info: https://github.com/Kametrixom/The-Swift-Make-It-Compile-Challenge

Challenge4.swift

// I really like this one

func doIt(inout s: D) {
	if case self = isUniquelyReferenced(&s),
		self.`self` = true where self {
		self.`self` = { [unowned x = [self, 7] as Self] n in
			print(x + n)
		} as () -> ()
	}
}

Semicolons for clarity.

import Foundation;typealias D=Bool;extension Bool{var`self`:Any{get{return true}set{}}};var`self`=true;typealias`Self`=NSArray;func+(_:`Self`,_:())->String{return""};func~=(_:Any,_:Bool)->D{return true};func isUniquelyReferenced(inout s:D)->D{return true}

@pyrtsa This does compile, however the syntax high-lighting doesn't match, good effort though!