* files.el (basic-save-buffer-1): Don't set buffer-file-coding-system-explicit.

Fixes: debbugs:4533

3 files changed, 16 insertions, 12 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index cc5aa18d27f..c0a91bb75dc 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2013-02-10  Chong Yidong  <cyd@gnu.org>
 
+        * files.el (basic-save-buffer-1): Do not set
+        buffer-file-coding-system-explicit (Bug#4533).
+
         * mail/emacsbug.el (report-emacs-bug): Change binding of
         report-emacs-bug-insert-to-mailer to C-c M-i (Bug#13510).
 
diff --git a/lisp/files.el b/lisp/files.el
index 9fca70d36f7..c9e5d2763fe 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4646,9 +4646,7 @@ Before and after saving the buffer, this function runs
             (basic-save-buffer-2))
         (basic-save-buffer-2))
     (if buffer-file-coding-system-explicit
-        (setcar buffer-file-coding-system-explicit last-coding-system-used)
-      (setq buffer-file-coding-system-explicit
-            (cons last-coding-system-used nil)))))
+        (setcar buffer-file-coding-system-explicit last-coding-system-used))))
 
 ;; This returns a value (MODES EXTENDED-ATTRIBUTES BACKUPNAME), like
 ;; backup-buffer.
diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index 995df2fb9a7..47c7087518e 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -1132,17 +1132,20 @@ FORM is a form to evaluate to define the coding-system."
       (put (intern name) 'coding-system-define-form form)
       (setq coding-system-alist (cons (list name) coding-system-alist)))))
 
-;; This variable is set in these three cases:
+;; This variable is set in these two cases:
 ;;   (1) A file is read by a coding system specified explicitly.
-;;       after-insert-file-set-coding sets the car of this value to
-;;       coding-system-for-read, and sets the cdr to nil.
-;;   (2) A buffer is saved.
-;;       After writing, basic-save-buffer-1 sets the car of this value
-;;       to last-coding-system-used.
-;;   (3) set-buffer-file-coding-system is called.
+;;       `after-insert-file-set-coding' sets the car of this value to
+;;       `coding-system-for-read', and sets the cdr to nil.
+;;   (2) `set-buffer-file-coding-system' is called.
 ;;       The cdr of this value is set to the specified coding system.
-;; This variable is used for decoding in revert-buffer and encoding in
-;; select-safe-coding-system.
+;; This variable is used for decoding in `revert-buffer' and encoding
+;; in `select-safe-coding-system'.
+;;
+;; When saving a buffer, if `buffer-file-coding-system-explicit' is
+;; already non-nil, `basic-save-buffer-1' sets its CAR to the value of
+;; `last-coding-system-used'.  (It used to set it unconditionally, but
+;; that seems unnecessary; see Bug#4533.)
+
 (defvar buffer-file-coding-system-explicit nil
   "The file coding system explicitly specified for the current buffer.
 The value is a cons of coding systems for reading (decoding) and