Luis Tung

I think template class `iter_impl` and `ordered_json` depend on each other when we use `nlohmann::detail::iter_impl`. So `nlohmann::ordered_json` should be explicit instantiate beforehand.

> As I've stated in the bug report, I don't think that's an acceptable solution. This can be fixed without penalizing every user who doesn't use `ordered_json`. Does explicit instantiation...

> It hurts everyone's compilation speed. And there is a solution that doesn't. > > Also, I'd like to understand this problem better to make sure we're not masking a...