feat: Update package.json to 1.6.1

Fix indent

.github/ISSUE_TEMPLATE/feature-request.yaml

@@ -12,6 +12,6 @@ body:
   - type: textarea
     id: feature-description
     attributes:
-      label: Feature destription
+      label: Feature description
     validations:
-      required: true
+      required: true

.github/ISSUE_TEMPLATE/improvement-request.yaml

@@ -12,6 +12,6 @@ body:
   - type: textarea
     id: improvement-description
     attributes:
-      label: Improvement destription
+      label: Improvement description
     validations:
-      required: true
+      required: true

.github/workflows/package.yaml

@@ -14,7 +14,7 @@ jobs:
     steps:
       # Checkout
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           lfs: true
 
@@ -39,7 +39,7 @@ jobs:
 
       # Upload
       - name: Upload .unitypackage
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: Unity Package
           path: Build

.github/workflows/release.yaml

@@ -18,7 +18,7 @@ jobs:
     outputs:
       sha: ${{ steps.commit.outputs.sha }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Output package.json (Before)
         run: cat ${{ env.TARGET_FILE}}
 
@@ -69,7 +69,7 @@ jobs:
     timeout-minutes: 15
     steps:
       - run: echo ${{ needs.update-packagejson.outputs.sha }}
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{ needs.update-packagejson.outputs.sha }}
 
@@ -97,7 +97,7 @@ jobs:
         working-directory: .
 
       # Store artifacts.
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: SerializeReference-Extensions.unitypackage
           path: ./Build/SerializeReference-Extensions.unitypackage
@@ -119,7 +119,7 @@ jobs:
           prerelease: false
 
       # Download(All) Artifacts to current directory
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
       
       # Upload to Releases(unitypackage)
       - uses: actions/upload-release-asset@v1

Assets/Example/Example.cs

@@ -1,4 +1,3 @@
-#if UNITY_2019_3_OR_NEWER
 using System.Collections.Generic;
 using System;
 using UnityEditor;
@@ -42,6 +41,17 @@ public class Grape : Food
 	}
 }
 
+[Serializable]
+[HideInTypeMenu]
+public class Banana : Food
+{
+	public Banana ()
+	{
+		name = "Banana";
+		kcal = 100f;
+	}
+}
+
 public class Example : MonoBehaviour
 {
 
@@ -60,7 +70,8 @@ public class Example : MonoBehaviour
 	[SerializeReference, SubclassSelector]
 	public Food foodTwo = new Peach();
 
-	[SerializeReference, SubclassSelector]
+	// UseToStringAsLabel support on UNITY_2021_3_OR_NEWER
+	[SerializeReference, SubclassSelector(UseToStringAsLabel = true)]
 	public Food foodThree = new Grape();
 
 	[SerializeReference]
@@ -115,6 +126,4 @@ public class AppleDrawer : PropertyDrawer
 		return EditorGUIUtility.singleLineHeight;
 	}
 }
-#endif
-
 #endif

Assets/Example/Example.unity

@@ -13,7 +13,7 @@ OcclusionCullingSettings:
 --- !u!104 &2
 RenderSettings:
   m_ObjectHideFlags: 0
-  serializedVersion: 9
+  serializedVersion: 10
   m_Fog: 0
   m_FogColor: {r: 0.5, g: 0.5, b: 0.5, a: 1}
   m_FogMode: 3
@@ -38,13 +38,12 @@ RenderSettings:
   m_ReflectionIntensity: 1
   m_CustomReflection: {fileID: 0}
   m_Sun: {fileID: 0}
-  m_IndirectSpecularColor: {r: 0.44657898, g: 0.4964133, b: 0.5748178, a: 1}
+  m_IndirectSpecularColor: {r: 0, g: 0, b: 0, a: 1}
   m_UseRadianceAmbientProbe: 0
 --- !u!157 &3
 LightmapSettings:
   m_ObjectHideFlags: 0
   serializedVersion: 12
-  m_GIWorkflowMode: 1
   m_GISettings:
     serializedVersion: 2
     m_BounceScale: 1
@@ -67,9 +66,6 @@ LightmapSettings:
     m_LightmapParameters: {fileID: 0}
     m_LightmapsBakeMode: 1
     m_TextureCompression: 1
-    m_FinalGather: 0
-    m_FinalGatherFiltering: 1
-    m_FinalGatherRayCount: 256
     m_ReflectionCompression: 2
     m_MixedBakeMode: 2
     m_BakeBackend: 1
@@ -104,7 +100,7 @@ NavMeshSettings:
   serializedVersion: 2
   m_ObjectHideFlags: 0
   m_BuildSettings:
-    serializedVersion: 2
+    serializedVersion: 3
     agentTypeID: 0
     agentRadius: 0.5
     agentHeight: 2
@@ -117,7 +113,7 @@ NavMeshSettings:
     cellSize: 0.16666667
     manualTileSize: 0
     tileSize: 256
-    accuratePlacement: 0
+    buildHeightMesh: 0
     maxJobWorkers: 0
     preserveTilesOutsideBounds: 0
     debug:
@@ -163,9 +159,17 @@ Camera:
   m_projectionMatrixMode: 1
   m_GateFitMode: 2
   m_FOVAxisMode: 0
+  m_Iso: 200
+  m_ShutterSpeed: 0.005
+  m_Aperture: 16
+  m_FocusDistance: 10
+  m_FocalLength: 50
+  m_BladeCount: 5
+  m_Curvature: {x: 2, y: 11}
+  m_BarrelClipping: 0.25
+  m_Anamorphism: 0
   m_SensorSize: {x: 36, y: 24}
   m_LensShift: {x: 0, y: 0}
-  m_FocalLength: 50
   m_NormalizedViewPortRect:
     serializedVersion: 2
     x: 0
@@ -199,13 +203,13 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 126803971}
+  serializedVersion: 2
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
   m_LocalPosition: {x: 0, y: 1, z: -10}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 0
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
 --- !u!1 &586792171
 GameObject:
@@ -326,13 +330,70 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 586792171}
+  serializedVersion: 2
+  m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
+  m_LocalPosition: {x: 0, y: 0, z: 0}
+  m_LocalScale: {x: 1, y: 1, z: 1}
+  m_ConstrainProportionsScale: 0
+  m_Children: []
+  m_Father: {fileID: 0}
+  m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!1 &994260143
+GameObject:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  serializedVersion: 6
+  m_Component:
+  - component: {fileID: 994260145}
+  - component: {fileID: 994260144}
+  m_Layer: 0
+  m_Name: Example_Generics
+  m_TagString: Untagged
+  m_Icon: {fileID: 0}
+  m_NavMeshLayer: 0
+  m_StaticEditorFlags: 0
+  m_IsActive: 1
+--- !u!114 &994260144
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 994260143}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: dff76005e1dfac84287448b12c4b160e, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  contravarianceActions:
+  - rid: 3354424774140624943
+  covarianceActions:
+  - rid: 3354424774140624944
+  references:
+    version: 2
+    RefIds:
+    - rid: 3354424774140624943
+      type: {class: DerivedAction1, ns: , asm: Assembly-CSharp}
+      data: 
+    - rid: 3354424774140624944
+      type: {class: NetworkActorAction1, ns: , asm: Assembly-CSharp}
+      data: 
+--- !u!4 &994260145
+Transform:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 994260143}
+  serializedVersion: 2
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
   m_LocalPosition: {x: 0, y: 0, z: 0}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 2
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
 --- !u!1 &1127138992
 GameObject:
@@ -359,9 +420,8 @@ Light:
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1127138992}
   m_Enabled: 1
-  serializedVersion: 10
+  serializedVersion: 11
   m_Type: 1
-  m_Shape: 0
   m_Color: {r: 1, g: 0.95686275, b: 0.8392157, a: 1}
   m_Intensity: 1
   m_Range: 10
@@ -420,11 +480,19 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1127138992}
+  serializedVersion: 2
   m_LocalRotation: {x: 0.40821788, y: -0.23456968, z: 0.10938163, w: 0.8754261}
   m_LocalPosition: {x: 0, y: 3, z: 0}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 1
   m_LocalEulerAnglesHint: {x: 50, y: -30, z: 0}
+--- !u!1660057539 &9223372036854775807
+SceneRoots:
+  m_ObjectHideFlags: 0
+  m_Roots:
+  - {fileID: 126803974}
+  - {fileID: 1127138994}
+  - {fileID: 586792173}
+  - {fileID: 994260145}

Assets/Example/Example_Generics.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+public interface IActor { }
+public interface IStandardActor : IActor { }
+public interface INetworkActor : IActor { }
+
+public interface IContravarianceAction<in T> where T : IActor {
+	void DoAction (T actor);
+}
+
+public interface ICovarianceAction<out T> where T : IActor
+{
+	T Actor { get; }
+}
+
+public interface IActorAction : IContravarianceAction<IActor>, ICovarianceAction<IActor> { }
+public interface IStandardActorAction : IContravarianceAction<IStandardActor>, ICovarianceAction<IStandardActor> { }
+public interface INetworkActorAction : IContravarianceAction<INetworkActor>, ICovarianceAction<INetworkActor> { }
+
+[Serializable]
+public sealed class StandardActorAction : IContravarianceAction<IStandardActor>, ICovarianceAction<IStandardActor>
+{
+	public void DoAction (IStandardActor actor)
+	{
+	}
+	public IStandardActor Actor => null;
+}
+
+[Serializable]
+public sealed class ActorAction : IContravarianceAction<IActor>, ICovarianceAction<IActor>
+{
+	public void DoAction (IActor actor)
+	{
+	}
+	public IActor Actor => null;
+}
+
+[Serializable]
+public abstract class BaseAction<T> : IContravarianceAction<T>, ICovarianceAction<T> where T : IActor
+{
+	public void DoAction (T actor) {
+	}
+	public T Actor => default;
+}
+
+[Serializable]
+public sealed class DerivedAction1 : BaseAction<IActor> { }
+
+[Serializable]
+public sealed class DerivedAction2 : BaseAction<INetworkActor> { }
+
+[Serializable]
+public sealed class DerivedAction3 : BaseAction<IStandardActor> { }
+
+[Serializable]
+public sealed class NetworkActorAction1 : INetworkActorAction
+{
+	public void DoAction (INetworkActor actor)
+	{
+	}
+	public INetworkActor Actor => null;
+}
+
+[Serializable]
+public sealed class NetworkActorAction2 : IContravarianceAction<INetworkActor>, ICovarianceAction<INetworkActor>
+{
+	public void DoAction (INetworkActor actor)
+	{
+	}
+	public INetworkActor Actor => null;
+}
+
+[Serializable]
+public sealed class NetworkActorAction3 : IContravarianceAction<IActor>, ICovarianceAction<IActor>
+{
+	public void DoAction (IActor actor)
+	{
+	}
+	public IActor Actor => null;
+}
+
+public class Example_Generics : MonoBehaviour
+{
+
+	[SerializeReference, SubclassSelector]
+	public List<IContravarianceAction<INetworkActor>> contravarianceActions = new List<IContravarianceAction<INetworkActor>>();
+
+	[SerializeReference, SubclassSelector]
+	public List<ICovarianceAction<INetworkActor>> covarianceActions = new List<ICovarianceAction<INetworkActor>>();
+
+}

Assets/Example/Example_Generics.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: dff76005e1dfac84287448b12c4b160e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/AdvancedTypePopup.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -137,5 +136,4 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 		}
 
 	}
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/MackySoft.SerializeReferenceExtensions.Editor.asmdef

@@ -12,9 +12,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
-        "UNITY_2019_3_OR_NEWER"
-    ],
+    "defineConstraints": [],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/ManagedReferenceUtility.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using System.Reflection;
 using UnityEditor;
 using UnityEngine;
@@ -44,5 +43,4 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 		}
 
 	}
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/PropertyDrawerCache.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using System.Collections.Generic;
 using UnityEditor;
 using System.Reflection;
@@ -78,5 +77,4 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 		}
 
 	}
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SerializedPropertyExtensions.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-using System.Collections.Generic;
+using System.Collections.Generic;
 using UnityEditor;
 
 namespace MackySoft.SerializeReferenceExtensions.Editor
@@ -27,5 +26,4 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 			}
 		}
 	}
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SubclassSelectorDrawer.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -22,7 +21,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 		}
 
 		const int k_MaxTypePopupLineCount = 13;
-		static readonly Type k_UnityObjectType = typeof(UnityEngine.Object);
+		
 		static readonly GUIContent k_NullDisplayName = new GUIContent(TypeMenuUtility.k_NullDisplayName);
 		static readonly GUIContent k_IsNotManagedReferenceLabel = new GUIContent("The property type is not manage reference.");
 
@@ -40,9 +39,24 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 				// Render label first to avoid label overlap for lists
 				Rect foldoutLabelRect = new Rect(position);
 				foldoutLabelRect.height = EditorGUIUtility.singleLineHeight;
-				foldoutLabelRect = EditorGUI.IndentedRect(foldoutLabelRect);
+
+				// NOTE: IndentedRect should be disabled as it causes extra indentation.
+				//foldoutLabelRect = EditorGUI.IndentedRect(foldoutLabelRect);
 				Rect popupPosition = EditorGUI.PrefixLabel(foldoutLabelRect, label);
 
+#if UNITY_2021_3_OR_NEWER
+				// Override the label text with the ToString() of the managed reference.
+				var subclassSelectorAttribute = (SubclassSelectorAttribute)attribute;
+				if (subclassSelectorAttribute.UseToStringAsLabel && !property.hasMultipleDifferentValues)
+				{
+					object managedReferenceValue = property.managedReferenceValue;
+					if (managedReferenceValue != null)
+					{
+						label.text = managedReferenceValue.ToString();
+					}
+				}
+#endif
+
 				// Draw the subclass selector popup.
 				if (EditorGUI.DropdownButton(popupPosition, GetTypeName(property), FocusType.Keyboard))
 				{
@@ -57,9 +71,17 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 					Rect foldoutRect = new Rect(position);
 					foldoutRect.height = EditorGUIUtility.singleLineHeight;
 
-#if UNITY_2022_2_OR_NEWER
+#if UNITY_2022_2_OR_NEWER && !UNITY_6000_0_OR_NEWER
 					// NOTE: Position x must be adjusted.
 					// FIXME: Is there a more essential solution...?
+					// The most promising is UI Toolkit, but it is currently unable to reproduce all of SubclassSelector features. (Complete provision of contextual menu, e.g.)
+					// 2021.3: No adjustment
+					// 2022.1: No adjustment
+					// 2022.2: Adjustment required
+					// 2022.3: Adjustment required
+					// 2023.1: Adjustment required
+					// 2023.2: Adjustment required
+					// 6000.0: No adjustment
 					foldoutRect.x -= 12;
 #endif
 
@@ -129,13 +151,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 				Type baseType = ManagedReferenceUtility.GetType(managedReferenceFieldTypename);
 				var popup = new AdvancedTypePopup(
-					TypeCache.GetTypesDerivedFrom(baseType).Append(baseType).Where(p =>
-						(p.IsPublic || p.IsNestedPublic) &&
-						!p.IsAbstract &&
-						!p.IsGenericType &&
-						!k_UnityObjectType.IsAssignableFrom(p) &&
-						Attribute.IsDefined(p,typeof(SerializableAttribute))
-					),
+					TypeSearch.GetTypes(baseType),
 					k_MaxTypePopupLineCount,
 					state
 				);
@@ -205,4 +221,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeMenuUtility.cs

@@ -1,9 +1,10 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
+using UnityEditor;
 
-namespace MackySoft.SerializeReferenceExtensions.Editor {
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
 	public static class TypeMenuUtility {
 
 		public const string k_NullDisplayName = "<null>";
@@ -41,5 +42,4 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 		}
 
 	}
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeSearch.cs

@@ -0,0 +1,142 @@
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using UnityEditor;
+using System.Reflection;
+
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+	public static class TypeSearch
+	{
+
+#if UNITY_2023_2_OR_NEWER
+		static readonly Dictionary<Type, List<Type>> m_TypeCache = new Dictionary<Type, List<Type>>();
+#endif
+
+		public static IEnumerable<Type> GetTypes (Type baseType)
+		{
+#if UNITY_2023_2_OR_NEWER
+			// NOTE: This is a generics solution for Unity 2023.2 and later.
+			// 2023.2 because SerializeReference supports generic type instances and because the behaviour is stable.
+			if (baseType.IsGenericType)
+			{
+				return GetTypesWithGeneric(baseType);
+			}
+			else
+			{
+				return GetTypesUsingTypeCache(baseType);
+			}
+#else
+			return GetTypesUsingTypeCache(baseType);
+#endif
+		}
+
+		static IEnumerable<Type> GetTypesUsingTypeCache (Type baseType)
+		{
+			return TypeCache.GetTypesDerivedFrom(baseType)
+				.Append(baseType)
+				.Where(IsValidType);
+		}
+
+#if UNITY_2023_2_OR_NEWER
+		static IEnumerable<Type> GetTypesWithGeneric (Type baseType)
+		{
+			if (m_TypeCache.TryGetValue(baseType, out List<Type> result))
+			{
+				return result;
+			}
+
+			result = new List<Type>();
+			Type genericTypeDefinition = null;
+			Type[] targetTypeArguments = null;
+			Type[] genericTypeParameters = null;
+
+			if (baseType.IsGenericType)
+			{
+				genericTypeDefinition = baseType.GetGenericTypeDefinition();
+				targetTypeArguments = baseType.GetGenericArguments();
+				genericTypeParameters = genericTypeDefinition.GetGenericArguments();
+			}
+			else
+			{
+				genericTypeDefinition = baseType;
+				targetTypeArguments = Type.EmptyTypes;
+				genericTypeParameters = Type.EmptyTypes;
+			}
+
+			IEnumerable<Type> types = AppDomain.CurrentDomain.GetAssemblies()
+				.SelectMany(x => x.GetTypes())
+				.Where(IsValidType);
+
+			foreach (Type type in types)
+			{
+				Type[] interfaceTypes = type.GetInterfaces();
+				foreach (Type interfaceType in interfaceTypes)
+				{
+					if (!interfaceType.IsGenericType || interfaceType.GetGenericTypeDefinition() != genericTypeDefinition)
+					{
+						continue;
+					}
+
+					Type[] sourceTypeArguments = interfaceType.GetGenericArguments();
+
+					bool allParametersMatch = true;
+
+					for (int i = 0; i < genericTypeParameters.Length; i++)
+					{
+						var variance = genericTypeParameters[i].GenericParameterAttributes & GenericParameterAttributes.VarianceMask;
+
+						Type sourceTypeArgument = sourceTypeArguments[i];
+						Type targetTypeArgument = targetTypeArguments[i];
+
+						if (variance == GenericParameterAttributes.Contravariant)
+						{
+							if (!sourceTypeArgument.IsAssignableFrom(targetTypeArgument))
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+						else if (variance == GenericParameterAttributes.Covariant)
+						{
+							if (!targetTypeArgument.IsAssignableFrom(sourceTypeArgument))
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+						else
+						{
+							if (sourceTypeArgument != targetTypeArgument)
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+					}
+
+					if (allParametersMatch)
+					{
+						result.Add(type);
+						break;
+					}
+				}
+			}
+
+			m_TypeCache.Add(baseType, result);
+			return result;
+		}
+#endif
+
+		static bool IsValidType (Type type)
+		{
+			return
+				(type.IsPublic || type.IsNestedPublic || type.IsNestedPrivate) &&
+				!type.IsAbstract &&
+				!type.IsGenericType &&
+				!typeof(UnityEngine.Object).IsAssignableFrom(type) &&
+				Attribute.IsDefined(type, typeof(SerializableAttribute)) &&
+				!Attribute.IsDefined(type, typeof(HideInTypeMenuAttribute));
+		}
+	}
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeSearch.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 5ea24172520aa2646954c1d246e7ba5d

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/AddTypeMenuAttribute.cs

@@ -1,6 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
-
-using System;
+using System;
 	
 /// <summary>
 /// An attribute that overrides the name of the type displayed in the SubclassSelector popup.
@@ -34,5 +32,4 @@ public sealed class AddTypeMenuAttribute : Attribute {
 		return (splittedDisplayName.Length != 0) ? splittedDisplayName[splittedDisplayName.Length - 1] : null;
 	}
 
-}
-#endif
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs

@@ -0,0 +1,9 @@
+using System;
+
+/// <summary>
+/// An attribute that hides the type in the SubclassSelector.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+public sealed class HideInTypeMenuAttribute : Attribute {
+
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 9f48f5d86a108b94a9c26381f5ce678c
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/MackySoft.SerializeReferenceExtensions.asmdef

@@ -8,9 +8,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
-        "UNITY_2019_3_OR_NEWER"
-    ],
+    "defineConstraints": [],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/SubclassSelectorAttribute.cs

@@ -1,12 +1,16 @@
-#if UNITY_2019_3_OR_NEWER
-using System;
+using System;
 using UnityEngine;
 
 /// <summary>
 /// Attribute to specify the type of the field serialized by the SerializeReference attribute in the inspector.
 /// </summary>
-[AttributeUsage(AttributeTargets.Field,AllowMultiple = false)]
-public sealed class SubclassSelectorAttribute : PropertyAttribute {
-	
-}
-#endif
+[AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
+public sealed class SubclassSelectorAttribute : PropertyAttribute
+{
+
+#if UNITY_2021_3_OR_NEWER
+	// NOTE: Use managedReferenceValue getter to invoke instance method in SubclassSelectorDrawer.
+	public bool UseToStringAsLabel { get; set; }
+#endif
+
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/package.json

@@ -2,7 +2,7 @@
 	"name": "com.mackysoft.serializereference-extensions",
 	"displayName": "SerializeReference Extensions",
 	"author": { "name": "MackySoft", "url": "https://github.com/mackysoft" },
-	"version": "1.3.1",
+	"version": "1.6.1",
 	"unity": "2021.3",
 	"description": "Provide popup to specify the type of the field serialized by the [SerializeReference] attribute in the inspector.",
 	"keywords": [ "SerializeReference", "Editor" ],

README.md

@@ -19,6 +19,7 @@ The `SubclassSelector` attribute allows you to easily set subclasses of those ab
 - **[New]** Restore values of previous object from JSON when subclass is changed. (required Unity 2021.3 or later)
 - **[New]** Copy & Paste the subclass properties. (required Unity 2021.3 or later)
 - **[New]** Clear & reset the subclass properties. (required Unity 2021.3 or later)
+- **[New]** Covariance / Contravariance support. (required Unity 2023.2 or later)
 
 > See below for the reason for the limitation of versions less than Unity 2021.3.
 > 
@@ -139,7 +140,7 @@ public struct StructCommand : ICommand {
 
 The `SubclassSelector` attribute supports types that meet the following conditions.
 
-- Public
+- Public or nested private
 - Not abstract
 - Not generic
 - Not unity object