I have to use std::string_view with %.*s as a string formatter every day. It is an incredible pain. Of course the solution is getting rid of printf style formatting, not string_view.
The hardest part of passing `std::string` to `printf` was getting the macro to convince the pre-standard-C++11 compiler that it was `constexpr` enough so that `-Werror=format` would work.
I found it was easiest to sometimes allocate a temporary, if the input wasn't known to be NUL-terminated.
