Jan 23, 2026
diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
        # Arbitrary keyword arguments are supported (but deprecated)
        with self.assertWarns(DeprecationWarning):
            self.assertEqual(ast.Constant(1, foo='bar').foo, 'bar')
        # gh-144169: non-string keys must not crash
        with self.assertWarns(DeprecationWarning):
            with self.assertRaises(TypeError):
                ast.Constant(1, **{object(): 'bar'})

        with self.assertRaisesRegex(TypeError, "Constant got multiple values for argument 'value'"):
            ast.Constant(1, value=2)
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
                else if (contains == 0) {
                    if (PyErr_WarnFormat(
                        PyExc_DeprecationWarning, 1,
                        "%.400s.__init__ got an unexpected keyword argument'%U'. "
                        "%.400s.__init__ got an unexpected keyword argument%R. "
                        "Support for arbitrary keyword arguments is deprecated "
                        "and will be removed in Python 3.15.",
                        Py_TYPE(self)->tp_name, key
diff --git a/Python/Python-ast.c b/Python/Python-ast.c
Original file line number	Diff line number	Diff line change
Expand Up		@@ -489,6 +489,10 @@ def test_classattrs(self):
		# Arbitrary keyword arguments are supported (but deprecated)
		with self.assertWarns(DeprecationWarning):
		self.assertEqual(ast.Constant(1, foo='bar').foo, 'bar')
		# gh-144169: non-string keys must not crash
		with self.assertWarns(DeprecationWarning):
		with self.assertRaises(TypeError):
		ast.Constant(1, **{object(): 'bar'})

		with self.assertRaisesRegex(TypeError, "Constant got multiple values for argument 'value'"):
		ast.Constant(1, value=2)
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -965,7 +965,7 @@ def visitModule(self, mod):
		else if (contains == 0) {
		if (PyErr_WarnFormat(
		PyExc_DeprecationWarning, 1,
		"%.400s.__init__ got an unexpected keyword argument'%U'. "
		"%.400s.__init__ got an unexpected keyword argument%R. "
		"Support for arbitrary keyword arguments is deprecated "
		"and will be removed in Python 3.15.",
		Py_TYPE(self)->tp_name, key
Expand Down