Could diagnostic passes (or other portions of Sema) be written in Swift?

[Slava_Pestov]

@jamieQ

to clarify – i'm assuming you're referring to the mandatory SILOptimizer passes; is that right? can those not be converted today for technical reasons, or is that a policy choice (or just no particular reason to do so, etc)?

I believe it's just to keep the compiler building without an existing swiftc for now. Not sure if that's policy or technical under your definition ;)