How to check typedesc type inside macro?

[mratsim]

With a lot of pain:

  * 
[https://github.com/nim-lang/Nim/issues/6785](https://github.com/nim-lang/Nim/issues/6785)
  * 
[https://github.com/nim-lang/Nim/issues/14021](https://github.com/nim-lang/Nim/issues/14021)
  * 
[https://github.com/nim-lang/RFCs/issues/44](https://github.com/nim-lang/RFCs/issues/44)



And unfortunately `typeof(t)` doesn't work either.