Question

I have a Visual Studio 6 workspace I m trying to convert to a Visual Studio 2008 solution. The output of said solution is a .dll. It has to be a .dll and it needs to statically link MFC as I can t redistribute MFC to existing customers.

The solution consists of three projects, say A, B, C. C is the Active Project, outputs the .dll and depends on B. B outputs a .lib and depends on A. A outputs a .lib.

In the General configuration properties I have A and B set to Static Library (.lib) and C set to Dynamic Library (.dll). All three projects are set to "Use MFC in a Static Library." Also, all three projects are set to "Multi-threaded" for Runtime Library and none of them have _AFXDLL defined.

Everything builds correctly up until the final linking stage where I see this:

1>nafxcw.lib(wincore.obj) : error LNK2005: _IsPlatformNT already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _InitMultipleMonitorStubs already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xGetSystemMetrics@4 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xMonitorFromPoint@12 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xMonitorFromRect@8 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xMonitorFromWindow@8 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xGetMonitorInfo@8 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xEnumDisplayMonitors@16 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _xEnumDisplayDevices@16 already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnGetSystemMetrics already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnMonitorFromWindow already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnMonitorFromRect already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnMonitorFromPoint already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnGetMonitorInfo already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnEnumDisplayMonitors already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_pfnEnumDisplayDevices already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_fMultiMonInitDone already defined in A.lib(Globals.obj)
1>nafxcw.lib(wincore.obj) : error LNK2005: _g_fMultimonPlatformNT already defined in A.lib(Globals.obj)
1>nafxcw.lib(viewprnt.obj) : error LNK2005: "public: virtual int __thiscall CPrintingDialog::OnInitDialog(void)" (?OnInitDialog@CPrintingDialog@@UAEHXZ) already defined in B.lib(ImagePropertiesDlg.obj)
1>nafxcw.lib(viewprnt.obj) : error LNK2005: "public: __thiscall CPrintingDialog::CPrintingDialog(class CWnd *)" (??0CPrintingDialog@@QAE@PAVCWnd@@@Z) already defined in B.lib(ImagePropertiesDlg.obj)
1>nafxcw.lib(viewprnt.obj) : error LNK2005: "public: virtual void __thiscall CPrintingDialog::OnCancel(void)" (?OnCancel@CPrintingDialog@@UAEXXZ) already defined in B.lib(ImagePropertiesDlg.obj)

I ve Googled the problem to death and seen other people with a similarish issue, but can t seem to solve it. I tried adding nafxcw.lib to the Ignored libraries for C, but that turned this batch of linker errors into 1500+ unresolved symbol errors. I can get it to compile/link if I make it dynamically link MFC, but like I said, I need it to statically link. I feel like I m missing something rather simple but can t seem to wrap my head around it. Any and all random thoughts and ideas will be greatly appreciated.

Answer 1

As is often the case, the solution turned out to be so mundane and obvious, I m still kicking myself for banging my head on it for so long.

Basically, project A referenced above was not a project I directly pulled from the old VS6 workspace, but rather a project that had previously been converted by another team for use in another application. I assumed it was functionally equivalent to the original one, but that is very much not the case. These linking errors are actual, valid multiply defined linking errors. When I started digging in, I found that the first batch of errors was from including multimon.h in project A (something I don t even need, just removed it) and the second batch is from a class that is actually defined in both A and B.

Like I said, I m still groaning over here, but at least I should be able to fix my problem now. Thanks for the help and always remember to NEVER assume ANYTHING.

Answer 2

When you tried ignoring the nafxcw library, did you add it back in to try to force a link order as suggested by this KB article? While your problem isn t an exact fit it may be related. Perhaps things could be resolved by monkeying with the link order.

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