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

[Tom de Vries]

On 10/13/22 12:11, Tsukasa OI 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.
> 
> If HAVE_DECL_GETOPT is defined to 1 and include/getopt.h is included from
> GNU libc's <unistd.h>, declaration of getopt is suppressed, causing errors
> on getopt callers.  This issue is possibly hidden so long because there are
> not so many true getopt callers in Binutils, GDB and GCC.  Still, this issue
> needs to be fixed for following components:
> 
> -   Binutils: gprofng
>      (not currently affected due to the configuration script but will be)
> -   GDB (sim): M32C simulator
> -   GDB (sim): RL78 simulator
> 
> To avoid not defining proper getopt declaration, we have to check
> __need_getopt macro to detect this include path.  With this commit, even if
> HAVE_DECL_GETOPT is 1, getopt is declared if:
> 
> -   The standard C library is GNU libc and
> -   __need_getopt macro is defined (<unistd.h> includes <getopt.h> to
>      declare getopt function).
> 

I've put this into the gdb try-buildbot, and it fixes the centos 
regression : 
https://builder.sourceware.org/buildbot/#/builders/118/builds/17 .

I didn't get emails to that effect for some reason, but visual 
inspection at https://builder.sourceware.org/ of the try build bots at 
gdb shows all green.

Thanks,
- Tom

> include/ChangeLog:
> 
> 	* getopt.h: Detect special include path on GNU libc 2.25 or older
> 	to prevent not declaring getopt function when necessary.
> ---
>   include/getopt.h | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/include/getopt.h b/include/getopt.h
> index d8103f97483..e941b811ace 100644
> --- a/include/getopt.h
> +++ b/include/getopt.h
> @@ -104,7 +104,14 @@ struct option
>      declaration without arguments.  If it is 0, we checked and failed
>      to find the declaration so provide a fully prototyped one.  If it
>      is 1, we found it so don't provide any declaration at all.  */
> -#if !HAVE_DECL_GETOPT
> +/* 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 THIS getopt.h.  If HAVE_DECL_GETOPT is
> +   defined to 1 and this file is included from GNU libc's <unistd.h>,
> +   declaration of getopt is suppressed, causing errors on getopt callers.
> +   To avoid not defining proper getopt declaration, we have to check
> +   __need_getopt macro when built with GNU libc to detect this include path.  */
> +#if !HAVE_DECL_GETOPT || (defined (__GNU_LIBRARY__) && defined (__need_getopt))
>   #if defined (__GNU_LIBRARY__) || defined (HAVE_DECL_GETOPT)
>   /* Many other libraries have conflicting prototypes for getopt, with
>      differences in the consts, in unistd.h.  To avoid compilation
> 
> base-commit: 927b2f4caf46e5ca49684c9a52a9786425c60fa2