bug#2042: Ido-mode : filtering does not keep ordering

[Leo <sdl.web@gmail.com>]

On 2012-09-16 17:29 +0800, Matthew Woodcraft wrote:
> I've been running with Leo's patch from this bug report for a couple of
> months.
>
> I also think that the changed behaviour is an improvement, and I've seen
> no problems.
>
> So could this be considered before the 24.3 freeze?

If Yidong doesn't object, I plan to commit something along these lines:

diff --git a/lisp/ido.el b/lisp/ido.el
index fe94c7f2..bb019574 100644
--- a/lisp/ido.el
+++ b/lisp/ido.el
@@ -493,6 +493,17 @@ (defcustom ido-enable-dot-prefix nil
   :type 'boolean
   :group 'ido)
 
+;; See http://debbugs.gnu.org/2042 for more info.
+(defcustom ido-buffer-disable-smart-matches t
+  "Non-nil means not to re-order matches for buffer switching.
+By default, ido aranges matches in the following order:
+
+  full-matches > suffix matches > prefix matches > remaining matches
+
+which can get in the way for buffer switching."
+  :type 'boolean
+  :group 'ido)
+
 (defcustom ido-confirm-unique-completion nil
   "Non-nil means that even a unique completion must be confirmed.
 This means that \\[ido-complete] must always be followed by \\[ido-exit-minibuffer]
@@ -3688,10 +3699,15 @@ (defun ido-set-matches-1 (items &optional do-full)
 	 (rex0 (if ido-enable-regexp text (regexp-quote text)))
 	 (rexq (concat rex0 (if slash ".*/" "")))
 	 (re (if ido-enable-prefix (concat "\\`" rexq) rexq))
-	 (full-re (and do-full (not ido-enable-regexp) (not (string-match "\$\\'" rex0))
+	 (full-re (and do-full
+		       (not ido-buffer-disable-smart-matches)
+		       (not ido-enable-regexp)
+		       (not (string-match "\$\\'" rex0))
 		       (concat "\\`" rex0 (if slash "/" "") "\\'")))
 	 (suffix-re (and do-full slash
-			 (not ido-enable-regexp) (not (string-match "\$\\'" rex0))
+			 (not ido-buffer-disable-smart-matches)
+			 (not ido-enable-regexp)
+			 (not (string-match "\$\\'" rex0))
 			 (concat rex0 "/\\'")))
 	 (prefix-re (and full-re (not ido-enable-prefix)
 			 (concat "\\`" rexq)))