https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78754
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- clang, ICC and GCC all accept it. ICC warns though: <source>(4): warning #2922: template parameter "Ts" cannot be used because it follows a parameter pack and cannot be deduced from the parameters of function template "foo" template<std::size_t ...Ns, typename ...Ts> ^ And MSVC errors out: <source>(5): error C3547: template parameter 'Ts' cannot be used because it follows a template parameter pack and cannot be deduced from the function parameters of 'foo'