I would suggest not mixing C and C++ syntax. You are bound to get very confused.
C++ syntax for what you are trying is:
struct MyFirstStruct
{
int i;
};
struct MySecondStruct : public MyFirstStruct
{
int j;
};
I suspect that VA will have no problem with this syntax. I would be surprised that mixing the syntaxes as you have in your example works, but then again we are talking about the liberal Microsoft compiler, here.