Add OPENSWIFTUI_TARGET_RELEASE support

Package.swift

@@ -23,11 +23,64 @@ let development = envEnable("OPENSWIFTUI_DEVELOPMENT", default: false)
 // Xcode use clang as linker which supports "-iframework" while SwiftPM use swiftc as linker which supports "-Fsystem"
 let systemFrameworkSearchFlag = isXcodeEnv ? "-iframework" : "-Fsystem"
 
+let releaseVersion = Context.environment["OPENSWIFTUI_TARGET_RELEASE"].flatMap { Int($0) } ?? 2021
+let platforms: [SupportedPlatform] = switch releaseVersion {
+case 2023:
+    [
+        .iOS(.v17),
+        .macOS(.v14),
+        .macCatalyst(.v17),
+        .tvOS(.v17),
+        .watchOS(.v9),
+        .visionOS(.v1),
+    ]
+case 2022:
+    [
+        .iOS(.v16),
+        .macOS(.v13),
+        .macCatalyst(.v16),
+        .tvOS(.v16),
+        .watchOS(.v8),
+    ]
+case 2021:
+    [
+        .iOS(.v15),
+        .macOS(.v12),
+        .macCatalyst(.v15),
+        .tvOS(.v15),
+        .watchOS(.v7),
+    ]
+default:
+    [
+        .iOS(.v13),
+        .macOS(.v10_15),
+        .macCatalyst(.v13),
+        .tvOS(.v13),
+        .watchOS(.v7), // WKApplicationMain is available for watchOS 7.0+
+        .visionOS(.v1),
+    ]
+}
+
 var sharedSwiftSettings: [SwiftSetting] = [
     .enableExperimentalFeature("AccessLevelOnImport"),
     .define("OPENSWIFTUI_SUPPRESS_DEPRECATED_WARNINGS"),
+    .define("OPENSWIFTUI_RELEASE_\(releaseVersion)"),
 ]
 
+switch releaseVersion {
+    case 2023:
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2023_API"))
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2022_API"))
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2021_API"))
+    case 2022:
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2022_API"))
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2021_API"))
+    case 2021:
+        sharedSwiftSettings.append(.define("OPENSWIFTUI_SUPPORT_2021_API"))
+    default:
+        break
+}
+
 let warningsAsErrorsCondition = envEnable("OPENSWIFTUI_WERROR", default: isXcodeEnv && development)
 if warningsAsErrorsCondition {
     sharedSwiftSettings.append(.unsafeFlags(["-warnings-as-errors"]))
@@ -78,14 +131,7 @@ let includePath = SDKPath.appending("/usr/lib/swift_static")
 
 let package = Package(
     name: "OpenSwiftUI",
-    platforms: [
-        .iOS(.v13),
-        .macOS(.v10_15),
-        .macCatalyst(.v13),
-        .tvOS(.v13),
-        .watchOS(.v7), // WKApplicationMain is available for watchOS 7.0+
-        .visionOS(.v1),
-    ],
+    platforms: platforms,
     products: [
         .library(name: "OpenSwiftUI", targets: ["OpenSwiftUI", "OpenSwiftUIExtension"]),
     ],

Sources/OpenSwiftUI/View/Shape/ForegroundStyle.swift

@@ -0,0 +1,29 @@
+@frozen
+public struct ForegroundStyle: ShapeStyle {
+    @inlinable
+    public init() {}
+
+    public static func _makeView<S>(view: _GraphValue<_ShapeView<S, ForegroundStyle>>, inputs: _ViewInputs) -> _ViewOutputs where S: Shape {
+        fatalError("TODO")
+    }
+}
+
+#if OPENSWIFTUI_SUPPORT_2021_API
+
+extension ForegroundStyle {
+    public func _apply(to shape: inout _ShapeStyle_Shape) {
+        fatalError("TODO")
+    }
+
+    public static func _apply(to type: inout _ShapeStyle_ShapeType) {
+        fatalError("TODO")
+    }
+}
+
+extension ShapeStyle where Self == ForegroundStyle {
+    @_alwaysEmitIntoClient
+    public static var foreground: ForegroundStyle {
+        .init()
+    }
+}
+#endif

Sources/OpenSwiftUI/View/Shape/Rectangle.swift

@@ -0,0 +1,25 @@
+import Foundation
+
+/// A rectangular shape aligned inside the frame of the view containing it.
+@frozen
+public struct Rectangle: Shape {
+    public func path(in rect: CGRect) -> Path {
+        fatalError("TODO")
+    }
+
+    /// Creates a new rectangle shape.
+    @inlinable
+    public init() {}
+
+    public typealias AnimatableData = EmptyAnimatableData
+
+    public typealias Body = _ShapeView<Rectangle, ForegroundStyle>
+}
+
+
+extension Shape where Self == Rectangle {
+    /// A rectangular shape aligned inside the frame of the view containing it.
+    public static var rect: Rectangle {
+        Rectangle()
+    }
+}

Sources/OpenSwiftUI/View/Shape/Shape.swift

@@ -0,0 +1,51 @@
+//
+//  Shape.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
+import Foundation
+
+/// A 2D shape that you can use when drawing a view.
+///
+/// Shapes without an explicit fill or stroke get a default fill based on the
+/// foreground color.
+///
+/// You can define shapes in relation to an implicit frame of reference, such as
+/// the natural size of the view that contains it. Alternatively, you can define
+/// shapes in terms of absolute coordinates.
+public protocol Shape: Animatable, View {
+    /// Describes this shape as a path within a rectangular frame of reference.
+    ///
+    /// - Parameter rect: The frame of reference for describing this shape.
+    ///
+    /// - Returns: A path that describes this shape.
+    func path(in rect: CGRect) -> Path
+
+    #if OPENSWIFTUI_SUPPORT_2021_API
+    /// An indication of how to style a shape.
+    ///
+    /// OpenSwiftUI looks at a shape's role when deciding how to apply a
+    /// ``ShapeStyle`` at render time. The ``Shape`` protocol provides a
+    /// default implementation with a value of ``ShapeRole/fill``. If you
+    /// create a composite shape, you can provide an override of this property
+    /// to return another value, if appropriate.
+    static var role: ShapeRole { get }
+    #endif
+}
+
+extension Shape {
+    public var body: _ShapeView<Self, ForegroundStyle> {
+        _ShapeView(shape: self, style: ForegroundStyle())
+    }
+}
+
+#if OPENSWIFTUI_SUPPORT_2021_API
+
+extension Shape {
+    public static var role: ShapeRole {
+        .fill
+    }
+}
+#endif

Sources/OpenSwiftUI/View/Shape/ShapeRole.swift

@@ -0,0 +1,27 @@
+//
+//  ShapeRole.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: Complete
+
+#if OPENSWIFTUI_SUPPORT_2021_API
+
+/// Ways of styling a shape.
+public enum ShapeRole: Sendable {
+    /// Indicates to the shape's style that SwiftUI fills the shape.
+    case fill
+
+    /// Indicates to the shape's style that SwiftUI applies a stroke to
+    /// the shape's path.
+    case stroke
+
+    /// Indicates to the shape's style that SwiftUI uses the shape as a
+    /// separator.
+    case separator
+}
+
+extension ShapeRole: Equatable {}
+extension ShapeRole: Hashable {}
+
+#endif

Sources/OpenSwiftUI/View/Shape/ShapeStyle.swift

@@ -0,0 +1,38 @@
+public protocol ShapeStyle {
+  @available(*, deprecated, message: "obsolete")
+  static func _makeView<S>(view: _GraphValue<_ShapeView<S, Self>>, inputs: _ViewInputs) -> _ViewOutputs where S : Shape
+
+    #if OPENSWIFTUI_SUPPORT_2021_API
+    func _apply(to shape: inout _ShapeStyle_Shape)
+
+    static func _apply(to type: inout _ShapeStyle_ShapeType)
+    #endif
+}
+
+
+#if OPENSWIFTUI_SUPPORT_2021_API
+
+public struct _ShapeStyle_Shape {
+    // TODO
+}
+
+public struct _ShapeStyle_ShapeType {
+    // TODO
+}
+
+extension ShapeStyle {
+    public static func _makeView<S>(view: _GraphValue<_ShapeView<S, Self>>, inputs: _ViewInputs) -> _ViewOutputs where S: Shape {
+        fatalError("TODO")
+    }
+
+    public func _apply(to shape: inout _ShapeStyle_Shape) {
+        fatalError("TODO")
+    }
+
+    public static func _apply(to type: inout _ShapeStyle_ShapeType) {
+        fatalError("TODO")
+    }
+}
+
+
+#endif

Sources/OpenSwiftUI/View/Shape/ShapeView.swift

@@ -0,0 +1,20 @@
+@frozen
+public struct _ShapeView<Content, Style>: PrimitiveView where Content : Shape, Style: ShapeStyle {
+    public var shape: Content
+    public var style: Style
+    public var fillStyle: FillStyle
+
+    @inlinable
+    public init(shape: Content, style: Style, fillStyle: FillStyle = FillStyle()) {
+        self.shape = shape
+        self.style = style
+        self.fillStyle = fillStyle
+    }
+
+
+    public static func _makeView(view: _GraphValue<_ShapeView<Content, Style>>, inputs: _ViewInputs) -> _ViewOutputs {
+        fatalError("TODO")
+    }
+
+    public typealias Body = Never
+}