Print a '-' sign for negative zero. Tested with

	#include <stdio.h>
	int main(void)
	{
		printf("%+f\n", -0.0);
		printf("%+f\n", +0.0);
		printf("%+f\n",  0.0);
		return 0;
	}

to output
-0.000000
+0.000000
+0.000000

PR:		bin/41823
Submitted by:	GOTO Kentaro <gotoken@notwork.org>
Liked by:	bde
MFC after:	3 weeks

1 files changed, 2 insertions, 7 deletions

diff --git a/lib/libc/stdio/vfprintf.c b/lib/libc/stdio/vfprintf.c
index 91bbe00..1802fc7 100644
--- a/lib/libc/stdio/vfprintf.c
+++ b/lib/libc/stdio/vfprintf.c
@@ -1409,13 +1409,8 @@ cvt(double value, int ndigits, int flags, char *sign, int *decpt,
 			ndigits++;
 		mode = 2;		/* ndigits significant digits */
 	}
-	if (value < 0) {
-		value = -value;
-		*sign = '-';
-	} else
-		*sign = '\000';
-	digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve,
-			dtoaresultp);
+	digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve, dtoaresultp);
+	*sign = dsgn != 0;
 	if ((ch != 'g' && ch != 'G') || flags & ALT) {
 		/* print trailing zeros */
 		bp = digits + ndigits;