BUG: C2512 Instantiating Template in Member Initializer

• The C/C++ Compiler (CL.EXE) included with:

  - Microsoft Visual C++, 32-bit Editions, version 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. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

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& _Pred = _Pr()) : _Tr(_Pred) {}
    };

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

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

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