Struct hack equivalent in C++

Question

The struct hack where you have an array of length 0 as the last member of a struct from C90 and C99 is well known, and with the introduction of flexible array members in C99

Answer 1

This is C++, so templates are available:

template 
struct hack {
    int filler;
    int thing [N];
};

Casting between different pointers to different instantiations will be the difficult issue, then.