X-Git-Url: https://git.hcoop.net/bpt/emacs.git/blobdiff_plain/a617e9133c6854861e327f90fe5f096a33abe4f3..ebfa69444dce5d5d807aaf0b067cd01259b85e51:/lisp/diff.el

diff --git a/lisp/diff.el b/lisp/diff.el
index 891fb97044..eb2e415289 100644
--- a/lisp/diff.el
+++ b/lisp/diff.el
@@ -34,6 +34,9 @@
 (defvar diff-switches "-c"
   "*A string or list of strings specifying switches to be be passed to diff.")
 
+(defvar diff-command "diff"
+  "*The command to use to run diff.")
+
 (defvar diff-regexp-alist
   '(
     ;; -u format: @@ -OLDSTART,OLDEND +NEWSTART,NEWEND @@
@@ -196,7 +199,7 @@ With prefix arg, prompt for diff switches."
     (unwind-protect
 	(let ((command
 	       (mapconcat 'identity
-			  (append '("diff")
+			  (append (list diff-command)
 				  ;; Use explicitly specified switches
 				  (if switches
 				      (if (consp switches)
@@ -266,8 +269,12 @@ The backup file is the first file given to `diff'."
       (or
        (let ((bak (make-backup-file-name fn)))
 	 (if (file-exists-p bak) bak))
-       (let* ((dir (file-name-directory fn))
-	      (base-versions (concat (file-name-nondirectory fn) ".~"))
+       ;; We use BACKUPNAME to cope with backups stored in a different dir.
+       (let* ((backupname (car (find-backup-file-name fn)))
+	      (dir (file-name-directory backupname))
+	      (base-versions (concat (file-name-sans-versions
+				      (file-name-nondirectory backupname))
+				     ".~"))
 	      (bv-length (length base-versions)))
 	 (concat dir
 		 (car (sort