message: Only allow -infinity for signed types
diff: @@ -105,7 +105,8 @@ bool try_parse_specials(std::string str, T& ret)
  ret = std::numeric_limits<T>::infinity();
  return true;
  }
  - else if (std::numeric_limits<T>::has_infinity && (str == "-infinity" || str == "-inf")) {
  + else if (std::numeric_limits<T>::has_infinity && std::numeric_limits<T>::is_signed &&
  + (str == "-infinity" || str == "-inf")) {
  ret = -std::numeric_limits<T>::infinity();
  return true;
  }
  