title: MFC C++ LINK 2019: unresolved external symbol "public: __thiscall
body: <p>VC2012, I have a solution with many projects.<br>
  I have made a "Common" project that contains classes to be used from another projects (for general purpose).<br>
  Under "Common" I added a class named </p>
  
  <blockquote>
    <p>"PreRequisitesManager" (cpp+h)</p>
  </blockquote>
  
  <p>and interface </p>
  
  <blockquote>
    <p>(PreRequisitesInterface).</p>
  </blockquote>
  
  <p>On "Client" project (Added as dependency the "Common" project) I have class </p>
  
  <blockquote>
    <p>ClientDlg</p>
  </blockquote>
  
  <p>. the interface was added as needed and added a member of type </p>
  
  <blockquote>
    <p>'PreRequisitesManager'</p>
  </blockquote>
  
  <p>. </p>
  
  <blockquote>
    <p>The ClientDlg.h includes "PreRequisitesManager.h"<br>
    PreRequisitesManager includes the PreRequisitesInterface.h.</p>
  </blockquote>
  
  <p>I am getting this:  </p>
  
  <blockquote>
    <p>GetCVClientDlg.obj : error LNK2019: unresolved external symbol
    "public: __thiscall
    CPreRequisitesManager::~CPreRequisitesManager(void)"
    (??1CPreRequisitesManager@@QAE@XZ) referenced in function
    __unwindfunclet$??0CGetCVClientDlg@@QAE@PAVCWnd@@@Z$0 GetCVClientDlg.obj : error LNK2019: unresolved external symbol
    "public: __thiscall
    CPreRequisitesManager::CPreRequisitesManager(void)"
    (??0CPreRequisitesManager@@QAE@XZ) referenced in function "public:
    __thiscall CGetCVClientDlg::CGetCVClientDlg(class CWnd *)" (??0CGetCVClientDlg@@QAE@PAVCWnd@@@Z) .</p>
  </blockquote>