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Q171819: FIX: Invalid Enum Value Causes Incompatible Binary Compatible

Article: Q171819
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0
Operating System(s): 
Keyword(s): kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

Incompatibility Warnings may appear when you are trying to make a project with
binary compatibility even though no subroutine or function declaration has
changed.

CAUSE
=====

If a function declaration contains an optional parameter with a default value in
the declaration that does not use a valid enum, Visual Basic will define it as a
short, which conflicts with the compiled version which is a long.

RESOLUTION
==========

Install Visual Studio 97 Service Pack 2 or use a valid enumeration in the
Function or Subroutine declaration.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been fixed in Visual Studio 97 Service
Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the
following article in the Microsoft Knowledge Base:

  Q170365 : INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97
Service Pack 2, please see the following article in the Microsoft Knowledge
Base:

  Q171554 : INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2

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

This will only affect optional default parameters that do not use valid
enumerations when setting the parameter to a default value.

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

1. Start a New ActiveX EXE in Visual Basic 5.0.

2. In the General Declarations section of Class1, place the following code:

        Public sub food( Optional x as DrawModeConstants = 1)
        End Sub

3. Select Project1 properties from the Project menu.

4. Select the Component Tab and then make sure that the Project Compatibility
  button is selected. Click OK.

5. Select Make Project1.exe from the File Menu. Click OK.

6. Select Project1 Properties from the Project menu.

7. Select the Component Tab and then make sure that Binary Compatibility is
  selected with the <path>/project1.exe file you recently created showing
  in the text box. Click OK.

8. Select Make Project1.exe from the File Menu. Click OK.

You will now get a dialog box that warns of incompatibilities in the declaration
of the version-compatible component. This should not be occurring because you
have not modified the subroutine declaration. If you continue and select
"Accept," you will get another message that recommends canceling the operation.

As a workaround, if the declaration above used a valid enumeration such as the
following, the error would not occur:

     Public Sub food( Optional x as DrawModeConstanst = vbBlackness)
     End Sub

Additional query words: kbDSupport

======================================================================
Keywords          : kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVBA500 kbVB500 kbZNotKeyword3
Version           : WINDOWS:5.0
Issue type        : kbbug
Solution Type     : kbfix

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