swift-mirror/test/Constraints/pack-expansion-expressions.swift

// RUN: %target-typecheck-verify-swift -target %target-swift-5.9-abi-triple

func tuplify<each T>(_ t: repeat each T) -> (repeat each T) {
  return (repeat each t)
}

func prepend<First, each Rest>(value: First, to rest: repeat each Rest) -> (First, repeat each Rest) {
  return (value, repeat each rest)
}

func concatenate<each T, each U>(_ first: repeat each T, with second: repeat each U) -> (repeat each T, repeat each U) {
  return (repeat each first, repeat each second)
}

func zip<each T, each U>(_ first: repeat each T, with second: repeat each U) -> (repeat (each T, each U)) {
  return (repeat (each first, each second))
}

func forward<each U>(_ u: repeat each U) -> (repeat each U) {
  return tuplify(repeat each u)
}

func forwardAndMap<each U, each V>(us u: repeat each U, vs v: repeat each V) -> (repeat [(each U, each V)]) {
  return tuplify(repeat [(each u, each v)])
}

func variadicMap<each T, each Result>(_ t: repeat each T, transform: repeat (each T) -> each Result) -> (repeat each Result) {
  return (repeat (each transform)(each t))
}

func coerceExpansion<each T>(_ value: repeat each T) {
  func promoteToOptional<each Wrapped>(_: repeat (each Wrapped)?) {}

  promoteToOptional(repeat each value)
}

func localValuePack<each T>(_ t: repeat each T) -> (repeat each T, repeat each T) {
  let local = repeat each t
  // expected-error@-1{{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument of a variadic type}}
  let localAnnotated: repeat each T = repeat each t
  // expected-error@-1{{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument of a variadic type}}

  return (repeat each local, repeat each localAnnotated)
}

protocol P {
  associatedtype A

  var value: A { get }

  func f(_ self: Self) -> Self

  func makeA() -> A
}

extension P {
  func makeA() -> [Self] { return [self] }
}


func outerArchetype<each T, U>(t: repeat each T, u: U) where repeat each T: P {
  let _: (repeat ((each T).A, U)) = (repeat ((each t).value, u))
}

func sameElement<each T, U>(t: repeat each T, u: U) where repeat each T: P, repeat each T == U {
  // expected-error@-1{{same-element requirements are not yet supported}}
  let _: (repeat each T) = (repeat (each t).f(u))
  // expected-error@-1 {{cannot convert value of type 'U' to expected argument type 'each T'}}
}

func forEachEach<each C, U>(c: repeat each C, function: (U) -> Void)
    where repeat each C: Collection, repeat (each C).Element == U {
  // expected-error@-1{{same-element requirements are not yet supported}}
  _ = (repeat (each c).forEach(function))
  // expected-error@-1 {{cannot convert value of type '(U) -> Void' to expected argument type '((each C).Element) throws -> Void'}}
}

func typeReprPacks<each T: ExpressibleByIntegerLiteral>(_ t: repeat each T) {
  _ = (repeat Array<each T>())
  _ = (repeat 1 as each T)

  _ = Array<each T>() // expected-error {{pack reference 'T' requires expansion using keyword 'repeat'}}
  _ = 1 as each T // expected-error {{pack reference 'T' requires expansion using keyword 'repeat'}}
  repeat Invalid<String, each T>("") // expected-error {{cannot find 'Invalid' in scope}}
}

func sameShapeDiagnostics<each T, each U>(t: repeat each T, u: repeat each U) {
  _ = (repeat (each t, each u)) // expected-error {{pack expansion requires that 'each T' and 'each U' have the same shape}}
  _ = (repeat Array<(each T, each U)>()) // expected-error {{pack expansion requires that 'each T' and 'each U' have the same shape}}
  _ = (repeat (Array<each T>(), each u)) // expected-error {{pack expansion requires that 'each T' and 'each U' have the same shape}}
}

func returnPackExpansionType<each T>(_ t: repeat each T) -> repeat each T { // expected-error {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument of a variadic type}}
  fatalError()
}

func returnEachPackReference<each T>(_ t: repeat each T) -> each T { // expected-error {{pack reference 'T' requires expansion using keyword 'repeat'}}
  fatalError()
}

// expected-error@+1 {{type pack 'T' must be referenced with 'each'}}{{63-63=each }}
func returnRepeatTuple<each T>(_ t: repeat each T) -> (repeat T) {
  fatalError()
}

// expected-error@+2 {{pack reference 'T' requires expansion using keyword 'repeat'}}
// expected-error@+1 {{type pack 'T' must be referenced with 'each'}}{{55-55=each }}
func parameterAsPackTypeWithoutExpansion<each T>(_ t: T) {
}

// expected-error@+2 {{pack reference 'T' requires expansion using keyword 'repeat'}}
// expected-error@+1 {{type pack 'T' must be referenced with 'each'}}{{57-57=each }}
func returnPackReference<each T>(_ t: repeat each T) -> T {
  fatalError()
}

func packTypeParameterOutsidePackExpansionType<each T>(_ t: T,
  // expected-error@-1 {{pack reference 'T' requires expansion using keyword 'repeat'}}
  // expected-error@-2 {{type pack 'T' must be referenced with 'each'}}{{61-61=each }}
                                                       _ a: Array<T>) {
  // expected-error@-1 {{pack reference 'T' requires expansion using keyword 'repeat'}}
  // expected-error@-2 {{type pack 'T' must be referenced with 'each'}}{{67-67=each }}
}

func expansionOfNonPackType<T>(_ t: repeat each T) {}
// expected-error@-1 {{'each' cannot be applied to non-pack type 'T'}}{{29-29=each }}
// expected-error@-2 {{pack expansion 'T' must contain at least one pack reference}}

func tupleExpansion<each T, each U>(
  _ tuple1: (repeat each T),
  _ tuple2: (repeat each U),
  _ tuple3: inout (repeat each T)
) {
  _ = forward(repeat each tuple1)

  _ = zip(repeat each tuple1, with: repeat each tuple1)
  _ = zip(repeat each tuple1, with: repeat each tuple1.element) // legacy syntax

  _ = zip(repeat each tuple1, with: repeat each tuple2)
  // expected-error@-1 {{global function 'zip(_:with:)' requires the type packs 'each T' and 'each U' have the same shape}}
  // expected-error@-2 {{pack expansion requires that 'each U' and 'each T' have the same shape}}

  _ = forward(repeat each tuple3)
}

protocol Generatable {
  static func generate() -> Self
}

func generateTuple<each T : Generatable>() -> (repeat each T) {
  (each T).generate()
  // expected-error@-1 {{pack reference 'T' requires expansion using keyword 'repeat'}}

  return (repeat (each T).generate())
}

func packElementInvalidBinding<each T>(_ arg: repeat each T) {
  _ = (repeat print(each arg))

  let x = 1
  repeat print(each x)
  // expected-error@-1 {{'each' cannot be applied to non-pack type 'Int'}}
  // TODO: fixit to remove 'each' keyword
}

func copyIntoTuple<each T>(_ arg: repeat each T) -> (repeat each T) {
  return (repeat each arg)
}
func callCopyAndBind<T>(_ arg: repeat each T) {
  // expected-error@-1 {{'each' cannot be applied to non-pack type 'T'}}{{22-22=each }}
  // expected-error@-2 {{pack expansion 'T' must contain at least one pack reference}}

  // Don't propagate errors for invalid declaration reference
  let result = copyIntoTuple(repeat each arg)
}

do {
  struct TestArgMatching {
    subscript<each T>(data arg: repeat each T) -> Int {
      get { 42 }
      set {}
    }

    subscript<each T>(simpleTuple args: (repeat each T)) -> Int {
      get { return 0 }
      set {}
    }

    subscript<each T>(compoundTuple args: (String, repeat each T)) -> Int {
      get { return 0 }
      set {}
    }
  }

  func test_that_variadic_generics_claim_unlabeled_arguments<each T>(_ args: repeat each T, test: inout TestArgMatching, extra: String) {
    func testLabeled<each U>(data: repeat each U) {}
    func testUnlabeled<each U>(_: repeat each U) {}
    func testInBetween<each U>(_: repeat each U, other: String) {}

    testLabeled(data: repeat each args) // Ok
    testLabeled(data: repeat each args, 1) // Ok
    testLabeled(data: repeat each args, 1, 2, 3) // Ok

    testUnlabeled(repeat each args) // Ok
    testUnlabeled(repeat each args, 1) // Ok
    testUnlabeled(repeat each args, 1, 2, 3) // Ok

    testInBetween(repeat each args, 1, 2.0, other: "") // Ok

    _ = test[data: repeat each args]
    _ = test[data: repeat each args, 0, ""]

    test[data: repeat each args, "", 42] = 0

    do {
      let first = ""
      let second = ""
      let third = 42

      _ = test[simpleTuple: (repeat each args)]
      _ = test[simpleTuple: (repeat each args, extra)]
      _ = test[simpleTuple: (first, second)]
      _ = test[compoundTuple: (first, repeat each args)]
      _ = test[compoundTuple: (first, repeat each args, extra)]
      _ = test[compoundTuple: (first, second, third)]
    }

    do {
      func testRef<each U>() -> (repeat each U, String) { fatalError() }
      func testResult<each U>() -> (repeat each U) { fatalError() }

      func experiment1<each U>() -> (repeat each U, String) {
        testResult() // Ok
      }

      func experiment2<each U>(_: () -> (repeat each U)) -> (repeat each U) { fatalError() }
      let _: (Int, String) = experiment2(testRef) // Ok
    }
  }
}

func test_pack_expansion_materialization_from_lvalue_base() {
  struct Data<Value> {}

  struct Test<each T> {
    var data: (repeat Data<each T>)

    init() {
      self.data = (repeat Data<each T>())
      _ = (repeat each data) // Ok

      var tmp = (repeat Data<each T>()) // expected-warning {{never mutated}}
      _ = (repeat each tmp) // Ok

      // TODO: Add subscript test-case when syntax is supported.
    }
  }
}

func takesFunctionPack<each T, R>(functions: repeat ((each T) -> R)) {}

func forwardFunctionPack<each T>(functions: repeat (each T) -> Bool) {
  takesFunctionPack(functions: repeat each functions)
}

func identity<T>(_ t: T) -> T { t }
func concrete(_: Int) {}

func invalidRepeat<each T>(t: repeat each T) {
  _ = repeat each t
  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}

  let _: Int = repeat each t
  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}

  identity(identity(repeat each t))
  // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'T'}}

  concrete(repeat each t)
  // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'Int'}}

  _ = [repeat each t]
  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}
}

// Make sure that single parameter initializers are handled correctly because
// the have special type-checking rules in Swift < 6.
func test_init_refs_with_single_pack_expansion_param() {
  struct Data<each V> {
    init(_: repeat each V) {}
  }

  _ = Data() // Ok
  _ = Data(42) // Ok
  _ = Data(42, "") // Ok

  struct EmptyAmbiguous<each V> {
    init(_: repeat each V) {} // expected-note {{found this candidate}}
    init(x: repeat each V) {} // expected-note {{found this candidate}}
  }

  _ = EmptyAmbiguous() // expected-error {{ambiguous use of 'init'}}
  _ = EmptyAmbiguous(x: 42)
  _ = EmptyAmbiguous(x: (42, "")) // Ok
}

func test_pack_expansions_with_closures() {
  func takesVariadicFunction<each T>(function: (repeat each T) -> Int) {}

  func test(fn: (Int, String) -> Int, x: Int) {
    takesVariadicFunction { fn(x, "") } // Ok
    takesVariadicFunction { y in fn(x, y) } // Ok
    takesVariadicFunction { y, z in fn(y, z) } // Ok
  }

  // rdar://108977234 - invalid error non-pack type instead of missing `Hashable` conformance
  func testEscapingCapture<each T>(_ t: repeat each T) -> () -> [AnyHashable] {
    return {
      var result = [AnyHashable]()
      repeat result.append(each t) // expected-error {{argument type 'each T' does not conform to expected type 'Hashable'}}
      return result
    }
  }
}

// rdar://107151854 - crash on invalid due to specialized pack expansion
func test_pack_expansion_specialization(tuple: (Int, String, Float)) {
  struct Data<each T> {
    init(_: repeat each T) {} // expected-note 4 {{'init(_:)' declared here}}
    init(vals: repeat each T) {}
    init<each U>(x: Int, _: repeat each T, y: repeat each U) {}
  }

  _ = Data<Int>() // expected-error {{missing argument for parameter #1 in call}}
  _ = Data<Int>(0) // Ok
  _ = Data<Int, String>(42, "") // Ok
  _ = Data<Int>(42, "") // expected-error {{pack expansion requires that 'Int' and 'Int, String' have the same shape}}
  _ = Data<Int, String>((42, ""))
  // expected-error@-1 {{initializer expects 2 separate arguments; remove extra parentheses to change tuple into separate arguments}} {{25-26=}} {{32-33=}}
  _ = Data<Int, String, Float>(vals: (42, "", 0))
  // expected-error@-1 {{pack expansion requires that 'Int, String, Float' and '(Int, String, Int)' have the same shape}}
  _ = Data<Int, String, Float>((vals: 42, "", 0))
  // expected-error@-1 {{initializer expects 3 separate arguments; remove extra parentheses to change tuple into separate arguments}} {{32-33=}} {{48-49=}}
  _ = Data<Int, String, Float>(tuple)
  // expected-error@-1 {{initializer expects 3 separate arguments}}
  _ = Data<Int, String, Float>(x: 42, tuple)
  // expected-error@-1 {{pack expansion requires that 'Int, String, Float' and '(Int, String, Float)' have the same shape}}
  _ = Data<Int, String, Float>(x: 42, tuple, y: 1, 2, 3)
  // expected-error@-1 {{pack expansion requires that 'Int, String, Float' and '(Int, String, Float)' have the same shape}}
  _ = Data<Int, String, Float>(x: 42, (42, "", 0), y: 1, 2, 3)
  // expected-error@-1 {{pack expansion requires that 'Int, String, Float' and '(Int, String, Int)' have the same shape}}

  struct Ambiguity<each T> {
    func test(_: repeat each T) -> Int { 42 }
    // expected-note@-1 {{'test' declared here}}
    func test(_: repeat each T) -> String { "" }
  }

  _ = Ambiguity<Int, String, Float>().test(tuple) // expected-error {{instance method 'test' expects 3 separate arguments}}
}

// rdar://107280056 - "Ambiguous without more context" with opaque return type + variadics
protocol Q {
  associatedtype B
}

do {
  struct G<each T>: Q {
    typealias B = (repeat each T)
  }

  func f<each T>(_: repeat each T) -> some Q {
    return G<repeat each T>() // Ok
  }
}

// Make sure that in-exact matches (that require any sort of conversion or load) on arguments are handled correctly.
do {
  var v: Float = 42 // expected-warning {{variable 'v' was never mutated; consider changing to 'let' constant}}

  func testOpt<each T>(x: Int?, _: repeat each T) {}
  testOpt(x: 42, "", v) // Load + Optional promotion

  func testLoad<each T, each U>(t: repeat each T, u: repeat each U) {}
  testLoad(t: "", v) // Load + default
  testLoad(t: "", v, u: v, 0.0) // Two loads

  func testDefaultWithExtra<each T, each U>(t: repeat each T, u: repeat each U, extra: Int?) {}
  testDefaultWithExtra(t: "", v, extra: 42)

  func defaults1<each T>(x: Int? = nil, _: repeat each T) {}
  defaults1("", 3.14) // Ok

  func defaults2<each T>(_: repeat each T, x: Int? = nil) {}
  defaults2("", 3.14) // Ok

  func defaults3<each T, each U>(t: repeat each T, u: repeat each U, extra: Int? = nil) {}
  defaults3(t: "", 3.14) // Ok
  defaults3(t: "", 3.14, u: 0, v) // Ok
  defaults3(t: "", 3.14, u: 0, v, extra: 42) // Ok

  struct Defaulted<each T> {
    init(t: repeat each T, extra: Int? = nil) {}
    init<each U>(t: repeat each T, u: repeat each U, other: Int? = nil) {}
  }

  _ = Defaulted(t: "a", 0, 1.0) // Ok
  _ = Defaulted(t: "b", 0) // Ok
  _ = Defaulted(t: "c", 1.0, u: "d", 0) // Ok
}

// rdar://108064941 - unused result diagnostic is unaware of Void packs
func test_no_unused_result_warning(arr: inout [Any]) {
  func test1<each T>(_ value: (repeat each T)) {
    repeat arr.append(each value.element) // no warning
  }

  func test2<each T>(_ value: repeat each T) {
    ((repeat arr.append(each value))) // no warning
  }
}

func test_partially_flattened_expansions() {
  struct S<each T> {
    init() {}

    func fn<each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) {
      return (repeat (each t, each u))
    }
  }

  _ = S().fn(t: 1, "hi", u: false, 1.0) // Ok
  _ = S<Int, String>().fn(t: 1, "hi", u: false, 1.0) // Ok
}

// rdar://109160060 - tuple with pack expansions is not convertible to Any
do {
  func test1<each T>(_: repeat (each T).Type) -> (repeat each T) {}
  print(test1(Int.self, String.self))

  func test2<each T>(_ s: [Any], t: repeat (each T).Type) -> (repeat each T) {
    var iter = s.makeIterator()
    return (repeat (iter.next()! as! (each T)))
  }

  print(test2([]))
  print(test2([1], t: Int.self))
  print(test2([1, "hi"], t: Int.self, String.self))
  print(test2([1, "hi", false], t: Int.self, String.self, Bool.self))

  func test3<each T>(v: Any) -> (Int, repeat each T) {
    return v // expected-error {{cannot convert return expression of type 'Any' to return type '(Int, repeat each T)'}}
  }
}

// rdar://107835215 - failed to produce a diagnostic for invalid pack expansion expression
do {
  func test1(x: Int) {
    repeat x
    // expected-error@-1:5 {{value pack expansion must contain at least one pack reference}}
  }

  func test2<T: Numeric>(_ x: T) {
    repeat print(x * 2)
    // expected-error@-1:5 {{value pack expansion must contain at least one pack reference}}
  }

  struct S<T> {
    init(_: T) {}
  }

  func test<each T>(x: repeat each T, y: Int) {
    func f<each A, each B>(_: repeat each A, y: repeat each B) {}
    f(repeat each x, y: repeat [S(y)])
    // expected-error@-1:25 {{value pack expansion must contain at least one pack reference}}
  }
}

// rdar://108904190 - top-level 'repeat' not allowed in single-expression closures
func test_pack_expansion_to_void_conv_for_closure_result<each T>(x: repeat each T) {
  let _: () -> Void = { repeat print(each x) } // Ok
  let _: () -> Void = { (repeat print(each x)) } // Ok
  let _: (Int) -> Void = { repeat ($0, print(each x)) } // expected-warning {{expression of type '/* shape: each T */ repeat (Int, ())' is unused}}
  let _: (Int, String) -> Void = { ($0, repeat ($1, print(each x))) } // expected-warning {{expression of type '(Int, /* shape: each T */ repeat (String, ()))' is unused}}
}

// rdar://109539394 - crash on passing multiple variadic lists to singly variadic callee
do {
  func test1<each T>(_: repeat each T) {}
  func test2<each T>(_: repeat each T) where repeat each T: RawRepresentable {} // expected-note {{where 'each T' = 'each T2'}}

  func caller<each T1, each T2>(t1: repeat each T1, t2: repeat each T2) {
    test1(repeat each t1, repeat each t2) // Ok
    test2(repeat each t2, repeat each t1) // expected-error {{local function 'test2' requires that 'each T2' conform to 'RawRepresentable'}}
  }
}

do {
  func overloaded<each T>(_ a: Int, _ b: repeat each T) -> (repeat each T) {
    return (repeat each b)
  }

  func overloaded() {}

  func test<each T>(_ a: repeat each T) {
    _ = (repeat overloaded(1, each a))
  }
}

func configure<T, each Element>(
  _ item: T,
  with configuration: repeat (ReferenceWritableKeyPath<T, each Element>, each Element)
) -> T {
  repeat item[keyPath: (each configuration).0] = (each configuration).1
  return item
}

// rdar://110819621 - generic parameter is bound before pack expansion type which result in inference failures
func test_that_expansions_are_bound_early() {
  struct Data {
    let prop: Int?
  }

  struct Value<each T> {
    init(_ body: (repeat each T) -> Bool) {}
  }

  func compute<Root, Value>(
    root: Root,
    keyPath: KeyPath<Root, Value>,
    other: Value) -> Bool { true }

  func test_keypath(v: Int) {
    let _: Value<Data> = Value({
        compute(
          root: $0,
          keyPath: \.prop,
          other: v
        )
      }) // Ok

    let _: Value = Value<Data>({
        compute(
          root: $0,
          keyPath: \.prop,
          other: v
        )
      }) // Ok
  }

  func equal<Value>(_: Value, _: Value) -> Bool {}

  func test_equality(i: Int) {
    let _: Value<Data> = Value({
        equal($0.prop, i) // Ok
      })
  }
}

do {
  func test<T>(x: T) {}

  func caller1<each T>(x: repeat each T) {
    _ = (repeat { test(x: each x) }())
  }

  func caller2<each T>(x: repeat each T) {
    _ = { (repeat test(x: each x)) }()
  }
}

// https://github.com/apple/swift/issues/66393
do {
  struct S<each T> {
    var property: (repeat each T) -> Void {
      get {}
    }

    func method(_: repeat each T) {}
  }
  S<Int, Bool>().method((5, true))
  // expected-error@-1 {{pack expansion requires that 'Int, Bool' and '(Int, Bool)' have the same shape}}

  S<Int, Bool>().method((5, true, 6))
  // expected-error@-1 {{pack expansion requires that 'Int, Bool' and '(Int, Bool, Int)' have the same shape}}

  S<Int, Bool>().property((5, true))
  // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'repeat each T'}}

  S<Int, Bool>().property((5, true, 6))
  // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'repeat each T'}}

  func foo<each U>(u: repeat each U) {
    S<repeat each U>().property((3, 4, 5))
    // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'repeat each T'}}

    // FIXME: The count of 'repeat each U' is not statically known, but error suggests that it is 1.
    S<repeat each U>().method((3, 4, 5))
    // expected-error@-1 {{pack expansion requires that 'each U' and '(Int, Int, Int)' have the same shape}}

    // FIXME: The count of '(Int, Int), repeat each U' is not statically known, but error suggests that it is 2.
    S<(Int, Int), repeat each U>().method((3, 4))
    // expected-error@-1 {{pack expansion requires that '(Int, Int), repeat each U' and '(Int, Int)' have the same shape}}

    // FIXME: The count of '(Int, Int), repeat each U' is not statically known, but error suggests that it is 2.
    S<(Int, Int), repeat each U>().property((3, 4))
    // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'repeat each T'}}
  }
}

// rdar://110401127 - name lookup bug when abstract tuple stored property shadows a global
do {
  let c = [false, true]
  _ = c

  struct ZipCollection<each C> {
    public let c: (repeat each C)

    func makeTuple() -> (repeat each C) {
      fatalError()
    }

    public func f() -> (repeat Optional<each C>) {
      _ = (repeat each makeTuple())
      _ = (repeat (each makeTuple()))
    }
  }
}

// rdar://112029630 - incorrect variadic generic overload ranking
do {
  func test1<T>(_: T...) {}
  // expected-note@-1 {{found this candidate}}
  func test1<each T>(_: repeat each T) {}
  // expected-note@-1 {{found this candidate}}

  test1(1, 2, 3) // expected-error {{ambiguous use of 'test1'}}
  test1(1, "a") // Ok

  func test2<each T>(_: repeat each T) {}
  // expected-note@-1 {{found this candidate}}
  func test2<each T>(vals: repeat each T) {}
  // expected-note@-1 {{found this candidate}}

  test2() // expected-error {{ambiguous use of 'test2'}}

  func test_different_requirements<A: BinaryInteger & StringProtocol>(_ a: A) {
    func test3<each T: BinaryInteger>(str: String, _: repeat each T) {}
    // expected-note@-1 {{found this candidate}}
    func test3<each U: StringProtocol>(str: repeat each U) {}
    // expected-note@-1 {{found this candidate}}

    test3(str: "", a, a)  // expected-error {{ambiguous use of 'test3'}}
  }
}

// rdar://112095973 - single-element tuples are not unwrapped in member references
do {
  struct V<Value> {
    let key: Int
  }

  struct S<each T> {
    let data: (repeat V<each T>)
  }

  func test<U>(_ value: S<U>) {
    _ = value.data.key // Ok
  }
}

// Pack Iteration
do {
  func test<each T>(_ t: repeat each T) {
    func nested() -> (repeat (Int, each T)) {}
    for (x, y) in repeat each nested() {}
    // expected-warning@-1 {{immutable value 'x' was never used; consider replacing with '_' or removing it}}
    // expected-warning@-2 {{immutable value 'y' was never used; consider replacing with '_' or removing it}}
  }
}

// Closures wrapped in a pack expansion
do {
  func takesClosure<T>(_ fn: () -> T) -> T { return fn() }

  func testClosure<each T>(_ t: repeat each T) -> (repeat each T) {
    (repeat takesClosure { each t }) // Ok
  }

  func testMultiStmtClosure<each T>(_ t: repeat each T) -> (repeat each T) {
     (repeat takesClosure {
       let v = each t
       return v
    }) // Ok
  }

  func takesAutoclosure<T>(_ fn: @autoclosure () -> T) -> T { return fn() }

  func f2<each T>(_ t: repeat each T) -> (repeat each T) {
    (repeat takesAutoclosure(each t)) // Ok
  }
}

// Crash-on-invalid - rdar://110711746
func butt<T>(x: T) {}

func rump<each T>(x: repeat each T) {
  let x = (repeat { butt(each x) }()) // expected-error {{missing argument label 'x:' in call}}
}

// Placement of `each` in expressions.
do {
  do {
    func overload<each U>(_: String, _: repeat each U) -> Int {}
    func overload<each T>(_: Int, _ b: repeat each T) -> (repeat each T) {}

    func test<each T>(
      t: repeat each T,
      t2: repeat (each T)?,
      t3: repeat () -> each T
    ) {
      _ = t
      // expected-error@-1{{value pack 'each T' must be referenced with 'each'}}

      forward(t)
      // expected-error@-1{{value pack 'each T' must be referenced with 'each'}}

      _ = each t
      // expected-error@-1{{pack reference 'each T' can only appear in pack expansion}}

      forward(each t)
      // expected-error@-1{{pack reference 'each T' can only appear in pack expansion}}

      let tuple = (repeat each t)
      _ = tuple
      _ = each tuple
      // expected-error@-1{{pack reference 'each T' can only appear in pack expansion}}

      // https://github.com/swiftlang/swift/issues/78393
      let _ = (t2)
      // expected-error@-1{{value pack '(each T)?' must be referenced with 'each'}}
      let _ = t3
      // expected-error@-1{{value pack '() -> each T' must be referenced with 'each'}}

      let _ = (repeat overload(42, t)) // expected-error {{value pack 'each T' must be referenced with 'each'}} {{36-36=each }}
      let _ = (repeat overload(42, each t)) // Ok
    }
  }

  // FIXME: https://github.com/swiftlang/swift/issues/78426
  do {
    func f<each T>(_: (repeat each T) -> (repeat each T)) {}
    // expected-error@+2 {{cannot infer type of closure parameter 'x' without a type annotation}}
    // expected-error@+1 {{cannot convert value of type '(Int, Int)' to closure result type '(_: _)'}}
    f { x in
      // Once this issue is fixed, verify that 'x' below is diagnosed correctly.
      // If it is not, please reopen https://github.com/swiftlang/swift/issues/78393.
      let _ = x
      return (1, 2)
    }
  }

  // rdar://107675464 - misplaced `each` results in `type of expression is ambiguous without a type annotation`
  do {
    func test_correct_each<each T: P>(_ value: repeat each T) -> (repeat (each T).A) {
      return (repeat (each value).makeA()) // Ok
    }

    func test_misplaced_each<each T: P>(_ value: repeat each T) -> (repeat (each T).A) {
      return (repeat each value.makeA())
      // expected-error@-1 {{value pack 'each T' must be referenced with 'each'}} {{27-27=(each }} {{32-32=)}}
    }
  }

  // rdar://110847476 - unrelated assignment and raw representable diagnostics
  do {
    struct Test<each Base: AsyncSequence> {
      let base: (repeat each Base)

      init(base: repeat each Base) {
        self.base = base
        // expected-error@-1 {{value pack 'each Base' must be referenced with 'each'}}
      }
    }
  }
}

// https://github.com/swiftlang/swift/issues/79623
do {
  protocol P<T>: Hashable {
    associatedtype T
  }

  struct S<each T> {
    var x: any P<(repeat each T)>
    var hashable: AnyHashable {
      AnyHashable(x)
    }
  }
}