Clean up *printf macros to avoid conflict with format archetypes.

We must define the macro "printf" with arguments, else it can mess
up format archetype attributes in builds where PG_PRINTF_ATTRIBUTE
is just "printf".  Fortunately, that's easy to do now that we're
requiring C99; we can use __VA_ARGS__.

On the other hand, it's better not to use __VA_ARGS__ for the rest
of the *printf crew, so that one can take the addresses of those
functions without surprises.

I'd proposed doing this some time ago, but forgot to make it happen;
buildfarm failures subsequent to 96bf88d reminded me.

Discussion: https://postgr.es/m/22709.1535135640@sss.pgh.pa.us
Discussion: https://postgr.es/m/20180926190934.ea4xvzhkayuw7gkx@alap3.anarazel.de

Author: tglsfdc

src/include/port.h

@@ -173,25 +173,19 @@ extern int	pg_fprintf(FILE *stream, const char *fmt,...) pg_attribute_printf(2,
 extern int	pg_printf(const char *fmt,...) pg_attribute_printf(1, 2);
 
 /*
- *	The GCC-specific code below prevents the pg_attribute_printf above from
- *	being replaced, and this is required because gcc doesn't know anything
- *	about pg_printf.
+ * We use __VA_ARGS__ for printf to prevent replacing references to
+ * the "printf" format archetype in format() attribute declarations.
+ * That unfortunately means that taking a function pointer to printf
+ * will not do what we'd wish.  (If you need to do that, you must name
+ * pg_printf explicitly.)  For printf's sibling functions, use
+ * parameterless macros so that function pointers will work unsurprisingly.
  */
-#ifdef __GNUC__
-#define vsnprintf(...)	pg_vsnprintf(__VA_ARGS__)
-#define snprintf(...)	pg_snprintf(__VA_ARGS__)
-#define sprintf(...)	pg_sprintf(__VA_ARGS__)
-#define vfprintf(...)	pg_vfprintf(__VA_ARGS__)
-#define fprintf(...)	pg_fprintf(__VA_ARGS__)
-#define printf(...)		pg_printf(__VA_ARGS__)
-#else
 #define vsnprintf		pg_vsnprintf
 #define snprintf		pg_snprintf
 #define sprintf			pg_sprintf
 #define vfprintf		pg_vfprintf
 #define fprintf			pg_fprintf
-#define printf			pg_printf
-#endif
+#define printf(...)		pg_printf(__VA_ARGS__)
 
 /* Replace strerror() with our own, somewhat more robust wrapper */
 extern char *pg_strerror(int errnum);

src/pl/plperl/plperl.h

@@ -102,13 +102,8 @@
 #ifdef vsnprintf
 #undef vsnprintf
 #endif
-#ifdef __GNUC__
-#define vsnprintf(...)	pg_vsnprintf(__VA_ARGS__)
-#define snprintf(...)	pg_snprintf(__VA_ARGS__)
-#else
 #define vsnprintf		pg_vsnprintf
 #define snprintf		pg_snprintf
-#endif							/* __GNUC__ */
 
 /* perl version and platform portability */
 #define NEED_eval_pv

src/pl/plpython/plpython.h

@@ -127,13 +127,8 @@ typedef int Py_ssize_t;
 #ifdef vsnprintf
 #undef vsnprintf
 #endif
-#ifdef __GNUC__
-#define vsnprintf(...)	pg_vsnprintf(__VA_ARGS__)
-#define snprintf(...)	pg_snprintf(__VA_ARGS__)
-#else
 #define vsnprintf				pg_vsnprintf
 #define snprintf				pg_snprintf
-#endif							/* __GNUC__ */
 
 /*
  * Used throughout, and also by the Python 2/3 porting layer, so it's easier to