swift-mirror/test/Sema/value_generics.swift

// RUN: %target-typecheck-verify-swift -disable-availability-checking

protocol P {}
protocol Q {}
class Class {}

func invalid<let N>() { // expected-error {{value generic 'N' must have an explicit value type declared}}
                        // expected-error@-1 {{generic parameter 'N' is not used in function signature}}
  let x: String = N // Fine, we bind to a hole.
}
func invalid<let N>(_: A<N>) {} // expected-error {{value generic 'N' must have an explicit value type declared}}

struct A<let N: Int> {
  var int: Int {
    N // OK
  }

  var uint: UInt {
    N // expected-error {{cannot convert return expression of type 'Int' to return type 'UInt'}}
  }

  var goodUInt: UInt {
    UInt(N) // OK
  }

  var intSelf: Int {
    N.self // OK
  }

  var n: N { // expected-error {{using value generic 'N' here is not allowed}}
    fatalError()
  }

  var nType: N.Type { // expected-error {{using value generic 'N' here is not allowed}}
    fatalError()
  }

  var a: A<N> { // OK
    fatalError()
  }
}

extension A where N == Int {} // expected-error {{cannot constrain value parameter 'N' to be type 'Int'}}

extension A where N == 123 {
  func thing() -> Int {
    N // OK (this used to crash the compiler in a concrete case 'where N == 123')
  }
}

func b(with a: A<123>) {} // OK
func c<let M: Int>(with a: A<M>) {} // OK
func d<T>(with a: A<T>) {} // expected-error {{cannot pass type 'T' as a value for generic value 'N'}}
func e(with a: A<Int>) {} // expected-error {{cannot pass type 'Int' as a value for generic value 'N'}}

func *<let X: Int, let Y: Int>(l: A<X>, r: A<Y>) -> Int { l.int * r.int }

struct Generic<T: ~Copyable & ~Escapable> {}
struct GenericWithIntParam<T: ~Copyable & ~Escapable, let N: Int> {}

extension Generic where T == 123 {} // expected-error {{cannot constrain type parameter 'T' to be integer '123'}}
extension Generic where T == 123.Type {} // expected-error {{cannot constrain type parameter 'T' to be integer '123'}}
                                         // expected-error@-1 {{expected '{' in extension}}
extension Generic where T == 123? {} // expected-error {{cannot constrain type parameter 'T' to be integer '123'}}
                                     // expected-error@-1 {{expected '{' in extension}}

func f(_: Generic<123>) {} // expected-error {{integer unexpectedly used in a type position}}
func g<let N: Int>(_: Generic<N>) {} // expected-error {{cannot use value type 'N' for generic argument 'T'}}
func h(_: (Int, 123)) {} // expected-error {{expected type}}
func i(_: () -> 123) {} // expected-error {{expected type}}
func j(_: (A<123>) -> ()) {} // OK
func k(_: some 123) {} // expected-error {{expected parameter type following ':'}}
func l(_: GenericWithIntParam<123, Int>) {}
// expected-error@-1 {{cannot pass type 'Int' as a value for generic value 'N'}}
// expected-error@-2 {{cannot use value type '123' for generic argument 'T'}}
func m(_: GenericWithIntParam<Int, 123>) {} // OK

typealias One = 1 // expected-error {{expected type in type alias declaration}}

// Unsupported type in value type parameter definition.
do {
  struct S1<let N: UInt8> {}
  // expected-error@-1:20 {{'UInt8' is not a supported value type for 'N'}}
  struct S2<let N: Any> {}
  // expected-error@-1:20 {{'Any' is not a supported value type for 'N'}}
  struct S3<let N: AnyObject> {}
  // expected-error@-1:20 {{'AnyObject' is not a supported value type for 'N'}}
  struct S4<let N: Class> {}
  // expected-error@-1:20 {{'Class' is not a supported value type for 'N'}}
  struct S5<let N: P> {}
  // expected-error@-1:20 {{'P' is not a supported value type for 'N'}}
  struct S6<let N: P & Q> {}
  // expected-error@-1:20 {{'P & Q' is not a supported value type for 'N'}}
  struct S7<let N: ~Copyable> {}
  // expected-error@-1:20 {{'~Copyable' is not a supported value type for 'N'}}
}

// Subtype constraint on value type parameter.

struct S1<let x: Int> where x: Class, x: P, x: P & Q, x: Int, x: ~Copyable {}
// expected-error@-1:30 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-2:40 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-3:46 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-4:56 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-5:64 {{cannot use type constraint with generic value parameter 'x'}}
extension S1 where x: Class, x: P, x: P & Q, x: Int, x: ~Copyable {}
// expected-error@-1:21 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-2:31 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-3:37 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-4:47 {{cannot use type constraint with generic value parameter 'x'}}
// expected-error@-5:55 {{cannot use type constraint with generic value parameter 'x'}}

struct C<let N: Int, let M: Int> {}

extension C where N == 123 { // expected-note {{where 'N' = '0'}}
                             // expected-note@-1 {{where 'N' = '0'}}
                             // expected-note@-2 {{where 'N' = 'T'}}
  func nIs123() {}
}

extension C where M == 321 { // expected-note {{where 'M' = '0'}}
                             // expected-note@-1 {{where 'M' = '0'}}
                             // expected-note@-2 {{where 'M' = 'T'}}
  func mIs123() {}
}

extension C where N == M { // expected-note {{where 'N' = '123', 'M' = '0'}}
                           // expected-note@-1 {{where 'N' = '0', 'M' = '321'}}
  func nAndMAreBothEqual() {}
}

func testC1(with c: C<0, 0>) {
  c.nIs123() // expected-error {{referencing instance method 'nIs123()' on 'C' requires the types '0' and '123' be equivalent}}
  c.mIs123() // expected-error {{referencing instance method 'mIs123()' on 'C' requires the types '0' and '321' be equivalent}}
  c.nAndMAreBothEqual() // OK
}

func testC2(with c: C<123, 0>) {
  c.nIs123() // OK
  c.mIs123() // expected-error {{referencing instance method 'mIs123()' on 'C' requires the types '0' and '321' be equivalent}}
  c.nAndMAreBothEqual() // expected-error {{referencing instance method 'nAndMAreBothEqual()' on 'C' requires the types '123' and '0' be equivalent}}
}

func testC3(with c: C<0, 321>) {
  c.nIs123() // expected-error {{referencing instance method 'nIs123()' on 'C' requires the types '0' and '123' be equivalent}}
  c.mIs123() // OK
  c.nAndMAreBothEqual() // expected-error {{referencing instance method 'nAndMAreBothEqual()' on 'C' requires the types '0' and '321' be equivalent}}
}

func testC4<let T: Int>(with c: C<T, T>) {
  c.nIs123() // expected-error {{referencing instance method 'nIs123()' on 'C' requires the types 'T' and '123' be equivalent}}
  c.mIs123() // expected-error {{referencing instance method 'mIs123()' on 'C' requires the types 'T' and '321' be equivalent}}
  c.nAndMAreBothEqual() // OK
}

struct D<let N: Int & P> {} // expected-error {{non-protocol, non-class type 'Int' cannot be used within a protocol-constrained type}}

struct E<A, let b: Int> { // expected-note {{'b' previously declared here}}
  static var b: Int { // expected-warning {{redeclaration of 'b' is deprecated and will be an error in Swift 5}}
                      // expected-note@-1 {{'b' declared here}}
    123
  }

  let b: String // expected-note {{'b' previously declared here}}
                // expected-note@-1 {{'b' declared here}}

  func b() {} // expected-error {{invalid redeclaration of 'b()'}}
              // expected-note@-1 {{'b' declared here}}

  func dumb() -> Int {
    Self.b // OK
  }

  static func dumb2() -> Int {
    Self.b // OK
  }
}

func testE1() -> Int {
  E<Int, 123>.b // OK
}

func testE2() -> Int {
  E<Int, 123>.A // expected-error {{type 'E<Int, 123>' has no member 'A'}}
}

func testE3<let c: Int>(_: E<Int, c>.Type) -> Int {
  E<Int, c>.b // OK
}

func testShadowing<let a: Int>(_: A<a>) {
  var a: String {
    "123"
  }

  let x: String = a // OK
  let y: Int = a // expected-error {{cannot convert value of type 'String' to specified type 'Int'}}

  print(a) // OK
  print(a.self) // OK
}

class F<let n: Int> {}
class G: F<3> {}

func hello() -> Int {
  G.n // OK
}

func testTypeOf() -> Int {
  let x = E<Int, 123>(b: "")
  return type(of: x).b // OK
}

func testTypeOf2<let c: Int>(_: E<Int, c>.Type) -> Int {
  let x = E<Int, c>(b: "")
  return type(of: x).b // OK
}

struct H<let I: Int> { // expected-note {{'I' previously declared here}}
  struct I {} // expected-warning {{redeclaration of 'I' is deprecated and will be an error in Swift 5}}
}

typealias J = E<Int, 123>.b // expected-error {{static property 'b' is not a member type of 'E<Int, 123>'}}