"Martin Ecker" writes:

Hello,

I wanted to use boost::variant, so I got the Boost libraries from CVS. While developing a small test program I discovered an issue in the MPL header file apply.hpp that prevented successful compilation on MSVC 7.1. In particular, starting on line 245 in boost/mpl/apply.hpp it says

// ISO98 C++, with minor concession to vc7

template< typename F, AUX_APPLY_N_PARAMS(i, typename T) > struct BOOST_PP_CAT(apply,i) { // Metafunction forwarding confuses vc7 typedef typename F::template apply< AUX_APPLY_N_PARAMS(i, T) >::type

BOOST_MPL_AUX_LAMBDA_SUPPORT( BOOST_PP_INC(i) , BOOST_PP_CAT(apply,i) , (F, AUX_APPLY_N_PARAMS(i,T)) ) };

The first typedef in that struct should be

// Metafunction forwarding confuses vc7 typedef typename F::template apply< AUX_APPLY_N_PARAMS(i, T) >::type type;

Thanks. This bug has gone unnoticed since October! But it's a little bit strange that you encountered it at all, since your compiler should be seeing the preprocessed header at boost/mpl/aux_/preprocessed/plain/apply.hpp (unless you've got BOOST_MPL_NO_PREPROCESSED_HEADERS defined, of course). -- Dave Abrahams Boost Consulting www.boost-consulting.com