FIX: C2512 Instantiating Template in Member Initializer

• The C/C++ Compiler (CL.EXE), used with:
  • Microsoft Visual C++, 32-bit Editions, versions 5.0sp1, 5.0sp3

SYMPTOMS

When a member initializer instantiates a template class that takes a const parameter in its constructor, you may receive the following error:

error C2512: no appropriate default constructor available

RESOLUTION

Declare a global object of the template class specialization that is used in the member initializer. When optimizations are used, this unreferenced global should be optimized away.

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

This is a regression from Visual C++ 5.0.

Sample Code

    // Compile options needed: none

    struct _Tree {
      _Tree(const int& _Parg) {}
    };

    template<class _Pr>
    struct set {
      _Tree _Tr;
      set(const _Pr&amp; _Pred = _Pr()) : _Tr(_Pred) {}
    };

    struct Boo
    {
      Boo();
      set<int>& _xSet;
    };

    //set<int> x;  // uncomment for workaround

    Boo::Boo()
     : _xSet(*new set<int>)  //C2512 here
    {} 

Additional query words: visual studio service pack

Keywords : kbVC600fix kbVS97sp3bug
Version : winnt:5.0sp1,5.0sp3
Platform : winnt
Issue type : kbbug