C奇怪的编译错误：错误：从“对象”类改变“对象”的含义

game.h:16:error: declaration of ‘Player* HalfSet::Player() const’

players.h:11:error: changes meaning of ‘Player’ from ‘class Player’

game.h:21:error: ‘Player’ is not a type

player.h文件(部分)

#ifndef PLAYERS_H
#define PLAYERS_H
using namespace std;

#include <string>
#include <vector>
#include <istream>
#include <iomanip>
#include "generics.h"

class Player{ //Line 11
public:
    //getters
    long Id() const;
    string FirstName() const;
    string LastName() const;
    string Country() const;
    //setters
    void setId(long id);
    void setFirstName(string s);
    void setLastName(string s);
    void setCountry(string s);
    //serializing functions
    void display(ostream &out);
    void read(istream &in);
    void write(ostream &out);
    //Initalizers
    Player();
    Player(istream &in);
    Player(string firstName,string lastName);
    Player(string firstName,string lastName,string country);
    Player(long id,string firstName,string country);
    ~Player();
private:
    long _id;
    string _firstName;
    string _lastName;
    string _country;
};

game.h文件(部分)

#ifndef GAME_H
#define GAME_H

#include "generics.h"
#include "players.h"
#include <string>
#include <vector>
#include <istream>
#include <iomanip>

using namespace std;

class HalfSet{
public:
    //getters
    Player* Player() const; //Line 16
    int GamesWon() const;
    int TotalPoints() const;
    int Errors() const;
    //setters
    void setPlayer(Player* p);
    void setGamesWon(int games);
    void setTotalPoints(int points);
    void setErrors(int errors);
    //Serialization
    void display(ostream &out) const;
    void read(istream &in) const;
    void write(ostream &out) const;
    //Initalizers
    HalfSet();
    ~HalfSet();
private:
    Player* _player;
    int _gamesWon;
    int _points;
    int _errors;
};

这里发生了什么？