static_cast error with Visual Studio .NET but not with VC6

Posted on 2003-10-31
Last Modified: 2008-02-01
I use a third party code to implement a plug-in architecture in my application (the code:

The code works fine with the compiler of VC6 but when I compile with VS .NET I received a lot of errors C2440 like this one:

static_cast' : cannot convert from 'int (__thiscall CViewInPlugIn::* )(LPCREATESTRUCT)' to 'int (__thiscall CWnd::* )(LPCREATESTRUCT)'
CViewInPlugIn is derived from CPlugInMap and CPlugInMap is derived from CCmdTarget. Maybe the new compiler can't cast a CCmdTarget class to a CWnd class? I know that VS.NET Compiler is more strict with Message Map but I don't know how to resolve or bypass this problem.

Here some parts of my code:

class CViewInPlugIn : public CPlugInMap  
      // ClassWizard generated virtual function overrides
      afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);

//Here my implementation

int CViewInPlugIn::OnCreate(LPCREATESTRUCT lpCreateStruct)

      return TRUE ;

and the declaration of CPlugInMap:
class _PLUGIN_API CPlugInMap : public CCmdTarget
      friend class CPlugInApp ;


Question by:Frankbe
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LVL 48

Accepted Solution

AlexFM earned 500 total points
ID: 9660628
I reproduced this error compiling the sample application from CodeProject. PlugIn1 project, MFExamplePI.cpp, lines:


The same error message in ON_WM_CREATE line. Solution - add the following lines in the beginning of cpp file:

#define ON_WM_CREATE() \
    { WM_CREATE, 0, 0, 0, AfxSig_is, \
        (AFX_PMSG) (AFX_PMSGW) \
        (reinterpret_cast< int (AFX_MSG_CALL CWnd::*)(LPCREATESTRUCT) > (OnCreate)) },

This is ON_WM_CREATE macro with static_cast replaced by reinterpret_cast. Not so nice, but should work.

Author Comment

ID: 9667051
When you execute the compiled program, do you receive an unhandled exception : access violation reading location 0x00000000?
LVL 48

Expert Comment

ID: 9669246
Actually, I didn't execute it at all. Possibly it contains some bugs, I don't know. If this happens also in VC++ 6, this is not result of ON_WM_CREATE compilation problem.

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