>>> So what is the point of _PyObject_GC_Calloc ?
>>
>> It calls calloc(size) instead of malloc(size)
>
> No, the question is why you didn't simply change _PyObject_GC_Malloc
> (which is a private function).

Oh ok, I didn't understand. I don't like changing the behaviour of
functions, but it's maybe fine if the function is private.