C++ (Qt)
template <class T>
class pointer_wrapper
{
public:
    pointer_wrapper(const T * p) : ptr(p) {}
 
    template <class R>
    friend bool operator<(const pointer_wrapper<R> &, const pointer_wrapper<R>&);
 
private:
    const T * ptr;
};
 
template <class R>
bool operator<(const pointer_wrapper<R> & x, const pointer_wrapper<R> & y)
{
    return *(x.ptr) < *(y.ptr);
}
 
 
std::map <pointer_wrapper<MyStruct> , int> theMap;
 

C++ (Qt)
MyStruct * myStruct;
theMap[myStruct] = 1;
...
 
theMap[pointer_wrapper(myStruct)] = 1;
...