Spot the bug(s)

#include <cstring>
#include <iostream>

class Array
{
public:
    Array()
        : m_data (new int[10] )
    {
    }
        ~Array()
    {
        delete[] m_data;
    }

    Array & operator=( const Array & other)
    {
        memcpy( m_data, other.m_data, sizeof(4)*10 );
        return *this;
    }
    int * m_data;
};

class User
{
public:
    User()
    {
    }

    ~User()
    {
    }

    User operator=( const User& other )
    {
        if(this == &other)return *this;
        m_f1 = other.m_f1;
        m_f2 = other.m_f2;
        m_array = other.m_array;
        return *this;
    }

    int & getFirstOfArray()
    {
        return m_array.m_data[0];
    }

private:
    int m_f1;
    double m_f2;
    Array m_array;
};

class Test
{
public:
    void SetUser( const User & user )
    {
        m_user = user;
    }
    int & getFirstOfArray()
    {
        return m_user.getFirstOfArray();
    }
private:
    User m_user;

};

int main(int argc, char** argv )
{
    Test test;
    User newUser;
    newUser.getFirstOfArray() = 255;
    std::cout << newUser.getFirstOfArray() << std::endl;

    test.SetUser( newUser );
    std::cout << test.getFirstOfArray() << std::endl; //invalid memory usage, potentially crash!

    return 0;
}