* files.el (hack-local-variables-prop-line)

(hack-local-variables, dir-locals-read-from-file): Bind
read-circle to nil before reading.
* lread.c (Vread_circle): New variable.
(read1): Disable recursive read if Vread_circle is nil.

2 files changed, 14 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index d47f354ba6a..760795f1870 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2009-04-29  Ulrich Mueller  <ulm@gentoo.org>
+
+        * lread.c (Vread_circle): New variable.
+        (read1): Disable recursive read if Vread_circle is nil.
+
 2009-04-29  Kenichi Handa  <handa@m17n.org>
 
         * fontset.h (set_default_ascii_font): Delete extern.
diff --git a/src/lread.c b/src/lread.c
index 8a4b96874ce..cb3f5b04633 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -125,6 +125,9 @@ Lisp_Object Vload_file_name;
 /* Function to use for reading, in `load' and friends.  */
 Lisp_Object Vload_read_function;
 
+/* Non-nil means read recursive structures using #n= and #n# syntax.  */
+Lisp_Object Vread_circle;
+
 /* The association list of objects read with the #n=object form.
    Each member of the list has the form (n . object), and is used to
    look up the object for the corresponding #n# construct.
@@ -2558,7 +2561,7 @@ read1 (readcharfun, pch, first_in_list)
               c = READCHAR;
             }
           /* #n=object returns object, but associates it with n for #n#.  */
-          if (c == '=')
+          if (c == '=' && !NILP (Vread_circle))
             {
               /* Make a placeholder for #n# to use temporarily */
               Lisp_Object placeholder;
@@ -2580,7 +2583,7 @@ read1 (readcharfun, pch, first_in_list)
               return tem;
             }
           /* #n# returns a previously read object.  */
-          if (c == '#')
+          if (c == '#' && !NILP (Vread_circle))
             {
               tem = Fassq (make_number (n), read_objects);
               if (CONSP (tem))
@@ -4215,6 +4218,10 @@ read multiple times.  The list is in the same order as the symbols
 were read in. */);
   Vread_symbol_positions_list = Qnil;
 
+  DEFVAR_LISP ("read-circle", &Vread_circle,
+               doc: /* Non-nil means read recursive structures using #N= and #N# syntax.  */);
+  Vread_circle = Qt;
+
   DEFVAR_LISP ("load-path", &Vload_path,
                doc: /* *List of directories to search for files to load.
 Each element is a string (directory name) or nil (try default directory).