DOCUMENT:Q166109  04-MAY-2001  [visualc]
TITLE   :FIX: Template Friend Function Causes Compiler Error C2248
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:5.0
OPER/SYS:
KEYWORDS:kbtool kbVC500bug kbVC600fixkbbuglist

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - The C/C++ Compiler (CL.EXE), used with:
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
    - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

The compiler generates a compiler error C2248 as follows:

   Error C2248: 'member' : cannot access member declared in class 'class'

under the following circumstances:

 - If a class declares a template function as a friend function, and

 - If the template function definition appears after the class definition.

RESOLUTION
==========

Do not declare a template function as a friend of a class.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.This problem was corrected in Microsoft
Visual C++ version 6.0.

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

The following sample demonstrates the problem and the workaround.

Sample Code
-----------

      /*
      Compile option: None
      */ 

      class X;

      template <class T> void AFunction(X &x, T &t);

      class X
      {
      private:

         int m_n;

      public:

         template <class T> friend void AFunction(X &x, T &t) ;

      };

      template <class T> void AFunction(X &x, T &t)
      {

         x.m_n = t; // C2248 here.

      }

      int main()
      {
         X x;
         int n;
         AFunction(x, n);

              return 0 ;
      }

NOTE: Defining the template function before the class definition eliminates the
compiler error C2248. But the compiler does not generate any code when you call
the template function.

Additional query words:

======================================================================
Keywords          : kbtool kbVC500bug kbVC600fix kbbuglist
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:5.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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Copyright Microsoft Corporation 2001.