Q199942: FIX: Tstcon32.exe Cannot Invoke Method with BSTR* Parameter Type

Article: Q199942
Product(s): Microsoft C Compiler
Version(s): 6.0
Operating System(s): 
Keyword(s): kbole kbActiveX kbCOMt kbContainer kbCtrl kbMFC kbMiscTools kbVC600bug kbDSupport kbGrp
Last Modified: 24-JUL-2002

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++.NET (2002) 
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SYMPTOMS
========

The ActiveX Control Test Container (version 6.0.8063) that ships with Visual C++
6.0 and Visual C++.NET fail to invoke a method of an MFC ActiveX control that
has BSTR* parameter type.

CAUSE
=====

Microsoft has confirmed that this is a bug in Visual C++ 6.0 and Visual C++.NET
ActiveX Control Test Container.

RESOLUTION
==========

To work around this issue:

- Use containers such as Visual Basic.

- Use LPCTSTR as the parameter type.

STATUS
======

Microsoft has confirmed that this is a problem in the Microsoft products that
are listed at the beginning of this article.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Use the MFC ActiveX ControlWizard to create an ActiveX control project.

2. Add a method to the ActiveX control as follows:

  void CMyControl::Test(BSTR FAR* Par1)
        {
           // TODO: Add your dispatch handler code here
           AfxMessageBox("In Test");
           return 0;
        }

3. Build the control project.

4. Insert the control to the ActiveX Control Test Container of Visual C++ 6.0 or
  Visual C++.NET.

5. Invoke the Test() method in the ActiveX Control Test Container and the
  message box does not appear. The following error is displayed in the output
  window of Visual C++:

  First-chance exception in TSTCON32.EXE (KERNEL32.DLL): 0xE06D7363: Microsoft
  C++ Exception. Warning: automation argument coercion failed. First-chance
  exception in TSTCON32.EXE (KERNEL32.DLL): 0xE06D7363: Microsoft C++

Additional query words:

======================================================================
Keywords          : kbole kbActiveX kbCOMt kbContainer kbCtrl kbMFC kbMiscTools kbVC600bug kbDSupport kbGrpDSMFCATL kbNoUpdate 
Technology        : kbAudDeveloper kbMFC
Version           : :6.0
Issue type        : kbbug
Solution Type     : kbfix

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