BUG: LNK2001 Error for Static Member in Class Template

• Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2, 4.0, 4.1, 4.2, 5.0

SYMPTOMS

Linker error LNK2001 is generated for static member variables of nested classes in class templates. The message states:

error LNK2001: unresolved external symbol "public: static int Outer<int>::Inner::sobj"(?sobj@Inner@?$Outer@H@@2HA)

RESOLUTION

Do not use static member variables in nested classes of class templates.

STATUS

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

MORE INFORMATION

The sample code below gives the error message LNK2001.

Sample Code

/* Compile options needed: none
*/ 

template<class T> class Outer
{
public:
    static T souter;

    class Inner
    {
    public:
        static T sobj;
    };
};

template <class T> double Outer<double>::souter = 1;

template <class T> int Outer<int>::Inner::sobj = 5;

void main()
{
    double dval = Outer<double>::souter;

    int i = Outer<int>::Inner::sobj;
} 

Additional query words: kbVC400bug

Keywords : kbCompiler kbCPPonly kbVC kbVC200bug kbVC210bug kbVC220bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug
Version : winnt:2.0,2.1,2.2,4.0,4.1,4.2,5.0
Platform : winnt
Issue type : kbbug