C++ 2017 - !!exclusive!!

std::map<int, std::string> src1,"a"; std::map<int, std::string> dst; dst.insert(src.extract(1)); Distinct enum class for raw memory representation (no arithmetic).

Type-safe union.

// in a header inline int global_counter = 0; Mandates copy elision for prvalues, making certain moves/constructors unnecessary even conceptually. c++ 2017