Episode 196: Runtime warning work only in half of the cases

[vladvlasov256]

Episode: 196
Time: 35:20

I've noticed that runtime warning in the equals() in the File.swift is fired only if lhs is non-equatable.

But what if rhs is non-equable too? Or rhs is the only one which is non-equatable here.

public func equals(_ lhs: Any, _ rhs: Any) -> Bool {
  ...

  guard
    let lhs = lhs as? any Equatable
  else {
    runtimeWarning(
      "Tried to compare a non-equatable error type: %@",
      ["\(type(of: lhs))"]
    )
    return false
  }

  ...
}

IMO, a version on 34th minute with two casts is more helpful for users. Or am I wrong?

[mbrandonw]

Hi @vladvlasov256, sorry we missed this question.

The reason it's only needed to check lhs is because there's only one place that equals is called, and in that case lhs are of the same type. Even though technically lhs and rhs could be different types by virtue of the fact that they are Anys, in practice that's not really the case. So it is sufficient to only warn if lhs is not equatable.