swift234

SIL: Avoid reentering type lowering when lowering struct and enum types.

Structs and enums may recursively refer to themselves in function types and metatypes, which don't actually affect the layout of the type. We don't need to fully lower the storage types of a struct or enum to lower the type; all we need to know is its classification. We can lazily lower the fields, avoiding reentry. Fixes a few dozen radars.

Swift SVN r19968