git.el: Set the default commit coding system from the repository config.

If not otherwise specified, take the default coding system for commits
from the 'i18n.commitencoding' repository configuration value.

Also set the buffer-file-coding-system variable in the log buffer to
make the selected coding system visible on the modeline.

Signed-off-by: Alexandre Julliard <julliard@winehq.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/emacs/git.el

@@ -75,10 +75,11 @@ then to `add-log-mailing-address' and then to `user-mail-address'."
   :type '(choice (const :tag "Default" nil)
                  (string :tag "Email")))
 
-(defcustom git-commits-coding-system 'utf-8
+(defcustom git-commits-coding-system nil
   "Default coding system for the log message of git commits."
   :group 'git
-  :type 'coding-system)
+  :type '(choice (const :tag "From repository config" nil)
+                 (coding-system)))
 
 (defcustom git-append-signed-off-by nil
   "Whether to append a Signed-off-by line to the commit message before editing."
@@ -236,6 +237,15 @@ and returns the process output as a string."
       (and (fboundp 'user-mail-address) (user-mail-address))
       (and (boundp 'user-mail-address) user-mail-address)))
 
+(defun git-get-commits-coding-system ()
+  "Return the coding system to use for commits."
+  (let ((repo-config (git-config "i18n.commitencoding")))
+    (or git-commits-coding-system
+        (and repo-config
+             (fboundp 'locale-charset-to-coding-system)
+             (locale-charset-to-coding-system repo-config))
+      'utf-8)))
+
 (defun git-escape-file-name (name)
   "Escape a file name if necessary."
   (if (string-match "[\n\t\"\\]" name)
@@ -327,7 +337,7 @@ and returns the process output as a string."
   "Call git-commit-tree with buffer as input and return the resulting commit SHA1."
   (let ((author-name (git-get-committer-name))
         (author-email (git-get-committer-email))
-        author-date log-start log-end args)
+        author-date log-start log-end args coding-system-for-write)
     (when head
       (push "-p" args)
       (push head args))
@@ -350,12 +360,12 @@ and returns the process output as a string."
                 (push "-p" args)
                 (push (match-string 1) args))))
         (setq log-start (point-min)))
-      (setq log-end (point-max)))
+      (setq log-end (point-max))
+      (setq coding-system-for-write buffer-file-coding-system))
     (git-get-string-sha1
      (with-output-to-string
        (with-current-buffer standard-output
-         (let ((coding-system-for-write git-commits-coding-system)
+         (let ((env `(("GIT_AUTHOR_NAME" . ,author-name)
-               (env `(("GIT_AUTHOR_NAME" . ,author-name)
                       ("GIT_AUTHOR_EMAIL" . ,author-email)
                       ("GIT_COMMITTER_NAME" . ,(git-get-committer-name))
                       ("GIT_COMMITTER_EMAIL" . ,(git-get-committer-email)))))
@@ -888,6 +898,7 @@ and returns the process output as a string."
   (let ((buffer (get-buffer-create "*git-commit*"))
         (merge-heads (git-get-merge-heads))
         (dir default-directory)
+        (coding-system (git-get-commits-coding-system))
         (sign-off git-append-signed-off-by))
     (with-current-buffer buffer
       (when (eq 0 (buffer-size))
@@ -912,6 +923,7 @@ and returns the process output as a string."
                                (git-get-committer-name) (git-get-committer-email)))))))
     (log-edit #'git-do-commit nil #'git-log-edit-files buffer)
     (setq font-lock-keywords (font-lock-compile-keywords git-log-edit-font-lock-keywords))
+    (setq buffer-file-coding-system coding-system)
     (re-search-forward (regexp-quote (concat git-log-msg-separator "\n")) nil t)))
 
 (defun git-find-file ()