Q167356: FIX: Same Name for Function and Class Causes C2079

Article: Q167356
Product(s): Microsoft C Compiler
Version(s): winnt:5.0
Operating System(s): 
Keyword(s): kbtool kbVC500bug kbVC600fixkbbuglist
Last Modified: 13-MAY-2001

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
- Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
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SYMPTOMS
========

If a single name refers to both a class name and a function name, errors similar
to the following may be incorrectly generated:

  error C2079: 'g1' uses undefined struct 'g' error C2875: using-declaration
  causes a multiple declaration of 'A::x' error C2513: 'struct B::x' :
  decl-specifier is missing a declarator before '='

RESOLUTION
==========

Replace the using declaration with a using directive. For example, in the
following code replace the using declarations:

     using B::f
     using B::g
     using B::x

with one:

  using namespace B;

Please see the MORE INFORMATION section for a sample that demonstrates the
workaround.

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

Section 7.3.3, paragraphs 4 thru 15 of the C++ Final Draft International
Specification discuss this language behaviour in detail:

  If the set of declarations and using-declarations for a single name are given
  in a declarative region, --they shall all refer to the same, or all refer to
  functions; or --exactly one declaration shall declare a class name or
  enumeration name and the other declarations shall all refer to the same
  entity or all refer to functions; in this case the class name or enumeration
  name is hidden.

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

      namespace A {
         int x;
      }
      namespace B {
         int i;
         struct g { };
         struct x { };
         void f(int);
         void f(double);
         void g(char);
      }
      void func()  {
         int i;
         void f(char);
         using B::f;
         f(3.5f);
         using B::g;
         g('a');
         struct g g1;     // error C2079
         using B::x;
         using A::x;     // error C2875
         x = 99;         // error C2513:
         struct x x1;
      }

      //Workaround
      namespace A {
         int x;
      }
      namespace B {
         int i;
         struct g { };
         struct x { };
         void f(int);
         void f(double);
         void g(char);
      }

      void func()  {
         using namespace B ;
         int i;
         void f(char);
         f(3.5f);
         g('a');
         struct g g1;
         using A::x;
         x = 99;
         struct x x1;
      }

Additional query words:

======================================================================
Keywords          : kbtool kbVC500bug kbVC600fix kbbuglist
Technology        : kbVCsearch kbAudDeveloper kbVC500 kbVC32bitSearch kbVC500Search
Version           : winnt:5.0
Issue type        : kbbug
Solution Type     : kbfix

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