decode-time now returns subsec too

The list that decode-time returns now contains an extra
trailing component that counts the subseconds part of the
original timestamp (Bug#36549).
This builds on a suggestion by Lars Ingebrigtsen in:
https://lists.gnu.org/r/emacs-devel/2019-07/msg00734.html
* doc/lispref/os.texi (Time Conversion):
* doc/misc/emacs-mime.texi (time-date):
* etc/NEWS: Document this.
* lisp/calendar/icalendar.el (icalendar--decode-isodatetime):
* lisp/calendar/iso8601.el (iso8601-parse)
(iso8601-parse-time, iso8601-parse-duration)
(iso8601--decoded-time):
* lisp/calendar/parse-time.el (parse-time-string):
* lisp/calendar/time-date.el (make-decoded-time)
(decoded-time-set-defaults):
* lisp/org/org.el (org-fix-decoded-time)
(org-parse-time-string):
* src/timefns.c (Fdecode_time):
Generate subsec member for decoded time.
* lisp/calendar/time-date.el (decoded-time-add)
Add the decoded subsec too.
* lisp/simple.el (decoded-time): New subsec member.
* src/data.c (Frem): Simplify zero-check to match that of new Fmod.
(integer_mod): New function, with most of the guts of the old Fmod.
Remove redundant zero-check.
(Fmod): Use it.
* src/timefns.c (Fencode_time): Handle new subsec member
or (with the obsolescent calling convention) subsec arg.
It defaults to 0.
* test/lisp/calendar/icalendar-tests.el:
(icalendar--decode-isodatetime):
* test/lisp/calendar/iso8601-tests.el (test-iso8601-date-years)
(test-iso8601-date-dates, test-iso8601-date-obsolete)
(test-iso8601-date-weeks, test-iso8601-date-ordinals)
(test-iso8601-time, test-iso8601-combined)
(test-iso8601-duration, test-iso8601-intervals)
(standard-test-dates, standard-test-time-of-day-fractions)
(standard-test-time-of-day-beginning-of-day)
(standard-test-time-of-day-utc)
(standard-test-time-of-day-zone)
(standard-test-date-and-time-of-day, standard-test-interval):
* test/lisp/calendar/parse-time-tests.el (parse-time-tests):
* test/src/timefns-tests.el (format-time-string-with-zone)
(encode-time-dst-numeric-zone):
Adjust to match new behavior.

4 files changed, 30 insertions, 10 deletions

diff --git a/lisp/calendar/icalendar.el b/lisp/calendar/icalendar.el
index c2688705e30..84f579ad44e 100644
--- a/lisp/calendar/icalendar.el
+++ b/lisp/calendar/icalendar.el
@@ -644,7 +644,7 @@ FIXME: multiple comma-separated values should be allowed!"
         ;; create the decoded date-time
         ;; FIXME!?!
 	(let ((decoded-time (list second minute hour day month year
-				  nil -1 zone)))
+				  nil -1 zone 0)))
 	  (condition-case nil
 	      (decode-time (encode-time decoded-time))
 	    (error
diff --git a/lisp/calendar/iso8601.el b/lisp/calendar/iso8601.el
index 30352c7e75f..51f5dff9091 100644
--- a/lisp/calendar/iso8601.el
+++ b/lisp/calendar/iso8601.el
@@ -129,7 +129,8 @@ well as variants like \"2008W32\" (week number) and
         (let ((time (iso8601-parse-time time-string)))
           (setf (decoded-time-hour date) (decoded-time-hour time))
           (setf (decoded-time-minute date) (decoded-time-minute time))
-          (setf (decoded-time-second date) (decoded-time-second time))))
+	  (setf (decoded-time-second date) (decoded-time-second time))
+	  (setf (decoded-time-subsec date) (decoded-time-subsec time))))
       ;; The time zone is optional.
       (when zone-string
         (setf (decoded-time-zone date)
@@ -236,6 +237,8 @@ well as variants like \"2008W32\" (week number) and
           (iso8601--decoded-time :hour hour
                                  :minute (or minute 0)
                                  :second (or second 0)
+				 ;; FIXME: Support subsec.
+				 :subsec 0
                                  :zone (and zone
                                             (* 60 (iso8601-parse-zone
                                                    zone)))))))))
@@ -274,7 +277,9 @@ Return the number of minutes."
                            :day (or (match-string 3 string) 0)
                            :hour (or (match-string 5 string) 0)
                            :minute (or (match-string 6 string) 0)
-                           :second (or (match-string 7 string) 0)))
+			   :second (or (match-string 7 string) 0)
+			   ;; FIXME: Support subsec.
+			   :subsec 0))
    ;; PnW: Weeks.
    ((iso8601--match iso8601--duration-week-match string)
     (let ((weeks (string-to-number (match-string 1 string))))
@@ -336,7 +341,7 @@ Return the number of minutes."
 
 (cl-defun iso8601--decoded-time (&key second minute hour
                                       day month year
-                                      dst zone)
+                                      dst zone subsec)
   (list (iso8601--value second)
         (iso8601--value minute)
         (iso8601--value hour)
@@ -345,7 +350,8 @@ Return the number of minutes."
         (iso8601--value year)
         nil
         dst
-        zone))
+        zone
+	subsec))
 
 (defun iso8601--encode-time (time)
   "Like `encode-time', but fill in nil values in TIME."
diff --git a/lisp/calendar/parse-time.el b/lisp/calendar/parse-time.el
index e28df97918e..9af93b5b1ee 100644
--- a/lisp/calendar/parse-time.el
+++ b/lisp/calendar/parse-time.el
@@ -27,7 +27,7 @@
 ;; Emacs.  However, parsing time strings is still largely a matter of
 ;; heuristics and no common interface has been designed.
 
-;; `parse-time-string' parses a time in a string and returns a list of 9
+;; `parse-time-string' parses a time in a string and returns a list of
 ;; values, just like `decode-time', where unspecified elements in the
 ;; string are returned as nil (except unspecfied DST is returned as -1).
 ;; `encode-time' may be applied on these values to obtain an internal
@@ -148,7 +148,7 @@ letters, digits, plus or minus signs or colons."
 
 ;;;###autoload
 (defun parse-time-string (string)
-  "Parse the time-string STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
+  "Parse the time in STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ SUBSEC).
 STRING should be something resembling an RFC 822 (or later) date-time, e.g.,
 \"Fri, 25 Mar 2016 16:24:56 +0100\", but this function is
 somewhat liberal in what format it accepts, and will attempt to
@@ -156,7 +156,7 @@ return a \"likely\" value even for somewhat malformed strings.
 The values returned are identical to those of `decode-time', but
 any unknown values other than DST are returned as nil, and an
 unknown DST value is returned as -1."
-  (let ((time (list nil nil nil nil nil nil nil -1 nil))
+  (let ((time (list nil nil nil nil nil nil nil -1 nil nil))
 	(temp (parse-time-tokenize (downcase string))))
     (while temp
       (let ((parse-time-elt (pop temp))
@@ -193,6 +193,10 @@ unknown DST value is returned as -1."
 				       (funcall this)))
 				 parse-time-val)))
 		  (setf (nth (pop slots) time) new-val))))))))
+    ;; FIXME: Currently parse-time-string does not parse subseconds.
+    ;; So if seconds were found, set subseconds to zero.
+    (when (nth 0 time)
+      (setf (nth 9 time) 0))
     time))
 
 (defun parse-iso8601-time-string (date-string)
diff --git a/lisp/calendar/time-date.el b/lisp/calendar/time-date.el
index 7505332011b..c22f4414201 100644
--- a/lisp/calendar/time-date.el
+++ b/lisp/calendar/time-date.el
@@ -423,6 +423,13 @@ changes in daylight saving time are not taken into account."
     (setq seconds (+ (* (or (decoded-time-hour delta) 0) 3600)
                      (* (or (decoded-time-minute delta) 0) 60)
                      (or (decoded-time-second delta) 0)))
+    (when (decoded-time-subsec delta)
+      (let* ((subsec (time-convert (time-add (decoded-time-subsec time)
+					     (decoded-time-subsec delta))
+				   t))
+	     (s (time-convert subsec 'integer)))
+	(setq seconds (+ seconds s))
+	(setf (decoded-time-subsec time) (time-subtract subsec s))))
 
     ;; Time zone adjustments are basically the same as time adjustments.
     (setq seconds (+ seconds (or (decoded-time-zone delta) 0)))
@@ -494,9 +501,9 @@ changes in daylight saving time are not taken into account."
 
 (cl-defun make-decoded-time (&key second minute hour
                                   day month year
-                                  dst zone)
+                                  dst zone subsec)
   "Return a `decoded-time' structure with only the keywords given filled out."
-  (list second minute hour day month year nil dst zone))
+  (list second minute hour day month year nil dst zone subsec))
 
 (defun decoded-time-set-defaults (time &optional default-zone)
   "Set any nil values in `decoded-time' TIME to default values.
@@ -526,6 +533,9 @@ TIME is modified and returned."
   (when (and (not (decoded-time-zone time))
              default-zone)
     (setf (decoded-time-zone time) 0))
+
+  (unless (decoded-time-subsec time)
+    (setf (decoded-time-subsec time) 0))
   time)
 
 (provide 'time-date)