fix failure of printf %g to strip trailing zeros in some cases

the code to strip trailing zeros was only looking in the last slot for
up to 9 zeros, assuming that the rounding code had already removed
fully-zero slots from the end. however, this ignored cases where the
rounding code did not run at all, which occur when the value being
printed is exactly representable in the requested precision.

the simplest solution is to move the code that strips trailing zero
slots to run unconditionally, immediately after rounding, rather than
as the last step of rounding.

(cherry picked from commit 89740868c9f1c84b8ee528468d12df1fa72cd392)

diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
index bec63ecf6425b42ed3e2285513b55e8877f88411..0be75498a36ce689ace70e1bd869819acaf10715 100644 (file)
--- a/src/stdio/vfprintf.c
+++ b/src/stdio/vfprintf.c
@@ -363,8 +363,8 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
                        }
                }
                if (z>d+1) z=d+1;
-               for (; !z[-1] && z>a; z--);
        }
+       for (; z>a && !z[-1]; z--);
        
        if ((t|32)=='g') {
                if (!p) p++;