Fix ViewAlias Body Accessor crash (#582)

Author: Kyle-Ye

Sources/OpenSwiftUI/View/Configuration/ViewAlias.swift

@@ -25,6 +25,36 @@ protocol ViewAlias: PrimitiveView {
     init()
 }
 
+// Audited for 6.5.4
+
+extension ViewAlias {
+    nonisolated public static func _makeView(view: _GraphValue<Self>, inputs: _ViewInputs) -> _ViewOutputs {
+        var inputs = inputs
+        guard let source = inputs.popLast(SourceInput<Self>.self) else {
+            return .init()
+        }
+        inputs.base.resetCurrentStyleableView()
+        return source.formula.makeView(view: view, source: source, inputs: inputs)
+    }
+
+    nonisolated public static func _makeViewList(view: _GraphValue<Self>, inputs: _ViewListInputs) -> _ViewListOutputs {
+        var inputs = inputs
+        guard let source = inputs.base.popLast(SourceInput<Self>.self) else {
+            return .emptyViewList(inputs: inputs)
+        }
+        inputs.base.resetCurrentStyleableView()
+        return source.formula.makeViewList(view: view, source: source, inputs: inputs)
+    }
+
+    nonisolated public static func _viewListCount(inputs: _ViewListCountInputs) -> Int? {
+        var inputs = inputs
+        guard let source = inputs.popLast(SourceInput<Self>.self) else {
+            return 0
+        }
+        return source.formula.viewListCount(source: source, inputs: inputs)
+    }
+}
+
 // MARK: - View + ViewAlias Extension
 
 extension View {

Tests/OpenSwiftUITests/View/Configuration/ViewAliasTests.swift

@@ -0,0 +1,80 @@
+//
+//  ViewAliasTests.swift
+//  OpenSwiftUITests
+
+import Foundation
+import Testing
+@testable import OpenSwiftUI
+@_spi(ForOpenSwiftUIOnly)
+import OpenSwiftUICore
+import OpenSwiftUITestsSupport
+
+@MainActor
+struct ViewAliasTests {
+    #if canImport(Darwin)
+    @Test
+    func optionalViewAliasDynamicProperty() async throws {
+        struct ContentView: View {
+            var confirmation: Confirmation?
+
+            @OptionalViewAlias
+            private var alias: ChildView.Alias?
+
+            var body: some View {
+                ChildView(confirmation: confirmation)
+                    .viewAlias(ChildView.Alias.self) { Color.red }
+                    .onAppear {
+                        #expect(alias == nil)
+                        confirmation?()
+                    }
+            }
+        }
+
+        struct ChildView: View {
+            var confirmation: Confirmation?
+
+            struct Alias: ViewAlias {}
+
+            @OptionalViewAlias
+            private var alias: Alias?
+
+            var body: some View {
+                Alias()
+                    .onAppear {
+                        #expect(alias != nil)
+                        confirmation?()
+                    }
+            }
+        }
+        try await triggerLayoutWithWindow(expectedCount: 2) { confirmation in
+            PlatformHostingController(
+                rootView: ContentView(
+                    confirmation: confirmation
+                )
+            )
+        }
+
+        // DisplayList expectation
+        let graph = ViewGraph(
+            rootViewType: ContentView.self,
+            requestedOutputs: [.displayList]
+        )
+        graph.instantiateOutputs()
+        graph.setRootView(ContentView())
+        graph.setProposedSize(CGSize(width: 100, height: 100))
+        let (displayList, _) = graph.displayList()
+        print(displayList.description)
+        let expectRegex = try! Regex(#"""
+        \(display-list
+          \(item #:identity \d+ #:version \d+
+            \(frame \([^)]+\)\)
+            \(effect
+              \(item #:identity \d+ #:version \d+
+                \(frame \([^)]+\)\)
+                \(content-seed \d+\)
+                \(color #[0-9A-F]{8}\)\)\)\)\)
+        """#)
+        #expect(displayList.description.contains(expectRegex))
+    }
+    #endif
+}