Only show "Back" when the marker stack is non-empty

* lisp/menu-bar.el (menu-bar-goto-menu): Use it.

* lisp/progmodes/xref.el (xref-marker-stack-empty-p): New function.

3 files changed, 11 insertions, 0 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 34e22af92a9..49640f89055 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,11 @@
 2015-01-03  Dmitry Gutov  <dgutov@yandex.ru>
 
+        * progmodes/xref.el (xref-marker-stack-empty-p): New function.
+
+        * menu-bar.el (menu-bar-goto-menu): Use it.
+
+2015-01-03  Dmitry Gutov  <dgutov@yandex.ru>
+
         * progmodes/xref.el (xref--window-configuration): New variable.
         (xref-show-location-at-point): New command.
         (xref--restore-window-configuration): New function.
diff --git a/lisp/menu-bar.el b/lisp/menu-bar.el
index 7d7e4660fb5..67cb3273d23 100644
--- a/lisp/menu-bar.el
+++ b/lisp/menu-bar.el
@@ -381,6 +381,7 @@
 
     (bindings--define-key menu [xref-pop]
       '(menu-item "Back" xref-pop-marker-stack
+                  :visible (not (xref-marker-stack-empty-p))
                   :help "Back to the position of the last search"))
 
     (bindings--define-key menu [xref-apropos]
diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index cb331e1c833..7bc6500a8de 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -301,6 +301,10 @@ backward."
       (let ((marker (ring-remove ring)))
         (set-marker marker nil nil)))))
 
+(defun xref-marker-stack-empty-p ()
+  "Return t if the marker stack is empty; nil otherwise."
+  (ring-empty-p xref--marker-ring))
+
 
 (defun xref--goto-location (location)
   "Set buffer and point according to xref-location LOCATION."