bpo-47128: Enhance Argument Clinic's NoneType return converter to give void

[arhadthedev]

This PR makes the following possible (note that the impl has a void return type):

/*[clinic input]
_io._IOBase.writelines -> NoneType
    lines: object
    /
[clinic start generated code]*/

static void
_io__IOBase_writelines_impl(PyObject *self, PyObject *lines)
/*[clinic end generated code: output=f3feca36db72dbd1 input=286ba711cb7291ad]*/

Previously, the return type would be Object * and a caller would replace non-Py_None values with NULL.

So now there is no need to track whether NULL or Py_None should be returned. Or should it be Py_RETURN_NONE? Argument Clinic does it by itself returning NULL on errors and Py_None otherwise:

static PyObject *
_io__IOBase_writelines(PyObject *self, PyObject *lines)
{
    PyObject *return_value = NULL;

    _io__IOBase_writelines_impl(self, lines);
    if (PyErr_Occurred()) {
        goto exit;
    }
    return_value = Py_None;
    Py_INCREF(Py_None);

exit:
    return return_value;
}

https://bugs.python.org/issue47128

[arhadthedev]

Tests / Check if generated files are up to date fails with the following report.

make regen-deepfreeze
make[1]: Entering directory '/home/runner/work/cpython/cpython'
./_bootstrap_python ./Programs/_freeze_module.py abc ./Lib/abc.py Python/frozen_modules/abc.h
make[1]: execvp: ./_bootstrap_python: Permission denied
make[1]: *** [Makefile:1194: Python/frozen_modules/abc.h] Error 127
make[1]: Leaving directory '/home/runner/work/cpython/cpython'
make: *** [Makefile:1313: regen-global-objects] Error 2
make: *** Waiting for unfinished jobs....

All other checks pass. Reopening the PR to retrigger the checks.

[arhadthedev]

The feature calls GIL-taking PyErr_Occurred. So I close the PR until GIL is removed so performance penalty decreases.

[arhadthedev]

GH-95019 fully removed the NoneType return converter. As a result, this PR has no sense to be reopened anymore.