dired: implement feature from 7b50ed5 differently

* lisp/dired.el (dired-buffers-for-dir): Restore to emacs-27 version.
(dired-buffers-for-dir-or-subdir): New function.
(dired-clean-up-after-deletion): Use dired-buffers-for-dir-or-subdir
instead dired-buffers-for-dir.

Author: tsdh

lisp/dired.el

@@ -2870,12 +2870,10 @@ You can then feed the file name(s) to other commands with \\[yank]."
 
 ;;; Keeping Dired buffers in sync with the filesystem and with each other
 
-(defun dired-buffers-for-dir (dir &optional file subdirs)
+(defun dired-buffers-for-dir (dir &optional file)
   "Return a list of buffers for DIR (top level or in-situ subdir).
 If FILE is non-nil, include only those whose wildcard pattern (if any)
 matches FILE.
-If SUBDIRS is non-nil, also include the dired buffers of
-directories below DIR.
 The list is in reverse order of buffer creation, most recent last.
 As a side effect, killed dired buffers for DIR are removed from
 `dired-buffers'."
@@ -2889,18 +2887,33 @@ As a side effect, killed dired buffers for DIR are removed from
 	(setq dired-buffers (delq elt dired-buffers)))
        ((dired-in-this-tree-p dir (car elt))
 	(with-current-buffer buf
-          (when (and (or subdirs
-                         (assoc dir dired-subdir-alist))
-	             (or (null file)
-		         (if (stringp dired-directory)
-		             (let ((wildcards (file-name-nondirectory
-					       dired-directory)))
-			       (or (zerop (length wildcards))
-			           (string-match-p (dired-glob-regexp wildcards)
-                                                   file)))
-		           (member (expand-file-name file dir)
-			           (cdr dired-directory)))))
-            (setq result (cons buf result)))))))
+          (and (assoc dir dired-subdir-alist)
+	       (or (null file)
+		   (if (stringp dired-directory)
+		       (let ((wildcards (file-name-nondirectory
+					 dired-directory)))
+			 (or (zerop (length wildcards))
+			     (string-match-p (dired-glob-regexp wildcards)
+                                             file)))
+		     (member (expand-file-name file dir)
+			     (cdr dired-directory))))
+               (setq result (cons buf result)))))))
+    result))
+
+(defun dired-buffers-for-dir-or-subdir (dir)
+  "Return a list of buffers for DIR or a subdirectory thereof.
+As a side effect, killed dired buffers for DIR are removed from
+`dired-buffers'."
+  (setq dir (file-name-as-directory dir))
+  (let (result buf)
+    (dolist (elt dired-buffers)
+      (setq buf (cdr elt))
+      (cond
+       ((null (buffer-name buf))
+	;; Buffer is killed - clean up:
+	(setq dired-buffers (delq elt dired-buffers)))
+       ((dired-in-this-tree-p (car elt) dir)
+        (setq result (cons buf result)))))
     result))
 
 (defun dired-glob-regexp (pattern)
@@ -3479,15 +3492,16 @@ confirmation.  To disable the confirmation, see
                                      (file-name-nondirectory fn))))
                (not dired-clean-confirm-killing-deleted-buffers))
            (kill-buffer buf)))
-    (let ((buf-list (dired-buffers-for-dir (expand-file-name fn)
-                                           nil 'subdirs)))
+    (let ((buf-list (dired-buffers-for-dir-or-subdir
+                     (expand-file-name fn))))
       (and buf-list
            (or (and dired-clean-confirm-killing-deleted-buffers
                     (y-or-n-p
                      (format
-                      (ngettext "Kill Dired buffer of %s, too? "
-                                "Kill Dired buffers of %s, too? "
-                                (length buf-list))
+                      (ngettext
+                       "Kill Dired buffer of %s, too? "
+                       "Kill Dired buffers of %s and its sub-directories, too? "
+                       (length buf-list))
                       (file-name-nondirectory
                        ;; FN may end in a / if `dired-listing-switches'
                        ;; contains -p, so we need to strip that