I got several requests by people asking to make my C++ WinReg code (which has been using C++17 in its main branch since many months) compile on older C++14 compilers (like VS 2017 in C++14 mode).
Now you can find the C++14-compatible version in this branch.
To make the code C++14-compatible, among other things, I removed the use of [[nodiscard]], removed std::variant (simply substituted with a couple of data members), and replaced the non-const std::wstring::data() method with &s[0].