duplicates:

• SR-1535 No == overload exists for comparing optional arrays.

Issue Description:

In Swift 4 (Xcode 9.1) I can't compare two optionals for equality (self.lineForms == item2.lineForms, where lineForms is [String]?). And indeed Equatable protocol only contains static func == (lhs: Self, rhs: Self) -> Bool, no optional versions. It's a bug, because https://github.com/apple/swift-evolution/blob/master/proposals/0121-remove-optional-comparison-operators.md clearly states "Variants of == and != which accept optional operands are still useful, and their results unsurprising, so they will remain.". And indeed, nil == nil is true, nil == non-nil is false (as well as non-nil == nil) and non-nil == non-nil should perform an actual comparison. I even can't create an extension to Equatable, because an error is shown that asks for at least one parameter of == to be of type Self (non-optional). Obviously, it's still possible to write (self.lineForms == nil && item2.lineForms == nil) || (self.lineForms = nil && self.lineForms), but this doesn't look good and there's no reason to use this instead of just a single == comparison.