* lisp/progmodes/prolog.el (prolog-find-value-by-system): Avoid error when

there's no inferior buffer.
(prolog-consult-compile): Don't use toggle-read-only.

Fixes: debbugs:10196

2 files changed, 10 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 4ab35890cae..33e20f297a9 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2011-12-03  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * progmodes/prolog.el (prolog-find-value-by-system): Avoid error when
+        there's no inferior buffer (bug#10196).
+        (prolog-consult-compile): Don't use toggle-read-only.
+
 2011-12-02  Michael Albinus  <michael.albinus@gmx.de>
 
         * net/tramp-sh.el (tramp-maybe-open-connection): Handle user
diff --git a/lisp/progmodes/prolog.el b/lisp/progmodes/prolog.el
index 24ca78ad4ef..5b229cc0c24 100644
--- a/lisp/progmodes/prolog.el
+++ b/lisp/progmodes/prolog.el
@@ -868,8 +868,9 @@ VERSION is of the format (Major . Minor)"
 (defun prolog-find-value-by-system (alist)
   "Get value from ALIST according to `prolog-system'."
   (let ((system (or prolog-system
-                    (buffer-local-value 'prolog-system
-                                        (prolog-inferior-buffer 'dont-run)))))
+                    (let ((infbuf (prolog-inferior-buffer 'dont-run)))
+                      (when infbuf
+                        (buffer-local-value 'prolog-system infbuf))))))
     (if (listp alist)
         (let (result
               id)
@@ -1522,7 +1523,7 @@ This function must be called from the source code buffer."
           ;; Emacs-20).
             (set (make-local-variable 'compilation-parse-errors-function)
                'prolog-parse-sicstus-compilation-errors))
-      (toggle-read-only 0)
+      (setq buffer-read-only nil)
       (insert command-string "\n"))
     (save-selected-window
       (pop-to-buffer buffer))