Make PyInitConfig_Free(NULL) a no-op

[serhiy-storchaka]

Feature or enhancement

I think that it would simplify the code if make PyInitConfig_Free(NULL) a no-op. Currently it requires the argument to be non-NULL. This would simplify the code:

PyInitConfig *config = NULL;
// some code
if (error_occurred) {
    goto Error;
}
config = PyInitConfig_Create();
if (config == NULL) {
    goto Error;
}
// some other code
if (error_occurred) {
    goto Error;
}
// more code
Error:
// release resources
if (config == NULL) {
    PyInitConfig_Free(config);
}
// release resources

Most Python resources are represented as Python objects, so Py_XDECREF(NULL) works for them. PyMem_Free(NULL) and PyRawMem_Free(NULL) work for raw memory blocks. PyInitConfig_Free() is one of few (or only one) API that cannot be used in such idiom.

Linked PRs

• gh-125234: Make PyInitConfig_Free(NULL) a no-op #125266

[efimov-mikhail]

is one of few (or only one)

I've made a list of such function implementations.

-> % grep -rnI 'PyAPI.*Py.*Free' | sed 's/.*) //' | grep -v '^_Py' 
PyMem_Free(void *ptr);
PyMem_RawFree(void *ptr);
PyObject_Free(void *ptr);
PyCode_GetFreevars(PyCodeObject *code);
PyInitConfig_Free(PyInitConfig *config);
PyInitConfig_FreeStrList(size_t length, char **items);

Function PyCode_GetFreevars, obviously, is not from the list of free functions.
From other 5 functions only PyInitConfig_Free can not be called with NULL.

IMO, make PyInitConfig_Free(NULL) a no-op is a good idea.