Why is the method strikethrough?

Question

I have defined a class like this:

internal class C {
    internal func method() -> Void {
        print("method called")
    }
}

If I declare a closure from that method, the method is shown strikethrough

let closure = C.init().meth
let closure2 = C.meth

The same happens if I use it in the autocasting paranthesis \(...)

print("\(C.init().meth)")

Xcode examples: