kishikawakatsumi

protocol A { static func foo() } extension Dictionary: A where Key == Value { static func foo() { print(type(of: self)) } } extension Array where Element: A { static func foo() { Element.foo() } } [String: String].foo() // Dictionary<String, String> [[String: String]].foo() // Dictionary<Dictionary<String, String>, Dictionary<String, String>>

Version:

swift-4.2-DEVELOPMENT-SNAPSHOT-2018-05-02-a

Output:

Dictionary<String, String>.Type Dictionary<String, String>.Type

Error: