Compiler Warning (level 4) C4435
'class1' : Object layout under /vd2 will change due to virtual base 'class2'
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.
Example
The following sample generates C4435.
// C4435.cpp
// compile with: /c /W4
#pragma warning(default : 4435)
class A
{
public:
virtual ~A() {}
};
class B : public virtual A // C4435
{};