Compilare: main.cpp: In function 'auto vt(size_t, Args&& ...)': main.cpp:19:8: warning: 'if constexpr' only available with '-std=c++17' or '-std=gnu++17' 19 | if constexpr(sizeof...(args) == 1) { | ^~~~~~~~~ main.cpp: In instantiation of 'void re(std::vector<_Tp>&, sec& ...) [with fir = int; sec = {}]': main.cpp:60:36: required from here main.cpp:39:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | for(int i = 1;i < x.size();i++) | ~~^~~~~~~~~~