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src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/ComWrappers.PlatformNotSupported.cs

@@ -6,6 +6,11 @@
 
 namespace System.Runtime.InteropServices
 {
+    [UnsupportedOSPlatform("android")]
+    [UnsupportedOSPlatform("browser")]
+    [UnsupportedOSPlatform("ios")]
+    [UnsupportedOSPlatform("maccatalyst")]
+    [UnsupportedOSPlatform("tvos")]
     public abstract partial class ComWrappers
     {
         public partial struct ComInterfaceDispatch

src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/ComWrappers.cs

@@ -69,6 +69,11 @@ public enum CreateObjectFlags
     /// <summary>
     /// Class for managing wrappers of COM IUnknown types.
     /// </summary>
+    [UnsupportedOSPlatform("android")]
+    [UnsupportedOSPlatform("browser")]
+    [UnsupportedOSPlatform("ios")]
+    [UnsupportedOSPlatform("maccatalyst")]
+    [UnsupportedOSPlatform("tvos")]
     [CLSCompliant(false)]
     public abstract partial class ComWrappers
     {

src/libraries/System.Runtime.InteropServices/ref/System.Runtime.InteropServices.cs

@@ -1125,6 +1125,11 @@ public enum CreateObjectFlags
         Aggregation = 4,
         Unwrap = 8,
     }
+    [System.Runtime.Versioning.UnsupportedOSPlatform("android")]
+    [System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
+    [System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
+    [System.Runtime.Versioning.UnsupportedOSPlatform("maccatalyst")]
+    [System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
     [System.CLSCompliantAttribute(false)]
     public abstract class ComWrappers
     {

src/libraries/System.Runtime.InteropServices/tests/System/Runtime/InteropServices/Marshal/AddRefTests.cs

@@ -9,6 +9,7 @@ namespace System.Runtime.InteropServices.Tests
     public class AddRefTests
     {
         [Fact]
+        [SkipOnMono("ComWrappers are not supported on Mono")]
         public void AddRef_ValidPointer_Success()
         {
             var cw = new ComWrappersImpl();

src/libraries/System.Runtime.InteropServices/tests/System/Runtime/InteropServices/Marshal/QueryInterfaceTests.cs

@@ -21,6 +21,7 @@ public static IEnumerable<object[]> QueryInterface_ValidInterface_TestData()
 
         [Theory]
         [MemberData(nameof(QueryInterface_ValidInterface_TestData))]
+        [SkipOnMono("ComWrappers are not supported on Mono")]
         public void QueryInterface_ValidInterface_Success(object o, string iidString)
         {
             var cw = new ComWrappersImpl();

src/libraries/System.Runtime.InteropServices/tests/System/Runtime/InteropServices/Marshal/ReleaseTests.cs

@@ -9,6 +9,7 @@ namespace System.Runtime.InteropServices.Tests
     public class ReleaseTests
     {
         [Fact]
+        [SkipOnMono("ComWrappers are not supported on Mono")]
         public void Release_ValidPointer_Success()
         {
             var cw = new ComWrappersImpl();