protocol_requirement.swift

// Test limitations on SPI protocol requirements.

// RUN: %target-typecheck-verify-swift -enable-library-evolution

// Reject SPI protocol requirements without a default implementation.
public protocol PublicProtoRejected {
  @_spi(Private)
  func reqWithoutDefault() // expected-error{{protocol requirement 'reqWithoutDefault()' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private)
  func reqWithSharedName(_: Int) // expected-error{{protocol requirement 'reqWithSharedName' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private)
  var property: Int { get set } // expected-error{{protocol requirement 'property' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private)
  var propertyWithoutSetter: Int { get set } // expected-error{{protocol requirement 'propertyWithoutSetter' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private)
  subscript(index: Int) -> Int { get set } // expected-error{{protocol requirement 'subscript(_:)' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private)
  init() // expected-error{{protocol requirement 'init()' cannot be declared '@_spi' without a default implementation in a protocol extension}}

  @_spi(Private) // expected-error{{'@_spi' attribute cannot be applied to this declaration}}
  associatedtype T
}

extension PublicProtoRejected {
  @_spi(Private)
  public var propertyWithoutSetter: Int { get { return 42 } }

  @_spi(Private)
  public func reqWithSharedName(_: String) {}
}

extension PublicProtoRejected where Self : Equatable {
  @_spi(Private)
  public func reqWithoutDefault() {
    // constrained implementation
  }
}

// Accept SPI protocol requirements with an implementation.
public protocol PublicProto {
  @_spi(Private)
  func reqWithDefaultImplementation()

  @_spi(Private)
  var property: Int { get set }

  @_spi(Private)
  subscript(index: Int) -> Int { get set }

  @_spi(Private)
  init()
}

extension PublicProto {
  @_spi(Private)
  public func reqWithDefaultImplementation() { }

  @_spi(Private)
  public var property: Int {
    get { return 42 }
    set { }
  }

  @_spi(Private)
  public subscript(index: Int) -> Int {
    get { return 42 }
    set { }
  }

  @_spi(Private)
  public init() { }
}

@_spi(Private)
public protocol SPIProtocol {
  @_spi(Private)
  func reqWithoutDefault()

  @_spi(Private)
  var property: Int { get set }

  @_spi(Private)
  var propertyWithoutSetter: Int { get set }

  @_spi(Private)
  subscript(index: Int) -> Int { get set }

  @_spi(Private)
  init()

  @_spi(Private)
  static var staticProperty: Int { get }
}

public protocol OtherProto {}
public protocol Proto {
  associatedtype A : Sequence where A.Element : OtherProto
}

public struct BadStruct {}
@_spi(Horse) extension BadStruct : OtherProto {}
public struct BadConforms : Proto { // expected-error {{cannot use conformance of 'BadStruct' to 'OtherProto' here; the conformance is declared as SPI}}
// expected-note@-1 {{in associated type 'Self.A.Element' (inferred as 'BadStruct')}}
  public typealias A = [BadStruct]
}

public struct OKStruct {}
@_spi(Horse) extension OKStruct : OtherProto {}
@_spi(Horse) public struct OKConforms : Proto {
  public typealias A = [OKStruct]
}