c++ - noexcept depending on method of member -

related this question, want specify private section after public interface.

template<class t, void (t::*f)()> class b { public:     void g(int y) noexcept(noexcept(x.*f()))     {} private:     t& x; }; 

but error clang x undeclared identifyer.

mm_test.cpp:14:34: error: use of undeclared identifier 'x'     void g(int y) noexcept(noexcept(x.*f()))                                     ^ 

it compiles fine if declaration of member x occurs before declaration of g. not supposed able use member variable in noexcept operator earlier in class definition declaration? if not, how achieve equivalent noexcept specifier without moving declaration of x ahead?