Mark typed sealed where possible

src/WinRT.Runtime/ComWrappersSupport.cs

@@ -768,7 +768,7 @@ private static ComInterfaceEntry ProvideIReferenceArray(Type arrayType)
             };
         }
 
-        internal class InspectableInfo
+        internal sealed class InspectableInfo
         {
             private readonly Lazy<string> runtimeClassName;
 

src/WinRT.Runtime/ComWrappersSupport.net5.cs

@@ -551,7 +551,7 @@ protected override void ReleaseObjects(IEnumerable objects)
             }
         }
 
-        unsafe class VtableEntries
+        unsafe sealed class VtableEntries
         {
             public ComInterfaceEntry* Data { get; }
             public int Count { get; }

src/WinRT.Runtime/ComWrappersSupport.netstandard2.0.cs

@@ -214,7 +214,7 @@ private static uint Do_Abi_Release(IntPtr pThis)
             return UnmanagedObject.FindObject<ComCallableWrapper>(pThis).Release();
         }
 
-        private class RuntimeWrapperCleanup
+        private sealed class RuntimeWrapperCleanup
         {
             public IntPtr _identityComObject;
             public System.WeakReference<object> _runtimeWrapper;
@@ -303,7 +303,7 @@ internal static T FindObject<T>(IntPtr thisPtr)
         }
     }
 
-    internal class ComCallableWrapper
+    internal sealed class ComCallableWrapper
     {
         private Dictionary<Guid, IntPtr> _managedQITable;
         private GCHandle _qiTableHandle;

src/WinRT.Runtime/ExceptionHelpers.cs

@@ -259,7 +259,7 @@ public static int GetHRForException(Exception ex)
         // the exception instance in the app to hold the error object alive.
         //
         [Serializable]
-        internal class __RestrictedErrorObject
+        internal sealed class __RestrictedErrorObject
         {
             // Hold the error object instance but don't serialize/deserialize it
             [NonSerialized]
@@ -404,7 +404,7 @@ internal static Exception GetExceptionForHR(this Exception innerException, int h
         }
     }
 
-    internal class ErrorStrings
+    internal static class ErrorStrings
     {
         internal static string Format(string format, params object[] args) => String.Format(format, args);
 

src/WinRT.Runtime/Interop/ExceptionErrorInfo.cs

@@ -51,7 +51,7 @@ void GetErrorDetails(
         string GetReference();
     }
 
-    internal class ManagedExceptionErrorInfo : IErrorInfo, ISupportErrorInfo
+    internal sealed class ManagedExceptionErrorInfo : IErrorInfo, ISupportErrorInfo
     {
         private readonly Exception _exception;
 

src/WinRT.Runtime/Interop/IAgileReference.net5.cs

@@ -141,7 +141,7 @@ static Vftbl()
     }
 
     [Guid("00000146-0000-0000-C000-000000000046")]
-    internal unsafe class IGlobalInterfaceTable : global::WinRT.Interop.IGlobalInterfaceTable
+    internal sealed unsafe class IGlobalInterfaceTable : global::WinRT.Interop.IGlobalInterfaceTable
     {
         [Guid("00000146-0000-0000-C000-000000000046")]
         [StructLayout(LayoutKind.Sequential)]

src/WinRT.Runtime/Interop/IAgileReference.netstandard2.0.cs

@@ -39,7 +39,7 @@ namespace ABI.WinRT.Interop
     using global::WinRT;
 
     [Guid("C03F6A43-65A4-9818-987E-E0B810D2A6F2")]
-    internal unsafe class IAgileReference : global::WinRT.Interop.IAgileReference
+    internal sealed unsafe class IAgileReference : global::WinRT.Interop.IAgileReference
     {
         [Guid("C03F6A43-65A4-9818-987E-E0B810D2A6F2")]
         public struct Vftbl
@@ -162,7 +162,7 @@ public IAgileObject(ObjectReference<Vftbl> obj)
     }
 
     [Guid("00000146-0000-0000-C000-000000000046")]
-    internal unsafe class IGlobalInterfaceTable : global::WinRT.Interop.IGlobalInterfaceTable
+    internal sealed unsafe class IGlobalInterfaceTable : global::WinRT.Interop.IGlobalInterfaceTable
     {
         [Guid("00000146-0000-0000-C000-000000000046")]
         [StructLayout(LayoutKind.Sequential)]

src/WinRT.Runtime/Interop/IContextCallback.cs

@@ -37,7 +37,7 @@ void ContextCallback(
 namespace ABI.WinRT.Interop
 {
     [Guid("000001da-0000-0000-C000-000000000046")]
-    unsafe class IContextCallback : global::WinRT.Interop.IContextCallback
+    internal sealed unsafe class IContextCallback : global::WinRT.Interop.IContextCallback
     {
         [Guid("000001da-0000-0000-C000-000000000046")]
         public struct Vftbl

src/WinRT.Runtime/Interop/IMarshal.cs

@@ -33,7 +33,7 @@ internal interface IMarshal
 namespace ABI.WinRT.Interop
 {
     [Guid("00000003-0000-0000-c000-000000000046")]
-    internal class IMarshal
+    internal sealed class IMarshal
     {
         internal static readonly Guid IID = new(0x00000003, 0, 0, 0xc0, 0, 0, 0, 0, 0, 0, 0x46);
 

src/WinRT.Runtime/Interop/IWeakReferenceSource.net5.cs

@@ -32,7 +32,7 @@ interface IWeakReference
         IObjectReference Resolve(Guid riid);
     }
 
-    internal class ManagedWeakReference : IWeakReference
+    internal sealed class ManagedWeakReference : IWeakReference
     {
         private readonly WeakReference<object> _ref;
         public ManagedWeakReference(object obj)

src/WinRT.Runtime/Interop/IWeakReferenceSource.netstandard2.0.cs

@@ -30,7 +30,7 @@ interface IWeakReference
         IObjectReference Resolve(Guid riid);
     }
 
-    internal class ManagedWeakReference : IWeakReference
+    internal sealed class ManagedWeakReference : IWeakReference
     {
         private WeakReference<object> _ref;
         public ManagedWeakReference(object obj)

src/WinRT.Runtime/MonoSupport.cs

@@ -10,7 +10,7 @@
 
 namespace WinRT
 {
-    internal class Mono
+    internal static class Mono
     {
         static Lazy<bool> _usingMono = new Lazy<bool>(() =>
         {
@@ -72,7 +72,7 @@ struct MonoInternalThread_x64
             public MonoThreadFlag flags;
         }
 
-        public class ThreadContext : IDisposable
+        public sealed class ThreadContext : IDisposable
         {
             static Lazy<HashSet<IntPtr>> _foreignThreads = new Lazy<HashSet<IntPtr>>();
 

src/WinRT.Runtime/ObjectReference.cs

@@ -444,7 +444,7 @@ private protected virtual T GetVftblForCurrentContext()
         }
     }
 
-    internal class ObjectReferenceWithContext<T> : ObjectReference<T>
+    internal sealed class ObjectReferenceWithContext<T> : ObjectReference<T>
     {
         private readonly IntPtr _contextCallbackPtr;
         private readonly IntPtr _contextToken;

src/WinRT.Runtime/Projections/Bindable.net5.cs

@@ -422,7 +422,7 @@ internal unsafe interface IEnumerable : global::System.Collections.IEnumerable,
     {
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IEnumerable));
 
-        public class AdaptiveFromAbiHelper : FromAbiHelper, global::System.Collections.IEnumerable
+        public sealed class AdaptiveFromAbiHelper : FromAbiHelper, global::System.Collections.IEnumerable
         {
             private readonly Func<IWinRTObject, global::System.Collections.IEnumerator> _enumerator;
 
@@ -480,7 +480,7 @@ private sealed class NonGenericToGenericIterator : global::Windows.Foundation.Co
             }
         }
 
-        public class ToAbiHelper : IBindableIterable
+        public sealed class ToAbiHelper : IBindableIterable
         {
             private readonly IEnumerable m_enumerable;
 
@@ -596,7 +596,7 @@ unsafe interface IList : global::System.Collections.IList, global::Microsoft.UI.
     {
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IList));
 
-        public class FromAbiHelper : global::System.Collections.IList
+        public sealed class FromAbiHelper : global::System.Collections.IList
         {
             private readonly global::Microsoft.UI.Xaml.Interop.IBindableVector _vector;
 

src/WinRT.Runtime/Projections/EventHandler.cs

@@ -57,9 +57,9 @@ public static IntPtr GetAbi(IObjectReference value) =>
 
         [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
 #if !NET
-        private class NativeDelegateWrapper
+        private sealed class NativeDelegateWrapper
 #else
-        private class NativeDelegateWrapper : IWinRTObject
+        private sealed class NativeDelegateWrapper : IWinRTObject
 #endif
         {
             private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;
@@ -187,9 +187,9 @@ public static IntPtr GetAbi(IObjectReference value) =>
 
         [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
 #if !NET
-        private class NativeDelegateWrapper
+        private sealed class NativeDelegateWrapper
 #else
-        private class NativeDelegateWrapper : IWinRTObject
+        private sealed class NativeDelegateWrapper : IWinRTObject
 #endif
         {
             private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;

src/WinRT.Runtime/Projections/Geometry.cs

@@ -7,7 +7,7 @@
 
 namespace Windows.Foundation
 {
-    internal class GSR
+    internal static class GSR
     {
         public static string ArgumentOutOfRange_NeedNonNegNum = "Non-negative number required.";
     }

src/WinRT.Runtime/Projections/ICustomPropertyProvider.net5.cs

@@ -26,7 +26,7 @@ interface ICustomProperty
 namespace ABI.Microsoft.UI.Xaml.Data
 {
     [Guid("30DA92C0-23E8-42A0-AE7C-734A0E5D2782")]
-    internal unsafe class ICustomProperty
+    internal sealed unsafe class ICustomProperty
     {
         [Guid("30DA92C0-23E8-42A0-AE7C-734A0E5D2782")]
         public struct Vftbl
@@ -234,7 +234,7 @@ internal static class ICustomProperty_Delegates
         public unsafe delegate int get_CanRead_7(IntPtr thisPtr, byte* value);
     }
 
-    internal class ManagedCustomProperty : global::Microsoft.UI.Xaml.Data.ICustomProperty
+    internal sealed class ManagedCustomProperty : global::Microsoft.UI.Xaml.Data.ICustomProperty
     {
         private readonly PropertyInfo _property;
 

src/WinRT.Runtime/Projections/ICustomPropertyProvider.netstandard2.0.cs

@@ -26,7 +26,7 @@ interface ICustomProperty
 namespace ABI.Microsoft.UI.Xaml.Data
 {
     [Guid("30DA92C0-23E8-42A0-AE7C-734A0E5D2782")]
-    internal unsafe class ICustomProperty
+    internal sealed unsafe class ICustomProperty
     {
         [Guid("30DA92C0-23E8-42A0-AE7C-734A0E5D2782")]
         public struct Vftbl
@@ -220,7 +220,7 @@ internal static class ICustomProperty_Delegates
         public unsafe delegate int get_CanRead_7(IntPtr thisPtr, byte* value);
     }
 
-    internal class ManagedCustomProperty : global::Microsoft.UI.Xaml.Data.ICustomProperty
+    internal sealed class ManagedCustomProperty : global::Microsoft.UI.Xaml.Data.ICustomProperty
     {
         private readonly PropertyInfo _property;
 

src/WinRT.Runtime/Projections/IDictionary.net5.cs

@@ -60,7 +60,7 @@ public static void DisposeAbi(IntPtr abi) =>
 
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IDictionary<K, V>));
 
-        public class FromAbiHelper : global::System.Collections.Generic.IDictionary<K, V>
+        public sealed class FromAbiHelper : global::System.Collections.Generic.IDictionary<K, V>
         {
             private readonly global::Windows.Foundation.Collections.IMap<K, V> _map;
             internal readonly Dictionary<K, (IntPtr, V)> _lookupCache = new();
@@ -438,7 +438,7 @@ public void Reset()
             }
         }
 
-        public class ToAbiHelper : global::Windows.Foundation.Collections.IMap<K, V>
+        public sealed class ToAbiHelper : global::Windows.Foundation.Collections.IMap<K, V>
         {
             private readonly global::System.Collections.Generic.IDictionary<K, V> _dictionary;
 

src/WinRT.Runtime/Projections/IEnumerable.net5.cs

@@ -69,7 +69,7 @@ public static void DisposeAbi(IntPtr abi) =>
 
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IEnumerable<T>));
 
-        public class FromAbiHelper : global::System.Collections.Generic.IEnumerable<T>
+        public sealed class FromAbiHelper : global::System.Collections.Generic.IEnumerable<T>
         {
             private readonly global::System.Collections.Generic.IEnumerable<T> _iterable;
 

src/WinRT.Runtime/Projections/IList.net5.cs

@@ -60,7 +60,7 @@ public static void DisposeAbi(IntPtr abi) =>
 
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IList<T>));
 
-        public class FromAbiHelper : global::System.Collections.Generic.IList<T>
+        public sealed class FromAbiHelper : global::System.Collections.Generic.IList<T>
         {
             private readonly global::Windows.Foundation.Collections.IVector<T> _vector;
 

src/WinRT.Runtime/Projections/IPropertyValue.net5.cs

@@ -209,7 +209,7 @@ private static T UnboxValue<T>(object value)
         }
 
 #pragma warning disable CS0649
-        private class Boxed<T>
+        private sealed class Boxed<T>
             where T : struct
         {
             public T Value;

src/WinRT.Runtime/Projections/IPropertyValue.netstandard2.0.cs

@@ -211,7 +211,7 @@ private static T UnboxValue<T>(object value)
         }
 
 #pragma warning disable CS0649
-        private class Boxed<T>
+        private sealed class Boxed<T>
             where T : struct
         {
             public T Value;

src/WinRT.Runtime/Projections/IReadOnlyDictionary.net5.cs

@@ -157,7 +157,7 @@ public void Reset()
             }
         }
 
-        public class FromAbiHelper : global::System.Collections.Generic.IReadOnlyDictionary<K, V>
+        public sealed class FromAbiHelper : global::System.Collections.Generic.IReadOnlyDictionary<K, V>
         {
             private readonly global::Windows.Foundation.Collections.IMapView<K, V> _mapView;
             private readonly global::System.Collections.Generic.IEnumerable<global::System.Collections.Generic.KeyValuePair<K, V>> _enumerable;
@@ -258,7 +258,7 @@ private static V Lookup(global::Windows.Foundation.Collections.IMapView<K, V> _t
 
         }
 
-        public class ToAbiHelper : global::Windows.Foundation.Collections.IMapView<K, V>
+        public sealed class ToAbiHelper : global::Windows.Foundation.Collections.IMapView<K, V>
         {
             private readonly global::System.Collections.Generic.IReadOnlyDictionary<K, V> _dictionary;
 
@@ -305,7 +305,7 @@ public V Lookup(K key)
 
             private sealed class ConstantSplittableMap : global::Windows.Foundation.Collections.IMapView<K, V>, global::System.Collections.Generic.IReadOnlyDictionary<K, V>
             {
-                private class KeyValuePairComparator : IComparer<global::System.Collections.Generic.KeyValuePair<K, V>>
+                private sealed class KeyValuePairComparator : IComparer<global::System.Collections.Generic.KeyValuePair<K, V>>
                 {
                     private static readonly IComparer<K> keyComparator = Comparer<K>.Default;
 

src/WinRT.Runtime/Projections/IReadOnlyDictionary.netstandard2.0.cs

@@ -320,7 +320,7 @@ public V Lookup(K key)
 
             private sealed class ConstantSplittableMap : global::Windows.Foundation.Collections.IMapView<K, V>, global::System.Collections.Generic.IReadOnlyDictionary<K, V>
             {
-                private class KeyValuePairComparator : IComparer<global::System.Collections.Generic.KeyValuePair<K, V>>
+                private sealed class KeyValuePairComparator : IComparer<global::System.Collections.Generic.KeyValuePair<K, V>>
                 {
                     private static readonly IComparer<K> keyComparator = Comparer<K>.Default;
 

src/WinRT.Runtime/Projections/IReadOnlyList.net5.cs

@@ -50,7 +50,7 @@ public static void DisposeAbi(IntPtr abi) =>
 
         public static string GetGuidSignature() => GuidGenerator.GetSignature(typeof(IReadOnlyList<T>));
 
-        public class FromAbiHelper : global::System.Collections.Generic.IReadOnlyList<T>
+        public sealed class FromAbiHelper : global::System.Collections.Generic.IReadOnlyList<T>
         {
             private readonly global::Windows.Foundation.Collections.IVectorView<T> _vectorView;
             private readonly global::System.Collections.Generic.IEnumerable<T> _enumerable;

src/WinRT.Runtime/Projections/IReferenceArray.net5.cs

@@ -61,7 +61,7 @@ private static unsafe int Do_Abi_get_Value_0(IntPtr thisPtr, out int ____return_
 
     [global::WinRT.ObjectReferenceWrapper(nameof(_obj))]
     [Guid("61C17707-2D65-11E0-9AE8-D48564015472")]
-    internal class IReferenceArray<T> : global::Windows.Foundation.IReferenceArray<T>
+    internal sealed class IReferenceArray<T> : global::Windows.Foundation.IReferenceArray<T>
     {
         public static IObjectReference CreateMarshaler(object value)
         {

src/WinRT.Runtime/Projections/IReferenceArray.netstandard2.0.cs

@@ -61,7 +61,7 @@ private static unsafe int Do_Abi_get_Value_0(IntPtr thisPtr, out int ____return_
 
     [global::WinRT.ObjectReferenceWrapper(nameof(_obj))]
     [Guid("61C17707-2D65-11E0-9AE8-D48564015472")]
-    internal class IReferenceArray<T> : global::Windows.Foundation.IReferenceArray<T>
+    internal sealed class IReferenceArray<T> : global::Windows.Foundation.IReferenceArray<T>
     {
         public static IObjectReference CreateMarshaler(object value)
         {

src/WinRT.Runtime/Projections/NotifyCollectionChangedEventArgs.cs

@@ -111,7 +111,7 @@ public unsafe int OldStartingIndex
 
     [global::WinRT.ObjectReferenceWrapper(nameof(_obj))]
     [Guid("5108EBA4-4892-5A20-8374-A96815E0FD27")]
-    internal unsafe sealed class WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory
+    internal sealed unsafe class WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory
     {
         [Guid("5108EBA4-4892-5A20-8374-A96815E0FD27")]
         [StructLayout(LayoutKind.Sequential)]

src/WinRT.Runtime/Projections/NotifyCollectionChangedEventHandler.cs

@@ -58,9 +58,9 @@ public static unsafe IObjectReference CreateMarshaler(global::System.Collections
 
         [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
 #if !NET
-        private class NativeDelegateWrapper
+        private sealed class NativeDelegateWrapper
 #else
-        private class NativeDelegateWrapper : IWinRTObject
+        private sealed class NativeDelegateWrapper : IWinRTObject
 #endif
         {
             private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;

src/WinRT.Runtime/Projections/PropertyChangedEventHandler.cs

@@ -57,9 +57,9 @@ public static unsafe IObjectReference CreateMarshaler(global::System.ComponentMo
 
         [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
 #if !NET
-        private class NativeDelegateWrapper
+        private sealed class NativeDelegateWrapper
 #else
-        private class NativeDelegateWrapper : IWinRTObject
+        private sealed class NativeDelegateWrapper : IWinRTObject
 #endif
         {
             private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;