Lazy NSObject + deinit = trap

Found an interesting foot-gun (only traps with NSObject classes and only with Foundation on Apple platforms): import Foundation class C: NSObject { lazy var foo: Int = { // Thread 1: abort with payload or reason // Cannot form weak reference to instance (0x1007e24f0) of class C. // It is possible that this object was over-released, or is in the process of deallocation. weak var y: C? = self return 1 }() deinit { _ = foo } } do { ...