You're right that there isn't a single standard convention for representing e.g. Option<bool>, but that's just as true of C. You'd just define a repr(C) compatible object that can be converted to or from Option<Foo>, and pass that through the ABI interface, while the conversion step would happen internally and transparently on both sides. That kind of marshaling is ubiquitous when using FFI.
Right, that's the whole point of this thread. The only stable ABI rust has is one where you can only use C's features at the boundaries. It would be really nice if that wasn't the case (ie. if you could express "real" rust types at a stable ABI boundary.)
As OP said, "I don't think deflecting by saying "but C is no safer" is super interesting". People seem intent on steering that conversation that way anyway, I guess.
