duplicates:

• SR-7187 False positive warning: cast always fails from '[Any]' to '[String?]'

Issue Description:

The compiler is giving me a warning

Cast from '[String : Any]' to unrelated type '[String : MyProtocol?]' always fails

but this isn't true - at runtime the cast works correctly.

Here's an example showing this:

// Create a protocol, and conform some types to it
protocol MyProtocol { }
extension Int: MyProtocol { }
extension String: MyProtocol { }


// Create a dictionary out of those types
let dictionary = [ "a": 1, "b": "2" ] as [String: Any]

 
// Warning here, but the cast works correctly at runtime
let castDictionary = dictionary as? [String: MyProtocol?]

The warning only appears if the dictionary is cast to [String: MyProtocol?]. Casting to [String: MyProtocol] works as expected.