**@ivanitto**: I agree with Varriount that it's best to declare the types in
Nim along with the correct C type pragmas. You don't have to define the entire
type, just enough to indicate its semantics to Nim and to identify it in the C
type system:
type
BoxOfStuff {.final, incompleteStruct, header: "<BoxOfStuff.h>",
importc: "BoxOfStuff".} = object
PBox {.header: "<BoxOfStuff.h>", importc: "pBox".} = ptr BoxOfStuff
Warehouse {.header: "<Warehouse.h>", importc: "Warehouse".} = object
shelf: ptr PBox
If you have no other choice, you can (ab)use C's type system, and treat
Warehouse as its C ABI type, which is just a pointer:
type
WarehouseUnsafeDontDoThis {.distinct.} = pointer
This will not work if you have C++ linkage though.
