test/expr/cast/optional.swift

// RUN: %target-parse-verify-swift

class Base : Hashable { 
  var hashValue: Int { return 0 }
}

func ==(lhs: Base, rhs: Base) -> Bool { return false }

// Inputs that are more optional than the output.
func f1(i: Int?, ii: Int??, a: [Base]?, d: [Base : Base]?) {
  let i2 = i as! Int // expected-error{{downcast from 'Int?' to 'Int' only unwraps optionals; did you mean to use '!'?}}
  let i3 = ii as! Int // expected-error{{downcast from 'Int??' to 'Int' only unwraps optionals; did you mean to use '!!'?}}
  let a2 = a as! [Base] // expected-error{{downcast from '[Base]?' to '[Base]' only unwraps optionals; did you mean to use '!'?}}
  let d2 = d as! [Base : Base] // expected-error{{downcast from '[Base : Base]?' to '[Base : Base]' only unwraps optionals; did you mean to use '!'?}}
}

func implicitCastOfLiteralToOptional() {
  var _: Int? = 0
  var _: String? = ""
  var _: [Int] = []
  var _: [Int : Int]? = [:]
  var _: Set<Int> = []
}