错误LNK2001：未解析的外部符号CATID_AppContainerCompatible

Question

I am trying to register BHO with APPcontainer.Now as per the blog http://blogs.msdn.com/b/ieinternals/archive/2012/03/23/understanding-ie10-enhanced-protected-mode-network-security-addons-cookies-metro-desktop.aspx

,I have defined following in same cpp file as DLLRegister

DEFINE_GUID(CATID_AppContainerCompatible, 0x59fb2056,0xd625,0x48d0,0xa9,0x44,0x1a,0x85,0xb5,0xab,0x26,0x40);    


STDAPI DllRegisterServer(void)
{
    // let ATL handle this
    HRESULT hr = _AtlModule.DllRegisterServer();

    ICatRegister* pcr = NULL ;

        hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr, NULL, CLSCTX_INPROC_SERVER, IID_ICatRegister, (void**)&pcr);
        if (FAILED(hr))
            return hr;
        if (SUCCEEDED(hr))
        {
            // Register this category as being "implemented" by
            // the class.
            CATID rgcatid[1] ;
            rgcatid[0] = CATID_AppContainerCompatible;
            hr = pcr->RegisterClassImplCategories(CLSID_ABC, 1, rgcatid);
        }

When I try to compile this code I am getting following error:

unresolved external symbol CATID_AppContainerCompatible

Not sure why this is coming. I can navigate to CATID_AppContainerCompatible definition by right click on it. any suggesitons??

I solved the issue. since DEFINE_GUID declares GUID as extern I need to put const GUID CATID_AppContainerCompatible ; in my file .After putting that statement its compiling.

Answer 1

DEFINE_GUID behavior depends on presence of INITGUID definition. This is a very frequent problem, so it makes no sense to repeat the details once again, here is further reading: How to avoid error "LNK2001 unresolved external" by using DEFINE_GUID .

To avoid falling into this trap you can use __declspec(uuid(...)) specifier and let compiler sort GUIDs out automatically, eg:

class __declspec(uuid("{26AFA816-359E-4094-90A8-BA73DE0035FA}")) 
  AppContainerCompatible;
// ...
rgcatid[0] = __uuidof(AppContainerCompatible); //CATID_AppContainerCompatible;

More on this: Referencing GUIDs