(Fdefvar): Allow defvaring a constant to itself quoted.

1 files changed, 10 insertions, 2 deletions

diff --git a/src/eval.c b/src/eval.c
index f625258229e..45effae295c 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -807,8 +807,16 @@ usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
 
   sym = Fcar (args);
   if (SYMBOL_CONSTANT_P (sym))
-    error ("Constant symbol `%s' specified in defvar",
-           SDATA (SYMBOL_NAME (sym)));
+    {
+      /* For updward compatibility, allow (defvar :foo (quote :foo)).  */
+      tem = Fcar (Fcdr (args));
+      if (! (CONSP (tem)
+             && EQ (XCAR (tem), Qquote)
+             && CONSP (XCDR (tem))
+             && EQ (XCAR (XCDR (tem)), sym)))
+        error ("Constant symbol `%s' specified in defvar",
+               SDATA (SYMBOL_NAME (sym)));
+    }
 
   tail = Fcdr (args);
   if (!NILP (Fcdr (Fcdr (tail))))