Re: compatability: bits/syscall.h requires C99

[Rich Felker <dalias@aerifal.cx>]

On Thu, Aug 23, 2012 at 10:07:49PM -0400, Rich Felker wrote:
> > OTOH, s/inline/__inline/g is probably better/more universal, since
> > __inline is supported on some alternate compilers.
> 
> No, that reduces musl's public interface from portable C99 to
> compiler-specific crap.

OK, after discussion on IRC, the 2 options under consideration are:

#if __STDC_VERSION__ < 199901L && defined(__GNUC__)
#define inline __inline
#define restrict __restrict
#elif __STDC_VERSION__ < 199901L
#define inline
#define restrict
#endif

and

#if __STDC_VERSION__ >= 199901L
#define __inline inline
#define __restrict restrict
#endif

added near the top of headers that need to use inline and/or restrict.

The former version has the benefit that the "inline" and "restrict"
keywords can be used as-is later in the header, without any __
uglification. The latter version has the benefit that it's fewer lines
of spam, does not explicitly refer to "GNU C", and that it does not
break the gratuitously-C99-incompatible C89 programs like

int main(int inline, char **restrict) { }

I'm not sure if this last issue really matters; certainly there are
plenty unfixable ways C89 programs can fail on a C99 implementation,
like:

assert(strtod("0x1",0)==0);

I'm kind of leaning towards the latter but I'd like to hear some
opinions before a final change is made. Whichever way we decide, I
think it'll make it possible to go and retrofit "restrict" everwhere
it belongs in the headers, which will in turn lead to better code in
some parts of musl.

Rich