Q192539: FIX: ‘using namespace std’ Before Friend Operator Fails Compile

Article: Q192539
Product(s): Microsoft C Compiler
Version(s): winnt:6.0
Operating System(s): 
Keyword(s): kberrmsg kbservicepack kbLangCPP kbVC600bug kbVS600sp2 kbVS600SP1 kbVS600sp3fix
Last Modified: 08-MAY-2002

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

When a "using namespace std" directive is placed before a friend operator
declaration, you may get one of the following two errors:

Case 1
------

  error C2248: [member variable name] : cannot access private member declared
  in class [class name] [file name] (line number) : see declaration of [member
  variable]

Case 2
------

  [file name](line number) : fatal error C1001: INTERNAL COMPILER ERROR

  (compiler file 'msc1.cpp', line 1786)
  Please choose the Technical Support command on the Visual C++ Help menu, or
  open the Technical Support help file for more information.

  Error executing cl.exe.

CAUSE
=====

The friend operator resolution fails in the compiler front-end when std
namespace is introduced.

RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem. This fix may receive additional
testing at a later time, to further ensure product quality. Therefore, if you
are not severely affected by this problem, Microsoft recommends that you wait
for the next Service Pack 3 for Visual Studio 6.0 that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services
to obtain the fix. For a complete list of Microsoft Product Support Services
phone numbers and information about support costs, please go to the following
address on the World Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English version of this fix should have the following file attributes or
later:

  Date      Time      Size        File Name  Version#      Platform
  -----------------------------------------------------------------

  9/15/98   08:26p    1,183,795   C1xx.dll   12.00.8257.0  (x86)



Workaround
----------

Do one of the following to work around this problem:

- Move the "using namespace std" directive after the friend operator
  declaration.
- Avoid using the "using namespace std" directive.
- Forward declare the operator and/or class.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.This bug was corrected in Visual Studio 6.0 Service
Pack 3. For more information about Visual Studio service packs, please see the
following articles in the Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION
================

Test1.cpp Reproduces the C2248 Error in Case 1
----------------------------------------------

     // test1.cpp
     // Compiler options needed: cl /c /GX
     #include <iostream>

     using namespace std;

     #ifdef WORKAROUND
     class CMyClass;
     ostream& operator <<(ostream &, const CMyClass &);
     #endif // WORKAROUND

     class CMyClass
     {
     public:

       friend ostream& operator <<(ostream &, const CMyClass &);
       // An alternative workaround is to define the operator in the
       // class declaration. In this case it is not necessary to forward
       // declare the class and friend function.

     private:

        int value;
     };

     ostream& operator <<(ostream& out, const CMyClass& m)
     {

        int i = m.value;  // C2248 Error
        return out;
     }

     void main()
     { }

Test2.cpp Reproduces the C1001 Error in Case 2
----------------------------------------------

     // test2.cpp
     // Compiler options needed: cl /c /GX
     #include <iostream>

     using namespace std;

     #ifdef WORKAROUND
     int operator+(int, const class &);
     #endif // WORKAROUND

     class CMyClass
     {
     public:

       friend int operator+(int, const CMyClass &);  // C1001 Error.

     };

     void main()
     { }

======================================================================
Keywords          : kberrmsg kbservicepack kbLangCPP kbVC600bug kbVS600sp2 kbVS600SP1 kbVS600sp3fix 
Technology        : kbVCsearch kbAudDeveloper kbVC600 kbVC32bitSearch
Version           : winnt:6.0
Issue type        : kbbug
Solution Type     : kbfix

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