Why does casting AnyHashable to NSObject always succeed?

[Danny]

That's not a direct comparison.

Why can any value be cast to `AnyObject`?

I was surprised to find that the following code produces a warning: func foo<T>(_ t: T) -> ObjectIdentifier? { if let r = t as? AnyObject { return ObjectIdentifier(r) } else { return nil } } Warning: Conditional cast from 'T' to 'AnyObject' always succeeds I explored a bit more by running this function with integers, and it seems that each unique value corresponds to a distinct object identifier: let a = 7 print(fooo(a)!) // ObjectIdentifier(0x89815300d8f91468) pr…

Given

struct S: Hashable { }

…

S() as AnyObject // Compiles
S() as AnyHashable // Compiles

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import typealias Foundation.NSObject

S() as NSObject // Cannot convert value of type 'S' to type 'NSObject' in coercion
S() as AnyHashable as NSObject // Compiles