PRB: L2029 Error on AFX_EXCEPTION_LINK When Building MFC DLL

The information in this article applies to:

• Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52

SYMPTOMS

When building a DLL that uses the Microsoft Foundation Classes (MFC), the Visual C++ linker reports the following error:

   error L2029: 'public: __far __pascal
   AFX_EXCEPTION_LINK::AFX_EXCEPTION_LINK(void)__near' :
   unresolved external

CAUSE

The MFC User DLL (_USRDLL) or Extension DLL (_AFXDLL) that you are building is made up of static libraries (.LIB) that also contain MFC code, and there is a TRY/CATCH/END_CATCH block in the static library code.

The problem occurs because of the compiler options used to build the static library. AFX_EXCEPTION_LINK needs to be defined as a __far struct rather than as a __near struct.

RESOLUTION

You need to make sure the static libraries are compiled with the same options you use to build the _USRDLL or _AFXDLL because that is where the code is being used. For example, you need to define the preprocessor symbol "_USRDLL" for _USRDLLs, and "_AFXDLL" for _AFXDLLs. You also need to compile for large memory model for both types of DLLs.

STATUS

This behavior is by design.

MORE INFORMATION

For more information on building _USRDLLs, please see MFC Tech Note 11. For more information on building _AFXDLLs, please see MFC Tech Note 33.