KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q263633: BUG: Error C2946 on Explicit Instantiation of Imported Templates

Article: Q263633
Product(s): Microsoft C Compiler
Version(s): winnt:6.0
Operating System(s): 
Keyword(s): kbtemplate kbCompiler kbCPPonly kbVC600bug kbDSupport
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 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

If you try to perform explicit instantiation of a template class or function
imported from another namespace by means of a using declaration or using
directive, you may receive the following error message:

  Test.cpp(8) : error C2946: explicit instantiation; 'class ?$A@H' is not a
  template-class specialization

RESOLUTION
==========

To work around this problem, qualify the template name with the name of the
namespace in which the template is defined.


STATUS
======

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

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

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

The following sample code demonstrates the bug:

  // Test.cpp
  // Compiler option needed: none
  namespace N {

  template <class T>
  struct A { };
  }

  using namespace N;             // This does not work.
  using N::A;                    // This also does not work.
  template class A<int>;

  // template class N::A<int>;   // This works.

Additional query words: "Compiler Error"

======================================================================
Keywords          : kbtemplate kbCompiler kbCPPonly kbVC600bug kbDSupport 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt: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.