Open Radar

 
Summary:
When using a generic struct (WeakContainer<T>) where the generic type needs to inherit from AnyObject, it can't be created by passing a protocol (declared with inheriting from `class`) for the generic type T, although no other object than one that inherits from AnyObject can implement said protocol.

Steps to Reproduce:
1. Create a generic type (e.g. struct WeakContainer<T: AnyObject>) with a generic type that needs to inherit from AnyObject
2. Create a protocol which inherits from class (e.g. MyDelegate: class).
3. Try to declare a variable of the generic type passing the protocol as generic parameter (e.g. WeakContainer<MyDelegate>)

Expected Results:
It should work without any errors since the only objects which are able to implement the protocol (e.g. MyDelegate) are classes which also implement AnyObject.

Actual Results:
Instead Xcode shows an error stating that the protocol can't be used as a concrete type conforming to AnyObject. (e.g.: Using 'MyDelegate' as concrete type conforming to protocol 'AnyObject' is not supported)

Version:
Xcode Version 7.2.1 (7C1002)
OS X Version 10.11.3 (15D21)

Notes:
A playground has been attached showing the problem.

Configuration: