feat(hosting): integrate hit-test handling and diagnostics

Sources/COpenSwiftUI/Shims/UIKit/_UIHitTestContext.h

@@ -27,7 +27,7 @@ NS_HEADER_AUDIT_BEGIN(nullability, sendability)
 @end
 
 OPENSWIFTUI_EXPORT
-_UIHitTestContext * _Nullable _UICurrentHitTestContext(void) OPENSWIFTUI_SWIFT_NAME(getter:_UIHitTestContext.current);
+_UIHitTestContext * _Nullable _UICurrentHitTestContext(void) OPENSWIFTUI_SWIFT_NAME(getter:_UIHitTestContext.current());
 
 NS_HEADER_AUDIT_END(nullability, sendability)
 

Sources/OpenSwiftUI/Integration/Hosting/AppKit/View/NSHostingView.swift

@@ -116,6 +116,8 @@ open class NSHostingView<Content>: NSView, XcodeViewDebugDataProvider where Cont
 
     package let eventBindingManager = EventBindingManager()
 
+    private var hitTestEventMonitor: Any?
+
     private lazy var eventBindingSource = BindingSource(hostingView: self)
 
     private lazy var eventBridge = AppKitEventBindingBridge(
@@ -284,7 +286,20 @@ open class NSHostingView<Content>: NSView, XcodeViewDebugDataProvider where Cont
             eventBindingManager.delegate = self
         }
         HostingViewRegistry.shared.add(self)
-        // TODO
+        if _eventDebugTriggers.contains(.hitTest) {
+            hitTestEventMonitor = NSEvent.addLocalMonitorForEvents(matching: .leftMouseDown) { [weak self] event in
+                guard let self, event.window === self.window else {
+                    return event
+                }
+                guard sequence(first: self as NSView, next: { $0.superview })
+                    .dropFirst().first(ofType: HostingViewProtocol.self) == nil else {
+                    return event
+                }
+                let point = self.convert(event.locationInWindow, from: nil)
+                self.printHitTest(point)
+                return event
+            }
+        }
         Update.end()
         // TODO
         setNeedsUpdate()
@@ -307,6 +322,9 @@ open class NSHostingView<Content>: NSView, XcodeViewDebugDataProvider where Cont
         updateRemovedState()
         // TODO
         HostingViewRegistry.shared.remove(self)
+        if let hitTestEventMonitor {
+            NSEvent.removeMonitor(hitTestEventMonitor)
+        }
     }
 
     /// The renderer configuration of the hosting view.

Sources/OpenSwiftUI/Integration/Hosting/UIKit/View/UIHostingView.swift

@@ -445,6 +445,45 @@ open class _UIHostingView<Content>: UIView, XcodeViewDebugDataProvider where Con
         foreignSubviews.remove(subview)
     }
 
+    // Audited for 6.5.4
+    override dynamic open func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
+        printHitTestIfNeeded(at: point, with: event)
+        let result = super.hitTest(point, with: event)
+        guard GestureContainerFeature.isEnabled,
+              _UIHitTestContext.current != nil || CoreTesting.isRunning
+        else {
+            return result
+        }
+        if let result, foreignSubviews.allObjects.contains(where: { result.isDescendant(of: $0) }) {
+            return result
+        }
+        currentEvent = event
+        guard !UIViewIgnoresTouchEvents(self), self.point(inside: point, with: event) else {
+            return nil
+        }
+        return self
+    }
+
+    // Audited for 6.5.4
+    private func printHitTestIfNeeded(at point: CGPoint, with event: UIEvent?) {
+        guard _eventDebugTriggers.contains(.hitTest), let event, event.type == .touches else {
+            return
+        }
+        guard sequence(first: self as UIView, next: { $0.superview })
+            .dropFirst().first(ofType: HostingViewProtocol.self) == nil
+        else {
+            return
+        }
+        let usesGestureContainer = GestureContainerFeature.isEnabled
+        let context = _UIHitTestContext.current
+        if usesGestureContainer {
+            guard let context else { return }
+            printHitTest(point, radius: context.radius)
+        } else {
+            guard context == nil else { return }
+            printHitTest(point)
+        }
+    }
 
     /// The UIKit notion of the safe area insets.
     open override var safeAreaInsets: UIEdgeInsets {