Replace utility functions with seq-uniq

* lisp/gnus/gnus-util.el (gnus-delete-duplicates):
* lisp/ibuf-ext.el (ibuffer-remove-duplicates): Redefine as
obsolete function alias for 'seq-uniq'.  Update callers.

lisp/gnus/gnus-util.el

@@ -750,15 +750,6 @@ nil.  See also `gnus-bind-print-variables'."
   (when (file-exists-p file)
     (delete-file file)))
 
-(defun gnus-delete-duplicates (list)
-  "Remove duplicate entries from LIST."
-  (let ((result nil))
-    (while list
-      (unless (member (car list) result)
-	(push (car list) result))
-      (pop list))
-    (nreverse result)))
-
 (defun gnus-delete-directory (directory)
   "Delete files in DIRECTORY.  Subdirectories remain.
 If there's no subdirectory, delete DIRECTORY as well."
@@ -1550,6 +1541,8 @@ lists of strings."
 ;; gnus-util.
 (autoload 'gnus-output-to-rmail "gnus-rmail")
 
+(define-obsolete-function-alias 'gnus-delete-duplicates #'seq-uniq "29.1")
+
 (provide 'gnus-util)
 
 ;;; gnus-util.el ends here

lisp/gnus/nnimap.el

@@ -555,7 +555,7 @@ during splitting, which may be slow."
                                ;; Look for the credentials based on
                                ;; the virtual server name and the address
                                (nnimap-credentials
-				(gnus-delete-duplicates
+                                (seq-uniq
 				 (list server nnimap-address))
                                 ports
                                 nnimap-user))))

lisp/gnus/nnmaildir.el

@@ -99,7 +99,7 @@ SUFFIX should start with \":2,\"."
   (let* ((flags (substring suffix 3))
 	 (flags-as-list (append flags nil))
 	 (new-flags
-	  (concat (gnus-delete-duplicates
+          (concat (seq-uniq
 		   ;; maildir flags must be sorted
 		   (sort (cons flag flags-as-list) #'<)))))
     (concat ":2," new-flags)))
@@ -1015,7 +1015,7 @@ This variable is set by `nnmaildir-request-article'.")
 	    dir (nnmaildir--nndir dir)
 	    dir (nnmaildir--marks-dir dir)
             ls (nnmaildir--group-ls nnmaildir--cur-server pgname)
-	    all-marks (gnus-delete-duplicates
+            all-marks (seq-uniq
 		       ;; get mark names from mark dirs and from flag
 		       ;; mappings
 		       (append
@@ -1697,7 +1697,7 @@ This variable is set by `nnmaildir-request-article'.")
             pgname (nnmaildir--pgname nnmaildir--cur-server gname)
             ls (nnmaildir--group-ls nnmaildir--cur-server pgname)
 	    all-marks (funcall ls marksdir nil "\\`[^.]" 'nosort)
-	    all-marks (gnus-delete-duplicates
+            all-marks (seq-uniq
 		       ;; get mark names from mark dirs and from flag
 		       ;; mappings
 		       (append

lisp/ibuf-ext.el

@@ -52,17 +52,6 @@
            (setq alist (remove it alist)) it))
   alist)
 
-;; borrowed from Gnus
-(defun ibuffer-remove-duplicates (list)
-  "Return a copy of LIST with duplicate elements removed."
-  (let ((new nil)
-	(tail list))
-    (while tail
-      (or (member (car tail) new)
-	  (setq new (cons (car tail) new)))
-      (setq tail (cdr tail)))
-    (nreverse new)))
-
 (defun ibuffer-split-list (fn elts)
   (declare (obsolete seq-group-by "29.1"))
   (let ((res (seq-group-by fn elts)))
@@ -799,7 +788,7 @@ specification, with the same structure as an element of the list
         (mapcar (lambda (mode)
                   (cons (format "%s" mode) `((mode . ,mode))))
                 (let ((modes
-                       (ibuffer-remove-duplicates
+                       (seq-uniq
                         (mapcar (lambda (buf)
 				  (buffer-local-value 'major-mode buf))
                                 (buffer-list)))))
@@ -1986,6 +1975,8 @@ defaults to one."
        (push buf ibuffer-do-occur-bufs)))
     (occur-1 regexp nlines ibuffer-do-occur-bufs)))
 
+(define-obsolete-function-alias 'ibuffer-remove-duplicates #'seq-uniq "29.1")
+
 (provide 'ibuf-ext)
 
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