readevalloop and GC

[Kyotaro HORIGUCHI]

In readevalloop() in lread.c creates marker object in every turn
of the loop when start is not nil, and the marker is not
GC-protected.

So, it may be freed by GC happened in evalfun (is typically
Feval) called just after.

lread.c:1410
|       if (!NILP (start) && continue_reading_p)
|         start = Fpoint_marker ();
|       unbind_to (count1, Qnil);
| 
|       val = (*evalfun) (val);    ;; GC will happen.

This problem was fixed by following patch.

BTW, I have seen the problem on Meadow when doing eval-region in
ps-print.el, but not on emacs.

-- 
Kyotaro HORIGUCHI

====
Index: lread.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/lread.c,v
retrieving revision 1.342
diff -u -2 -r1.342 lread.c
--- lread.c     1 Nov 2005 19:46:16 -0000       1.342
+++ lread.c     13 Nov 2005 17:17:27 -0000
@@ -1317,5 +1317,5 @@
   register Lisp_Object val;
   int count = SPECPDL_INDEX ();
-  struct gcpro gcpro1;
+  struct gcpro gcpro1, gcpro2;
   struct buffer *b = 0;
   int continue_reading_p;
@@ -1333,5 +1333,17 @@
   readchar_backlog = -1;
 
-  GCPRO1 (sourcename);
+  if (! NILP (start))
+    {    
+      if (NUMBERP (start))
+       {
+         Lisp_Object tmp = start;
+         start = Fmake_marker ();
+         Fset_marker (start, tmp, Qnil);
+       }
+      else if (! MARKERP (start))
+       wrong_type_argument (Qinteger_or_marker_p, start);
+    }
+
+  GCPRO2 (sourcename, start);
 
   LOADHIST_ATTACH (sourcename);
@@ -1401,5 +1413,5 @@
 
       if (!NILP (start) && continue_reading_p)
-       start = Fpoint_marker ();
+       set_marker_both (start , Qnil, PT, PT_BYTE);
       unbind_to (count1, Qnil);