Unknown override specifier + missing type specifier
<p>I'm using Visual Studio 2015 Update 2.
I have two headers called Error.h and Game.h.</p>

<p>Error.h:</p>

<pre><code>#ifndef _Error_H
#define _Error_H

#include "Main.h"
#include "Core.h"
#include &lt;Log.h&gt;
#include &lt;CWindows.h&gt;

// ErrorIDs
enum
{
    ErrUnknownID = 0,
    blah,
    blah2,
    blah3
};

struct ErrInfo
{
    unsigned int  eiID;
    String        strCaption; // String is another class which implemented from std::string which works fine!
    String        strText;
    bool          bFixable = false;
};

// Static errors
extern ErrInfo WinNotSupported;
// blah blah

class Error
{

public:
    void Initialize();
    bool ShowError(ErrInfo ErrorInfo);
    BOOL FixError(unsigned int uiErrorID);

    // -----------------------------------------
    // --------------- Singleton ---------------
    // -----------------------------------------
public:
    static Error&amp; Instance()
    {
        static Error instance;
        return instance;
    }

    static Error *InstancePtr()
    {
        return &amp;Instance();
    }
private:
    Error()
    {

    }

public:
    Error(Error const&amp;) = delete;
    void operator=(Error const&amp;) = delete;
};

#endif // !_Error_H
</code></pre>

<p>And Game.h:</p>

<pre><code>#ifndef _Game_H
#define _Game_H

#include "Main.h"
#include "Error.h"
#include "Core.h"
#include &lt;CWindows.h&gt;
#include &lt;AFile.h&gt;

struct missingfileSt
{
    String    strFileURL;
    String    strDLFileName;
    String    strFileName;
    String    strChecksum;
    long long llSize;
    ErrInfo   errError; // Many errors here &lt;-
};

struct deletablefileSt
{
    String  strFileName;
    ErrInfo errError; // Many errors here too
};

#define siMissingFiles   7
#define siDeletableFiles 5

class Game
{
public:

    void ValidateFiles();
    DWORD dwGamePID;
    missingfileSt   mfMissingFiles[siMissingFiles];
    deletablefileSt dfDeletableFiles[siDeletableFiles];

    // -----------------------------------------
    // --------------- Singleton ---------------
    // -----------------------------------------
public:
    static Game&amp; Instance()
    {
        static Game instance;
        return instance;
    }

    static Game *InstancePtr()
    {
        return &amp;Instance();
    }
private:
    Game()
    {
        dwGamePID = 0;
    }

public:
    Game(Game const&amp;) = delete;
    void operator=(Game const&amp;) = delete;
};

#endif // !_Game_H
</code></pre>

<p>Now, when I compile I get many errors from Game.h and all of them are:</p>

<pre><code>Error C3646 'errError': unknown override specifier
Error C4430 missing type specifier - int assumed. Note: C++ does not support default-int
</code></pre>

<p>I got really confused, why errors!?
Also I must say, in header Core.h it will include Error.h again but it mustn't be problem!</p>