Q140604: FIX: ‘using’ Declaration Doesn’t Overload Base Class Members

Article: Q140604
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate
Last Modified: 11-FEB-2002

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The information in this article applies to:

- The C/C++ Compiler (CL.EXE), used with:
   - Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

Attempting to overload member functions located in a base class from a derived
class with a 'using' declaration, may result in the following compiler error:

  error C2664: 'function': cannot convert parameter 'number' from 'type1' to
  'type2'

CAUSE
=====

This particular problem occurs if the member functions that are being overloaded
are declared before the 'using' declaration in the class definition.

RESOLUTION
==========

Place the 'using' declaration above the declarations for the member functions
you want to overload. See the comments in the following code sample:

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

  #include "iostream.h"

  class A
  {
  public:
     int f(int) {cout << "In A::f(int)!!!\n";return 0;}
  };

  class B : public A
  {
  public:
     int f(char*){cout << "In D::f(char*)!!!\n";return 0;}
     using A::f;        // <<== move this above the int f(char*)
                        //  declaration to fix the problem.
  };

  void main()
  {
     B d;
     d.A::f(1);
     d.f(1);            // <<== C2664 happens here
     d.f("Hi There");
  }

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This problem was corrected in Microsoft Visual C++ .NET.

REFERENCES
==========

For more information on the 'using' declaration, please see:

  \Visual C++ Books\C/C++\C++ Language\Reference\Declarations\ Namespaces\using
  Declaration

Additional query words: kbVC400bug

======================================================================
Keywords          : kbCompiler kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug
Solution Type     : kbfix

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

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