Seems I can't "unforget" erroneously forgotten files, so will have to forget them and then re-add them
// Boost.Function library
// Copyright Douglas Gregor 2002-2003. Use, modification and
// distribution is subject to the Boost Software License, Version
// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// For more information, see http://www.boost.org
#define BOOST_FUNCTION_NUM_ARGS 7
#include <boost/function/detail/maybe_include.hpp>
#undef BOOST_FUNCTION_NUM_ARGS