`pythonrun.c`: main_module ref leak in `_PyRun_SimpleStringFlagsWithName`

[A0su]

Bug report

Bug description:

Bug report

Bug description:

This is a sub-issue for #146102 and original gist details can be found here

Existing code:

int
_PyRun_SimpleStringFlagsWithName(const char *command, const char* name, PyCompilerFlags *flags) {
    PyObject *main_module = PyImport_AddModuleRef("__main__");
    if (main_module == NULL) {
        return -1;
    }
    PyObject *dict = PyModule_GetDict(main_module);  // borrowed ref

    PyObject *res = NULL;
    if (name == NULL) {
        res = PyRun_StringFlags(command, Py_file_input, dict, dict, flags);
    } else {
        PyObject* the_name = PyUnicode_FromString(name);
        if (!the_name) {
            PyErr_Print();
            return -1;
        }
        res = _PyRun_StringFlagsWithName(command, the_name, Py_file_input, dict, dict, flags, 0);
        Py_DECREF(the_name);
    }
    Py_DECREF(main_module);
    if (res == NULL) {
        PyErr_Print();
        return -1;
    }

    Py_DECREF(res);
    return 0;
}

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-146355: Fix main_module ref leak in _PyRun_SimpleStringFlagsWithName #146356