DOCUMENT:Q281913  01-APR-2001  [vbwin]
TITLE   :BUG: Referencing Type Libraries May Render Platform Dependent
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER::4.0,5.0,6.0
OPER/SYS:
KEYWORDS:kbCompiler kbVBp kbVBp400bug kbVBp500bug kbVBp600bug kbGrpDSVB kbDSupport

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The information in this article applies to:

 - Microsoft Visual Basic Enterprise Edition for Windows, versions 4.0, 5.0, 6.0 
 - Microsoft Visual Basic Professional Edition for Windows, versions 4.0, 5.0, 6.0 
 - Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

After compiling a Visual Basic project that references more than one type
library on one platform (such as a Microsoft Windows 2000-based computer), the
resulting binary fails to run on other platforms (such as Microsoft Windows NT
4-, Microsoft Windows 95-, Microsoft Windows 98-, and Microsoft Windows ME-based
computers) and gets an Access Violation (AV).

CAUSE
=====

The Visual Basic compiler is case sensitive when it is reading entries for
dllname in type libraries. As a result, if a project references two or more type
libraries and the dllname entry for the same DLL is spelled in different cases
in different libraries, such as dllname("kernel32.dll") in library A, and
dllname("KERNEL32.DLL") in library B, the compiler generates two import sections
for the same DLL and renders the binary platform dependent.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

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

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

1. Set up a Windows 2000-based computer and a Windows NT 4-based computer, both
   with the latest service packs. Also install Visual Basic and Visual C++ 6.0
   with Service Pack 5 on both computers.

2. On the Windows 2000-based computer, copy-and-paste the following Interface
   Description Language (IDL) code into Notepad, and save it as lcase.idl.
   Compile it with MIDL.EXE, "midl lcase.idl" (without the quotation marks). The
   resulting type library is named lcase.tlb.

   [
     uuid(D618AA4D-814A-47a2-9AC1-DDE18EDF1C54),
     version(1.0),
     helpstring("Lower case test")
   ]
   library lcasetest
   {
       [
         dllname("kernel32.dll"),
         version(1.0),
         helpstring("Sleep function exported by kernel32.dll")
       ]
       module lcasetest {
           [
   			entry("Sleep"), 
   			helpstring("sleep - lcase test.")
   		]
           void _stdcall Sleep([in] long dwMS);
       };
   };

3. As in step 1, build ucase.tlb with the following IDL code:

   [
     uuid(3F215C63-D0AD-4980-93F2-5DDF850061E4),
     version(1.0),
     helpstring("Upper case test")
   ]
   library ucasetest
   {
       [
         dllname("KERNEL32.DLL"),
         version(1.0),
         helpstring("Sleep function exported by kernel32.dll")
       ]
       module lcasetest {
           [
   			entry("Sleep"), 
   			helpstring("sleep - ucase test.")
   		]
           void _stdcall Sleep([in] long dwMS);
       };
   };

4. Create a Visual Basic Standard EXE project. Form1 is created by default.

5. On the Project menu, click to select References. In the References dialog
   box, browse to lcase.tlb and ucase.tlb, select both libraries, and then click
   OK.

6. Add the following code to Form1:

   Private Sub Form_Load()
       lcasetest.Sleep 1
       ucasetest.Sleep 1
   End Sub

7. On the File menu, click to Save the project, and then select Make
   Project1.exe to compile the project.

8. Run the executable, Project1.exe, and note that the form appears with no
   errors.

9. Copy Project1.exe to the Windows NT 4-based computer and run it. Note that an
   Access Violation occurs.

10. Copy and compile the same project on the Windows NT 4-based computer and run
   it on both the Windows NT 4- and Windows 2000-based computers. Note that it
   fails on the Windows 2000-based computer.

Additional query words: tlbpatch

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Keywords          : kbCompiler kbVBp kbVBp400bug kbVBp500bug kbVBp600bug kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400
Version           : :4.0,5.0,6.0
Issue type        : kbbug
Solution Type     : kbnofix

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Copyright Microsoft Corporation 2001.