swift234

SILGen: Diagnose recursive types.

This isn't the theoretically purest way to do it--when we find ourselves reentering TypeLowering, instead of asserting, complain about the type being recursive. There's a nonzero chance this will complain about legitimate cases we just don't implement correctly, but it beats crashing. Recover by returning an address-only TypeLowering, which is sufficient to keep SILGen moving after the failure. <rdar://problem/16423940>

Swift SVN r20789