duplicates:

• SR-6192 Spurious "Cast from ... to unrelated type ... always fails" warning when implicitly converting an empty collection

Issue Description:

let x: [String] = []
let y = x as? [Int] // Cast from '[String]' to unrelated type '[Int]' always fails
print(y as Any) // Optional([]) 

Warning says that the cast always fails. It's not true. It should instead say

Cast from '[String]' to unrelated type '[Int]' always fails, unless the array is empty