Function is_negative

extlibs/fmt/include/fmt/format.h:741–743

// Same as `value < 0` but doesn't produce warnings if T is an unsigned type.
template <typename T, FMT_ENABLE_IF(std::numeric_limits<T>::is_signed)>
FMT_CONSTEXPR bool is_negative(T value) {
  return value < 0;
}
template <typename T, FMT_ENABLE_IF(!std::numeric_limits<T>::is_signed)>
FMT_CONSTEXPR bool is_negative(T) {
  return false;