safety fix: do not access type struct field "tp_finalize" if the type states...

safety fix: do not access type struct field "tp_finalize" if the type states that it does not have it (because the struct might really be shorter in that case)

Cython/Compiler/ModuleNode.py

@@ -1350,8 +1350,9 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
             else:
                 finalised_check = (
                     '(!PyType_IS_GC(Py_TYPE(o)) || !_PyGC_FINALIZED(o))')
-            code.putln("if (unlikely(Py_TYPE(o)->tp_finalize) && %s) {" %
-                       finalised_check)
+            code.putln(
+                "if (unlikely(PyType_HasFeature(Py_TYPE(o), Py_TPFLAGS_HAVE_FINALIZE)"
+                " && Py_TYPE(o)->tp_finalize) && %s) {" % finalised_check)
             # if instance was resurrected by finaliser, return
             code.putln("if (PyObject_CallFinalizerFromDealloc(o)) return;")
             code.putln("}")