FIX: Virtual Base Class Destructor Called More than Once

• The C/C++ Compiler (CL.EXE), used with:
  • Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1, 4.2, 5.0

SYMPTOMS

If an exception is thrown from the constructor of a class that is derived from a virtual base class, the destructor for the virtual base class is called more than once. This doesn't happen if the exception is thrown from any other member function.

RESOLUTION

There is no workaround. Avoid throwing exceptions from the constructor.

For additional information about the two-phased construction, please see the following article in the Microsoft Knowledge Base:

Q132893 PRB: Exceptions Thrown During Construction Can Orphan Memory

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

Steps to Reproduce Behavior

   //compiler options needed  /GX

    #include <iostream.h>
    class A
    {
      public:
            A() { cout << "In A-ctor" << endl;}
            ~A(){ cout << "In A-dtor" << endl;}
    };

    class B1 : public  virtual   A
    {
      public:
              B1() { cout << "In B1-ctor" << endl;}
            ~B1(){ cout << "In B1-dtor" << endl;}
    };

    class B2 : public  virtual  A
    {
      public:
              B2() { cout << "In B2-ctor" << endl;}
            ~B2(){ cout << "In B2-dtor" << endl;}
    };

    class C : public B1 ,public B2
    {
      public:
          C(){
         cout << "In C-ctor...throw Exception" << endl;
         throw int(1); //incorrect destructor calls...
             }

          ~C(){ cout << "In C-dtor" << endl;}
    };

    void main()
    {
      try
       {
         C c;

       }
      catch (int ex)
       {
         cout << "Caught Exception #" << ex << endl;
         }
    } 

   In A-ctor
   In B1-ctor
   In B2-ctor
   In C-ctor...throw Exception
   In B2-dtor
   In A-dtor
   In B1-dtor
   In A-dtor
   In A-dtor
   Caught Exception #1 

   In A-ctor
   In B1-ctor
   In B2-ctor
   In C-ctor...throw Exception
   In B2-dtor
   In B1-dtor
   In A-dtor
   Caught Exception #1 

Additional query words:

Keywords : kbtool kbCompiler kbCPPonly kbVC kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600fix
Version : winnt:4.0,4.1,4.2,5.0
Platform : winnt
Issue type : kbbug