if_while_var.swift

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

struct NonOptionalStruct { let property: Any }
enum NonOptionalEnum { case foo }

func foo() -> Int? { return .none }
func nonOptionalStruct() -> NonOptionalStruct { fatalError() }
func nonOptionalEnum() -> NonOptionalEnum { fatalError() }
func use(_ x: Int) {}
func modify(_ x: inout Int) {}

if let x = foo() {
  use(x)
  modify(&x) // expected-error{{cannot pass immutable value as inout argument: 'x' is a 'let' constant}}
}

use(x) // expected-error{{cannot find 'x' in scope}}

if var x = foo() {
  use(x)
  modify(&x)
}

if let x { // expected-error{{cannot find 'x' in scope}}
  use(x)
}

if var x { // expected-error{{cannot find 'x' in scope}}
  use(x)
}

use(x) // expected-error{{cannot find 'x' in scope}}

let nonOptional = nonOptionalStruct()

if let x = nonOptionalStruct() { _ = x} // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}
if let x = nonOptionalEnum() { _ = x} // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalEnum'}}

if let nonOptional { _ = nonOptional } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}
if var nonOptional { nonOptional = nonOptionalStruct(); _ = nonOptional } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}

guard let nonOptional else { _ = nonOptional; fatalError() } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}
guard var nonOptional else { _ = nonOptional; fatalError() } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}

if let nonOptional.property { }
// expected-error@-1 {{unwrap condition requires a valid identifier}}
// expected-error@-2 {{initializer for conditional binding must have Optional type, not 'Any'}}

if var nonOptional.property { }
// expected-error@-1 {{unwrap condition requires a valid identifier}}
// expected-error@-2 {{initializer for conditional binding must have Optional type, not 'Any'}}

guard let _ = nonOptionalStruct() else { fatalError() } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalStruct'}}
guard let _ = nonOptionalEnum() else { fatalError() } // expected-error{{initializer for conditional binding must have Optional type, not 'NonOptionalEnum'}}

let optional: String? = nil
if case let optional? { _ = optional } // expected-error{{variable binding in a condition requires an initializer}}
if case let .some(optional) { _ = optional } // expected-error{{variable binding in a condition requires an initializer}}
if case .some(let optional) { _ = optional } // expected-error{{variable binding in a condition requires an initializer}}

if case let x? = nonOptionalStruct() { _ = x } // expected-error{{'?' pattern cannot match values of type 'NonOptionalStruct'}}
if case let x? = nonOptionalEnum() { _ = x } // expected-error{{'?' pattern cannot match values of type 'NonOptionalEnum'}}

if let x { _ = x } // expected-error{{cannot find 'x' in scope}}

if let optional: String { _ = optional }
if let optional: Int { _ = optional } // expected-error{{cannot convert value of type 'String?' to specified type 'Int?'}}

class B {} // expected-note * {{did you mean 'B'?}}
class D : B {}// expected-note * {{did you mean 'D'?}}

// TODO poor recovery in these cases
if let {}
// expected-error@-1 {{expected '{' after 'if' condition}}
// expected-error@-2 {{unwrap condition requires a valid identifier}}
// expected-error@-3 {{initializer for conditional binding must have Optional type, not '() -> ()'}}

if let x = { } // expected-error{{'{' after 'if'}} expected-error{{initializer for conditional binding must have Optional type, not '() -> ()'}}
// expected-warning@-1{{value 'x' was defined but never used}}

if let x = foo() {
  _ = x
} else {
  // TODO: more contextual error? "x is only available on the true branch"?
  use(x) // expected-error{{cannot find 'x' in scope}}
}

if let x = foo() {
  use(x)
} else if let y = foo() { // expected-note {{did you mean 'y'?}}
  use(x) // expected-error{{cannot find 'x' in scope}}
  use(y)
} else {
  use(x) // expected-error{{cannot find 'x' in scope}}
  use(y) // expected-error{{cannot find 'y' in scope}}
}

var opt: Int? = .none

if let opt {
  use(opt)
  opt = 10 // expected-error{{cannot assign to value: 'opt' is a 'let' constant}}
}

if var opt {
  use(opt)
  opt = 10
}

if let x = opt {} // expected-warning {{value 'x' was defined but never used; consider replacing with boolean test}} {{4-12=}} {{15-15= != nil}}
if var x = opt {} // expected-warning {{value 'x' was defined but never used; consider replacing with boolean test}} {{4-12=}} {{15-15= != nil}}

// <rdar://problem/20800015> Fix error message for invalid if-let
let someInteger = 1
if let y = someInteger { _ = y }  // expected-error {{initializer for conditional binding must have Optional type, not 'Int'}}
if case let y? = someInteger { _ = y }  // expected-error {{'?' pattern cannot match values of type 'Int'}}

// Test multiple clauses on "if let".
if let x = opt, let y = opt, x != y,
   let a = opt, var b = opt { // expected-warning {{immutable value 'a' was never used; consider replacing with '_' or removing it}} expected-warning {{variable 'b' was never used; consider replacing with '_' or removing it}}
}

// Leading boolean conditional.
if 1 != 2, let x = opt,
   y = opt,  // expected-error {{expected 'let' in conditional}} {{4-4=let }}
   x != y,
   let a = opt, var b = opt { // expected-warning {{immutable value 'a' was never used; consider replacing with '_' or removing it}} expected-warning {{variable 'b' was never used; consider replacing with '_' or removing it}}
}

// <rdar://problem/20457938> typed pattern is not allowed on if/let condition
if 1 != 2, let x : Int? = opt {} // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}}
// expected-warning @-1 {{explicitly specified type 'Int?' adds an additional level of optional to the initializer, making the optional check always succeed}} {{20-24=Int}}

if 1 != 2, case let x? : Int? = 42 {} // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}}
// expected-warning @-1 {{non-optional expression of type 'Int' used in a check for optionals}}



// Test error recovery.
// <rdar://problem/19939746> Improve error recovery for malformed if statements
if 1 != 2, { // expected-error {{cannot convert value of type '() -> ()' to expected condition type 'Bool'}}
} // expected-error {{expected '{' after 'if' condition}}
if 1 != 2, 4 == 57 {}
if 1 != 2, 4 == 57, let x = opt {} // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}}

// Test that these don't cause the parser to crash.
if true { if a == 0; {} }   // expected-error {{cannot find 'a' in scope}} expected-error {{expected '{' after 'if' condition}}
if a == 0, where b == 0 {}  // expected-error {{cannot find 'a' in scope}} expected-error {{expected expression in conditional}}




func testIfCase(_ a : Int?) {
  if case nil = a, a != nil {}
  if case let (b?) = a, b != 42 {}
  
  if let case (b?) = a, b != 42 {}  // expected-error {{pattern matching binding is spelled with 'case let', not 'let case'}} {{6-10=}} {{14-14= let}}
  
  if a != nil, let c = a, case nil = a { _ = c}
  
  if let p? = a {_ = p}  // expected-error {{pattern matching in a condition implicitly unwraps optionals}} {{11-12=}}
  
  
  if let .some(x) = a {_ = x}  // expected-error {{pattern matching in a condition requires the 'case' keyword}} {{6-6=case }}

  if case _ = a {}  // expected-warning {{'if' condition is always true}}
  while case _ = a {}  // expected-warning {{'while' condition is always true}}

}

// <rdar://problem/20883147> Type annotation for 'let' condition still expected to be optional
func testTypeAnnotations() {
  if let x: Int = Optional(1) {_ = x}
  if let x: Int = .some(1) {_ = x}

  if case _ : Int8 = 19 {}  // expected-warning {{'if' condition is always true}}
}

func testShadowing(_ a: Int?, b: Int?, c: Int?, d: Int?) {
  guard let a = a, let b = a > 0 ? b : nil else { return }
  _ = b

  if let c = c, let d = c > 0 ? d : nil {
    _ = d
  }
}

func testShadowingWithShorthand(_ a: Int?, b: Int?, c: Int?, d: Int?) {
  guard let a, let b = a > 0 ? b : nil else { return }
  _ = b

  if let c, let d = c > 0 ? d : nil {
    _ = d
  }
}

func useInt(_ x: Int) {}

func testWhileScoping(_ a: Int?) {
  while let x = a { }
  useInt(x) // expected-error{{cannot find 'x' in scope}}
}

func testWhileShorthand(_ b: Int?) {
  while let b { _ = b }
}

// Matching a case with a single, labeled associated value.
public enum SomeParseResult<T> {
  case error(length: Int)
  case repeated(value: String, repetitions: Int)
  // expected-note@-1{{'repeated(value:repetitions:)' declared here}}

  var _error: Int? {
    if case .error(let result) = self { return result }
    return nil
  }

  var _error2: Int? {
    if case .error(length: let result) = self { return result }
    return nil
  }

  var _error3: Int? {
    if case .error(wrong: let result) = self { return result } // expected-error{{tuple pattern element label 'wrong' must be 'length'}}
    return nil
  }

  var _repeated: (String, Int)? {
    if case .repeated(let value, let repetitions) = self {
      return (value, repetitions)
    }
    return nil
  }

  var _repeated2: (String, Int)? {
    if case .repeated(value: let value, let repetitions) = self {
      return (value, repetitions)
    }
    return nil
  }

  var _repeated3: (String, Int)? {
    if case .repeated(let value, repetitions: let repetitions) = self {
      return (value, repetitions)
    }
    return nil
  }

  var _repeated4: (String, Int)? {
    if case .repeated(value: let value, repetitions: let repetitions) = self {
      return (value, repetitions)
    }
    return nil
  }

  var _repeated5: (String, Int)? {
    if case .repeated(value: let value, wrong: let repetitions) = self { // expected-error{{tuple pattern element label 'wrong' must be 'repetitions'}}
      return (value, repetitions)
    }
    return nil
  }
}

func matchImplicitTupling(pr: SomeParseResult<Int>) {
  if case .repeated(let x) = pr { // expected-warning{{enum case 'repeated' has 2 associated values; matching them as a tuple is deprecated}}
    let y: Int = x // expected-error{{cannot convert value of type '(value: String, repetitions: Int)' to specified type 'Int'}}
  }
}

// Cope with an ambiguity between a case name and a static member. Prefer the
// case.
enum CaseStaticAmbiguity {
  case C(Bool)

  var isC: Bool {
    if case .C = self { return true }
    return false
  }

  static func C(_: Int) -> CaseStaticAmbiguity { return .C(true) }
}

// Case name/static member ambiguity along with implicit optional unwrapping.
enum HasPayload {
  case payload(Int, Bool)

  static func payload(_ bool: Bool, int: Int) -> HasPayload {
    .payload(int, bool)
  }
}

class UsesPayload {
  private var eOpt: HasPayload? = nil

  deinit {
    if case .payload(_, let x) = eOpt {
      _ = x
    }
  }
}

// https://github.com/apple/swift/issues/55698
do {
  let a = 1
  let b = Int?.none
  if let c = b ?? a { _ = c } // expected-error {{initializer for conditional binding must have Optional type, not 'Int'}}
}