Q138752: FIX: C4114 Warning When Using Templates and Const Keyword

Article: Q138752
Product(s): Microsoft C Compiler
Version(s): 2.x4.0,4.1,4.2
Operating System(s): 
Keyword(s): kbCompiler kbCPPonly kbVC kbVC500fix
Last Modified: 30-JUL-2001

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

- Microsoft C/C++ Compiler (CL.EXE), used with:
   - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, versions 2.x4.0, 4.1, 4.2 
-------------------------------------------------------------------------------

SYMPTOMS
========

Using a class or function template may incorrectly generate a C4114 warning. The
sample code in this article demonstrates a case where this occurs.

CAUSE
=====

The compiler incorrectly expands the type of the function parameter to const T
as it expands a template with type const T when the definition of a function or
member function template has a parameter that takes a const T.

The Help file gives the following information for C4114:

- Same type qualifier used more than once.

- A type qualifier (const, volatile, signed, or unsigned) was used more than
  once in the same type declaration or definition. The second occurrence of the
  qualifier was ignored. This is a warning when Microsoft extensions are
  enabled (/Ze) and an error when extensions are disabled (/Za).

- The following is an example of this warning:

  

  volatile volatile int i;   // warning

RESOLUTION
==========

This warning can be safely ignored. To disable all occurrences of this warning,
use the #pragma warning preprocessor directive. The Help file demonstrates how
to use this pragma.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 5.0.

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

Sample Code to Reproduce Problem
--------------------------------

     // test.cpp
     // Compile options needed - none
     template <class T>
     struct f
     {
       void goo( const T & r){ T t=r;};
     };

     void main()
     {
         f<const int> h;

         // the following line of code causes
         // goo( const const int ) to be expanded
         h.goo( 2 );
     }

Additional query words: kbVC400bug 2.00 2.10 2.20 9.00 9.10 10.00 10.10 10.20

======================================================================
Keywords          : kbCompiler kbCPPonly kbVC kbVC500fix 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :2.x4.0,4.1,4.2
Issue type        : kbbug
Solution Type     : kbfix

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

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.