warning C4251: 'CObj1::m_Obj2 : class 'CObj2' needs to have dll-interface to be used by clients of class 'CObj1'

[Stephen Howe]

Hi

Using VS2005 Professional

I have bog-standard Win32 DLL, and it has an export header file like so

#ifdef MOD_EXPORTS
#define MOD_API __declspec(dllexport)
#else
#define MOD_API __declspec(dllimport)
#endif

class MOD_API CObj1
{

private:
CObj2 m_Obj2;
};


Now CObj2 resides in a proper library file (not an import library but a real library)
Both the Win32 DLL and the proper library use the RTL in DLL form yet I am getting

warning C4251: 'CObj1::m_Obj2 : class 'CObj2' needs to have dll-interface to be used by clients of class 'CObj1'

How do I eliminate this warning correctly (I dont mean shut the compiler up with a pragma, but I do if the warning is spurious)?
For that matter, how do I give CObj2 a DLL interface?

Thanks

Stephen Howe

[Igor Tandetnik]

Post by Stephen Howe
I have bog-standard Win32 DLL, and it has an export header file like so
#ifdef MOD_EXPORTS
#define MOD_API __declspec(dllexport)
#else
#define MOD_API __declspec(dllimport)
#endif
class MOD_API CObj1
{
CObj2 m_Obj2;
};
Now CObj2 resides in a proper library file (not an import library but
a real library)
Both the Win32 DLL and the proper library use the RTL in DLL form yet I am getting
warning C4251: 'CObj1::m_Obj2 : class 'CObj2' needs to have
dll-interface to be used by clients of class 'CObj1'
How do I eliminate this warning correctly (I dont mean shut the
compiler up with a pragma, but I do if the warning is spurious)? For
that matter, how do I give CObj2 a DLL interface?

You give it a DLL interface the same way you gave it to CObj1:

class MOD_API CObj2 {...};

The compiler probably could have realized that m_Obj2 is private and inaccessible to clients of CObj1, but it doesn't. It assumes that, if a class is exported to a DLL, all its members' types should also be exported.

[Stephen Howe]

Post by Igor Tandetnik

Post by Stephen Howe
How do I eliminate this warning correctly (I dont mean shut the
compiler up with a pragma, but I do if the warning is spurious)? For
that matter, how do I give CObj2 a DLL interface?

class MOD_API CObj2 {...};
The compiler probably could have realized that m_Obj2 is private and inaccessible to clients of CObj1, but it doesn't. It assumes that, if a class is exported to a DLL, all its members' types should also be exported.

So that means the warning is spurious Igor?
I hope MS updates the warning so it is issued under more restricted circumstances (i.e. when relevant)

The class is internal to the main class. It is actually a wrapper around FILE * (so that it if the destructor is called and the
file is still open, it is closed).

Thanks

Stephen Howe

[Igor Tandetnik]

Post by Stephen Howe

Post by Igor Tandetnik

Post by Stephen Howe
How do I eliminate this warning correctly (I dont mean shut the
compiler up with a pragma, but I do if the warning is spurious)? For
that matter, how do I give CObj2 a DLL interface?

class MOD_API CObj2 {...};
The compiler probably could have realized that m_Obj2 is private and inaccessible to clients of CObj1, but it doesn't. It
assumes that, if a class is exported to a DLL, all its members' types should also be exported.

So that means the warning is spurious Igor?

If CObj2 is not accessible to external clients by any means, then yes it is.