Compiler Warning (level 4) C4435
This warning is off by default. See Compiler Warnings That Are Off by Default for more information.
Under the default compile option of /vd1, the derived class does not have a vtordisp field for the indicated virtual base. If /vd2 or #pragma vtordisp(2) is in effect, a vtordisp field will be present, changing the object layout. This can lead to binary compatibility problems if interacting modules are compiled with different vtordisp settings.