Attachment: Download

duplicates:

• SR-55 non-@objc protocol existentials do not conform to their own protocol type

Issue Description:

class Alpha<T> where T: AnyObject {
    private let value: T
    init(_ value: T) {
        self.value = value
    }
}

protocol Beta: AnyObject {}

class Gamma: Beta {}

print(Alpha<Beta>(Gamma()))

Expected:

• The above code should compile: The requirement on generic `T` is that is that it extends from `AnyObject`. Since protocol `Beta` also extends from `AnyObject` it holds that any class `Foo` that implements protocol `Beta` will also extend from `AnyObject`

Actual:

• Code does not compile. Error message is error: "'Alpha' requires that 'Beta' be a class type"

Note: `class` and `AnyObject` are type-aliased to the same thing, so changing to `Beta: class` produces the same error

Also, this works as expected:

class Alpha<T> where T: AnyObject {
    private let value: T
    init(_ value: T) {
        self.value = value
    }
}
class Beta {}
class Gamma: Beta {}
print(Alpha<AnyObject>(Gamma()))