Re: check for C99-compliant snprintf

[Albert Chin]

On Mon, Feb 19, 2007 at 04:47:47PM -0800, Ben Pfaff wrote:
> Albert Chin <address@hidden> writes:
> 
> > On Mon, Feb 19, 2007 at 03:53:10PM -0800, Ben Pfaff wrote:
> >> Albert Chin <address@hidden> writes:
> >> 
> >> > Huh? So, if vsnprintf() exists, you assume it's C99-compliant? glib
> >> > has a check for this, AC_FUNC_VSNPRINTF_C99, because that's not the
> >> > case on some systems. And, we found that Solaris and AIX 5.1 do not
> >> > have a C99-compliant vsnprintf(). The attached program returns -1 on
> >> > Solaris 6/SPARC thru Solaris 9/SPARC which has vsnprintf(), for
> >> > example.
> >> 
> >> It's not hard to check at runtime whether [v]snprintf is
> >> C99-compliant, as your example shows.  A previous version of my
> >> proposed change did just that.  Paul Eggert requested that I try
> >> to make it a compile- or link-time check, because the alternative
> >> was to assume that [v]snprintf needed to be replaced if we were
> >> cross-compiling.  I wasn't aware that these other systems have
> >> non-compliant [v]snprintf, so I didn't check for them.
> >> 
> >> Is it better to try to enumerate non-compliant systems at
> >> compile/link time, or to assume non-compliance when
> >> cross-compiling?  Neither choice is ideal.  What's more likely to
> >> be accepted into gnulib?
> >
> > How about assuming compliance when cross-compliance but enumerate,
> > when cross-compiling, the systems that fail? When not cross-compiling,
> > let's perform the compile-time check.
> 
> I'm willing to fix my proposed change so that it does this.
> 
> It appears, based on online documentation, that snprintf is C99
> compliant in AIX 5.2 and above.  Is that correct?

Correct.

> If so, then will the following successfully detect the systems with
> broken snprintf: 
>         #if defined _AIX && !defined _AIX52
>         /* broken */
>         #endif
> 
> How do you test for Solaris 6 through 9?  The list at
> predef.sf.net is not very helpful on this, because it doesn't
> give any hint how to test for a range of Solaris versions, only
> for particular versions.

I doubt anyone is cross-compiling on Solaris or AIX so I just wouldn't
worry about the cross-compiler case for them.

-- 
albert chin (address@hidden)