(dired-diff): Use `dired-dwim-target-directory'

if current dired buffer has no buffer mark.

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index dbc3d7630408e357973130a2e18035fbb9af8e58..b31d20782f38f25e6a0ec75ffefb73747bcce678 100644 (file)
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -64,7 +64,10 @@ With prefix arg, prompt for second argument SWITCHES,
                                   (if default
                                       (concat "(default " default ") ")
                                     ""))
-                          (dired-current-directory) default t)
+                          (if default
+                              (dired-current-directory)
+                            (dired-dwim-target-directory))
+                          default t)
           (if current-prefix-arg
               (read-string "Options for diff: "
                            (if (stringp diff-switches)