Re: [Bug?] SIG2STR_MAX not good for #if

[Joel Sherrill <joel@rtems.org>]

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On Mon, Jun 19, 2023, 4:00 AM Corinna Vinschen <vinschen@redhat.com> wrote:

> On Jun 19 14:15, Mingye Wang wrote:
> > When building schilytools on MSYS2, I got hit with:
> >
> > ```
> > defs.h:1288:21: error: missing binary operator before token "("
> >  1288 | #if     NUMBUFLEN < SIG2STR_MAX
> > ```
> >
> > For context, the source goes:
> >
> > ```
> > #define     NUMBUFLEN   21  /* big enough for 64 bits */
> > #if NUMBUFLEN < SIG2STR_MAX
> > #undef      NUMBUFLEN
> > #define     NUMBUFLEN   (SIG2STR_MAX-1)
> > #endif
> > ```
> >
> > A cursory inspection of /usr/include leads me to this "#define
> > SIG2STR_MAX (sizeof("RTMAX+") + sizeof("4294967295") - 1)" definition;
> > redefining it with a plain number makes the build go through. Looking
> > up the newlib source code, it appears that the definition is not
> > specific to MSYS2 or Cygwin, but common to all newlib distributions.
> >
> > The wording proposed for SIG2STR_MAX by geoffclare in comment 4975[1]
> > under the POSIX issue 8 bug report requires that the definition is
> > suitable for #if, which newlib currently violates. Now this isn't
> > quite standard yet and is subject to change, so I can't say for sure
> > this is newlib's bug.
> >
> >   [1]: https://www.austingroupbugs.net/view.php?id=1138#c4975
>
> We could redefine SIG2STR_MAX as static values (still dependent on
> __SIZEOF_INT__) and prepend the sizeof expressions as comments.
>

FWIW This appears to be a common extension and ere does not appear in the
POSIX standard.

Given that, it should be compatible with glibc

--joel

>
> Do you want to provide a patch?
>
>
> Thanks,
> Corinna
>
>