Remove unused custom marshaler code and move ICustomMarshaler and Color marshalling handling to managed code

src/coreclr/System.Private.CoreLib/src/Microsoft/Win32/OAVariantLib.cs

@@ -20,6 +20,7 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.Marshalling;
+using System.StubHelpers;
 
 namespace Microsoft.Win32
 {
@@ -73,8 +74,7 @@ internal static unsafe partial class OAVariantLib
                 if (source is int || source is uint)
                 {
                     uint sourceData = source is int ? (uint)(int)source : (uint)source;
-                    // Int32/UInt32 can be converted to System.Drawing.Color
-                    Variant.ConvertOleColorToSystemColor(ObjectHandleOnStack.Create(ref result), sourceData, targetClass.TypeHandle.Value);
+                    result = ColorMarshaler.ConvertToManaged((int)sourceData);
                     Debug.Assert(result != null);
                     return result;
                 }

src/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs

@@ -2,9 +2,14 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+#if FEATURE_COMINTEROP
+using System.Runtime.InteropServices.CustomMarshalers;
+#endif
 using System.Runtime.InteropServices.Marshalling;
+using System.Runtime.Versioning;
 using System.Text;
 
 namespace System.StubHelpers
@@ -792,16 +797,6 @@ internal static void ClearNative(IntPtr pMarshalState, in object pManagedHome, I
 
     internal static unsafe partial class MngdRefCustomMarshaler
     {
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "CustomMarshaler_GetMarshalerObject")]
-        private static partial void GetMarshaler(IntPtr pCMHelper, ObjectHandleOnStack retMarshaler);
-
-        internal static ICustomMarshaler GetMarshaler(IntPtr pCMHelper)
-        {
-            ICustomMarshaler? marshaler = null;
-            GetMarshaler(pCMHelper, ObjectHandleOnStack.Create(ref marshaler));
-            return marshaler!;
-        }
-
         internal static unsafe void ConvertContentsToNative(ICustomMarshaler marshaler, in object pManagedHome, IntPtr* pNativeHome)
         {
             // COMPAT: We never pass null to MarshalManagedToNative.
@@ -1395,8 +1390,28 @@ internal static void SetPendingExceptionObject(Exception? exception)
             s_pendingExceptionObject = exception;
         }
 
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "StubHelpers_CreateCustomMarshalerHelper")]
-        internal static partial IntPtr CreateCustomMarshalerHelper(IntPtr pMD, int paramToken, IntPtr hndManagedType);
+        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "StubHelpers_CreateCustomMarshaler")]
+        internal static partial void CreateCustomMarshaler(IntPtr pMD, int paramToken, IntPtr hndManagedType, ObjectHandleOnStack customMarshaler);
+
+#if FEATURE_COMINTEROP
+        [SupportedOSPlatform("windows")]
+        internal static object GetIEnumeratorToEnumVariantMarshaler() => EnumeratorToEnumVariantMarshaler.GetInstance(string.Empty);
+#endif
+
+        internal static object CreateCustomMarshaler(IntPtr pMD, int paramToken, IntPtr hndManagedType)
+        {
+#if FEATURE_COMINTEROP
+            if (OperatingSystem.IsWindows()
+                && hndManagedType == typeof(System.Collections.IEnumerator).TypeHandle.Value)
+            {
+                return GetIEnumeratorToEnumVariantMarshaler();
+            }
+#endif
+
+            object? retVal = null;
+            CreateCustomMarshaler(pMD, paramToken, hndManagedType, ObjectHandleOnStack.Create(ref retVal));
+            return retVal!;
+        }
 
         //-------------------------------------------------------
         // SafeHandle Helpers
@@ -1575,4 +1590,37 @@ internal static void ValidateObject(object obj, IntPtr pMD)
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal static extern IntPtr NextCallReturnAddress();
     }  // class StubHelpers
+
+#if FEATURE_COMINTEROP
+    internal static class ColorMarshaler
+    {
+        private static readonly MethodInvoker s_oleColorToDrawingColorMethod;
+        private static readonly MethodInvoker s_drawingColorToOleColorMethod;
+
+        internal static readonly IntPtr s_colorType;
+
+#pragma warning disable CA1810 // explicit static cctor
+        static ColorMarshaler()
+        {
+            Type colorTranslatorType = Type.GetType("System.Drawing.ColorTranslator, System.Drawing.Primitives", throwOnError: true)!;
+            Type colorType = Type.GetType("System.Drawing.Color, System.Drawing.Primitives", throwOnError: true)!;
+
+            s_colorType = colorType.TypeHandle.Value;
+
+            s_oleColorToDrawingColorMethod = MethodInvoker.Create(colorTranslatorType.GetMethod("FromOle", [typeof(int)])!);
+            s_drawingColorToOleColorMethod = MethodInvoker.Create(colorTranslatorType.GetMethod("ToOle", [colorType])!);
+        }
+#pragma warning restore CA1810 // explicit static cctor
+
+        internal static object ConvertToManaged(int managedColor)
+        {
+            return s_oleColorToDrawingColorMethod.Invoke(null, managedColor)!;
+        }
+
+        internal static int ConvertToNative(object? managedColor)
+        {
+            return (int)s_drawingColorToOleColorMethod.Invoke(null, managedColor)!;
+        }
+    }
+#endif
 }

src/coreclr/System.Private.CoreLib/src/System/Variant.cs

@@ -7,6 +7,7 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.Marshalling;
+using System.StubHelpers;
 
 #pragma warning disable CA1416 // COM interop is only supported on Windows
 
@@ -17,12 +18,6 @@ internal static partial class Variant
     {
         internal static bool IsSystemDrawingColor(Type type) => type.FullName == "System.Drawing.Color"; // Matches the behavior of IsTypeRefOrDef
 
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "Variant_ConvertSystemColorToOleColor")]
-        internal static partial uint ConvertSystemColorToOleColor(ObjectHandleOnStack obj);
-
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "Variant_ConvertOleColorToSystemColor")]
-        internal static partial void ConvertOleColorToSystemColor(ObjectHandleOnStack objret, uint value, IntPtr pMT);
-
         [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "Variant_ConvertValueTypeToRecord")]
         private static partial void ConvertValueTypeToRecord(ObjectHandleOnStack obj, out ComVariant pOle);
 
@@ -163,7 +158,7 @@ internal static void MarshalHelperConvertObjectToVariant(object? o, out ComVaria
 
                 case { } when IsSystemDrawingColor(o.GetType()):
                     // System.Drawing.Color is converted to UInt32
-                    pOle = ComVariant.Create(ConvertSystemColorToOleColor(ObjectHandleOnStack.Create(ref o)));
+                    pOle = ComVariant.Create((uint)ColorMarshaler.ConvertToNative(o));
                     break;
 
                 // DateTime, decimal handled by IConvertible case

src/coreclr/classlibnative/bcltype/variant.cpp

@@ -18,40 +18,6 @@
 #include "vars.hpp"
 #include "variant.h"
 
-extern "C" uint32_t QCALLTYPE Variant_ConvertSystemColorToOleColor(QCall::ObjectHandleOnStack obj)
-{
-    QCALL_CONTRACT;
-
-    uint32_t ret = 0;
-
-    BEGIN_QCALL;
-
-    GCX_COOP();
-    OBJECTREF srcObj = obj.Get();
-
-    GCPROTECT_BEGIN(srcObj);
-    ret = ConvertSystemColorToOleColor(&srcObj);
-    GCPROTECT_END();
-
-    END_QCALL;
-
-    return ret;
-}
-
-extern "C" void QCALLTYPE Variant_ConvertOleColorToSystemColor(QCall::ObjectHandleOnStack objRet, uint32_t oleColor, MethodTable* pMT)
-{
-    QCALL_CONTRACT;
-
-    BEGIN_QCALL;
-
-    GCX_COOP();
-    SYSTEMCOLOR systemColor{};
-    ConvertOleColorToSystemColor(oleColor, &systemColor);
-    objRet.Set(pMT->Box(&systemColor));
-
-    END_QCALL;
-}
-
 extern "C" void QCALLTYPE Variant_ConvertValueTypeToRecord(QCall::ObjectHandleOnStack obj, VARIANT * pOle)
 {
     QCALL_CONTRACT;

src/coreclr/classlibnative/bcltype/variant.h

@@ -20,8 +20,6 @@
 #include <cor.h>
 #include "olevariant.h"
 
-extern "C" uint32_t QCALLTYPE Variant_ConvertSystemColorToOleColor(QCall::ObjectHandleOnStack obj);
-extern "C" void QCALLTYPE Variant_ConvertOleColorToSystemColor(QCall::ObjectHandleOnStack objRet, uint32_t oleColor, MethodTable* pMT);
 extern "C" void QCALLTYPE Variant_ConvertValueTypeToRecord(QCall::ObjectHandleOnStack obj, VARIANT* pOle);
 
 #endif // _VARIANT_H_

src/coreclr/pal/inc/rt/palrt.h

@@ -716,8 +716,6 @@ typename std::remove_reference<T>::type&& move( T&& t );
 #define __RPC__inout
 #define __RPC__deref_out_ecount_full_opt(x)
 
-typedef DWORD OLE_COLOR;
-
 typedef HANDLE HWND;
 
 typedef struct _LIST_ENTRY {

src/coreclr/vm/callhelpers.h

@@ -473,7 +473,6 @@ class MethodDescCallSite
         MDCALLDEF_VOID(     CallWithValueTypes, TRUE)
         MDCALLDEF_ARGSLOT(  CallWithValueTypes, _RetArgSlot)
         MDCALLDEF_REFTYPE(  CallWithValueTypes, TRUE,   _RetOBJECTREF,  Object*,    OBJECTREF)
-        MDCALLDEF(          CallWithValueTypes, TRUE,   _RetOleColor,   OLE_COLOR,  OTHER_ELEMENT_TYPE)
 #undef OTHER_ELEMENT_TYPE
 #undef MDCALL_ARG_SIG_STD_RETTYPES
 #undef MDCALLDEF

src/coreclr/vm/corelib.h

@@ -384,11 +384,6 @@ DEFINE_CLASS(ICUSTOM_ATTR_PROVIDER, Reflection,             ICustomAttributeProv
 DEFINE_METHOD(ICUSTOM_ATTR_PROVIDER,GET_CUSTOM_ATTRIBUTES,  GetCustomAttributes,        IM_Type_RetArrObj)
 
 DEFINE_CLASS(ICUSTOM_MARSHALER,     Interop,                ICustomMarshaler)
-DEFINE_METHOD(ICUSTOM_MARSHALER,    MARSHAL_NATIVE_TO_MANAGED,MarshalNativeToManaged,   IM_IntPtr_RetObj)
-DEFINE_METHOD(ICUSTOM_MARSHALER,    MARSHAL_MANAGED_TO_NATIVE,MarshalManagedToNative,   IM_Obj_RetIntPtr)
-DEFINE_METHOD(ICUSTOM_MARSHALER,    CLEANUP_NATIVE_DATA,    CleanUpNativeData,          IM_IntPtr_RetVoid)
-DEFINE_METHOD(ICUSTOM_MARSHALER,    CLEANUP_MANAGED_DATA,   CleanUpManagedData,         IM_Obj_RetVoid)
-DEFINE_METHOD(ICUSTOM_MARSHALER,    GET_NATIVE_DATA_SIZE,   GetNativeDataSize,          IM_RetInt)
 
 DEFINE_CLASS(ICUSTOMADAPTER,    Interop,    ICustomAdapter)
 
@@ -929,7 +924,10 @@ DEFINE_METHOD(STUBHELPERS,          KEEP_ALIVE_VIA_CLEANUP_LIST,    KeepAliveVia
 DEFINE_METHOD(STUBHELPERS,          DESTROY_CLEANUP_LIST,   DestroyCleanupList,         SM_RefCleanupWorkListElement_RetVoid)
 DEFINE_METHOD(STUBHELPERS,          GET_HR_EXCEPTION_OBJECT, GetHRExceptionObject,      SM_Int_RetException)
 DEFINE_METHOD(STUBHELPERS,          GET_PENDING_EXCEPTION_OBJECT, GetPendingExceptionObject,      SM_RetException)
-DEFINE_METHOD(STUBHELPERS,          CREATE_CUSTOM_MARSHALER_HELPER, CreateCustomMarshalerHelper, SM_IntPtr_Int_IntPtr_RetIntPtr)
+DEFINE_METHOD(STUBHELPERS,          CREATE_CUSTOM_MARSHALER, CreateCustomMarshaler, SM_IntPtr_Int_IntPtr_RetObj)
+#ifdef FEATURE_COMINTEROP
+DEFINE_METHOD(STUBHELPERS,          GET_IENUMERATOR_TO_ENUM_VARIANT_MARSHALER, GetIEnumeratorToEnumVariantMarshaler, SM_RetObj)
+#endif // FEATURE_COMINTEROP
 
 DEFINE_METHOD(STUBHELPERS,          CHECK_STRING_LENGTH,    CheckStringLength,          SM_Int_RetVoid)
 
@@ -1001,6 +999,11 @@ DEFINE_METHOD(MNGD_SAFE_ARRAY_MARSHALER, CONVERT_CONTENTS_TO_NATIVE,  ConvertCon
 DEFINE_METHOD(MNGD_SAFE_ARRAY_MARSHALER, CONVERT_SPACE_TO_MANAGED,    ConvertSpaceToManaged,      SM_IntPtr_RefObj_IntPtr_RetVoid)
 DEFINE_METHOD(MNGD_SAFE_ARRAY_MARSHALER, CONVERT_CONTENTS_TO_MANAGED, ConvertContentsToManaged,   SM_IntPtr_RefObj_IntPtr_RetVoid)
 DEFINE_METHOD(MNGD_SAFE_ARRAY_MARSHALER, CLEAR_NATIVE,                ClearNative,                SM_IntPtr_RefObj_IntPtr_RetVoid)
+
+DEFINE_CLASS(COLORMARSHALER, StubHelpers, ColorMarshaler)
+DEFINE_METHOD(COLORMARSHALER, CONVERT_TO_NATIVE,  ConvertToNative,  SM_Obj_RetInt)
+DEFINE_METHOD(COLORMARSHALER, CONVERT_TO_MANAGED, ConvertToManaged, SM_Int_RetObj)
+DEFINE_FIELD(COLORMARSHALER, COLOR_TYPE, s_colorType)
 #endif // FEATURE_COMINTEROP
 END_ILLINK_FEATURE_SWITCH()
 
@@ -1035,7 +1038,6 @@ DEFINE_METHOD(MNGD_REF_CUSTOM_MARSHALER, CONVERT_CONTENTS_TO_NATIVE,  ConvertCon
 DEFINE_METHOD(MNGD_REF_CUSTOM_MARSHALER, CONVERT_CONTENTS_TO_MANAGED, ConvertContentsToManaged,   SM_ICustomMarshaler_RefObj_PtrIntPtr_RetVoid)
 DEFINE_METHOD(MNGD_REF_CUSTOM_MARSHALER, CLEAR_NATIVE,                ClearNative,                SM_ICustomMarshaler_RefObj_PtrIntPtr_RetVoid)
 DEFINE_METHOD(MNGD_REF_CUSTOM_MARSHALER, CLEAR_MANAGED,               ClearManaged,               SM_ICustomMarshaler_RefObj_PtrIntPtr_RetVoid)
-DEFINE_METHOD(MNGD_REF_CUSTOM_MARSHALER, GET_MARSHALER,               GetMarshaler,               SM_IntPtr_RetICustomMarshaler)
 
 DEFINE_CLASS(ASANY_MARSHALER,            StubHelpers,                 AsAnyMarshaler)
 DEFINE_METHOD(ASANY_MARSHALER,           CTOR,                        .ctor,                      IM_IntPtr_RetVoid)