I'm trying to use thread and intrusive libraries with VS 2008 (9.0.21022.8) In 32-bit mode (Win32 platform) everything works just fine. However, when I switch the configuration to x64, two problems appear: Intrusive problem: ================== With default settings, just including produces the follwing error: C:\Users\zvrba\Work\boost_1_37_0\boost/intrusive/detail/mpl.hpp(191) : error C2953: 'boost::intrusive::detail::is_unary_or_binary_function_impl ' : class template has already been defined I have traced that back to the BOOST_INTRUSIVE_TT_TEST_MSC_FUNC_SIGS define, which is active when compiling with MS extensions turned on. Thread problem: =============== I turned off MS extensions, and this fixes the problem with the intrusive library (the header is included before the thread header). However, then I get the following error: C:\Users\zvrba\Work\boost_1_37_0\boost/config/requires_threads.hpp(29) : fatal error C1189: #error : "Threading support unavaliable: it has been explicitly disabled with BOOST_DISABLE_THREADS" This error is dependent on the language extensions being enabled or not. Fix: ==== I have temporarily solved the problem by hacking the list.hpp header: #if defined(_MSC_EXTENSIONS) && !defined(__BORLAND__) //#define BOOST_INTRUSIVE_TT_TEST_MSC_FUNC_SIGS #endif (the commented line is the fix). The cause is probably the following comment in the documentation: "On Itanium Processor Family (IPF) and x64 processors, __cdecl is accepted and ignored by the compiler" (same for __stdcall) This makes the decorated and undecorated signatures equivalent, so I tend to believe that this fix would be correct with the additional [&& !defined(_WIN64)] clause.