Hello all, Does this Addable concept definition make sense to you? Is there any error? #include <boost/concept_check.hpp> template<typename T> struct Addable { // User-defined concept. BOOST_CONCEPT_USAGE(Addable) { return_type(x + y); // Check addition `T operator+(T x, T y)`. } private: T x; T y; void return_type(T const&); // Used to check addition returns type `T`. }; It's not making Sun's linker happy: "/opt/sunstudio12.1/bin/CC" -g -library=stlport4 -features=tmplife -features=tmplrefstatic -library=stlport4 -m64 -KPIC -o "/scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq" "/scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq.o" -Bdynamic -lrt -Bstatic -Bdynamic Undefined???first referenced symbol ??? in file void Addable<int>::return_type(const int&) /scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq.o ld: fatal: Symbol referencing errors. No output written to /scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq But the error might also be somewhere else in the program that checks the concept, I'm still debugging... Thanks a lot. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-concept-check-addable-tp4572138p457... Sent from the Boost - Dev mailing list archive at Nabble.com.