(vc-diff-switches): Doc fix.

2 files changed, 32 insertions, 9 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 21f805ed537..57cb3703c0e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,25 @@
+2008-12-03  Glenn Morris  <rgm@gnu.org>
+
+        * vc.el (vc-diff-switches): Doc fix.
+        * vc-bzr.el (vc-bzr-diff-switches): Doc fix.  Add t as option.
+        (vc-bzr-log-switches): Doc fix.
+        * vc-cvs.el (vc-cvs-diff-switches): Doc fix.  Add t as option.
+        * vc-git.el (vc-git-diff-switches): Doc fix.
+        * vc-hg.el (vc-hg-diff-switches): Doc fix.
+        * vc-mcvs.el (vc-mcvs-diff-switches): Doc fix.
+        * vc-mtn.el (vc-mtn-diff-switches): Doc fix.
+        * vc-rcs.el (vc-rcs-diff-switches): Doc fix.  Add t as option.
+        * vc-sccs.el (vc-sccs-diff-switches): Doc fix.  Add t as option.
+
+        * vc-arch.el (vc-arch-diff-switches): New option, for consistency with
+        other backends.
+        (vc-arch-diff): Apply switches.
+
+        * vc-cvs.el (vc-cvs-diff): Use vc-diff-switches or diff-switches rather
+        than appending.
+
+        * vc-sccs.el (vc-sccs-register-switches): Remove leading * from doc.
+
 2008-12-03  Daiki Ueno  <ueno@unixuser.org>
 
         * epa.el (epa--show-key): Use past tense of "expire" if the key
diff --git a/lisp/vc.el b/lisp/vc.el
index 865a4018eb1..b87fe7137d4 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -697,16 +697,17 @@ These are passed to the checkin program by \\[vc-register]."
 
 (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
-`diff-switches', `vc-diff-switches', and `vc-BACKEND-diff-switches' to
-get the switches for that command.  Thus, `vc-diff-switches' should
-contain switches that are specific to version control, but not
-specific to any particular backend."
-  :type '(choice (const :tag "None" nil)
+When running diff under a given BACKEND, VC uses the first
+non-nil value of `vc-BACKEND-diff-switches', `vc-diff-switches',
+and `diff-switches', in that order.  Since nil means to check the
+next variable in the sequence, either of the first two may use
+the value t to mean no switches at all.  `vc-diff-switches'
+should contain switches that are specific to version control, but
+not specific to any particular backend."
+  :type '(choice (const :tag "Unspecified" nil)
+                 (const :tag "None" t)
                  (string :tag "Argument String")
-                 (repeat :tag "Argument List"
-                         :value ("")
-                         string))
+                 (repeat :tag "Argument List" :value ("") string))
   :group 'vc
   :version "21.1")