Q135536: FIX: C2985 Error When Template Class Has Static Data Member

Article: Q135536
Product(s): Microsoft C Compiler
Version(s): 2.00 2.10 2.20
Operating System(s): 
Keyword(s): kbGenInfo kbLangCPP kbVC kbArtTypeINFkbbuglist kbfixlist
Last Modified: 02-AUG-2001

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

- Microsoft Visual C++, versions 2.0, 2.1, 2.2 
-------------------------------------------------------------------------------

SYMPTOMS
========

A template class that contains a static data member of a type that was not
pre-defined, such as a struct or a class, causes this error:

  

  C2985 <var name> : invalid static data member; template class < template
  class name> already has a function member of the same name.

This error occurs on the line where the static data member is externally
declared.

RESOLUTION
==========

Explicitly initialize the static data member when it is declared. This may
require adding a constructor to the structure (see the sample code).

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 Microsoft Visual C++,
32-bit Edition, version 4.0.

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

  /* Compile options needed: None (compiler defaults will do)
  */ 
  struct A {
  //   A() {}  // ctor added for explicit initialization
     void some_funct(){}
  };
  template <class T> struct B {
      static A static_member;
      void func() { static_member.some_funct(); }
  };
  // error will occur on the following line:

  template <class T> A B<T>::static_member /* = A() */ ;

  void main()
  {
     B<int> b;

     b.func();
  }

This code, as shown, generates the error. To work around the problem, change the
line where A() is declared and defined from a comment into an executed line, and
do the same for the = A() on the line where the error is occurring. This
explicitly initializes the data member when it is declared.

Additional query words: 2.00 2.10 2.20 9.0 9.00 9.1 9.10 visualc VC cl

======================================================================
Keywords          : kbGenInfo kbLangCPP kbVC kbArtTypeINF kbbuglist kbfixlist
Technology        : kbVCsearch kbAudDeveloper kbVC220 kbVC200 kbVC210
Version           : 2.00 2.10 2.20
Issue type        : kbbug
Solution Type     : kbfix

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