tree.c (mapcar): When dealing with a DECL, use it's constant value, if any.

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	* tree.c (mapcar): When dealing with a DECL, use it's constant
	value, if any.
	* pt.c (lookup_template_class): Don't mangle the names of template
	classes whose arguments are unknown.
	* pt.c (tsubst_expr): Handle GOTO_STMT correctly.

From-SVN: r18803

gcc/cp/tree.c

@@ -1473,8 +1473,18 @@ mapcar (t, func)
       /* Rather than aborting, return error_mark_node.  This allows us
 	 to report a sensible error message on code like this:
 
-	 void g() { int i; f<i>(7); } */
-      return error_mark_node;
+	 void g() { int i; f<i>(7); } 
+
+         In a case like:
+
+           void g() { const int i = 7; f<i>(7); }
+
+	 however, we must actually return the constant initializer.  */
+      tmp = decl_constant_value (t);
+      if (tmp != t)
+	return mapcar (tmp, func);
+      else
+	return error_mark_node;
 
     case PARM_DECL:
       {