Linker error when compiling vshadow, part of the Volume Shadow Copy Service SDK

Question

I am getting this linker error when trying to compile the c++ project for the VSS SDK

Error   1 error LNK2019: unresolved external symbol "long __stdcall ShouldBlockRevert(wchar_t const *,bool *)" (?ShouldBlockRevert@@YGJPB_WPA_N@Z) referenced in function "public: void __thiscall VssClient::RevertToSnapshot(struct _GUID)" (?RevertToSnapshot@VssClient@@QAEXU_GUID@@@Z) revert.obj vshadow

The ShouldBlockRevert is used twice, once when it is declared at the top, and once when it is actually used.

Declared here:

HRESULT APIENTRY ShouldBlockRevert(IN LPCWSTR wszVolumeName, OUT bool* pbBlock);

and used here:

CHECK_COM(::ShouldBlockRevert(Snap.m_pwszOriginalVolumeName, &bBlock));
    if (bBlock)
    {
        ft.WriteLine(L"Revert is disabled on the volume %s because of writers",
                Snap.m_pwszOriginalVolumeName);
        return;
    }

Sorry, I'm not that good with c++.

Answer 1

According to this blog post:

As it happens, I ran dumpbin /exports on vssapi.lib, and found that it does export ShouldBlockRevert, but thanks to C++ name mangling the mangled name is different. Why is it different? Because in vssapi.lib, the first argument to ShouldBlockRevert isn’t wchar_t, it’s unsigned short. “So what”, you’re thinking, “they’re equivalent”. And I don’t disagree, but the compiler treats them as different types for name manging purposes. What’s the fix? Well, disable the intrinsic wchar_t type in the C/C++ Language property page in the project properties (equivalent to the /Zc:wchar_t- switch if you’re one of the two people on the planet who build Visual C++ projects with makefiles).

Once that’s done, the LPCWSTR macro is defined to unsigned short, name mangling matches, planets align, and you can link. QED.