Re: [pgsql-hackers-win32] snprintf causes regression

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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.

> Also, what happened to fprintf? We're going to need that too for
> localization of the client programs.

It was never there. I will add it now.

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