1 files changed, 15 insertions, 4 deletions

diff --git a/lisp/gud.el b/lisp/gud.el
index 08b0ee92f33..862ecd3e38f 100644
--- a/lisp/gud.el
+++ b/lisp/gud.el
@@ -71,6 +71,8 @@ Supported debuggers include gdb, sdb, dbx, xdb, perldb, pdb (Python), jdb, and b
 (defvar gud-minor-mode nil)
 (put 'gud-minor-mode 'permanent-local t)
 
+(defvar gud-keep-buffer nil)
+
 (defun gud-symbol (sym &optional soft minor-mode)
   "Return the symbol used for SYM in MINOR-MODE.
 MINOR-MODE defaults to `gud-minor-mode.
@@ -188,7 +190,8 @@ Uses `gud-<MINOR-MODE>-directories' to find the source files."
       ;; Copy `gud-minor-mode' to the found buffer to turn on the menu.
       (with-current-buffer buf
         (set (make-local-variable 'gud-minor-mode) minor-mode)
-        (set (make-local-variable 'tool-bar-map) gud-tool-bar-map))
+        (set (make-local-variable 'tool-bar-map) gud-tool-bar-map)
+        (make-local-variable 'gud-keep-buffer))
       buf)))
 
 ;; ======================================================================
@@ -2513,17 +2516,25 @@ Obeying it means displaying in another window the specified file and line."
         (progn
           (save-excursion
             (set-buffer buffer)
+            (if (not (or (verify-visited-file-modtime buffer) gud-keep-buffer))
+                (progn
+                  (if
+                      (yes-or-no-p 
+                       (format "File %s changed on disk.  Reread from disk? "
+                               (buffer-name)))
+                      (revert-buffer t t)
+                    (setq gud-keep-buffer t))))
             (save-restriction
               (widen)
               (goto-line line)
               (setq pos (point))
               (setq overlay-arrow-string "=>")
               (or overlay-arrow-position
-                  (setq overlay-arrow-position (make-marker)))
+              (setq overlay-arrow-position (make-marker)))
               (set-marker overlay-arrow-position (point) (current-buffer)))
             (cond ((or (< pos (point-min)) (> pos (point-max)))
-                   (widen)
-                   (goto-char pos))))
+            (widen)
+            (goto-char pos))))
           (set-window-point window overlay-arrow-position)))))
 
 ;; The gud-call function must do the right thing whether its invoking