let x: [Int]

let x: [Int: String]

let x: Int?

func x(a: [Int], b: Int) -> [Int: Any]

let x: Int!

extension Array {
  func x() { }
}

extension Dictionary {
  func x() { }
}

let x: CustomArray<String>

var currentIndex: Array<OnboardingPage>.Index?

func x(a: [Int], b: Int) -> Array<Int>.Index

unsafeBitCast(nonOptionalT, to: Optional<T>.self)

type is Optional<String>.Type

let x: Foo.Optional<String>

let x: ↓Array<String>

let x: ↓Dictionary<Int, String>

let x: ↓Optional<Int>

let x: ↓ImplicitlyUnwrappedOptional<Int>

func x(a: ↓Array<Int>, b: Int) -> [Int: Any]

func x(a: [Int], b: Int) -> ↓Dictionary<Int, String>

func x(a: ↓Array<Int>, b: Int) -> ↓Dictionary<Int, String>

let x = ↓Array<String>.array(of: object)

let x: ↓Swift.Optional<String>