swift

974e61d4 - Sema: Loosen exportability checking for non-publicly imported types

Sema: Loosen exportability checking for non-publicly imported types This one is specific. Allow extensions to define public members to package types implicitly exporting their memory layout when imported non-publicly. Enabling exportability checks for non-library-evolution by default as a warning triggered marking such types as implicitly exported to clients. This in turn enabled erroring on the extensions in clients when imported non-publicly. This error would be source breaking and shouldn't be required in such a context. We may even consider lifting this restriction entierly, even for public types imported non-public.