Issue #26718: super.__init__ no longer leaks memory if called multiple times.

NOTE: A direct call of super.__init__ is not endorsed!

Lib/test/test_super.py

@@ -171,6 +171,15 @@ class TestSuper(unittest.TestCase):
         c = f().__closure__[0]
         self.assertRaises(TypeError, X.meth, c)
 
+    def test_super_init_leaks(self):
+        # Issue #26718: super.__init__ leaked memory if called multiple times.
+        # This will be caught by regrtest.py -R if this leak.
+        # NOTE: Despite the use in the test a direct call of super.__init__
+        # is not endorsed.
+        sp = super(float, 1.0)
+        for i in range(1000):
+            super.__init__(sp, int, i)
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS

@@ -10,6 +10,9 @@ Release date: tba
 Core and Builtins
 -----------------
 
+- Issue #26718: super.__init__ no longer leaks memory if called multiple times.
+  NOTE: A direct call of super.__init__ is not endorsed!
+
 - Issue #25339: PYTHONIOENCODING now has priority over locale in setting the
   error handler for stdin and stdout.
 

Objects/typeobject.c

@@ -7336,9 +7336,9 @@ super_init(PyObject *self, PyObject *args, PyObject *kwds)
         Py_INCREF(obj);
     }
     Py_INCREF(type);
-    su->type = type;
-    su->obj = obj;
-    su->obj_type = obj_type;
+    Py_XSETREF(su->type, type);
+    Py_XSETREF(su->obj, obj);
+    Py_XSETREF(su->obj_type, obj_type);
     return 0;
 }