Function next_code_point

extlibs/fmt/include/fmt/format.h:2403–2409

template <typename Char>
FMT_CONSTEXPR const Char* next_code_point(const Char* begin, const Char* end) {
  if (const_check(sizeof(Char) != 1) || (*begin & 0x80) == 0) return begin + 1;
  do {
    ++begin;
  } while (begin != end && (*begin & 0xc0) == 0x80);
  return begin;
}

// Parses fill and alignment.
template <typename Char, typename Handler>