Jan 13, 2026 · Jan 12, 2026
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
                self.assertGreaterEqual(eq_count, 1)

    def test_clear_at_lookup(self):
        # gh-140551 dict crash if clear is called at lookup stage
        class X:
            def __hash__(self):
                return 1
        self.assertEqual(len(d), 1)

    def test_split_table_update_with_str_subclass(self):
        # gh-142218: inserting into a split table dictionary with a non str
        # key that matches an existing key.
        class MyStr(str): pass
        class MyClass: pass
        obj = MyClass()
        obj.attr = 1
        obj.__dict__[MyStr('attr')] = 2
        self.assertEqual(obj.attr, 2)

    def test_split_table_insert_with_str_subclass(self):
        # gh-143189: inserting into split table dictionary with a non str
        # key that matches an existing key in the shared table but not in
        # the dict yet.

        class MyStr(str): pass
        class MyClass: pass

        obj = MyClass()
        obj.attr1 = 1

        obj2 = MyClass()
        d = obj2.__dict__
        d[MyStr("attr1")] = 2
        self.assertIsInstance(list(d)[0], MyStr)


 class CAPITest(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Core and Builtins/2025-12-30-06-48-48.gh-issue-143189.in_sv2.rst b/Misc/NEWS.d/next/Core and Builtins/2025-12-30-06-48-48.gh-issue-143189.in_sv2.rst
 Fix crash when inserting a non-:class:`str` key into a split table
 dictionary when the key matches an existing key in the split table
 but has no corresponding value in the dict.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
 insertdict(PyInterpreterState *interp, PyDictObject *mp,
           PyObject *key, Py_hash_t hash, PyObject *value)
 {
    PyObject *old_value;
    PyObject *old_value = NULL;
    Py_ssize_t ix;

    ASSERT_DICT_LOCKED(mp);

    }

    if (ix ==DKIX_EMPTY) {
    if (old_value ==NULL) {
        // insert_combined_dict() will convert from non DICT_KEYS_GENERAL table
        // into DICT_KEYS_GENERAL table if key is not Unicode.
        // We don't convert it before _Py_dict_lookup because non-Unicode key
        // may change generic table into Unicode table.
        //
        // NOTE: ix may not be DKIX_EMPTY because split table may have key
        // without value.
        if (insert_combined_dict(interp, mp, hash, key, value) < 0) {
            goto Fail;
        }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1655,6 +1655,7 @@ def make_pairs():
		self.assertGreaterEqual(eq_count, 1)

		def test_clear_at_lookup(self):
		# gh-140551 dict crash if clear is called at lookup stage
		class X:
		def __hash__(self):
		return 1
Expand All		@@ -1675,13 +1676,31 @@ def __eq__(self, other):
		self.assertEqual(len(d), 1)

		def test_split_table_update_with_str_subclass(self):
		# gh-142218: inserting into a split table dictionary with a non str
		# key that matches an existing key.
		class MyStr(str): pass
		class MyClass: pass
		obj = MyClass()
		obj.attr = 1
		obj.__dict__[MyStr('attr')] = 2
		self.assertEqual(obj.attr, 2)

		def test_split_table_insert_with_str_subclass(self):
		# gh-143189: inserting into split table dictionary with a non str
		# key that matches an existing key in the shared table but not in
		# the dict yet.

		class MyStr(str): pass
		class MyClass: pass

		obj = MyClass()
		obj.attr1 = 1

		obj2 = MyClass()
		d = obj2.__dict__
		d[MyStr("attr1")] = 2
		self.assertIsInstance(list(d)[0], MyStr)


		class CAPITest(unittest.TestCase):

Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		Fix crash when inserting a non-:class:`str` key into a split table
		dictionary when the key matches an existing key in the split table
		but has no corresponding value in the dict.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1832,7 +1832,7 @@ static int
		insertdict(PyInterpreterState interp, PyDictObject mp,
		PyObject key, Py_hash_t hash, PyObject value)
		{
		PyObject *old_value;
		PyObject *old_value = NULL;
		Py_ssize_t ix;

		ASSERT_DICT_LOCKED(mp);
Expand All		@@ -1856,11 +1856,14 @@ insertdict(PyInterpreterState interp, PyDictObject mp,

		}

		if (ix ==DKIX_EMPTY) {
		if (old_value ==NULL) {
		// insert_combined_dict() will convert from non DICT_KEYS_GENERAL table
		// into DICT_KEYS_GENERAL table if key is not Unicode.
		// We don't convert it before _Py_dict_lookup because non-Unicode key
		// may change generic table into Unicode table.
		//
		// NOTE: ix may not be DKIX_EMPTY because split table may have key
		// without value.
		if (insert_combined_dict(interp, mp, hash, key, value) < 0) {
		goto Fail;
		}
Expand Down