Open Radar

 
Summary:

An NSManagedObject subclass written in Swift which implements a protocol leads to linker errors if a property from the protocol is also @NSManaged.

Steps to Reproduce:

Consider the following Swift program:

import CoreData
 
@objc protocol Foo {
  var bar: String { get set }
}
 
class Bar: NSManagedObject, Foo {
  @NSManaged var bar: String
}
 
let b = Bar()

and compile it using `xcrun swiftc main.swift`

Expected Results:

Ideally, the program compiles and links successfully. Another option would be that it is rejected by the compiler in some fashion, because this case is unsupported on purpose.

Actual Results:

Linker errror:

$ xcrun swiftc nsmanaged.swift 
Undefined symbols for architecture x86_64:
  "__TFC9nsmanaged3Barg3barSS", referenced from:
      __TFC9nsmanaged3Barm3barSS in nsmanaged-9a8736.o
ld: symbol(s) not found for architecture x86_64
<unknown>:0: error: linker command failed with exit code 1 (use -v to see invocation)

Regression:

This has been possible in Objective-C

Notes: -