debugging macros (again)

[James Hu]

Hello.  I remember debugging macros were discussed sometime
last year, but I did not pay too close attention then.
Could someone advise me via email if the following header file
is ok?

/* debug.h:	My debugging macros */
#ifdef DEBUG
#  ifdef IN_MAIN_OBJECT

#  include <stdarg.h>

int debug_level = 0;

void BUG(int priority, char *fmt, ...)
{
    va_list ap;

    if (priority < 0) return;
    if ((-debug_level != priority) && (debug_level < priority)) return;
    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);
}


#  else /* NOT MAIN */

    extern int debug_level;
    extern void BUG(int, char *,...);

#  endif /* MAIN */

#else /* NOT DEBUG */

#  ifdef IN_MAIN_OBJECT

     void BUG(int x, char *s,...) {}

#  else /* NOT MAIN */

     extern void BUG(int, char *,...);

#  endif /* MAIN */

#endif /* DEBUG */

/* end of debug.h */


My primary concern, of course, is if the compiler will optimize
the null function call down to doing nothing at all.
Thanks for any help.