One small glitch in the 2009-02-11 signals2 snapshot [1]. When a source file containing only: #include <boost/signals2.hpp> is compiled with Visual Studio 2005, it produces: cl /EHsc /I libraries/include signals2-glitch.cpp Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.762 for 80x86 Copyright (C) Microsoft Corporation. All rights reserved. signals2-glitch.cpp libraries/include\boost/signals2/deconstruct.hpp(510) : error C2874: using-declaration causes a multiple declaration of 'boost::signals2::detail::deconstruct_access' libraries/include\boost/signals2/deconstruct.hpp(233) : see declaration of 'boost::signals2::detail::deconstruct_access' This is the line in question, near the bottom of boost/signals2/deconstruct.hpp: using detail::deconstruct_access; I'm not sure what the intent is for that line, but removing it solves that problem without, as far as I'm aware, introducing new problems. I've attached a patch file. This line caused me no problems on Mac or Linux. Neither does its removal. [1] http://www.boostpro.com/vault/index.php?action=downloadfile&filename=signals2-2009-02-11.zip&directory=thread_safe_signals& *** boost/signals2/deconstruct.hpp~ Thu Feb 5 18:58:10 2009 --- boost/signals2/deconstruct.hpp Mon Feb 23 15:05:44 2009 *************** *** 507,514 **** return detail::deconstruct_access::deconstruct<T>(a1,a2,a3,a4,a5,a6,a7,a8,a9); } - using detail::deconstruct_access; - #endif } // namespace signals2 --- 507,512 ----