C / C++ / MFC

bool IsEqualRel(double a, double b, double eps = 1e-5)
{
  _ASSERTE(a!= 0 && b != 0);
  if (a==b) return true;
  if (a<0 != b<0) return false;
  return fabs((a-b)/a+b)) < eps;
}

bool IsZero(double a, double eps = 1e-5)
{
  return a==0 || fabs(a) < eps;
}

// RelBugRepro.cpp : reproduces a seemingly optimizer problem in VC& SP5 or SP6
// an annotated version is also available

#include <comdef.h>

// ------------ HELPER -----------------------------------------
// Mostly mock objects and -functions.  For the actual function exposing the issue, see below
inline GUID GetSomeID()
{
   static const GUID someid_ = 
   { 0x11112222, 0x3333, 0x4444, { 0x55, 0x55, 0x66, 0x66, 0x77, 0x77, 0x88, 0x88 } };
   
   return someid_;
}

IUnknownPtr GetSomeUnknown()  // I need a working IUnknown, I guess a mock would do, too
{
   try
   {
      static IUnknownPtr unk;
      struct __declspec(uuid("{CFC399AF-D876-11d0-9C10-00C04FC99C8E}")) idMSXML;
      if (unk==NULL)
         unk.CreateInstance(__uuidof(idMSXML));
      if (unk != NULL)
         return unk;
   }
   catch(...) {} 

   DebugBreak(); // failed to create object, some other problem
   return NULL;
}

// inheriting twice from IUnknownPtr. Of course the original is a bit more functional :)
struct CPtrWrap : IUnknownPtr
{
    CPtrWrap(IUnknownPtr unk) : IUnknownPtr(unk) {}
};

struct CFinalPtr : public CPtrWrap
{
   CFinalPtr(CPtrWrap psw) : CPtrWrap(psw) {}
};

// this function gets called with invalid parameters
static IUnknownPtr GetItem(GUID id, long l0, long l1)
{
   return (id == GetSomeID()) ? GetSomeUnknown() : NULL;
}

// mock for MFC CCmdUI
struct CEnableMe
{
   virtual void Enable(BOOL bOn = TRUE) {}
};


// mock for MFC CWinApp
struct CMyOneApp
{
   int m_mainFrame;
   CMyOneApp() : m_mainFrame(1) {}
   void UpdateEditDuplicate(CEnableMe * pCmdUI);
};

// ========= the function in question ===================
void CMyOneApp::UpdateEditDuplicate(CEnableMe * pCmdUI) 
{
   try {
      bool enable = false;

      { 
         rand();
         GUID ParentID = GetSomeID();
         CFinalPtr itParent = GetItem(ParentID, 0, 0);

         if (itParent == NULL) _com_issue_error(E_POINTER);
         enable = m_mainFrame != NULL;
      }
      pCmdUI->Enable( enable );
      return;
   } catch(_com_error ce)
   {  
      // Anything goes here
      OutputDebugString(" *********** FAILED ***********\n");
   }
}                                                                                


// ------------ WinMain --------------------
int APIENTRY WinMain(HINSTANCE,HINSTANCE,LPSTR,int)
{
   CEnableMe cmdUI;
   CoInitialize(0); // required since we call the GetUnknown
   
   CMyOneApp app;
   app.UpdateEditDuplicate(&cmdUI);
   return 0;
   CoUninitialize();
}

--------------------Configuration: RelBugRepro - Win32 Release--------------------
Compiling...
RelBugRepro.cpp
Linking...
LINK : warning LNK4089: all references to "OLEAUT32.dll" discarded by /OPT:REF

RelBugRepro.exe - 0 error(s), 1 warning(s)

struct B : public A
{  
   B(A a) : A(a) {}
};

struct C : public B
{  
   C(B b) : B(b) {}
};