Fix Semantics.forced crash issue and add test case

Sources/OpenSwiftUI/Core/Semantic/Semantics.swift

@@ -18,7 +18,7 @@ struct Semantics: CustomStringConvertible, Comparable, Hashable {
 
     var value: UInt32
 
-    static let forced: Semantics? = {
+    static var forced: Semantics? = {
         if dyld_program_sdk_at_least(.init(semantics: firstRelease)) {
             return nil
         } else {
@@ -38,7 +38,10 @@ struct Semantics: CustomStringConvertible, Comparable, Hashable {
 extension dyld_build_version_t {
     @inline(__always)
     init(_ value: UInt64) {
-        self.init(platform: dyld_platform_t(value), version: UInt32(value >> 32))
+        self.init(
+            platform: dyld_platform_t(value & 0xFFFF_FFFF),
+            version: UInt32((value >> 32) & 0xFFFF_FFFF)
+        )
     }
 
     @inline(__always)

Tests/OpenSwiftUITests/Core/Semantics/FeatureTests.swift

@@ -0,0 +1,22 @@
+//
+//  FeatureTests.swift
+//  OpenSwiftUITests
+
+@testable import OpenSwiftUI
+import Testing
+
+struct FeatureTests {
+    @Test
+    func defaultValue() {
+        struct Feature1: Feature {
+            static var isEnable: Bool { false }
+        }
+
+        struct Feature2: Feature {
+            static var isEnable: Bool { true }
+        }
+
+        #expect(Feature1.defaultValue == false)
+        #expect(Feature2.defaultValue == true)
+    }
+}

Tests/OpenSwiftUITests/Core/Semantics/SemanticFeatureTests.swift

@@ -0,0 +1,57 @@
+//
+//  SemanticFeatureTests.swift
+//  OpenSwiftUITests
+
+@testable import OpenSwiftUI
+import Testing
+
+struct SemanticFeatureTests {
+    /// Represent a minimum version
+    struct SemanticFeature1: SemanticFeature {
+        static var introduced: Semantics { .init(value: 0x0000_0000) }
+    }
+
+    /// Represent a middle version
+    struct SemanticFeature2: SemanticFeature {
+        static var introduced: Semantics { .init(value: 0xFFFF_0000) }
+    }
+
+    /// Represent a maximum version
+    struct SemanticFeature3: SemanticFeature {
+        static var introduced: Semantics { .init(value: 0xFFFF_FFFF) }
+    }
+
+    @Test
+    func defaultEnable() async throws {
+        #expect(Semantics.forced == nil)
+        #if canImport(Darwin)
+        #expect(SemanticFeature1.isEnable == true)
+        #expect(SemanticFeature2.isEnable == false)
+        #expect(SemanticFeature3.isEnable == false)
+        #else
+        #expect(SemanticFeature1.isEnable == true)
+        #expect(SemanticFeature2.isEnable == true)
+        #expect(SemanticFeature3.isEnable == true)
+        #endif
+    }
+
+    @Test
+    func changeForceEnable() async throws {
+        do {
+            let oldValue = Semantics.forced
+            Semantics.forced = SemanticFeature2.introduced
+            defer { Semantics.forced = oldValue }
+            #expect(SemanticFeature1.isEnable == true)
+            #expect(SemanticFeature2.isEnable == true)
+            #expect(SemanticFeature3.isEnable == false)
+        }
+        do {
+            let oldValue = Semantics.forced
+            Semantics.forced = SemanticFeature3.introduced
+            defer { Semantics.forced = oldValue }
+            #expect(SemanticFeature1.isEnable == true)
+            #expect(SemanticFeature2.isEnable == true)
+            #expect(SemanticFeature3.isEnable == true)
+        }
+    }
+}

Tests/OpenSwiftUITests/Core/Semantics/SemanticsTests.swift

@@ -0,0 +1,26 @@
+//
+//  SemanticsTests.swift
+//  OpenSwiftUITests
+
+@testable import OpenSwiftUI
+import Testing
+
+struct SemanticsTests {
+    @Test
+    func forced() {
+        #if canImport(Darwin)
+        if #available(iOS 13, macOS 10.15, *) {
+            #expect(Semantics.forced == nil)
+        } else {
+            #expect(Semantics.forced != nil)
+        }
+        #else
+        #expect(Semantics.forced == nil)
+        #endif
+    }
+
+    @Test
+    func compare() {
+        #expect(Semantics.v1 < Semantics.v2)
+    }
+}