C++ interop flag makes NSTrackingArea behave differently

[ByunghoonKim]

Description
When -enable-experimental-cxx-interop flag is added to Project > Build Settings > Swift Compiler - Custom Flags > Other Swift Flags, Xcode suddenly complains

'Option' is not a member type of class 'AppKit.NSTrackingArea'.

Without the flag, this works:

let opt: NSTrackingArea.Options = [.mouseEnteredAndExited, .mouseMoved, .activeInKeyWindow, .inVisibleRect]

With the flag, this works:

let opt: NSTrackingAreaOptions = NSTrackingMouseEnteredAndExited|NSTrackingMouseMoved|NSTrackingActiveInKeyWindow|NSTrackingInVisibleRect

Steps to reproduce

struct ContentView: View {
    var body: some View {
        VStack {
            Text("hi")
                .frame(width:400, height:400)
                .border(.red)
                .mouseTracking()

        }
        .padding()
    }
}

import SwiftUI
import AppKit

extension View {
    func mouseTracking() -> some View {
        self.modifier(MouseTrackingViewModifier())
    }
}

struct MouseTrackingViewModifier: ViewModifier {
    func body(content: Content) -> some View {
        content.background {
            GeometryReader { geom in
                MouseTrackingViewRep(frame: geom.frame(in: .local))
            }
        }
    }
}

struct MouseTrackingViewRep: NSViewRepresentable {
    let frame: NSRect
    
    typealias NSViewType = MouseTrackingView
    
    func makeNSView(context: Context) -> NSViewType {
        MouseTrackingView(self, frame: frame)
    }
    
    func updateNSView(_ nsView: NSViewType, context: Context) {
    }
}

class MouseTrackingView: NSView {    
    let parent: MouseTrackingViewRep
    override var isFlipped: Bool { true }
    
    init(_ parent: MouseTrackingViewRep, frame: NSRect) {
        self.parent = parent
        super.init(frame: frame)
                
        // when Swift only
        let opt: NSTrackingArea.Options = [.mouseEnteredAndExited, .mouseMoved, .activeInKeyWindow, .inVisibleRect]
        // when -enable-experimental-cxx-interop
//        let opt: NSTrackingAreaOptions = NSTrackingMouseEnteredAndExited|NSTrackingMouseMoved|NSTrackingActiveInKeyWindow|NSTrackingInVisibleRect
        let trackingArea = NSTrackingArea(rect: self.bounds, options: opt, owner: self, userInfo: nil)
        self.addTrackingArea(trackingArea)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func mouseEntered(with event: NSEvent) {
        print("mouse Entered")
    }
    
    override func mouseExited(with event: NSEvent) {
        print("mouse Exited")
    }
    
    override func mouseMoved(with event: NSEvent) {
        let mouseLocation = self.convert(event.locationInWindow, from: nil)
        print("mouse (\(mouseLocation.x), \(mouseLocation.y))")
    }
}

Expected behavior

Either changing the code is not required, or some documentation of the behavior.

Environment

• Swift compiler version info

swift-driver version: 1.75.2 Apple Swift version 5.8 (swiftlang-5.8.0.124.2 clang-1403.0.22.11.100)
Target: arm64-apple-macosx13.0

• Xcode version info

Xcode 14.3
Build version 14E222b

• Deployment target:
  macOS 13.3

[linshaolong5240]

When -enable-experimental-cxx-interop flag is added to Project > Build Settings > Swift Compiler - Custom Flags > Other Swift Flags

/// Type 'NSSearchPathDomainMask' (aka 'Int') has no member 'userDomainMask'
try? FileManager.default.url(for: .downloadsDirectory, in: .userDomainMask, appropriateFor: nil, create: false)

///Reference to member 'atomic' cannot be resolved without a contextual type
///Value of type 'Data' has no member 'write'
let data = Data()
data.write(to: url, options: [.atomic])

/// Value of type 'CGBitmapInfo' (aka 'UInt32') has no member 'rawValue'
  public func resize(in rect: CGRect, size: CGSize) -> CGImage? {
      guard let context = CGContext(data: nil, width: Int(size.width), height: Int(size.height), bitsPerComponent: self.bitsPerComponent, bytesPerRow: self.bitsPerComponent * Int(size.width), space: self.colorSpace!, bitmapInfo: self.bitmapInfo.rawValue) else {
          return nil
      }
      context.draw(self, in: rect)
      guard let cgImage = context.makeImage() else {
          return nil
      }
      return cgImage
  }

[zoecarver]

@ByunghoonKim I think your issue is resolved on main.

@linshaolong5240 this PR will resolve your issue: #66452

[ByunghoonKim]

Thank you for the update.
@zoecarver And I have to say, I enjoyed your WWDC23 "Mix Swift and C++" presentation. :)

[zoecarver]

Thank you, Byunghoon!