Problem linking a LIB, a DLL and a EXE together in VisualStudio 2010

Hi everybody,

I encountered a problem with a project which contains one LIB, one DLL and one EXE in a way the DLL uses functions from the LIB, the EXE uses function from the LIB and the DLL.

In this case it seems all symbols exported by the LIB are linked twice, once into the DLL, once into the EXE. This at least blows up the resulting binaries. Further this causes i.e. global variables from the LIB aren't really global, there's one instance in the DLL and another one in the EXE, so the use of global variables from the LIB doesn't work as expected.

Does anyone know if there's a way to workaround this? Since for the DLL a LIB is built too maybe it's possible to link the other LIB into it - any ideas?

You can follow these steps if you want to reproduce the problem:

- Create a solution with a console application (below called LibTest), a LIB (BaseLib) and a DLL (ExtLib)
- In 'Common Properties->Framework and References' add the LIB as reference in the DLL and add both the LIB and the DLL as reference in the EXE.
- Implement the following functions in the appropriate files:

// BASE.H
#include <ostream>

extern int baseval;
extern void foo( std::ostream& os );

// BASE.CPP
#include "Base.h"

int baseval = 42;

void foo( std::ostream& os )
{
	os << "foo() called, &foo = 0x" << std::hex << &foo << ", &baseval = 0x" << &baseval << std::endl;
}

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// EXTLIB.H
#include <iostream>

#ifdef EXTLIB_EXPORTS
#define EXTLIB_API __declspec(dllexport)
#else
#define EXTLIB_API __declspec(dllimport)
#endif

EXTLIB_API void bar( std::ostream& os );

// EXTLIB.CPP
#include "ExtLib.h"
#include "../BaseLib/Base.h"

EXTLIB_API void bar( std::ostream& os )
{
	foo( os );
}

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// LIBTEST.CPP
#include <iostream>
#include <tchar.h>

#include "../BaseLib/Base.h"
#include "../ExtLib/ExtLib.h"

int _tmain(int argc, _TCHAR* argv[])
{
	foo( std::cout );
	bar( std::cout );
	return 0;
}

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(I unset the 'Use precompiled header' setting, you can do so too or add #include "stdafx.h" to every CPP file).

When I run this program the output is like

foo() called, &foo = 0x00C910A0, &baseval = 0x00C93018
foo() called, &foo = 0x5AD21080, &baseval = 0x5AD23010

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When I change the DLL to build to a LIB instead the same doesn't happen, there the output looks like

foo() called, &foo = 0x00AE10E0, &baseval = 0x00AE3018
foo() called, &foo = 0x00AE10E0, &baseval = 0x00AE3018

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Thanks in advance,

best regards,

ZOPPO