Re: void variable

[Stefan Monnier <monnier@iro.umontreal.ca>]

>     Maybe we could arrange for defvar to burp a warning if the var is
>     currently let-bound?
> That sounds like a good idea.  It should be possible to do this
> by searching the specpdl.

The patch below seems to work well.  Any objection (or suggestion of
a better message)?


        Stefan


--- orig/src/eval.c
+++ mod/src/eval.c
@@ -747,6 +747,20 @@
 	XSYMBOL (sym)->constant = 0;
       if (NILP (tem))
 	Fset_default (sym, Feval (Fcar (tail)));
+      else
+	{ /* Check if there is really a global binding rather than just a let
+	     binding that shadows the global unboundness of the var.  */
+	  struct specbinding *pdl = specpdl_ptr;
+	  while (--pdl >= specpdl)
+	    {
+	      if (!pdl->func && EQ (pdl->symbol, sym) && EQ (pdl->old_value, Qunbound))
+		{
+		  message_with_string ("%s is still globally unbound",
+				       SYMBOL_NAME (sym), 1);
+		  pdl = specpdl; /* Don'tlook further.  */
+		}
+	    }
+	}
       tail = Fcdr (tail);
       tem = Fcar (tail);
       if (!NILP (tem))