1if tst -D_ISOC99_SOURCE -lm note{ _ISOC99_SOURCE plays nice }end link{
2		#include <sys/types.h>
3		#include <sys/stat.h>
4		#include <stdlib.h>
5		#include <unistd.h>
6		#include <math.h>
7		int main() { return signbit(-0.0); }
8	}end {
9		#ifndef _ISOC99_SOURCE
10		#define _ISOC99_SOURCE	1
11		#endif
12	}
13endif
14