Re: [Emacs-diffs] trunk r114533: Revert 114527

[Dmitry Gutov <dgutov@yandex.ru>]

On 05.10.2013 21:43, Stefan Monnier wrote:
>> `last-coding-system-used' is unreliable: it can be modified by other
>> functions in `after-save-hook'.
>
> Indeed.  Why not use buffer-file-coding-system?

Because its value doesn't change (from the initial `undecided-unix') 
even after the buffer is saved with new, non-ASCII characters.

Should this be considered a bug?

So far I've decided to use `select-safe-coding-system-function', but it 
just adds to the mess:

=== modified file 'lisp/progmodes/ruby-mode.el'
--- lisp/progmodes/ruby-mode.el	2013-10-05 17:21:22 +0000
+++ lisp/progmodes/ruby-mode.el	2013-10-05 18:49:48 +0000
@@ -452,6 +452,9 @@
        (let ((coding-system
               (or coding-system-for-write
                   buffer-file-coding-system)))
+        (when (string-match-p "\\`undecided-" (symbol-name coding-system))
+          (setq coding-system (funcall select-safe-coding-system-function
+                                       (point-min) (point-max) nil 
#'identity)))
          (if coding-system
              (setq coding-system
                    (or (coding-system-get coding-system 'mime-charset)