Q167113: FIX: C2734, C2166: Caused by Template Function with const ref

Article: Q167113
Product(s): Microsoft C Compiler
Version(s): winnt:4.2,4.2b,5.0
Operating System(s): 
Keyword(s): kbtool kbVC500bug kbVC600fix
Last Modified: 04-MAY-2001

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The information in this article applies to:

- The C/C++ Compiler (CL.EXE), used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2b 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2b 
   - 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
========

The compiler generates the compiler error C2734 and C2166, when compiling a
template function with a const reference of class T as an argument, where class
T is a template parameter.

  C2734: 'identifier' : const object must be initialized if not extern C2166:
  l-value specifies const object

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 Visual C++ version 6.0
for Windows.

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

The following sample demonstrates the problem and the workaround.

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

      /* Compiler Options: None
      */ 
      //#define WORKAROUND1 // uncomment this line for workaround1
      //#define WORKAROUND2 // uncomment this line for workaround2

      template <class T>
      T Test (const T& arg1)

     {

      #ifndef WORKAROUND1
          T x ;
        x = arg1;
      #else
         T x = arg1 ; // WORKAROUND 1
      #endif

          return x;

     }

      int main()
     {
      #ifndef WORKAROUND2
          int testValue = Test ( 7 );
     #else
         int testValue = Test <int> ( 7 ); // WORKAROUND 2
     #endif

      return 0;
     }

Additional query words:

======================================================================
Keywords          : kbtool kbVC500bug kbVC600fix 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:4.2,4.2b,5.0
Issue type        : kbbug
Solution Type     : kbfix

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