[PATCH] include: Declare getopt function on old GNU libc

[Tsukasa OI]

On 2022/10/13 20:59, Pedro Alves wrote:
> On 2022-10-13 11:11 a.m., Tsukasa OI via Binutils wrote:
>> On GNU libc <= 2.25, <unistd.h> includes <getopt.h> with __need_getopt macro
>> defined.  That <getopt.h> is intended to be a part of GNU libc but
>> <unistd.h> actually includes include/getopt.h in this project.
> 
> Messy.

Well, I have to agree.

> 
> Do we really still need this getopt.h header?
> 
> gnulib, at:
> 
>  https://www.gnu.org/software/gnulib/manual/html_node/getopt_002eh.html
> 
> says:
> 
>   "This header file is missing on some platforms: AIX 5.1, HP-UX 11, MSVC 14."
> 
> AIX 5.1 is from 2001.
> HP-UX 11 is from 1997.
> We don't support building with MSVC AFAIK.
> 
> Can't we just get rid of it?
> 

I feel this is too unsafe to do that (unless you assume getopt_long and
getopt_long_only are always available on the system).

Even if this patch is unacceptable, I don't want to revert previous
changes to sim/configure{,.ac} either (it's necessary to prevent a build
failure with Clang).  It's also a hack but to stop using getopt
(entirely) may be an option, changing following files:

-   sim/igen/igen.c
-   sim/m32c/main.c
-   sim/rl78/main.c

I mean, we could replace getopt with getopt_long plus dummy longopts.
This way, CentOS (7) regression will (also) be gone.

What do you think?

Thanks,
Tsukasa