I'm having problems compiling non-explicitly-declared mpl::set types. Here's an example: <block1> typedef set<char> set1_t; BOOST_MPL_ASSERT_RELATION(size::value, ==, 1); //test iterating through the mpl.set: typedef begin::type set1_itr0_t; BOOST_MPL_ASSERT((is_same::type, char>::type)); typedef next::type set1_itr1_t; BOOST_MPL_ASSERT((is_same::type>::type)); </block1> In block1, I declare a set with one type, char, and then iterate over it. This code compiles, as expected. <block2> typedef set<> empty_set; BOOST_MPL_ASSERT_RELATION(size::value, ==, 0); typedef insert::type set2_t; BOOST_MPL_ASSERT_RELATION(size::value, ==, 1); //test iterating through the mpl.set: typedef begin::type set2_itr0_t; BOOST_MPL_ASSERT((is_same::type, char>::type)); typedef next::type set2_itr1_t;//compile error at this line BOOST_MPL_ASSERT((is_same::type>::type)); </block2> In block2, I declare a set with no types, then insert a char type, then iterate over the resulting sequence. At the line where I get the second iterator, I get a compile error: boost\mpl\set\aux_\iterator.hpp(52) : error C3083: 'next_': the symbol to the left of a '::' must be a type boost\mpl\eval_if.hpp(41) : see reference to class template instantiation 'boost::mpl::next<T>' being compiled with [ T=boost::mpl::s_iterboost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,b...> ] boost\mpl\set\aux_\iterator.hpp(56) : see reference to class template instantiation 'boost::mpl::eval_if' being compiled with [ C=boost::mpl::has_keyboost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,b...::type>, F1=boost::mpl::identityboost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,b...>>, F2=boost::mpl::nextboost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,b...>> ] source.cpp(120) : see reference to class template instantiation 'boost::mpl::next<T>' being compiled with [ T=set2_itr0_t ] MSVS 8.0 is the compiler(_MSC_VER == 1400). Am I missing an obvious error in my code? Thanks! _________________________________________________________________ Need a break? Find your escape route with Live Search Maps. http://maps.live.com/default.aspx?ss=Restaurants~Hotels~Amusement%20Park&cp=33.832922~-117.915659&style=r&lvl=13&tilt=-90&dir=0&alt=-1000&scene=1118863&encType=1&FORM=MGAC01