Calculate the length of the resulting string if the specified args were to be formatted according to the specification given by the specified fmtStr, and return the result.
Declared in <bslfmt_format_imp.h>
template<class... t_ARGS>
std::size_t
formatted_size(
bslfmt::format_string<t_ARGS...> fmtStr,
t_ARGS const&... args);