I spent a long time thinking about this. My conclusion is that the simplest way to achieve this, at least in GCC, is to create a #copy directive that allows a macro, together with its stack, to be copied to another. GCC already allows stack expansion with push and pop but it can only be expanded once; the #copy directive would fix that.

If you get anything close to that working, that would be a godsend. It is the last remaining piece of the puzzle for me to implement complete RTTI in C. It would certainly help to minimize glib boiler plate code too.

I'd really like it to be part of c2x, but I think it is too late now. If it is implemented by either GCC or Clang, the remaining other would certainly it too since it is too useful. So getting it to work in any of these would be good enough for me.

How can I track/follow your progress?