throwing_functions.swift

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

enum Exception : Error { case A }

// Basic syntax ///////////////////////////////////////////////////////////////
func bar() throws -> Int { return 0 }
func foo() -> Int { return 0 }


// Currying ///////////////////////////////////////////////////////////////////
func curry1() {

}

func curry1Throws() throws {

}

func curry2() -> () -> () {
	return curry1
}

func curry2Throws() throws -> () -> () {
	return curry1
}

func curry3() -> () throws -> () {
	return curry1Throws
}

func curry3Throws() throws -> () throws -> () {
	return curry1Throws
}

var a : () -> () -> () = curry2
var b : () throws -> () -> () = curry2Throws
var c : () -> () throws -> () = curry3
var d : () throws -> () throws -> () = curry3Throws

// Partial application ////////////////////////////////////////////////////////

protocol Parallelogram {
  static func partialApply1(_ a: Int) throws
}

func partialApply2<T: Parallelogram>(_ t: T) {
  _ = T.partialApply1
}

// Overload resolution/////////////////////////////////////////////////////////
func barG<T>(_ t : T) throws -> T { return t }
func fooG<T>(_ t : T) -> T { return t }

var bGE: (_ i: Int) -> Int = barG // expected-error{{invalid conversion from throwing function of type '(Int) throws -> Int' to non-throwing function type '(Int) -> Int'}}
var bg: (_ i: Int) throws -> Int = barG
var fG: (_ i: Int) throws -> Int = fooG

func fred(_ callback: (UInt8) throws -> ()) throws { }

func rachel() -> Int { return 12 }
func donna(_ generator: () throws -> Int) -> Int { return generator() } // expected-error {{call can throw, but it is not marked with 'try' and the error is not handled}}

_ = donna(rachel)

func barT() throws -> Int { return 0 } // expected-note{{}}
func barT() -> Int { return 0 } // expected-error{{invalid redeclaration of 'barT()'}}

func fooT(_ callback: () throws -> Bool) {} //OK
func fooT(_ callback: () -> Bool) {}

// Throwing and non-throwing types are not equivalent.
struct X<T> { }

func specializedOnFuncType1(_ x: X<(String) throws -> Int>) { }
func specializedOnFuncType2(_ x: X<(String) -> Int>) { }
func testSpecializedOnFuncType(_ xThrows: X<(String) throws -> Int>,
                               xNonThrows: X<(String) -> Int>) {
  specializedOnFuncType1(xThrows) // ok
  specializedOnFuncType1(xNonThrows) // expected-error{{invalid conversion from throwing function of type '(String) -> Int' to non-throwing function type '(String) throws -> Int'}}
  specializedOnFuncType2(xThrows)  // expected-error{{invalid conversion from throwing function of type '(String) throws -> Int' to non-throwing function type '(String) -> Int'}}
  specializedOnFuncType2(xNonThrows) // ok
}

// Subtyping
func subtypeResult1(_ x: (String) -> ((Int) -> String)) { }
func testSubtypeResult1(_ x1: (String) -> ((Int) throws -> String),
                        x2: (String) -> ((Int) -> String)) {
  subtypeResult1(x1) // expected-error{{invalid conversion from throwing function of type '(Int) throws -> String' to non-throwing function type '(Int) -> String'}}
  subtypeResult1(x2)
}

func subtypeResult2(_ x: (String) -> ((Int) throws -> String)) { }
func testSubtypeResult2(_ x1: (String) -> ((Int) throws -> String),
                        x2: (String) -> ((Int) -> String)) {
  subtypeResult2(x1)
  subtypeResult2(x2)
}

func subtypeArgument1(_ x: (_ fn: ((String) -> Int)) -> Int) { }
func testSubtypeArgument1(_ x1: (_ fn: ((String) -> Int)) -> Int,
                          x2: (_ fn: ((String) throws -> Int)) -> Int) {
  subtypeArgument1(x1)
  subtypeArgument1(x2)
}

func subtypeArgument2(_ x: (_ fn: ((String) throws -> Int)) -> Int) { }
func testSubtypeArgument2(_ x1: (_ fn: ((String) -> Int)) -> Int,
                          x2: (_ fn: ((String) throws -> Int)) -> Int) {
  subtypeArgument2(x1) // expected-error{{invalid conversion from throwing function of type '(String) throws -> Int' to non-throwing function type '(String) -> Int'}}
  subtypeArgument2(x2)
}

// Closures
var c1 = {() throws -> Int in 0}
var c2 : () throws -> Int = c1 // ok
var c3 : () -> Int = c1 // expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c4 : () -> Int = {() throws -> Int in 0} // expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c5 : () -> Int = { try c2() } // expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c6 : () throws -> Int = { do { _ = try c2() } ; return 0 }
var c7 : () -> Int = { do { try c2() } ; return 0 } // expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c8 : () -> Int = { do { _ = try c2()  } catch _ { var x = 0 } ; return 0 } // expected-warning {{initialization of variable 'x' was never used; consider replacing with assignment to '_' or removing it}}
var c9 : () -> Int = { do { try c2()  } catch Exception.A { var x = 0 } ; return 0 }// expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c10 : () -> Int = { throw Exception.A; return 0 } // expected-error{{invalid conversion from throwing function of type '() throws -> Int' to non-throwing function type '() -> Int'}}
var c11 : () -> Int = { try! c2() }
var c12 : () -> Int? = { try? c2() }

// Initializers
struct A {
    init(doomed: ()) throws {}
}

func fi1() throws {
    A(doomed: ()) // expected-error {{call can throw but is not marked with 'try'}} // expected-warning{{unused}}
    // expected-note@-1 {{did you mean to use 'try'?}} {{5-5=try }}
    // expected-note@-2 {{did you mean to handle error as optional value?}} {{5-5=try? }}
    // expected-note@-3 {{did you mean to disable error propagation?}} {{5-5=try! }}
}

struct B {
 init() throws {}
 init(foo: Int) {}
}

B(foo: 0) // expected-warning{{unused}}

// rdar://problem/33040113 - Provide fix-it for missing "try" when calling throwing Swift function

class E_33040113 : Error {}
func rdar33040113() throws -> Int {
    throw E_33040113()
}

let _ = rdar33040113() // expected-error {{call can throw but is not marked with 'try'}}
// expected-note@-1 {{did you mean to use 'try'?}} {{9-9=try }}
// expected-note@-2 {{did you mean to handle error as optional value?}} {{9-9=try? }}
// expected-note@-3 {{did you mean to disable error propagation?}} {{9-9=try! }}

enum MSV : Error {
  case Foo, Bar, Baz
  case CarriesInt(Int)
}

func genError() throws -> Int { throw MSV.Foo }

struct IllegalContext {
  var x1: Int = genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  let x2 = genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  var x3 = try genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  let x4: Int = try genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  var x5 = B() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  var x6 = try B() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  var x7 = { // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}
    return try genError()
  }()

  var x8: Int = {
    do {
      return genError() // expected-error {{call can throw but is not marked with 'try'}}
      // expected-note@-1 {{did you mean to use 'try'?}}
      // expected-note@-2 {{did you mean to handle error as optional value?}}
      // expected-note@-3 {{did you mean to disable error propagation?}}
    } catch {
      return 0
    }
  }()

  var x9: Int = {
    do {
      return try genError()
    } catch {
      return 0
    }
  }()

  var x10: B = {
    do {
      return try B()
    } catch {
      return B(foo: 0)
    }
  }()

  lazy var y1: Int = genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y2 = genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y3 = try genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y4: Int = try genError() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y5 = B() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y6 = try B() // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}

  lazy var y7 = { // expected-error {{call can throw, but errors cannot be thrown out of a property initializer}}
    return try genError()
  }()

  lazy var y8: Int = {
    do {
      return genError() // expected-error {{call can throw but is not marked with 'try'}}
      // expected-note@-1 {{did you mean to use 'try'?}}
      // expected-note@-2 {{did you mean to handle error as optional value?}}
      // expected-note@-3 {{did you mean to disable error propagation?}}
    } catch {
      return 0
    }
  }()

  lazy var y9: Int = {
    do {
      return try genError()
    } catch {
      return 0
    }
  }()

  lazy var y10: B = {
    do {
      return try B()
    } catch {
      return B(foo: 0)
    }
  }()

  func foo(_ x: Int = genError()) {} // expected-error {{call can throw, but errors cannot be thrown out of a default argument}}

  func catcher() throws {
    do {
      _ = try genError()
    } catch MSV.CarriesInt(genError()) { // expected-error {{call can throw, but errors cannot be thrown out of a catch pattern}}
    } catch MSV.CarriesInt(let i) where i == genError() { // expected-error {{call can throw, but errors cannot be thrown out of a catch guard expression}}
    }
  }
}

// Crash in 'uncovered try' diagnostic when calling a function value - rdar://46973064
struct FunctionHolder {
  let fn: () throws -> ()
  func receive() {
    do {
      _ = fn()
      // expected-error@-1 {{call can throw but is not marked with 'try'}}
      // expected-note@-2 {{did you mean to use 'try'?}}
      // expected-note@-3 {{did you mean to handle error as optional value?}}
      // expected-note@-4 {{did you mean to disable error propagation?}}
      _ = "\(fn())"
      // expected-error@-1 {{call can throw but is not marked with 'try'}}
      // expected-note@-2 {{did you mean to use 'try'?}}
      // expected-note@-3 {{did you mean to handle error as optional value?}}
      // expected-note@-4 {{did you mean to disable error propagation?}}
    } catch {}
  }
}