bpo-31770: Prevent a crash and refleaks when calling sqlite3.Cursor.__init__() more than once (#3968)

1 files changed, 18 insertions, 0 deletions

diff --git a/Lib/sqlite3/test/regression.py b/Lib/sqlite3/test/regression.py
index 7dd0050528..3ff9abd989 100644
--- a/Lib/sqlite3/test/regression.py
+++ b/Lib/sqlite3/test/regression.py
@@ -24,6 +24,8 @@
 import datetime
 import unittest
 import sqlite3 as sqlite
+import weakref
+from test import support
 
 class RegressionTests(unittest.TestCase):
     def setUp(self):
@@ -376,6 +378,22 @@ class RegressionTests(unittest.TestCase):
                 counter += 1
         self.assertEqual(counter, 3, "should have returned exactly three rows")
 
+    def CheckBpo31770(self):
+        """
+        The interpreter shouldn't crash in case Cursor.__init__() is called
+        more than once.
+        """
+        def callback(*args):
+            pass
+        con = sqlite.connect(":memory:")
+        cur = sqlite.Cursor(con)
+        ref = weakref.ref(cur, callback)
+        cur.__init__(con)
+        del cur
+        # The interpreter shouldn't crash when ref is collected.
+        del ref
+        support.gc_collect()
+
 
 def suite():
     regression_suite = unittest.makeSuite(RegressionTests, "Check")