fix: preserve inset content layout and view lists

Sources/OpenSwiftUICore/Layout/Modifier/InsetViewModifier.swift

@@ -113,7 +113,7 @@ extension View {
 
 @available(OpenSwiftUI_v3_0, *)
 @frozen
-public struct _InsetViewModifier<Content>: ViewModifier where Content: View {
+public struct _InsetViewModifier<Content>: ViewModifier, MultiViewModifier, PrimitiveViewModifier where Content: View {
     @usableFromInline
     var content: Content
 
@@ -139,7 +139,7 @@ public struct _InsetViewModifier<Content>: ViewModifier where Content: View {
     ) -> _ViewOutputs {
         var primaryInputs = inputs
         var secondaryInputs = inputs
-        secondaryInputs.base.pushStableIndex(0)
+        primaryInputs.base.pushStableIndex(0)
         secondaryInputs.implicitRootType = _ZStackLayout.self
         secondaryInputs.base.pushStableIndex(1)
 
@@ -226,6 +226,7 @@ public struct _InsetViewModifier<Content>: ViewModifier where Content: View {
         for key in inputs.preferences.keys {
             key.visitKey(&visitor)
         }
+        visitor.result.layoutComputer = layoutComputer
         return visitor.result
     }
 }

Tests/OpenSwiftUICoreTests/Layout/Modifier/InsetViewModifierTests.swift

@@ -0,0 +1,93 @@
+//
+//  InsetViewModifierTests.swift
+//  OpenSwiftUICoreTests
+
+import Foundation
+import OpenAttributeGraphShims
+@_spi(ForOpenSwiftUIOnly) @testable import OpenSwiftUICore
+import OpenSwiftUITestsSupport
+import Testing
+
+@MainActor
+@Suite(.tags(.aigc), .disabled(if: attributeGraphVendor == .oag))
+struct InsetViewModifierTests {
+    @Test
+    func safeAreaInsetPreservesViewListChildren() {
+        checkViewList(
+            TupleView((Color.red, Color.blue))
+                .safeAreaInset(edge: .top, spacing: 0) {
+                    Color.clear.frame(height: 12)
+                }
+        )
+    }
+
+    @Test
+    func safeAreaPaddingPreservesViewListChildren() {
+        checkViewList(
+            TupleView((Color.red, Color.blue))
+                .safeAreaPadding(.horizontal, 20)
+        )
+    }
+
+    @Test(arguments: [VerticalEdge.top, .bottom])
+    func verticalSafeAreaInsetPreservesContentLayout(edge: VerticalEdge) {
+        checkLayout(
+            Color.red.frame(width: 32, height: 48)
+                .safeAreaInset(edge: edge, spacing: 0) {
+                    Color.clear.frame(width: 12, height: 12)
+                },
+            expectedSize: CGSize(width: 32, height: 60)
+        )
+    }
+
+    @Test(arguments: [HorizontalEdge.leading, .trailing])
+    func horizontalSafeAreaInsetPreservesContentLayout(edge: HorizontalEdge) {
+        checkLayout(
+            Color.red.frame(width: 32, height: 48)
+                .safeAreaInset(edge: edge, spacing: 0) {
+                    Color.clear.frame(width: 12, height: 12)
+                },
+            expectedSize: CGSize(width: 44, height: 48)
+        )
+    }
+
+    @Test(arguments: [
+        (Edge.top, CGSize(width: 32, height: 60)),
+        (.bottom, CGSize(width: 32, height: 60)),
+        (.leading, CGSize(width: 44, height: 48)),
+        (.trailing, CGSize(width: 44, height: 48)),
+    ])
+    func safeAreaPaddingPreservesContentLayout(edge: Edge, expectedSize: CGSize) {
+        checkLayout(
+            Color.red.frame(width: 32, height: 48)
+                .safeAreaPadding(Edge.Set(edge), 12),
+            expectedSize: expectedSize
+        )
+    }
+
+    private func checkLayout<Content: View>(_ content: Content, expectedSize: CGSize) {
+        Update.perform {
+            let graph = ViewGraph(rootViewType: Content.self, requestedOutputs: .layout)
+            defer { graph.invalidate() }
+            graph.setRootView(content)
+            #expect(graph.sizeThatFits(.unspecified) == expectedSize)
+        }
+    }
+
+    private func checkViewList<Content: View>(_ content: Content) {
+        Update.perform {
+            let graph = ViewGraph(rootViewType: Content.self)
+            defer { graph.invalidate() }
+            graph.rootSubgraph.apply {
+                let inputs = _ViewListInputs(graph.graphInputs)
+                let outputs = Content._makeViewList(
+                    view: _GraphValue(Attribute(value: content)),
+                    inputs: inputs
+                )
+                #expect(outputs.staticCount == 2)
+                #expect(outputs.nextImplicitID == 2)
+                #expect(outputs.makeAttribute(inputs: inputs).value.count(style: .init()) == 2)
+            }
+        }
+    }
+}