We're not ready to start emitting warnings when type-checking modules from
interface. It is causing performance regressions and spurious diagnostics to be
emitted.
Reverts a small part of https://github.com/swiftlang/swift/pull/80360.
Resolves rdar://148257136.
An objcImpl bug previously caused `@_hasStorage` to be emitted inside some extensions in module interfaces. An earlier commit in this PR created an error for this, but for backwards compatibility, it would actually be better to simply ignore the attribute in module interfaces. Modify TypeCheckStorage to emit a warning, not an error, in this situation.
Additionally, modify the module interface loader to show warnings when you verify a module interface, but not for other module interface uses (like compiling or importing one). The assumption here is that if you’re verifying a module interface, you’re either the author of the module that created it or you’re investigating a problem with it, and in either case you’d like to be told about minor defects in case they’re related.
Fixes rdar://144811653 thoroughly.
A bug in `@objc @implementation` is causing incorrect `@_hasStorage` attributes to be printed into module interfaces. As an initial step towards fixing this, diagnose bad `@_hasStorage` attributes and treat them as computed properties so that these malformed interfaces don’t cause compiler crashes.
Partially fixes rdar://144811653.
