Issue: Attempt to use MSIL code from this assembly during native code initialization

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C++/CLI

Hello Everyone,

I have the following issue I would like to share with you:

I added to a dynamic library with MFC feature, the /clr option.

Since I have added this option, the library seems to behave properly expect that I cannot set code into DllMain statment as I was doing before the modification.

Let's add a MessageBox after CoInitialize:

#pragma unmanaged
extern "C" int APIENTRY
DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
{
	g_hThisDll = hInstance;

    switch (dwReason)
	{
		case DLL_PROCESS_ATTACH:
			CoInitialize(NULL);

			::MessageBox(NULL, "DllMain", "mpOLEAutomationCLR", MB_OK);
			break;

		case DLL_THREAD_ATTACH:
			break;
		case DLL_THREAD_DETACH:
			delete g_pcfOleAutomationCLR;
			CoUninitialize();
			break;
		case DLL_PROCESS_DETACH:
			break;
    }	
	return TRUE;

}

Now, if I run:
C:\Windows\SysWOW64\regsvr32.exe ".\Debug\mpOLEAutomationCLR.dll"

It prompts the following error dialog box:
Errorregistration message.

If I remove the MessageBox line:

#pragma unmanaged
extern "C" int APIENTRY
DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
{
    g_hThisDll = hInstance;

    switch (dwReason)
    {
        case DLL_PROCESS_ATTACH:
            CoInitialize(NULL);

            //::MessageBox(NULL, "DllMain", "mpOLEAutomationCLR", MB_OK);
            break;

        case DLL_THREAD_ATTACH:
            break;
        case DLL_THREAD_DETACH:
            delete g_pcfOleAutomationCLR;
            CoUninitialize();
            break;
        case DLL_PROCESS_DETACH:
            break;
    }
    return TRUE;

}

The regsv32.exe command line will return the expected messagebox.

Expected registration message.

I have added the sample program project to show you or try the issue.
Sample program link

Does somebody have a explanation or a fix to allow me to add code into the DllMain entry point.

Thank you very much in advance.
Happy end year season.
Best regards.
SuperMiqi