Support OFFSET and (OFFSET ABBR) time zone rules

This simplifies Gnus and VC time zone support, by letting them
feed the output of ‘current-time-zone’ and ‘decode time’ to
primitives that accept time zone arguments.
* doc/lispref/os.texi (Time Zone Rules, Time Conversion):
* etc/NEWS:
* lisp/gnus/message.el (message-insert-formatted-citation-line):
* lisp/org/org.el (org-timestamp-format):
* src/editfns.c (Fformat_time_string, Fdecode_time):
(Fcurrent_time_string, Fcurrent_time_zone, Fset_time_zone_rule):
Document new behavior.
* lisp/gnus/gmm-utils.el (gmm-format-time-string):
* lisp/vc/add-log.el (add-log-iso8601-time-zone):
Mark as obsolete, as it is now just an alias or narrow wrapper
around format-time-string.
* src/editfns.c (tzlookup): Also support integer OFFSET and
list (OFFSET ABBR) as time zone rules.
(Fencode_time): No longer need a special case for a cons ZONE.
(Fcurrent_time_zone): If the time zone string is missing, compute
it the same way the other new code does.

1 files changed, 2 insertions, 31 deletions

diff --git a/lisp/gnus/gmm-utils.el b/lisp/gnus/gmm-utils.el
index f6455cf9f1a..7aa52794e4c 100644
--- a/lisp/gnus/gmm-utils.el
+++ b/lisp/gnus/gmm-utils.el
@@ -256,37 +256,8 @@ If mode is nil, use `major-mode' of the current buffer."
 		 (string-match "^\\(.+\\)-mode$" mode)
 		 (match-string 1 mode))))))
 
-(defun gmm-format-time-string (format-string &optional time tz)
-  "Use FORMAT-STRING to format the time TIME, or now if omitted.
-The optional TZ specifies the time zone in a number of seconds; any
-other non-nil value will be treated as 0.  Note that both the format
-specifiers `%Z' and `%z' will be replaced with a numeric form. "
-;; FIXME: is there a smart way to replace %Z with a time zone name?
-  (if (and (numberp tz) (not (zerop tz)))
-      (let ((st 0)
-	    (case-fold-search t)
-	    ls nd rest)
-	(setq time (if time
-		       (copy-sequence time)
-		     (current-time)))
-	(if (>= (setq ls (- (cadr time) (car (current-time-zone)) (- tz))) 0)
-	    (setcar (cdr time) ls)
-	  (setcar (cdr time) (+ ls 65536))
-	  (setcar time (1- (car time))))
-	(setq tz (format "%s%02d%02d"
-			 (if (>= tz 0) "+" "-")
-			 (/ (abs tz) 3600)
-			 (/ (% (abs tz) 3600) 60)))
-	(while (string-match "%+z" format-string st)
-	  (if (zerop (% (- (setq nd (match-end 0)) (match-beginning 0)) 2))
-	      (progn
-		(push (substring format-string st (- nd 2)) rest)
-		(push tz rest))
-	    (push (substring format-string st nd) rest))
-	  (setq st nd))
-	(push (substring format-string st) rest)
-	(format-time-string (apply 'concat (nreverse rest)) time))
-    (format-time-string format-string time t)))
+(define-obsolete-function-alias 'gmm-format-time-string 'format-time-string
+  "25.2")
 
 (provide 'gmm-utils)