We have been using call_traits from Boost version 1.29.0 in conjunction with MSVC 7.0. When attempting to recompile this code under MSVC 7.1, using either Boost 1.29.0 or 1.30.0, we now encounter compilation errors. A simple example of the usage pattern is: ############################################################### #include class A { public: template<typename _Source> void doSomething ( typename boost::call_traits<_Source>::param_type value ) { } }; class B { public: explicit B(double d = 1.0, int i = 42) : _d(d), _i(i) {} B(B const& b) : _d(b._d), _i(b._i) {} private: double _d; int _i; }; extern "C" int main(int argc, char* argv[]) { A a; B b; a.doSomething(b); return 0; } ############################################################# The new compiler generates the error message: c:\Documents and Settings\rbowen\My Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(34) : error C2783: 'void A::doSomething (boost::call_traits<_Source>::param_type)' : could not deduce template argument for '_Source' c:\Documents and Settings\rbowen\My Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(11) : see declaration of 'A::doSomething' As an experiment, I manually included the older logic for call_traits by cutting and pasting the relevant classes into my source from 'detail/ob_call_traits.hpp' and still encountered the same error. Has anyone else experienced this? Is this (yet another) MS compiler bug?