Visual Studio allows unrelated class method to access nested private class? - c++

Question

I am trying to build my project on both linux and windows. The project is already working on windows but I am facing a very weird error on GCC. Consider the following code:
Class Base {
private:
MessageInfo *createMsg();
}
Class MessageInfo {
private:
class Message{
...
}
public:
Message *messages[MAX_NO_MESSAGES];
...
}
MessageInfo *Base::createMsg(){
...
MessageInfo *newMsg = new MessageInfo;
newMsg->messages[i] = new MessageInfo::Message();
...
}
Now the problem is that in Visual Studio every thing compiles but in GCC I get the following error:
*Error: Class MessageInfo::Message is private
I am really surprised that the code actually compiles in Visual Studio but not in GCC. Any Suggestions???
EDIT:
I think I have to ask my question in a better way. My question is how is that even possible to compile such code in VS 2005??? I tried my code in VS2013 and it gave me the same error as GCC. So I am not arguing that the code is correct!

Answer 1

This does not compile in Visual Studio 2013:
class MessageInfo {
class Message { };
public:
Message *messages[256];
};
class Base {
MessageInfo *createMsg();
};
MessageInfo *Base::createMsg() {
MessageInfo *newMsg = new MessageInfo;
newMsg->messages[0] = new MessageInfo::Message(); // won't compile
}
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
The error, as you would expect, is:
error C2248: 'MessageInfo::Message' : cannot access private class declared in class 'MessageInfo'

Answer 2

Compilers are so different and I'm not really sure why VS would allow that to compile, any compiler I've used would have thrown a compile error.
What you're doing though is a bad way to think of a class. If you have the
class Message {...};
private in MessageInfo, then you shouldn't be able to access it anywhere outside of the class. We would only want Message to be available inside of the MessageInfo class and nowhere else. So you shouldn't return a Message* as you do in MessageInfo and you won't be able to access the Message() constructor as you do in main. Programming this way isn't allowed because otherwise it would completely goes against the purpose of encapsulation. If you really do want Message to be available to anyone, then make it public, but usually the inner workings of a class are hidden away from the user good reason: they shouldn't need to worry about it.

Answer 3

As suggested by egrunin I used the code that he suggested in his comment. Apparently you cannot compile that code in Visual Studio 2013 but I successfully compiled it on my machine using Visual Studio 2005. Here is the complete code that
used:
// Test.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
class MessageInfo {
class Message { };
public:
Message *messages[256];
};
class Base {
MessageInfo *createMsg();
};
MessageInfo *Base::createMsg() {
MessageInfo *newMsg = new MessageInfo;
newMsg->messages[0] = new MessageInfo::Message(); // won't compile
return newMsg;
}
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
Am I doing some thing wrong here???
P.S:
I tried the code on Visual Studio 2010 and I got the cannot access private class declared in class 'MessageInfo' error!! Can anyone compile this code on Visual Studio 2005 so that I know what is wrong with VS 2005????