I guess if you set the compiler's standard flag to C++14 or C++11, etc. and it compiles without warning or error, then you are not using any C++17 features. How

I guess if you set the compiler's standard flag to C++14 or C++11, etc. and it compiles without warning or error, then you are not using any C++17 features. How exactly this would be useful remains to be seen!