I don't know, but I see the error for incomplete type, so try #define BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT lib/gcc/mingw32/4.5.2/include/c++/bits/stl_pair.h:77:11: error: 'std::pair<_T1, _T2>::second' has incomplete type \boost_1_46_1/boost/variant/variant_fwd.hpp:232:12: error: forward declaration of 'struct boost::recursive_variant_' /////////////////////////////////////////////////////////////////////////////// // type recursive_variant_ // // Tag type indicates where recursive variant substitution should occur. // #if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT) struct recursive_variant_; // line 232: ERROR here #else typedef mpl::arg<1> recursive_variant_; #endif ------------------------------ Message: 5 Date: Fri, 18 Nov 2011 11:37:51 +0100 From: "Bodmer Marc" <Marc.Bodmer@bystronic.com> To: <qiaozhiqiang@leadcoretech.com> Cc: boost-users@lists.boost.org Subject: Re: [Boost-users] recursive_variant map recursion / incompletetype error Message-ID: <0456E5B751F6DB4A83688EED49C9CAF70E101096@CHNIS191.bystronic.metal.firm> Content-Type: text/plain; charset="utf-8" Hi, thanks for your help. This works for me. Do you have any clue why this is needed?