printf_arginfo_size_function error handling

["Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>]

Hi,

I've been re-reading the docs for printf_register_specifier(), and
there's something in an example code that doesn't make much sense:

<https://www.gnu.org/software/libc/manual/html_node/Printf-Extension-Example.html>
[[

int
print_widget_arginfo (const struct printf_info *info, size_t n,
                      int *argtypes)
{
  /* We always take exactly one argument and this is a pointer to the
     structure.. */
  if (n > 0)
    argtypes[0] = PA_POINTER;
  return 1;
}

]]

In the code above there is a check that n>0, but:

What can a user do if n<=0 ?  There's no error reporting method, is there?
And, is it possible for such a case to happen?  What to do there?

I think either using an assert() or not checking at all might make more
sense (depending on how possible is n<=0 to happen).  The current check
continues as if everything was fine, just without setting argtypes[0],
so if there's an error, it will be carried to some future stage, where
nasal daemons might unexpectedly happen.

Thanks,

Alex

-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/