Pitch: Protocol-based Actor Isolation

[Chris_Lattner3 (Chris Lattner)]

I posted a significant update to this proposal (incorporating Doug's feedback above) on a pitch #2 thread. Thank you for all the feedback!

-Chris

[CTMacUser (Daryle Walker)]

@Douglas_Gregor

It's semantically sound, and very convenient, so I expect we'll end up getting many overlapping retroactive conformances of "Array of something" to ActorSendable . We can absolutely say "don't do that, wrap it in a struct that does the same thing," but it's an unfortunate bit of advice we would have to give.

Maybe we need some sort of protocol poison? It's like the desired AnyValue facility; it directly requires a value type, but would work by poisoning against reference types. (But AnyValue is easier since the determining factor, value vs. reference types, can't be overridden by the user, unlike conforming to arbitrary protocols.)