未定义对“ vtable for MAA”的引用

Question

在编程过程中，我收到一条我无法解决的错误消息。请帮忙！ 关于第23行（声明了MAA类的地方）的错误消息：“未定义对'vtable for MAA的引用'”

class MAA : public IAA {
    friend class Builder;
public:
    void executar() override;
private:
    void autenticar() override;
};

class IAA { friend class Builder; public: virtual void executar() = 0; virtual ~IAA() {} private: virtual void autenticar() = 0; protected: Controller* controller = nullptr; ISA* servico = nullptr; };