Articles like this are one of the reasons I don't profess to know C++ well. I know almost all of the features in isolation, and many in combination, but new combinations are being discovered with novel and surprising effects, like this article demonstrates.

This is not a good advertisement for C++. It would have been much healthier to not have had such a powerful and under-researched template instantiation mechanism, and instead have a genuine compile-time macro language. It's hard to see a way back though. Everything added - like constexpr functions - to make compile-time execution more sane, can be put back into the mix to complect things even further.