Look up the ICustomMarshaler implementation methods based on runtime type

src/coreclr/vm/custommarshalerinfo.cpp

@@ -67,13 +67,6 @@ CustomMarshalerInfo::CustomMarshalerInfo(LoaderAllocator *pLoaderAllocator, Type
     STRINGREF CookieStringObj = StringObject::NewString(strCookie, cCookieStrBytes);
     GCPROTECT_BEGIN(CookieStringObj);
 #endif
-
-    // Load the method desc's for all the methods in the ICustomMarshaler interface.
-    m_pMarshalNativeToManagedMD = GetCustomMarshalerMD(CustomMarshalerMethods_MarshalNativeToManaged, hndCustomMarshalerType);
-    m_pMarshalManagedToNativeMD = GetCustomMarshalerMD(CustomMarshalerMethods_MarshalManagedToNative, hndCustomMarshalerType);
-    m_pCleanUpNativeDataMD = GetCustomMarshalerMD(CustomMarshalerMethods_CleanUpNativeData, hndCustomMarshalerType);
-    m_pCleanUpManagedDataMD = GetCustomMarshalerMD(CustomMarshalerMethods_CleanUpManagedData, hndCustomMarshalerType);
-
     // Load the method desc for the static method to retrieve the instance.
     MethodDesc *pGetCustomMarshalerMD = GetCustomMarshalerMD(CustomMarshalerMethods_GetInstance, hndCustomMarshalerType);
 
@@ -103,15 +96,26 @@ CustomMarshalerInfo::CustomMarshalerInfo(LoaderAllocator *pLoaderAllocator, Type
     };
 
     // Call the GetCustomMarshaler method to retrieve the custom marshaler to use.
-    OBJECTREF CustomMarshalerObj = getCustomMarshaler.Call_RetOBJECTREF(GetCustomMarshalerArgs);
+    OBJECTREF CustomMarshalerObj = NULL;
+    GCPROTECT_BEGIN(CustomMarshalerObj);
+    CustomMarshalerObj = getCustomMarshaler.Call_RetOBJECTREF(GetCustomMarshalerArgs);
     if (!CustomMarshalerObj)
     {
         DefineFullyQualifiedNameForClassW()
         COMPlusThrow(kApplicationException,
                      IDS_EE_NOCUSTOMMARSHALER,
                      GetFullyQualifiedNameForClassW(hndCustomMarshalerType.GetMethodTable()));
     }
+    // Load the method desc's for all the methods in the ICustomMarshaler interface based on the type of the marshaler object.
+    TypeHandle customMarshalerObjType = CustomMarshalerObj->GetMethodTable();
+
+    m_pMarshalNativeToManagedMD = GetCustomMarshalerMD(CustomMarshalerMethods_MarshalNativeToManaged, customMarshalerObjType);
+    m_pMarshalManagedToNativeMD = GetCustomMarshalerMD(CustomMarshalerMethods_MarshalManagedToNative, customMarshalerObjType);
+    m_pCleanUpNativeDataMD = GetCustomMarshalerMD(CustomMarshalerMethods_CleanUpNativeData, customMarshalerObjType);
+    m_pCleanUpManagedDataMD = GetCustomMarshalerMD(CustomMarshalerMethods_CleanUpManagedData, customMarshalerObjType);
+
     m_hndCustomMarshaler = pLoaderAllocator->AllocateHandle(CustomMarshalerObj);
+    GCPROTECT_END();
 
     // Retrieve the size of the native data.
     if (m_bDataIsByValue)

src/tests/Interop/ICustomMarshaler/Primitives/ICustomMarshaler.cs

@@ -365,7 +365,7 @@ public void Parameter_NotICustomMarshaler_ThrowsApplicationException()
         {
             Assert.Throws<ApplicationException>(() => NonICustomMarshalerMethod(""));
         }
-    
+
         [DllImport(LibcLibrary, EntryPoint = "atoi", CallingConvention = CallingConvention.Cdecl)]
         public static extern int NonICustomMarshalerMethod([MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(string))] string str);
 
@@ -509,7 +509,7 @@ public void CleanUpNativeData(IntPtr pNativeData) { }
 
         [Fact]
         public void Parameter_GetInstanceMethodThrows_ThrowsActualException()
-        {            
+        {
             Assert.Throws<NotImplementedException>(() => ThrowingGetInstanceMethod(""));
         }
 
@@ -588,6 +588,58 @@ public struct StructWithCustomMarshalerField
         [DllImport(LibcLibrary, EntryPoint = "atoi", CallingConvention = CallingConvention.Cdecl)]
         public static extern int StructWithCustomMarshalerFieldMethod(StructWithCustomMarshalerField c);
 
+
+        [Fact]
+        public void Parameter_DifferentCustomMarshalerType_MarshalsCorrectly()
+        {
+            Assert.Equal(234, DifferentCustomMarshalerType("5678"));
+        }
+
+        public class OuterCustomMarshaler : ICustomMarshaler
+        {
+            public void CleanUpManagedData(object ManagedObj) => throw new NotImplementedException();
+            public void CleanUpNativeData(IntPtr pNativeData) => throw new NotImplementedException();
+
+            public int GetNativeDataSize() => throw new NotImplementedException();
+
+            public IntPtr MarshalManagedToNative(object ManagedObj) => throw new NotImplementedException();
+            public object MarshalNativeToManaged(IntPtr pNativeData) => throw new NotImplementedException();
+
+            public static ICustomMarshaler GetInstance(string cookie) => new InnerCustomMarshaler();
+
+            private interface ILargeInterface
+            {
+                void Method1();
+                void Method2();
+                void Method3();
+                void Method4();
+                void Method5();
+                void Method6();
+            }
+
+            private class InnerCustomMarshaler : ILargeInterface, ICustomMarshaler
+            {
+                public void Method1() => throw new InvalidOperationException();
+                public void Method2() => throw new InvalidOperationException();
+                public void Method3() => throw new InvalidOperationException();
+                public void Method4() => throw new InvalidOperationException();
+                public void Method5() => throw new InvalidOperationException();
+                public void Method6() => throw new InvalidOperationException();
+
+                public void CleanUpManagedData(object ManagedObj) { }
+                public void CleanUpNativeData(IntPtr pNativeData) => Marshal.FreeCoTaskMem(pNativeData);
+
+                public int GetNativeDataSize() => IntPtr.Size;
+
+                public IntPtr MarshalManagedToNative(object ManagedObj) => Marshal.StringToCoTaskMemAnsi("234");
+                public object MarshalNativeToManaged(IntPtr pNativeData) => null;
+            }
+        }
+
+        [DllImport(LibcLibrary, EntryPoint = "atoi", CallingConvention = CallingConvention.Cdecl)]
+        public static extern int DifferentCustomMarshalerType([MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(OuterCustomMarshaler))] string str);
+
+
         public static int Main(String[] args)
         {
             return new ICustomMarshalerTests().RunTests();