They were always enabled, meaning migrating from Swift 4 -> 4.2 would pick up
the associated fixits and add @objc unnecessarily in many places.
Resolves rdar://problem/39951671
This allows the migrator to pick up fix-its from notes such as:
“Argument of #selector refers to instance method '___' that is not
exposed to Objective-C”
Add some more testing for minimal/complete workflows, and upstream
the cross-file fix-it test.
rdar://problem/32228948
Based on recommendations in SE-0160, there are two migration workflows:
- Conservative: Maintain @objc visibility that was inferred in Swift 3
by adding @objc to all declarations that were implicitily visible to
the Objective-C runtime. This is invoked in the migrator by adding the
-migrate-keep-objc-visibility flag.
- Minimal: Only declarations that must be visible to Objective-C based
on their uses (or in cases like dynamic vars) are migrated.
rdar://problem/31876357
