‘args#0’ is not a constant expression under c++20

[hsgui]

in flare/base/tsc.h

inline std::uint64_t TscElapsed(std::uint64_t start, std::uint64_t to) {
  if (FLARE_UNLIKELY(start >= to)) {
    FLARE_LOG_WARNING_IF_EVERY_N(
        start - to > 1'000'000, 100,
        "Unexpected: TSC goes backward for more than 1M cycles (0.5ms on "
        "2GHz). You will likely see some unreasonable timestamps. Called with "
        "start = {}, to = {}.",
        start, to);
    return 0;
  }
  return to - start;
}

when the code calls into the following code:

template <class... Ts>
std::string FormatLog([[maybe_unused]] const char* file,
                      [[maybe_unused]] int line, const Ts&... args) noexcept {
  std::string result;

  WritePrefixTo(&result);
  if constexpr (sizeof...(Ts) != 0) {
    try {
      result += fmt::format(args...);
    } catch (const std::exception& xcpt) {
      // Presumably a wrong format string was provided?
      LOG(FATAL) << "Failed to format log at [" << file << ":" << line
                 << "]: " << xcpt.what();
    }
  }
  return result;
}

there is a compiling issue: