Someone

class classA
{};

class classB
{};

class Test
{
    struct SomeStruct
    {
        ClassA var1;
        ClassB var2;
    };
    SomeStruct test1;

    // once test1 is used within this function my debugger will report that var1 and var2 within test1 are 'incomplete types'
    void SomeFunc();
};