Another broken 1D point implementation

anotherbrokenpoint.cpp

struct PointAgainBroken {
  private:
    int x_;
    void SetXToSeven() {
        this->x_ = 7;
    }
  public:
    PointAgainBroken(int x) : x_(x) {}

    int GetX() const {
        this->SetXToSeven(); // Compiler error: not allowed to call non-const member function on this.
        return this->x_;
    }  
};