Disable spurious -Warray-bounds for ypclnt.c (bug 26687)

[DJ Delorie]

Joseph Myers <joseph@codesourcery.com> writes:
> Included among the GCC 11 warnings listed in bug 26687, but not fixed
> when that bug was marked as FIXED, are -Warray-bounds warnings in
> nis/ypclnt.c.  These are all for different calls to the same piece of
> code, which already has a comment explaining that the element accessed
> is in a common prefix of the various structures.  On the basis of that
> comment, this patch treats the warning as a false positive and
> disables it for that code.

Understood...

> diff --git a/nis/ypclnt.c b/nis/ypclnt.c
> +#include <libc-diag.h>

Ok.

> +  DIAG_PUSH_NEEDS_COMMENT;
> +  /* This cast results in a warning that a ypresp_val is partly
> +     outside the bounds of the actual object referenced, but as
> +     explained below only the stat element (in a common prefix) is
> +     accessed.  */
> +  DIAG_IGNORE_NEEDS_COMMENT (11, "-Warray-bounds");
>    if (status == YPERR_SUCCESS)
>      /* We cast to ypresp_val although the pointer could also be of
>         type ypresp_key_val or ypresp_master or ypresp_order or
>         ypresp_maplist.  But the stat element is in a common prefix so
>         this does not matter.  */
>      status = ypprot_err (((struct ypresp_val *) resp)->stat);
> +  DIAG_POP_NEEDS_COMMENT;

Ok.  I suppose there are more "clever" ways of hiding this (as noted in
other emails, like supersets, etc) or even casting to ypstat* directly,
but this does what you intend nonetheless.

LGTM.

Reviewed-by: DJ Delorie <dj@redhat.com>