Function handle_char_specs

extlibs/fmt/include/fmt/format.h:1300–1307

template <typename Char, typename Handler>
FMT_CONSTEXPR void handle_char_specs(const basic_format_specs<Char>* specs,
                                     Handler&& handler) {
  if (!specs) return handler.on_char();
  if (specs->type && specs->type != 'c') return handler.on_int();
  if (specs->align == align::numeric || specs->sign != sign::none || specs->alt)
    handler.on_error("invalid format specifier for char");
  handler.on_char();
}

template <typename Char, typename Handler>
FMT_CONSTEXPR void handle_cstring_type_spec(Char spec, Handler&& handler) {