[api-digester] Teach the api-digester about hasMissingDesignatedInitializers

Because we won’t be serializing this attribute, add custom diagnostics for the cases where:

- We add @_hasMissingDesignatedInits to an open class, which means subclasses won’t be able to inherit its inits
- We remove @_inheritsConvenienceInitializers, which means APIs are removed

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -98,6 +98,10 @@ ERROR(objc_name_change,none,"%0 has ObjC name change from %1 to %2", (StringRef,
 
 ERROR(desig_init_added,none,"%0 has been added as a designated initializer to an open class", (StringRef))
 
+ERROR(added_invisible_designated_init,none,"%0 has new designated initializers that are not visible to clients", (StringRef))
+
+ERROR(not_inheriting_convenience_inits,none,"%0 no longer inherits convenience inits from its superclass", (StringRef))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

include/swift/IDE/DigesterEnums.def

@@ -132,6 +132,8 @@ KEY_BOOL(HasStorage, hasStorage)
 KEY_BOOL(ReqNewWitnessTableEntry, reqNewWitnessTableEntry)
 KEY_BOOL(IsABIPlaceholder, isABIPlaceholder)
 KEY_BOOL(IsExternal, isExternal)
+KEY_BOOL(HasMissingDesignatedInitializers, hasMissingDesignatedInitializers)
+KEY_BOOL(InheritsConvenienceInitializers, inheritsConvenienceInitializers)
 
 KEY(kind)