An initializer list bug

    // point.h
    class Graph { /*...*/ };
    class Point {
    private:
        Graph& m_g;
        int    m_x;
        int    m_y;
    public:
        Point( Graph& g, int x, int y );
    };
    // point.cpp
    Point::Point( Graph& g, int x, int y )
    :   m_g( g ),
        m_x( x ),
        m_y( m_x ) // UH-OH... m_x could still be garbage,
    {}             // so m_y might get it, too!
    // main.cpp
    void main()
    {
        Graph gr;
        Point pt( gr, 10, 20 );
    }

• Nice demo of GIGO principal in action: garbage in, garbage out!