c ++错误C2662不能将'this'指针从'const Type'转换为'Type&'

我试图重载c ++操作符==但是得到一些错误...

I am trying to overload the c++ operator== but im getting some errors...

错误C2662：'CombatEvent :: getType'：无法转换'this 'const CombatEvent'指向'CombatEvent&'

error C2662: 'CombatEvent::getType' : cannot convert 'this' pointer from 'const CombatEvent' to 'CombatEvent &'

此错误在此行

if (lhs.getType() == rhs.getType())

查看下面的代码：

class CombatEvent {

public:
    CombatEvent(void);
    ~CombatEvent(void);

    enum CombatEventType {
        AttackingType,
        ...
        LowResourcesType
    };

    CombatEventType getType();
    BaseAgent* getAgent();

    friend bool operator<(const CombatEvent& lhs, const CombatEvent& rhs) {

        if (lhs.getType() == rhs.getType())
            return true;

        return false;
    }

    friend bool operator==(const CombatEvent& lhs, const CombatEvent& rhs) {

        if (lhs.getType() == rhs.getType())
            return true;

        return false;
    }

private: 
    UnitType unitType;
}

可以帮助吗？