Avoid some excess precision in time arithmetic

* doc/misc/emacs-mime.texi (time-date):
Adjust example to match new behavior.
* etc/NEWS: Mention this.
* lisp/calendar/time-date.el (decoded-time-add)
(decoded-time--alter-second):
Don’t lose underestimate precision of seconds component.
* src/bignum.c (mpz): Grow by 1.
* src/timefns.c (trillion_factor): New function.
(timeform_sub_ps_p): Remove.
(time_arith): Avoid unnecessarily-large hz, by reducing the hz
to a value no worse than the worse hz of the two arguments.
The result is always exact unless an error is signaled.
* test/src/timefns-tests.el (timefns-tests--decode-time):
New function.
(format-time-string-with-zone): Test (decode-time LOOK ZONE t)
resolution as well as its numeric value.

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/misc/emacs-mime.texi b/doc/misc/emacs-mime.texi
index eb829b06124..131a358ba59 100644
--- a/doc/misc/emacs-mime.texi
+++ b/doc/misc/emacs-mime.texi
@@ -1568,7 +1568,7 @@ Here's a bunch of time/date/second/day examples:
 
 (time-subtract '(905595714000000 . 1000000)
                '(905595593000000000 . 1000000000))
-@result{} (121000000000 . 1000000000)
+@result{} (121000000 . 1000000)
 
 (days-between "Sat Sep 12 12:21:54 1998 +0200"
               "Sat Sep 07 12:21:54 1998 +0200")