[SR-7368] Bugs of self-referencing Default Property Values in subclasses

[an0]

Previous ID	SR-7368
Radar	None
Original Reporter	@an0
Type	Bug
Status	Resolved
Resolution	Duplicate

Attachment: Download

Environment

Xcode 9.3

Additional Detail from JIRA

Votes	0
Component/s
Labels	Bug
Assignee	None
Priority	Medium

md5: 0da77bdeedb7ef554ed87067dd965c4e

duplicates:

• [SR-4559] Method called 'self' can be confused with regular 'self' #47136

Issue Description:

If I understand it correctly, self-reference should not be allowed in Default Property Values. Actually such properties should not support initialization-directly-to-final-value at all and must be var instead of let because:

• Stored properties must be initialized before super.init,

• But self cannot be used before super.init.

However currently this code compiles:

class ViewController: UIViewController {
    let tapGR = UITapGestureRecognizer(target: self, action: #selector(handleTap))

    override func viewDidLoad() {
        super.viewDidLoad()
        print(tapGR) // <UITapGestureRecognizer: 0x6000001eff00; state = Possible; view = <UIView 0x7fba644051b0>; target= <(action=handleTapWithSender:, target=<(null) 0x0>)>>
        view.addGestureRecognizer(tapGR)
    }

    @objc private func handleTap(sender: UITapGestureRecognizer) {
        print(sender)
    }
}

but it doesn't really work: tapGR is not really connected to self, as we can see tapGR.target is null and handleTap will never be called.