Decode all incoming messages in rcirc.el

Also allow automatic coding system detection if
rcirc-decode-coding-system is nil.

See discussion in http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8744

lisp/ChangeLog

 2011-05-30  Leo Liu  <sdl.web@gmail.com>
 
 	* net/rcirc.el (rcirc-debug-buffer): Use visible buffer name.
+	(rcirc-print): Decode all incoming messages (bug#8744).
+	(rcirc-decode-coding-system): Allow value nil for automatic coding
+	system detection.
 
 2011-05-29  Chong Yidong  <cyd@stupidchicken.com>
 

lisp/net/rcirc.el

@@ -314,9 +314,11 @@ Called with 5 arguments, PROCESS, SENDER, RESPONSE, TARGET and TEXT."
   :type 'boolean
   :group 'rcirc)
 
-(defcustom rcirc-decode-coding-system 'utf-8
-  "Coding system used to decode incoming irc messages."
+(defcustom rcirc-decode-coding-system nil
+  "Coding system used to decode incoming irc messages.
+If nil automatically detect the coding system."
   :type 'coding-system
+  :version "24.1"
   :group 'rcirc)
 
 (defcustom rcirc-encode-coding-system 'utf-8
@@ -1480,9 +1482,9 @@ record activity."
 	      (old-point (point-marker))
 	      (fill-start (marker-position rcirc-prompt-start-marker)))
 
+	  (setq text (decode-coding-string text (or rcirc-decode-coding-system
+						    (detect-coding-string text t))))
 	  (unless (string= sender (rcirc-nick process))
-	    ;; only decode text from other senders, not ours
-	    (setq text (decode-coding-string text rcirc-decode-coding-system))
 	    ;; mark the line with overlay arrow
 	    (unless (or (marker-position overlay-arrow-position)
 			(get-buffer-window (current-buffer))