Function pgrx_pg_sys::get_func_arg_info

pub unsafe fn get_func_arg_info(
    arg_procTup: HeapTuple,
    arg_p_argtypes: *mut *mut Oid,
    arg_p_argnames: *mut *mut *mut c_char,
    arg_p_argmodes: *mut *mut c_char
) -> c_int