Given a negative zero as input, the negative sign is silently truncated. It should be preserved.

  const char* json = "{\"negative\": -0.0, \"positive\": 0.0}";
  rapidjson::Document d;
  d.Parse(json);

  rapidjson::StringBuffer buffer;
  rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
  d.Accept(writer);

  // Outputs {"negative":0.0,"positive":0.0}
  std::cout << buffer.GetString() << std::endl;

This also happens to integers, but I'm not sure how that should be handled. The javascript spec is quite clear that negative and positive zero should be distinguished, but most programming languages does not differentiate between -(int)0 and +(int)0.