duplicates:

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

Issue Description:

This code compiles. In Xcode, it even colors self as though it's a keyword.

import UIKit

class C: NSObject {
    let button: UIButton = {
       let button = UIButton()
        button.addTarget(self,
                         action: #selector(f),
                         for: .touchUpInside)
        return button
    }()
    
    @objc
    func f() {   
    }
}

But self is actually NSObject.self, which is a function.

Note that in a non-NSObject subclass, this code does not compile, with the error "error: use of unresolved identifier 'self'". So I'm guessing that the compiler currently has a hack of some sort to prevent self from referring to NSObject.self as in the class object in this context, since that would be confusing. And that that's why the compiler allows NSObject.self to not be backticked.

Note that

class C {
    func self() {
    }
}

also doesn't compile, nor does refering to a func `self`() function without backticks, so allowing this is clearly wrong.