DOCUMENT:Q190085  07-AUG-1998  [vbwin]
TITLE   :BUG: No Binary Compatibility Error With Null GUIDs Enums
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:6.0
OPER/SYS:WINDOWS
KEYWORDS:

======================================================================
---------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, version 6.0
---------------------------------------------------------------------

SYMPTOMS
========

If you use Enums from some Microsoft libraries as parameters and then
change the Enum to a different one with the project set to Binary
Compatibility, an incompatibility error is not generated as expected.

CAUSE
=====

Most Microsoft libraries and all Visual Basic generated DLLs contain Enums
that have GUIDs. However, the libraries listed in the MORE INFORMATION
section below have Enums with NULL GUIDs.

If a library has NULL GUIDs for the Enums, it is possible to change
parameters of methods to different Enums and still not get an
incompatibility error, even though Binary Compatibility is set.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products
listed at the beginning of this article. We are researching this
bug and will post new information here in the Microsoft Knowledge
Base as it becomes available.

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

The following libraries have NULL GUIDs for Enums, and will therefore
exhibit this problem when used as a parameter:

   Microsoft DAO 2.5/3.51 Compatibility Library
   Microsoft DAO 3.51 Object Library
   Microsoft Data Environment Extensibility Objects 1.0
   Microsoft Dialog Automation Objects
   Microsoft OLE DB Service Component 1.0 Type Library
   Microsoft OLE DB Simple Provider 1.5 Library
   Microsoft Remote Data Services 2.0 Library
   Microsoft Scripting Runtime
   Microsoft Transaction Server Type Library
   Microsoft WebClass Library v1.0

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

1. Create a new ActiveX DLL project in Visual Basic. Class1 is created by
   default.

2. Add a Reference to one of the libraries listed above by selecting
   References from the Project menu.

3. Paste the following code into Class1:

      Public Sub Test(a As <<choose an Enum from a library above>>) End Sub

4. Compile as Project1.dll.

5. Set Binary Compatibility to Project1.dll by selecting Project Properties
   from the Project menu, then selecting the Components tab. Check Binary
   Compatibility and select the Project1.dll.

6. Modify the code in Class1 to be:

    Public Sub Test(a As <<choose a different Enum from the library chosen
    in Step 2>>)
    End Sub

7. Compile Project2.dll. Note that the DLL compiles without any
   incompatibility error.

Additional query words: kbDSupport kbVBp600bug kbCompiler kbdss kbVBp
======================================================================
Version           : WINDOWS:6.0
Platform          : WINDOWS
Issue type        : kbbug

=============================================================================

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Copyright Microsoft Corporation 1998.