こんなの入ってたんだ https://github.com/apple/swift/pull/7125

Simplifying implementation of ExpressibleByStringLiteral by therealbnut · Pull Request #7125 · apple/swift

Added default implementations for ExpressibleByUnicodeScalarLiteral and ExpressibleByExtendedGraphemeClusterLiteral init(unicodeScalarLiteral value: UnicodeScalar) init(extendedGraphemeClusterLiter...