Q141459: PRB: Can’t Export from Static Libraries w/_declspec(dllexport)

Article: Q141459
Product(s): Microsoft Programming Utilities
Version(s): 1.0,2.0,2.1,2.2,4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbtshoot kbVC200 kbVC210 kbVC220 kbVC400 kbVC500 kbVC600
Last Modified: 01-JAN-2001

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The information in this article applies to:

- The Microsoft Linker (LINK.EXE), version 1.0, used with:
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2, 4.0, 5.0, 6.0 
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SYMPTOMS
========

When you build a DLL from component libraries (.lib files) that have functions
declared with _declspec(dllexport) to export them from the DLL, the functions
aren't exported or even included in the DLL. If you use the linker /warn option,
the linker will display the LNK4005 warning to indicate that no .obj files were
included from the static libraries.

RESOLUTION
==========

For the functions to be exported and included in the DLL, you must list the
functions to be exported in a .def file, or use the linker /export option when
building the DLL.

NOTE: This is only necessary when the functions are contained in .lib files that
are used to build a DLL.

The following sample code illustrates this scenario, and shows how you can make
sure the exported functions are included.

Sample Code
-----------

     /* Compile options needed: none
     */ 

     /* EXPORT.C */ 

     __declspec( dllexport ) void func()
     {
     }

     @rem **** Buildit.bat

     cl /MT /c export.c

     @rem **** build static library

     link /lib /out:static.lib export.obj

     @rem **** build DLL

     link /dll /machine:ix86 /warn /out:export.dll static.lib

     @rem **** using the following link line instead of the previous one
     @rem **** solves the problem: have to force a reference to func so it is
          **** included

     @rem link /dll /machine:ix86 /warn /export:func /out:export.dll
     static.lib

     dumpbin /exports export.dll

     rem **** DUMPBIN should have reported func as exported

STATUS
======

This behavior is by design.

Additional query words:

======================================================================
Keywords          : kbcode kbtshoot kbVC200 kbVC210 kbVC220 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbLINKSearch
Version           : :1.0,2.0,2.1,2.2,4.0,5.0,6.0
Issue type        : kbprb

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