Computed variable to return type conforming protocol.

gistfile1.swift

protocol TestProtocol {
}

class TestClass : TestProtocol {
}

class TestClass2 {
}

struct Test {
  var a: TestClass.Type {
    get {
      return TestClass.self
    }
  }

  var b: TestProtocol.Type {
    get {
      return TestClass.self
    }
  }

  var c: TestProtocol.Type {
    get {
      return TestClass2.self // Type 'TestClass2' does not conform to protocol 'TestProtocol'
    }
  }
}