Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > >> I'm not sure that macros can have variable number of arguments on all
> > >> supported platforms. I've been burnt by this before.
> >
> > > The actual patch is:
> >
> > > + #ifdef __GNUC__
> > > + #define vsnprintf(...) pg_vsnprintf(__VA_ARGS__)
> > > + #define snprintf(...) pg_snprintf(__VA_ARGS__)
> > > + #define printf(...) pg_printf(__VA_ARGS__)
> > > + #else
> > > + #define vsnprintf pg_vsnprintf
> > > + #define snprintf pg_snprintf
> > > + #define printf pg_printf
> > > + #endif
> >
> > Uh, why bother with the different approach for gcc?
>
> Because if we don't do that then the code above fails:
>
> extern int pg_snprintf(char *str, size_t count, const char *fmt,...)
> /* This extension allows gcc to check the format string */
> __attribute__((format(printf, 3, 4)));
>
> The issue is that the "printf" here is interpreted specially by the
> compiler to mean "check arguments as printf". If the preprocessor
> changes that, we get a failure. The good news is that only gcc supports
> arg checking using __attribute__ and it also supports the __VA_ARGS__
> macros. What I think we do lose is argument checking for non-gcc, but
> this seems as close as we can get.
I am adding a comment explaining why those macros are used.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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