Update Plugin classes to fix static usages (ISX-1840)

- Add a flag to guard against re-initializing Plugins within PerformDefaultPluginInitialization()
- Refactor SteamSupport to fix Init/Shutdown flows and improve state management
- Refactor PlayerInput's static fields into a single GlobalState struct (matching other classes)
- Move EnhancedTouch static fields into Touch's GlobalState struct
- Minor refactoring of SteamSupport to improve init/cleanp-up flows (especially with tests)

Author: timkeo

Assets/Tests/InputSystem/Plugins/SteamTests.cs

@@ -36,13 +36,7 @@ public override void Setup()
     public override void TearDown()
     {
         base.TearDown();
-        m_SteamAPI = null;
-
-        SteamSupport.s_API = null;
-        SteamSupport.s_InputDevices = null;
-        SteamSupport.s_ConnectedControllers = null;
-        SteamSupport.s_InputDeviceCount = 0;
-        SteamSupport.s_HooksInstalled = false;
+        SteamSupport.Shutdown();
     }
 
     [Test]

Packages/com.unity.inputsystem/InputSystem/InputSystem.cs

@@ -3802,8 +3802,24 @@ private static void RunInitialUpdate()
         }
 
 #if !UNITY_DISABLE_DEFAULT_INPUT_PLUGIN_INITIALIZATION
+
+        #if UNITY_EDITOR
+        // Plug-ins must only be initialized once, since many of them use static fields.
+        // When Domain Reloads are disabled, we must guard against this method being called a second time.
+        private static bool s_PluginsInitialized = false;
+        #endif
+
         internal static void PerformDefaultPluginInitialization()
         {
+            #if UNITY_EDITOR
+            if (s_PluginsInitialized)
+            {
+                Debug.Assert(false, "Attempted to re-initialize InputSystem Plugins!");
+                return;
+            }
+            s_PluginsInitialized = true;
+            #endif
+
             UISupport.Initialize();
 
             #if UNITY_EDITOR || UNITY_STANDALONE || UNITY_WSA || UNITY_ANDROID || UNITY_IOS || UNITY_TVOS || UNITY_VISIONOS

Packages/com.unity.inputsystem/InputSystem/InputSystemTestHooks.cs

@@ -28,6 +28,8 @@ internal static void TestHook_InitializeForPlayModeTests(bool enableRemoting, II
                 InputSystem.SetUpRemoting();
 
 #if !UNITY_DISABLE_DEFAULT_INPUT_PLUGIN_INITIALIZATION
+            // Reset the flag so can re-initialize Plugins between tests.
+            InputSystem.s_PluginsInitialized = false;
             InputSystem.PerformDefaultPluginInitialization();
 #endif
         }
@@ -42,6 +44,7 @@ internal static void TestHook_SimulateDomainReload(IInputRuntime runtime)
             InputSystem.s_DomainStateManager.OnBeforeSerialize();
             InputSystem.s_DomainStateManager = null;
             InputSystem.s_Manager = null; // Do NOT Dispose()! The native memory cannot be freed as it's reference by saved state
+            InputSystem.s_PluginsInitialized = false;
             InputSystem.InitializeInEditor(true, runtime);
         }
 #endif // UNITY_EDITOR

Packages/com.unity.inputsystem/InputSystem/Plugins/DualShock/DualShockGamepadHID.cs

@@ -675,8 +675,8 @@ public DualSenseHIDInputReport ToHIDInputReport()
         [StructLayout(LayoutKind.Explicit)]
         internal struct DualSenseHIDMinimalInputReport
         {
-            public static int ExpectedSize1 = 10;
-            public static int ExpectedSize2 = 78;
+            public const int ExpectedSize1 = 10;
+            public const int ExpectedSize2 = 78;
 
             [FieldOffset(0)] public byte reportId;
             [FieldOffset(1)] public byte leftStickX;

Packages/com.unity.inputsystem/InputSystem/Plugins/EnhancedTouch/EnhancedTouchSupport.cs

@@ -63,10 +63,7 @@ public static class EnhancedTouchSupport
         /// Whether enhanced touch support is currently enabled.
         /// </summary>
         /// <value>True if EnhancedTouch support has been enabled.</value>
-        public static bool enabled => s_Enabled > 0;
-
-        private static int s_Enabled;
-        private static InputSettings.UpdateMode s_UpdateMode;
+        public static bool enabled => Touch.s_GlobalState.enhancedTouchEnabled > 0;
 
         /// <summary>
         /// Enable enhanced touch support.
@@ -82,8 +79,8 @@ public static class EnhancedTouchSupport
         /// </remarks>
         public static void Enable()
         {
-            ++s_Enabled;
-            if (s_Enabled > 1)
+            ++Touch.s_GlobalState.enhancedTouchEnabled;
+            if (Touch.s_GlobalState.enhancedTouchEnabled > 1)
                 return;
 
             InputSystem.onDeviceChange += OnDeviceChange;
@@ -107,8 +104,8 @@ public static void Disable()
         {
             if (!enabled)
                 return;
-            --s_Enabled;
-            if (s_Enabled > 0)
+            --Touch.s_GlobalState.enhancedTouchEnabled;
+            if (Touch.s_GlobalState.enhancedTouchEnabled > 0)
                 return;
 
             InputSystem.onDeviceChange -= OnDeviceChange;
@@ -131,7 +128,7 @@ internal static void Reset()
             Touch.s_GlobalState.editorState.Destroy();
             Touch.s_GlobalState.editorState = default;
             #endif
-            s_Enabled = 0;
+            Touch.s_GlobalState.enhancedTouchEnabled = 0;
         }
 
         private static void SetUpState()
@@ -141,7 +138,7 @@ private static void SetUpState()
             Touch.s_GlobalState.editorState.updateMask = InputUpdateType.Editor;
             #endif
 
-            s_UpdateMode = InputSystem.settings.updateMode;
+            Touch.s_GlobalState.enhancedTouchUpdateMode = InputSystem.settings.updateMode;
 
             foreach (var device in InputSystem.devices)
                 OnDeviceChange(device, InputDeviceChange.Added);
@@ -186,7 +183,7 @@ private static void OnDeviceChange(InputDevice device, InputDeviceChange change)
         private static void OnSettingsChange()
         {
             var currentUpdateMode = InputSystem.settings.updateMode;
-            if (s_UpdateMode == currentUpdateMode)
+            if (Touch.s_GlobalState.enhancedTouchUpdateMode == currentUpdateMode)
                 return;
             TearDownState();
             SetUpState();

Packages/com.unity.inputsystem/InputSystem/Plugins/EnhancedTouch/Touch.cs

@@ -587,6 +587,10 @@ internal struct GlobalState
             internal CallbackArray<Action<Finger>> onFingerMove;
             internal CallbackArray<Action<Finger>> onFingerUp;
 
+            // Used by EnhancedTouchSupport but placed here to consolidate static fields
+            internal int enhancedTouchEnabled;
+            internal InputSettings.UpdateMode enhancedTouchUpdateMode;
+
             internal FingerAndTouchState playerState;
 #if UNITY_EDITOR
             internal FingerAndTouchState editorState;