[sr-dev] [kamailio/kamailio] python3: `PyErr_SetString` is a void function. It doesn't return NULL. (PR #3231)

[Matthias Urlichs]

Just compile the old code! You get a ton of warnings that PyErr_SetString "returns" `void`.

Python has, at heart, a very simple API. A C function **either** returns an object **or** it sets an exception (and returns NULL). Never both! (Or None for that matter.)

PyNone is a regular Python object. NULL is not, it's the API's marker for raising an exception.

Thus, the old code works perfectly well as long as it doesn't raise an exception. If/when it does, depending on the whims of the C compiler, the return value for the old version might be anything whatsoever. Even NULL if you're lucky.

Python has a ton of somewhat-higher-level error-generating functions which explicitly return NULL so that you can use the old construct but sadly PyErr_SetString is not one of these.

https://docs.python.org/3/c-api/exceptions.html

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