[boost] [parameter][type_traits] is_base_and_derived change broken parameter library

From: Doug Gregor (dgregor_at_[hidden])
Date: 2007-09-13 16:02:11

John Maddock's fix to is_base_and_derived to make it complain about  
the use of incomplete types (see http://svn.boost.org/trac/boost/ 
changeset/39219) broke something within the parameter library.

I've committed the following patch to the parameter library, which  
fixes the problem.  Unless there was a particular reason not to  
include the "maybe" header from arg_list.hpp?

        - Doug

Index: aux_/arg_list.hpp
===================================================================
--- aux_/arg_list.hpp   (revision 39245)
+++ aux_/arg_list.hpp   (working copy)
@@ -11,6 +11,7 @@
#include <boost/parameter/aux_/default.hpp>
#include <boost/parameter/aux_/parameter_requirements.hpp>
#include <boost/parameter/aux_/yesno.hpp>
+#include <boost/parameter/aux_/maybe.hpp>
#include <boost/parameter/config.hpp>
#include <boost/mpl/apply.hpp>
@@ -158,10 +159,6 @@ no_tag operator*(empty_arg_list, KW*);
template <class KW, class T>
struct tagged_argument;
-// Forward declaration for arg_list::operator[], with
-// IS_XXX helper
-struct maybe_base;
-
template <class T>
struct is_maybe
    : is_base_and_derived<maybe_base, T>