Functions setting exceptions

Hello, attached there is a patch to implement PySequence_SetItem, which *doesn't* steal a reference as the PyList/PyTuple variants do, and returns 0 on success, -1 on error. After cleaning many genuine errors in psycopg, mostly about unchecked return values, I'm left with several false positives related exactly to this type of functions, returning 0 on success, -1 on failure and setting an exception. Each of these functions caller is reported as "returning (PyObject*)NULL without setting an exception". Is there any way to flag the behaviour of these functions? An __attribute__? I'm trying implementing it but time is out for tonight. I've find how to register the attribute callback but haven't found yet where and how to use it. -- Daniele