+                              check_free_after_iterating
 
 # Test result of triple loop (too big to inline)
 TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
@@ -921,6 +922,9 @@ class TestCase(unittest.TestCase):
         lst.extend(gen())
         self.assertEqual(len(lst), 760)
 
+    def test_free_after_iterating(self):
+        check_free_after_iterating(self, iter, SequenceClass, (0,))
+
 
 def test_main():
     run_unittest(TestCase)
diff --git a/Lib/test/test_ordered_dict.py b/Lib/test/test_ordered_dict.py
index 78b3e83..85e4841 100644
--- a/Lib/test/test_ordered_dict.py
+++ b/Lib/test/test_ordered_dict.py
@@ -267,6 +267,15 @@ class TestOrderedDict(unittest.TestCase):
         items = [('a', 1), ('c', 3), ('b', 2)]
         self.assertEqual(list(MyOD(items).items()), items)
 
+    def test_free_after_iterating(self):
+        test_support.check_free_after_iterating(self, iter, OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: d.iterkeys(), OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: d.itervalues(), OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: d.iteritems(), OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewkeys()), OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewvalues()), OrderedDict)
+        test_support.check_free_after_iterating(self, lambda d: iter(d.viewitems()), OrderedDict)
+
 class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
     type2test = OrderedDict
 
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index d9ea098..6baaccf 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -340,6 +340,9 @@ class TestJointOps(unittest.TestCase):
         gc.collect()
         self.assertTrue(ref() is None, "Cycle was not collected")
 
+    def test_free_after_iterating(self):
+        test_support.check_free_after_iterating(self, iter, self.thetype)
+
 class TestSet(TestJointOps):
     thetype = set
 
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index 956936f..85f9965 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -1659,3 +1659,21 @@ def strip_python_stderr(stderr):
     """
     stderr = re.sub(br"\[\d+ refs\]\r?\n?$", b"", stderr).strip()
     return stderr
+
+
+def check_free_after_iterating(test, iter, cls, args=()):
+    class A(cls):
+        def __del__(self):
+            done[0] = True
+            try:
+                next(it)
+            except StopIteration:
+                pass
+
+    done = [False]
+    it = iter(A(*args))
+    # Issue 26494: Shouldn't crash
+    test.assertRaises(StopIteration, next, it)
+    # The sequence should be deallocated just after the end of iterating
+    gc_collect()
+    test.assertTrue(done[0])
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 63fb831..93224e1 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1857,6 +1857,11 @@ class UnicodeTest(
                     unicode_encodedecimal(u"123" + s, "xmlcharrefreplace"),
                     '123' + exp)
 
+    def test_free_after_iterating(self):
+        test_support.check_free_after_iterating(self, iter, unicode)
+        test_support.check_free_after_iterating(self, reversed, unicode)
+
+
 def test_main():
     test_support.run_unittest(__name__)