/vdn - Suppress or Enable Virtual Base Class (Windows CE 5.0)
This option, /vdn where n is zero or one, applies only to C++ code that uses virtual bases.
If a derived class overrides a virtual function that it inherits from a virtual base class, and a constructor or a destructor for the derived base class calls that function using a pointer to the virtual base class, the compiler might introduce additional hidden vtordisp fields into the classes with virtual bases.
The /vd0 option suppresses the addition of the hidden vtordisp constructor or destructor displacement member. The /vd1 option, the default, enables them where they are necessary.
Turn off vtordisps only if you are sure that all class constructors and destructors call virtual functions virtually.
The /vd option affects an entire compilation module. Use the vtordisp pragma to suppress and then re-enable vtordisp fields on a class-by-class basis.
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