Patch implementing vc-diff-command

[Colin Marquardt]

Hi,

the following patch for vc.el (against an older CVS snapshot of
emacs) adds the customize option `vc-diff-command'. Reason is that
on Solaris, I need to call "gdiff" in order to be able to use the
"-u" switch.

Cheers,
  Colin

--- vc.el.orig  Mon May 17 15:31:29 2004
+++ vc.el       Mon May 17 15:37:07 2004
@@ -538,6 +538,12 @@
   :type '(repeat string)
   :group 'vc)
 
+(defcustom vc-diff-command "diff"
+  "*A string specifying the diff command under VC."
+  :type 'string
+  :group 'vc
+  :version "21.1")
+
 (defcustom vc-diff-switches nil
   "*A string or list of strings specifying switches for diff under VC.
 When running diff under a given BACKEND, VC concatenates the values of
@@ -1764,7 +1770,7 @@
                      (vc-version-backup-file file rel2)))
         (coding-system-for-read (vc-coding-system-for-diff file)))
     (if (and file-rel1 file-rel2)
-        (apply 'vc-do-command "*vc-diff*" 1 "diff" nil
+        (apply 'vc-do-command "*vc-diff*" 1 vc-diff-command nil
               (append (vc-switches nil 'diff)
                       (list (file-relative-name file-rel1)
                             (file-relative-name file-rel2))))