Starting with the advent of modern C++ in the early 2000s, C++ programming became more about computing things during compilation instead of deferring them to runtime. It's much cheaper to detect errors during compilation than to debug them later on. Similarly, it's much faster to have the result ready before the program is started instead of calculating it later on.
At first, there was template metaprogramming, but with C++11 onward, each new standard brought additional features for compile-time compute: be it type traits, constructs such as std::enable_if or std::void_t, or C++20's consteval for computing stuff only at compile time.
One feature that improved over the years was the constexpr keyword and its related code. C++20 really improved and extended constexpr. Now, you can not only write regular simple constexpr functions thanks to the previous standards (quite an improvement from C++11's single-expression ones), but you...