bug#11770: 24.1.50; Unable to mouse-mark regions in the info reader

[Stefan Monnier]

>> When marking stuff in an info file via double click, I often get a
>> backtrace like the following:
>> 
>> Debugger entered--Lisp error: (args-out-of-range 1 262195)
>> buffer-substring-no-properties(1 262195)
>> pop-mark()
>> mouse-drag-track((down-mouse-1 (#<window 3 on *info*> 262195 (10 . 308) 
>> 26997248 nil 262195 (1 . 14) nil (3 . 6) (7 . 15))) t)
>> mouse-drag-region((down-mouse-1 (#<window 3 on *info*> 262195 (10 . 308) 
>> 26997248 nil 262195 (1 . 14) nil (3 . 6) (7 . 15))))
>> call-interactively(mouse-drag-region nil nil)
>> 
>> 
>> It does not seem to happen at the beginning of the info file, but is
>> rather common at the end of large info files (like in "(emacs) Bugs").
>> 

> I remember reporting something similar in

> http://lists.gnu.org/archive/html/emacs-devel/2011-04/msg00399.html

I installed the patch below which should fix this problem.


        Stefan


--- src/editfns.c       2012-06-22 21:17:42 +0000
+++ src/editfns.c       2012-06-28 19:07:10 +0000
@@ -283,8 +283,12 @@
     error ("The mark is not set now, so there is no region");
 
   if ((PT < XFASTINT (m)) == (beginningp != 0))
-    m = make_number (PT);
-  return m;
+    return make_number (PT);
+  else
+    { /* Clip to the current narrowing (bug#11770).  */
+      ptrdiff_t mark = XFASTINT (m);
+      return make_number (mark < BEGV ? BEGV : mark > ZV ? ZV : m);
+    }
 }
 
 DEFUN ("region-beginning", Fregion_beginning, Sregion_beginning, 0, 0, 0,