Forward declare-only header?

[mcourteaux]

Would it be possible to provide a header meant for forward declaring only? This would save roughly 10k lines of code for all the compilation units that do not really need the details of json but just a pointer/reference or the size of the nlohmann::json class.

Then we could do in header files:

#include <json_fd.hpp>

nlohmann::json *json_ptr;

This would allow me to speed up compilation of my project quite a bit, as I use your json project here and there, but turns out to be included in a large portion of the compilation units.

[mcourteaux]

Oh gosh. There is an issue for this. #381

[nlohmann]

No problem! If you have any further idea, just add comments.