Hi,

I have a COM object implemented in ATL. The CoClass implements two
interface. The default interface IInterface1 is a dispatch interface. The
non-default interface IInterface2 is an IUnknown interface.

Using dotnet interop I can create object instances, I can also be able to
cast the instance to IInterface2. dotnet interop sounds perfect.

However when I wrap this small piece of code in a separate thread, I get a
cast invalid exception. Let me descibe it in more detail using pseudo-code.

public static void TestInterop()
{
   MyCom c = new MyCom();
   IInterface1 i1 = (IInterface1)c;
   IInterface2 i2 = (IInterface2)c;
}

when I directly call this function from the main thread, everything works
perfectly. However when I call the this function using the following code:

public static void Main()
{
   Thread t = new Thread(new ThreadStart(TestInterop)));
   t.Start();
   t.Join();
}

I got the disgusting cast invalid exception. Although I run the code in a
thread, I create the object in the thread, I run the code in the same
thread. I never try to call the function from other threads. I just do not
understand it really matters to run it from the main thread or from a
separate thread.

To make sure it is not a problem from my COM component. I then program in
VC++. With CreateThread, it works OK. So anybody have the same experience?
Do I miss something here? Or it is interop bug?