Q240871: BUG: Explicitly Specified Template Functions Not Overloaded

Article: Q240871
Product(s): Microsoft C Compiler
Version(s): winnt:5.0,6.0
Operating System(s): 
Keyword(s): kbtemplate kbCompiler kbCPPonly kbLangCPP kbSTL kbVC kbVC500 kbVC500bug kbVC600 kbVC600
Last Modified: 03-MAY-2001

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

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

SYMPTOMS
========

If all the template parameters are not used in function arguments or return type
of a template function, the template functions are not overloaded correctly.

Please refer to the sample in the "More Information" Section for details.

CAUSE
=====

The bug is the result of the way the compiler decorates template function names.
Name Decoration uses the arguments and return type and doesn't use the
explicitly specified template argument type. Therefore, all three template
function instantiations receive the same decorated name, as seen in the sample
code the "More Information" section.

RESOLUTION
==========

Use dummy arguments to the function.

STATUS
======

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

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

Please refer to the C++ Standard, section 14.8.1, for information on explicit
template argument specification.

Steps to Reproduce Behavior
---------------------------

The following sample code demonstrates the problem:

  #include<iostream>
  //#define WORKAROUND
  #ifdef WORKAROUND
  template <class T>
  void f(T dummy = 0)
       {
       std::cout <<typeid(T).name() <<std::endl;
       }
  #else
  template <class T>
  void f(void)
       {
       std::cout <<typeid(T).name() <<std::endl;
       }
  #endif

  int main(void)
       {
       f<bool>();
       f<char>();
       f<int>();
       return 0;
       }

  Output :
  int
  int
  int

Additional query words: STL

======================================================================
Keywords          : kbtemplate kbCompiler kbCPPonly kbLangCPP kbSTL kbVC kbVC500 kbVC500bug kbVC600 kbVC600bug kbDSupport 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:5.0,6.0
Issue type        : kbbug
Solution Type     : kbpending

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.