Hi Environment: MS 7.1 compile with MS implementation of STL Boost 1.32.0 Summary: I get an internal compiler error using boost::variant as a parameter of a boost::signal compiling with MSDEV 7.1, but not with gcc3.3/3.4 or MinGW (3.5). Does anyone knows a workaround other than not using boost::signals? Details Using a signal with a variant of 2 simple classes (see code snippet) leads to an internal compiler error C1001. Using pragma command to turn optimisation off as Suggested by the compiler does not change a thing Does anyone knows a workaround? Regards, jom Here's the bad code snippet: #include <boost/bind.hpp> #include <boost/signals.hpp> #include <boost/variant.hpp> #include <vector> class MessageException : public std::exception { public: MessageException() : std::exception( "Message error" ) {} }; class Message { public: typedef std::vector<unsigned char> Content; Message(unsigned int p, unsigned char def = ' ') : m_vector( p, def ) {} const Content& message() {return m_vector;} private: Content m_vector; }; typedef boost::variant<MessageException, Message> MessageVariant; class TestWrap { public: TestWrap(){} typedef boost::signal1<void, MessageVariant> MessageSignal; //typedef boost::signal<void (MessageVariant)> MessageSignal; void send_signal (MessageVariant& variant) { m_message_signal( variant ); } private: MessageSignal m_message_signal; };