* subr.el (delete-consecutive-dups): New function.

* ido.el (ido-set-matches-1): Use it.
* progmodes/octave.el (inferior-octave-completion-table): Use it.
* ido.el (ido-remove-consecutive-dups): Remove.

lisp/ChangeLog

+2013-05-17  Leo Liu  <sdl.web@gmail.com>
+
+	* subr.el (delete-consecutive-dups): New function.
+	* ido.el (ido-set-matches-1): Use it.
+	* progmodes/octave.el (inferior-octave-completion-table): Use it.
+	* ido.el (ido-remove-consecutive-dups): Remove.
+
 2013-05-17  Stefan Monnier  <monnier@iro.umontreal.ca>
 	* progmodes/f90.el (f90-keywords-re, f90-keywords-level-3-re)

lisp/ido.el

@@ -3785,7 +3785,7 @@ This is to make them appear as if they were \"virtual buffers\"."
 	   (if (string-match re name)
 	       (setq matches (cons item matches)))))
        items))
-    matches))
+    (delete-consecutive-dups matches t)))
 
 
 (defun ido-set-matches ()
@@ -4676,21 +4676,6 @@ For details of keybindings, see `ido-find-file'."
 			      ido-temp-list))))
     (ido-to-end summaries)))
 
-(defun ido-remove-consecutive-dups (list)
-  "Remove consecutive duplicates in LIST.
-Use `equal' for comparison.  First and last elements are
-considered consecutive."
-  (let ((tail list)
-	(last (make-symbol ""))
-	(result nil))
-    (while (consp tail)
-      (unless (equal (car tail) last)
-	(push (setq last (car tail)) result))
-      (setq tail (cdr tail)))
-    (nreverse (or (and (equal last (car list))
-		       (cdr result))
-		  result))))
-
 ;;; Helper functions for other programs
 
 (put 'dired-do-rename 'ido 'ignore)
@@ -4808,7 +4793,7 @@ DEF, if non-nil, is the default value."
 	(ido-directory-nonreadable nil)
 	(ido-directory-too-big nil)
 	(ido-context-switch-command 'ignore)
-	(ido-choice-list (ido-remove-consecutive-dups choices)))
+	(ido-choice-list choices))
     ;; Initialize ido before invoking ido-read-internal
     (ido-common-initialization)
     (ido-read-internal 'list prompt hist def require-match initial-input)))

lisp/progmodes/octave.el

@@ -38,7 +38,9 @@
 (require 'newcomment)
 (eval-and-compile
   (unless (fboundp 'user-error)
-    (defalias 'user-error 'error)))
+    (defalias 'user-error 'error))
+  (unless (fboundp 'delete-consecutive-dups)
+    (defalias 'delete-consecutive-dups 'delete-dups)))
 (eval-when-compile
   (unless (fboundp 'setq-local)
     (defmacro setq-local (var val)
@@ -777,8 +779,8 @@ startup file, `~/.emacs-octave'."
          (inferior-octave-send-list-and-digest
           (list (concat "completion_matches (\"" command "\");\n")))
          (setq cache (list command (float-time)
-                           (sort (delete-dups inferior-octave-output-list)
-                                 'string-lessp))))
+                           (delete-consecutive-dups
+                            (sort inferior-octave-output-list 'string-lessp)))))
        (car (cddr cache))))))
 
 (defun inferior-octave-completion-at-point ()

lisp/subr.el

@@ -376,6 +376,23 @@ one is kept."
       (setq tail (cdr tail))))
   list)
 
+;; See http://lists.gnu.org/archive/html/emacs-devel/2013-05/msg00204.html
+(defun delete-consecutive-dups (list &optional circular)
+  "Destructively remove `equal' consecutive duplicates from LIST.
+First and last elements are considered consecutive if CIRCULAR is
+non-nil."
+  (let ((tail list) last)
+    (while (consp tail)
+      (if (equal (car tail) (cadr tail))
+	  (setcdr tail (cddr tail))
+	(setq last (car tail)
+	      tail (cdr tail))))
+    (if (and circular
+	     (cdr list)
+	     (equal last (car list)))
+	(nbutlast list)
+      list)))
+
 (defun number-sequence (from &optional to inc)
   "Return a sequence of numbers from FROM to TO (both inclusive) as a list.
 INC is the increment used between numbers in the sequence and defaults to 1.