(select-safe-coding-system): Try to

use an auto-coding (if any) before anything else.  If the found
auto-coding is invalid, show a warning message.

1 files changed, 82 insertions, 54 deletions

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index d503eebe6d9..077a196f474 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -820,7 +820,7 @@ returned without any user interaction.  See also the command
 `prefer-coding-system'.
 
 However, the user is queried if the chosen coding system is
-inconsistent with what would be selected by `set-auto-coding' from
+inconsistent with what would be selected by `find-auto-coding' from
 coding cookies &c. if the contents of the region were read from a
 file.  (That could lead to data corruption in a file subsequently
 re-visited and edited.)
@@ -850,7 +850,33 @@ and TO is ignored."
            (not (listp default-coding-system)))
       (setq default-coding-system (list default-coding-system)))
 
-  (let ((no-other-defaults nil))
+  (let ((no-other-defaults nil)
+        auto-cs)
+    (unless (or (stringp from) find-file-literally)    
+      ;; Find an auto-coding that is specified for the the current
+      ;; buffer and file from the region FROM and TO.
+      (save-excursion
+        (save-restriction
+          (widen)
+          (goto-char from)
+          (setq auto-cs (find-auto-coding (or file buffer-file-name "")
+                                          (- to from)))
+          (if auto-cs
+              (if (coding-system-p (car auto-cs))
+                  (setq auto-cs (car auto-cs))
+                (display-warning
+                 :warning
+                 (format "\
+Invalid coding system `%s' is specified
+for the current buffer/file by the %s.
+It is highly recommended to fix it before writing to a file."
+                         (car auto-cs)
+                         (if (eq (cdr auto-cs) :coding) ":coding tag"
+                           (format "variable `%s'" (cdr auto-cs)))))
+                (or (yes-or-no-p "Really proceed with writing? ")
+                    (error "Save aborted"))
+                (setq auto-cs nil))))))
+
     (if (eq (car default-coding-system) t)
         (setq no-other-defaults t
               default-coding-system (cdr default-coding-system)))
@@ -860,6 +886,15 @@ and TO is ignored."
           (mapcar (function (lambda (x) (cons x (coding-system-base x))))
                   default-coding-system))
 
+    (if (and auto-cs (not no-other-defaults))
+        ;; If the file has a coding cookie, try to use it before anything
+        ;; else (i.e. before default-coding-system which will typically come
+        ;; from file-coding-system-alist).
+        (let ((base (coding-system-base auto-cs)))
+          (or (memq base '(nil undecided))
+              (rassq base default-coding-system)
+              (push (cons auto-cs base) default-coding-system))))
+
     ;; From now on, the list of defaults is reversed.
     (setq default-coding-system (nreverse default-coding-system))
 
@@ -893,56 +928,49 @@ and TO is ignored."
              (coding-system-get preferred 'mime-charset)
              (not (rassq base default-coding-system))
              (push (cons preferred base)
-                   default-coding-system)))))
-
-  (if select-safe-coding-system-accept-default-p
-      (setq accept-default-p select-safe-coding-system-accept-default-p))
-
-  (let ((codings (find-coding-systems-region from to))
-        (coding-system nil)
-        safe rejected unsafe)
-    (if (eq (car codings) 'undecided)
-        ;; Any coding system is ok.
-        (setq coding-system t)
-      ;; Classify the defaults into safe, rejected, and unsafe.
-      (dolist (elt default-coding-system)
-        (if (memq (cdr elt) codings)
-            (if (and (functionp accept-default-p)
-                     (not (funcall accept-default-p (cdr elt))))
-                (push (car elt) rejected)
-              (push (car elt) safe))
-          (push (car elt) unsafe)))
-      (if safe
-          (setq coding-system (car safe))))
-
-    ;; If all the defaults failed, ask a user.
-    (when (not coding-system)
-      (setq coding-system (select-safe-coding-system-interactively
-                           from to codings unsafe rejected (car codings))))
-
-    (if (vectorp (coding-system-eol-type coding-system))
-        (let ((eol (coding-system-eol-type buffer-file-coding-system)))
-          (if (numberp eol)
-              (setq coding-system
-                    (coding-system-change-eol-conversion coding-system eol)))))
-
-    (if (eq coding-system t)
-        (setq coding-system buffer-file-coding-system))
-    ;; Check we're not inconsistent with what `coding:' spec &c would
-    ;; give when file is re-read.
-    ;; But don't do this if we explicitly ignored the cookie
-    ;; by using `find-file-literally'.
-    (unless (or (stringp from)
-                find-file-literally
-                (and coding-system
-                     (memq (coding-system-type coding-system) '(0 5))))
-      (let ((auto-cs (save-excursion
-                       (save-restriction
-                         (widen)
-                         (narrow-to-region from to)
-                         (goto-char (point-min))
-                         (set-auto-coding (or file buffer-file-name "")
-                                          (buffer-size))))))
+                   default-coding-system))))
+
+    (if select-safe-coding-system-accept-default-p
+        (setq accept-default-p select-safe-coding-system-accept-default-p))
+
+    (let ((codings (find-coding-systems-region from to))
+          (coding-system nil)
+          safe rejected unsafe)
+      (if (eq (car codings) 'undecided)
+          ;; Any coding system is ok.
+          (setq coding-system t)
+        ;; Classify the defaults into safe, rejected, and unsafe.
+        (dolist (elt default-coding-system)
+          (if (memq (cdr elt) codings)
+              (if (and (functionp accept-default-p)
+                       (not (funcall accept-default-p (cdr elt))))
+                  (push (car elt) rejected)
+                (push (car elt) safe))
+            (push (car elt) unsafe)))
+        (if safe
+            (setq coding-system (car safe))))
+
+      ;; If all the defaults failed, ask a user.
+      (when (not coding-system)
+        (setq coding-system (select-safe-coding-system-interactively
+                             from to codings unsafe rejected (car codings))))
+
+      (if (vectorp (coding-system-eol-type coding-system))
+          (let ((eol (coding-system-eol-type buffer-file-coding-system)))
+            (if (numberp eol)
+                (setq coding-system
+                      (coding-system-change-eol-conversion coding-system eol)))))
+
+      (if (eq coding-system t)
+          (setq coding-system buffer-file-coding-system))
+      ;; Check we're not inconsistent with what `coding:' spec &c would
+      ;; give when file is re-read.
+      ;; But don't do this if we explicitly ignored the cookie
+      ;; by using `find-file-literally'.
+      (when (and auto-cs
+                 (not (and
+                       coding-system
+                       (memq (coding-system-type coding-system) '(0 5)))))
         ;; Merge coding-system and auto-cs as far as possible.
         (if (not coding-system)
             (setq coding-system auto-cs)
@@ -974,8 +1002,8 @@ and TO is ignored."
                      (format "Selected encoding %s disagrees with \
 %s specified by file contents.  Really save (else edit coding cookies \
 and try again)? " coding-system auto-cs))
-              (error "Save aborted")))))
-    coding-system))
+              (error "Save aborted"))))
+      coding-system)))
 
 (setq select-safe-coding-system-function 'select-safe-coding-system)