BUG: The default behavior of the for statement destroys the object incorrectly (823841)

MyClass mc = 10;
for(;mc;--mc)
{
}
printf("Value of mc.m_i = %d\n",mc.m_i);

MORE INFORMATION

Steps to Reproduce the Behavior

1. Start Visual Studio .NET 2002.
2. On the File menu, point to New, and then click Project.
3. Click Visual C++ Projects under Project Types, and then click Win32 Console Application under Templates.
4. Paste the following code in the .cpp project:

   class MyClass
   {
   
   public:
   	int m_i;
       MyClass(int i):m_i(i)
       {
           printf("From the constructor = %d\n",m_i);
       }
       ~MyClass()
       {
           printf("From The destructor = %d\n", m_i);
       }
       operator bool ()
       {
           return m_i != 0?true:false;
       }
       MyClass& operator-- ()
       {
           --m_i; 
           return *this;
       }
   };
   
   int _tmain(int argc, _TCHAR* argv[])
   {
       for(MyClass mc = 10;mc;--mc)
       {
       }
       printf("Value of mc.m_i = %d\n",mc.m_i);
       return 0;
   }

5. Press the CTRL + F5 key combination to compile and to run the project. You may receive the following output in the Console window:
   From the constructor = 10
   From The desctructor = 0
   Value of mc.m_i = 0

Notice that the object is destroyed as it goes outside the scope of the for statement.

Note According to the C++ standards (Section 6.5.3.3 of ISO:IES 14882:1998 E), the variable that is declared in the init-expression of the for statement has a scope that is limited to the scope of the for statement. Accessing the variable outside the scope of the for statement causes undefined behavior.

By default, under /Ze (Microsoft Extension for C++), a variable that is declared in a for statement remains in scope until the enclosing scope ends for the for statement.

Visual C++ 6.0 does not destroy the object because the object goes outside the scope of the for statement.

Be careful when you convert a project from Visual C++ 6.0 to Visual C++ .NET 2002. Generally, you declare and initialize Standard Template Library ( STL) iterators in the init-expression element of the for statement, and when you compile and run the converted projects in Visual C++ .NET 2002, you may receive unwanted results.