Add metadata update handler to System.ComponentModel.TypeConverter

src/libraries/System.ComponentModel.TypeConverter/src/System.ComponentModel.TypeConverter.csproj

@@ -70,6 +70,7 @@
     <Compile Include="System\ComponentModel\MemberDescriptor.cs" />
     <Compile Include="System\ComponentModel\PropertyDescriptorCollection.cs" />
     <Compile Include="System\ComponentModel\ProvidePropertyAttribute.cs" />
+    <Compile Include="System\ComponentModel\ReflectionCachesUpdateHandler.cs" />
     <Compile Include="System\ComponentModel\ReflectEventDescriptor.cs" />
     <Compile Include="System\ComponentModel\ReflectPropertyDescriptor.cs" />
     <Compile Include="System\ComponentModel\ReflectTypeDescriptionProvider.cs" />
@@ -253,6 +254,7 @@
     <Reference Include="System.Runtime" />
     <Reference Include="System.Runtime.Extensions" />
     <Reference Include="System.Runtime.InteropServices" />
+    <Reference Include="System.Runtime.Loader" />
     <Reference Include="System.Runtime.Serialization.Formatters" />
     <Reference Include="System.Text.RegularExpressions" />
     <Reference Include="System.Threading" />

src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/ReflectTypeDescriptionProvider.cs

@@ -204,6 +204,15 @@ private static EnumConverter CreateEnumConverter(Type type)
 
         private static Hashtable ExtendedPropertyCache => LazyInitializer.EnsureInitialized(ref s_extendedPropertyCache, () => new Hashtable());
 
+        /// <summary>Clear the global caches this maintains on top of reflection.</summary>
+        internal static void ClearReflectionCaches()
+        {
+            Volatile.Write(ref s_propertyCache, null);
+            Volatile.Write(ref s_eventCache, null);
+            Volatile.Write(ref s_attributeCache, null);
+            Volatile.Write(ref s_extendedPropertyCache, null);
+        }
+
         /// <summary>
         /// Adds an editor table for the given editor base type.
         /// Typically, editors are specified as metadata on an object. If no metadata for a

src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/ReflectionCachesUpdateHandler.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+using System.ComponentModel;
+using System.Reflection;
+using System.Reflection.Metadata;
+
+[assembly: MetadataUpdateHandler(typeof(ReflectionCachesUpdateHandler))]
+
+namespace System.ComponentModel
+{
+    internal static class ReflectionCachesUpdateHandler
+    {
+        public static void BeforeUpdate(Type[]? types)
+        {
+            // ReflectTypeDescriptionProvider maintains global caches on top of reflection.
+            // Clear those.
+            ReflectTypeDescriptionProvider.ClearReflectionCaches();
+
+            // Each type descriptor may also cache reflection-based state that it gathered
+            // from ReflectTypeDescriptionProvider.  Clear those as well.
+            if (types is not null)
+            {
+                foreach (Type type in types)
+                {
+                    TypeDescriptor.Refresh(type);
+                }
+            }
+            else
+            {
+                foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
+                {
+                    TypeDescriptor.Refresh(assembly);
+                }
+            }
+        }
+    }
+}

src/libraries/System.ComponentModel.TypeConverter/tests/ReflectionCachesUpdateHandlerTests.cs

@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Reflection;
+using Xunit;
+
+namespace System.ComponentModel.Tests
+{
+    [SimpleUpdateTest]
+    public class ReflectionCachesUpdateHandlerTests
+    {
+        [Fact]
+        public void ReflectionCachesUpdateHandler_CachesCleared()
+        {
+            AttributeCollection ac1 = TypeDescriptor.GetAttributes(typeof(ReflectionCachesUpdateHandlerTests));
+            AttributeCollection ac2 = TypeDescriptor.GetAttributes(typeof(ReflectionCachesUpdateHandlerTests));
+            Assert.Equal(ac1.Count, ac2.Count);
+            Assert.Equal(1, ac1.Count);
+            Assert.Same(ac1[0], ac2[0]);
+
+            MethodInfo beforeUpdate = typeof(TypeDescriptionProvider).Assembly.GetType("System.ComponentModel.ReflectionCachesUpdateHandler", throwOnError: true).GetMethod("BeforeUpdate");
+            Assert.NotNull(beforeUpdate);
+            beforeUpdate.Invoke(null, new object[] { null });
+
+            AttributeCollection ac3 = TypeDescriptor.GetAttributes(typeof(ReflectionCachesUpdateHandlerTests));
+            Assert.NotSame(ac1[0], ac3[0]);
+        }
+    }
+
+    [AttributeUsage(AttributeTargets.All)]
+    internal sealed class SimpleUpdateTestAttribute : Attribute { }
+}

src/libraries/System.ComponentModel.TypeConverter/tests/System.ComponentModel.TypeConverter.Tests.csproj

@@ -104,6 +104,7 @@
     <Compile Include="Mocks\MockServiceProvider.cs" />
     <Compile Include="MultilineStringConverterTests.cs" />
     <Compile Include="NullableConverterTests.cs" />
+    <Compile Include="ReflectionCachesUpdateHandlerTests.cs" />
     <Compile Include="PropertyDescriptorCollectionTests.cs" />
     <Compile Include="PropertyDescriptorTests.cs" />
     <Compile Include="ProvidePropertyAttributeTests.cs" />