Microsoft KB Archive/155292

Knowledge Base

FIX: Destructor Not Called When DEBUG_NEW Is Defined

Article ID: 155292

Article Last Modified on 12/10/2003

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APPLIES TO

• Microsoft Visual C++ 4.0 Standard Edition
• Microsoft Visual C++ 4.1 Subscription
• Microsoft Visual C++ 4.2 Enterprise Edition
• Microsoft Visual C++ 5.0 Enterprise Edition
• Microsoft Visual C++ 4.2 Professional Edition
• Microsoft Visual C++ 5.0 Professional Edition

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This article was previously published under Q155292

SYMPTOMS

If new is defined as DEBUG_NEW and a call to new is made for a class that takes a reference to another class in the member initialization, then the destructor is not called for the referenced class for versions 4.0, 4.1, and 4.2.

This is illustrated in the output from the following example:

   ClassA Constructor
   ClassB Constructor
   ClassB Destructor
                

The destructor for ClassA is not called.

NOTE: The Visual C++ 5.0 compiler generates the following error if you try to compile the sample code:

fatal error C1001: INTERNAL COMPILER ERROR
(compiler file 'E:\utc\src\\P2\ehexcept.c', line 516)

RESOLUTION

The best way to work around the problem is to move the new statement to be within the body of the constructor. For example,

   ClassC() {
      mClassB = new ClassB("Goodbye");
   }
                

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3 and Visual C++ 6.0.

For more information, please see the following article in the Microsoft Knowledge Base:

170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Sample Code

   /* Compile options needed: /D_DEBUG
   */ 
   #include <afx.h>
   #include <iostream.h>

   #ifdef _DEBUG
   #define new DEBUG_NEW
   #endif

   class ClassA {
   public:
       ClassA(const char *) { cout<< "ClassA Constructor" << endl; }
       ~ClassA()            { cout<< "ClassA Destructor"  << endl; }
   };

   class ClassB {
   public:
       ClassB(const ClassA&){ cout << "ClassB Constructor" << endl;}
       ~ClassB()            { cout << "ClassB Destructor"  << endl;}
   };

   class ClassC {
   public:
       ClassB *mClassB;
       ClassC()
            :mClassB(new ClassB("Goodbye") )    // Error
       {
       //    mClassB = new ClassB("Goodbye");   // Workaround
       }
       ~ClassC() { delete mClassB; }
   };

   void main() {
       ClassC TestClassInstance;
   }
                

Keywords: kbbug kbfix kbvs97sp3fix kbvc600fix kbcodegen kbcpponly kbcode kbcompiler KB155292

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