Re: musl as a framework to test applications' compatibility with POSIX (was: NULL)

[Rich Felker <dalias@aerifal.cx>]

On Mon, Jan 14, 2013 at 12:45:27PM +0400, Vasily Kulikov wrote:
> Hi,
> 
> On Mon, Jan 14, 2013 at 01:11 -0500, Rich Felker wrote:
> > In any case, this thread has gotten WAY off-topic, going all over the
> > place into territory about the merits and demerits of different
> > languages and anti-FSF politics. Those topics may be worth discussing
> > in some contexts, but it seems to have left everybody really confused
> > about the issues at hand, which are:
> > 
> > - whether we should work around broken programs that pass NULL to
> >   variadic functions
> > 
> > - and if so, how
> > 
> > The emerging consensus seems to be using
> > 
> > #define NULL 0L
> > 
> > unconditionally in both C and C++ mode.
> 
> If such slick and unobvious places of C/POSIX/C++/gcc/etc. applications
> are explicitly detected and handled, then probably it worth implementing
> some checker in libc/toolchain which is detected (probably at runtime)
> and warning is emitted at runtime/compile-time?  gcc'isms, UBs, etc.
> 
> In musl libc it can be implemented as -DI_WANT_TO_DETECT_GCCISMS.

At the very least, this would have to be a macro in the reserved
namespace. However, I'm skeptical of using musl as a tool for checking
this, especially since the check only works on 64-bit systems and does
not help the compiler produce a warning/error, but only causes random,
hard-to-diagnose crashes. It looks like cppcheck is adding (or has
already added?) a test for incorrectly passing NULL to variadic
functions, which is probably where the check belongs.

Rich