http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48615
--- Comment #1 from Thomas Henlich <thenlich at users dot sourceforge.net>
2011-04-23 07:49:33 UTC ---
I think I found the problematic code in write_float:
if (f->format == FMT_F || f->format == FMT_EN || f->format == FMT_G
|| ((f->format == FMT_D || f->format == FMT_E)
&& dtp->u.p.scale_factor != 0))
{
/* Always convert at full precision to avoid double rounding. */
ndigits = MIN_FIELD_WIDTH - 4 - edigits;
}
else
{
/* The number of digits is known, so let printf do the rounding. */
if (f->format == FMT_ES)
ndigits = f->u.real.d + 1;
else
ndigits = f->u.real.d;
if (ndigits > MIN_FIELD_WIDTH - 4 - edigits)
ndigits = MIN_FIELD_WIDTH - 4 - edigits;
}
"let printf do the rounding" means the result will always be rounded according
to the rounding rules of printf, which is for GLIBC: "If the value being
printed cannot be expressed accurately in the specified number of digits, the
value is rounded to the nearest number that fits."
