(select-message-coding-system): New

function.
(set-language-environment-coding-systems): Set
default-sendmail-coding-system.

1 files changed, 24 insertions, 0 deletions

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index 2ebc5f147a8..c2874981750 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -489,6 +489,29 @@ Please select one from the following safe coding systems:\n"
 
 (setq select-safe-coding-system-function 'select-safe-coding-system)
 
+(defun select-message-coding-system ()
+  "Return a coding system to encode the outgoing message of the current buffer.
+It at first tries the first coding system found in these variables
+in this order:
+  (1) local value of `buffer-file-coding-system'
+  (2) value of `sendmail-coding-system'
+  (3) value of `default-buffer-file-coding-system'
+  (4) value of `default-sendmail-coding-system'
+If the found coding system can't encode the current buffer,
+or none of them are bound to a coding system,
+it asks a user to select a proper coding system."
+  (let ((coding (or (and (local-variable-p 'buffer-file-coding-system)
+                         buffer-file-coding-system)
+                    sendmail-coding-system
+                    default-buffer-file-coding-system
+                    default-sendmail-coding-system)))
+    (if (eq coding 'no-conversion)
+        ;; We should never use no-conversion for outgoing mails.
+        (setq coding nil))
+    (if (fboundp select-safe-coding-system-function)
+        (funcall select-safe-coding-system-function
+                 (point-min) (point-max) coding)
+      coding)))
 
 ;;; Language support staffs.
 
@@ -1189,6 +1212,7 @@ specifies the character set for the major languages of Western Europe."
     (if priority
         (let ((categories (mapcar 'coding-system-category priority)))
           (set-default-coding-systems default-coding)
+          (setq default-sendmail-coding-system default-coding)
           (set-coding-priority categories)
           (while priority
             (set (car categories) (car priority))