错误 - 无效使用不完整的类型/转发声明

Question

我的问题很常见,但我一直在寻找和尝试我找到的所有解决方案,但仍然无效.所以任何帮助将不胜感激!=)

提前致谢!

我在编译时遇到此错误:

g++ -ISFML/include -Iclasses/ -W -Wall -Werror   -c -o classes/Object.o classes/Object.cpp
In file included from classes/Core.hh:18:0,
         from classes/Object.hh:4,
         from classes/Object.cpp:1:
classes/MapLink.hh:9:1: error: invalid use of incomplete type ‘struct Object’
classes/MapLink.hh:6:7: error: forward declaration of ‘struct Object’
In file included from classes/Core.hh:19:0,
         from classes/Object.hh:4,
         from classes/Object.cpp:1:
classes/Player.hh:9:1: error: invalid use of incomplete type ‘struct Object’
classes/MapLink.hh:6:7: error: forward declaration of ‘struct Object’
make: *** [classes/Object.o] Error 1

所以基本上,我有一个主要包含(main.cpp)

#include "Core.hh"

int        main(void)
{
  ...
}

这是包含我所有包含的头文件(Core.hh)

#ifndef __CORE_HH__
# define __CORE_HH__

#include ...
#include "Object.hh"
#include "MapLink.hh"
#include "Player.hh"

class Core
{
  ...
};

#endif /* __CORE_HH__ */

然后是导致我麻烦的文件(Object.hh)

#ifndef __OBJECT_HH__
# define __OBJECT_HH__

#include "Core.hh"

class Object
{
  ...
};

#endif /* __OBJECT_HH__ */

(MapLink.hh)

#ifndef __MAPLINK_H__
# define __MAPLINK_H__

#include "Core.hh"

class Object;

class MapLink : public Object
{
  ...
};

#endif /* __MAPLINK_H__ */

(Player.hh)

#ifndef __PLAYER_H__
# define __PLAYER_H__

#include "Core.hh"

class Object;

class Player : public Object
{
  ...
};

#endif /* __PLAYER_H__ */

Answer 1

问题#1:
您必须仅从完全声明的类派生,否则编译器将不知道该怎么做.
删除前向声明class Object;.

问题2:
你有一个循环依赖:

• 在"Core.hh"中包含"Object.hh","MapLink.hh"和"Player.hh".
• 在"Object.hh","MapLink.hh"和"Player.hh"中包含"Core.hh".

您需要确保每个类完全包含它继承的类.
我不确定这些类是如何相互作用的,你应该在问题中提供详细信息.
我的猜测是你需要修改你的内容如下:

• 修改"MapLink.hh"和"PlayerLink.hh",使它们包含"Object.hh",而不是"Core.hh"
• 修改"Object.hh",使其不包含"Core.hh".