Fix porting inconsistency about rounding to even.

* doc/lispref/numbers.texi (Numeric Conversions, Rounding Operations):
Document that 'round' and 'fround' round to even.
* src/floatfns.c (emacs_rint) [!HAVE_RINT]: Round to even.
This way, the unusual !HAVE_RINT case acts like the usual
HAVE_RINT case, and we can fix the documentation accordingly.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/floatfns.c b/src/floatfns.c
index 4de5f480259..ac0447ce6d6 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -428,7 +428,9 @@ round2 (EMACS_INT i1, EMACS_INT i2)
 static double
 emacs_rint (double d)
 {
-  return floor (d + 0.5);
+  double d1 = d + 0.5;
+  double r = floor (d1);
+  return r - (r == d1 && fmod (r, 2) != 0);
 }
 #endif