Fix DynamicLayoutMap index issue

Example/OpenSwiftUIUITests/Layout/Stack/ZStackIndexUITests.swift

@@ -10,7 +10,7 @@ import SnapshotTesting
 @Suite(.snapshots(record: .never, diffTool: diffTool))
 struct ZStackIndexUITests {
     @Test
-    func zIndexExample() {
+    func rotateOverlap() {
         struct ContentView: View {
             var body: some View {
                 VStack {
@@ -30,11 +30,9 @@ struct ZStackIndexUITests {
                 }
             }
         }
-        withKnownIssue {
-            openSwiftUIAssertSnapshot(
-                of: ContentView(),
-                size: CGSize(width: 200, height: 200)
-            )
-        }
+        openSwiftUIAssertSnapshot(
+            of: ContentView(),
+            size: CGSize(width: 200, height: 200)
+        )
     }
 }

Sources/OpenSwiftUICore/Layout/Dynamic/DynamicLayoutMap.swift

@@ -31,17 +31,23 @@ package struct DynamicLayoutMap {
             map.first(where: { $0.id == id })?.value ?? .init()
         }
         set {
-            let index = map.firstIndex(where: { $0.id == id })
-            if let index {
-                if newValue.isEmpty {
-                    map.remove(at: index)
-                } else {
-                    map[index].value = newValue
-                }
-            } else {
+            if map.isEmpty {
                 if !newValue.isEmpty {
                     map.insert((id, newValue), at: 0)
                 }
+            } else {
+                let index = map.lowerBound { $0.id < id }
+                if index != map.count, map[index].id == id {
+                    if newValue.isEmpty {
+                        map.remove(at: index)
+                    } else {
+                        map[index].value = newValue
+                    }
+                } else {
+                    if !newValue.isEmpty {
+                        map.insert((id, newValue), at: index)
+                    }
+                }
             }
             sortedSeed = .zero
         }

Tests/OpenSwiftUICoreTests/Layout/ZIndexTests.swift

@@ -3,9 +3,9 @@
 //  OpenSwiftUICoreTests
 
 import OpenAttributeGraphShims
-@_spi(ForOpenSwiftUIOnly)
 import OpenSwiftUICore
 import Testing
+import Foundation
 
 @MainActor
 struct ZIndexTests {
@@ -16,4 +16,45 @@ struct ZIndexTests {
         collection.zIndex = 1.5
         #expect(collection.zIndex.isApproximatelyEqual(to: 1.5))
     }
+
+    #if canImport(Darwin)
+    @Test
+    func zIndexDisplayList() {
+        struct ContentView: View {
+            var body: some View {
+                GeometryReader { proxy in
+                    VStack {
+                        Color.white
+                            .frame(width: 100, height: 100, alignment: .center)
+                            .zIndex(1)
+                        Color.black
+                            .frame(width: 100, height: 100, alignment: .center)
+                   }
+                    .frame(width: 200, height: 200)
+                }
+                .ignoresSafeArea()
+            }
+        }
+        let graph = ViewGraph(
+            rootViewType: ContentView.self,
+            requestedOutputs: [.layout, .displayList]
+        )
+        graph.instantiateOutputs()
+        graph.setRootView(ContentView())
+        graph.setProposedSize(CGSize(width: 1000, height: 1000))
+        let (displayList, _) = graph.displayList()
+        let expectRegex = try! Regex(#"""
+        \(display-list
+          \(item #:identity \d+ #:version \d+
+            \(frame \(50.0 104.0; 100.0 100.0\)\)
+            \(content-seed \d+\)
+            \(color #000000FF\)\)
+          \(item #:identity \d+ #:version \d+
+            \(frame \(50.0 -4.0; 100.0 100.0\)\)
+            \(content-seed \d+\)
+            \(color #FFFFFFFF\)\)\)
+        """#)
+        #expect(displayList.description.contains(expectRegex))
+    }
+    #endif
 }