If you're willing to use one measly little macro - solely to smuggle the format string in a constexpr manner - instead of insisting on using templates everywhere, you can use a printf wrapper with essentially 0 compile-time overhead. And the only runtime overhead is if you have to copy a `string_view` back into a `string` to add the `NUL`-terminator.

You do still need templates for the arguments (unless you're willing to resort to nasty preprocessor hackery, which would be needed if doing this in C - hmm, are the lifetime-of-temporary rules different too?), but it's pretty easy to just do:

  my_asprintf_or_whatever(to_borrowed_primitive(to_owning_primitive(arg))...)

where `to_owning_primitive` is the ADL'ed function you implement for every type you want to print, and `to_borrowed_primitive` probably only needs to be implemented for each string type (though I did find it also useful for wrapped integers of unknown size/rank, such as `time_t`).