Swift object and struct instances are retained if an empty method of theirs is captured

SelfRetainedByEmptyMethodCapture.swift

import Foundation

final class A {
    func someMethod() {}
}

struct B {
    let a: A
    func someMethod() {}
}

struct Capturing {
    let closure: () -> Void
}

var capturing: Capturing!
weak var weakA: A?

// Object instance is retained by capturing method...

autoreleasepool {
    _ = {
        let a = A()
        capturing = Capturing(closure: a.someMethod)
        weakA = a
    }()
}

print(weakA == nil ? "released" : "retained")

// ... and same for a struct instance (we use a object var to find out)

autoreleasepool {
    _ = {
        let b = B(a: A())
        capturing = Capturing(closure: b.someMethod)
        weakA = b.a
    }()
}

print(weakA == nil ? "released" : "retained")