Microsoft KB Archive/839998

= FIX: Error C2555 occurs when you compile code by using Visual C++ .NET 2003 =

Article ID: 839998

Article Last Modified on 5/15/2006

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APPLIES TO


 * Microsoft Visual C++ .NET 2003 Standard Edition

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SYMPTOMS
When you create an application by using Microsoft Visual C++ .NET 2003, if you use a nested class in a derived class, the compiler generates error C2555. When this problem occurs, you receive an error message that is similar to the following:

error C2555: 'Dervied::NestedDerived::GetEditObject': overriding virtual function return type differs and is not covariant from 'Base::NestedBase ::GetEditObject'

This problem occurs if the nested class that you use in the derived class is derived from a nested class in the base class. This error message states that the return types are not covariant. However, the return types are covariant.



RESOLUTION
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Visual Studio .NET 2003 that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version       Size       File name --  01-Apr-2004  01:12  13.10.4092.0    933,888  C1.dll 01-Apr-2004 01:13  13.10.4092.0  2,207,744  C1xx.dll 01-Apr-2004 07:49  13.10.4092.0  1,966,080  Feacp.dll 01-Apr-2004 01:20                    5,342  Feacp.lib



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
To reproduce this problem, compile the following sample code: //test.cpp //cl test.cpp //Error C2555 class Base { public: class NestedBase {        public: virtual Base *  GetEditObject ; };        virtual NestedBase*        Edit  ; };

class Derived : public Base { public: class NestedDerived : public NestedBase {        public: virtual Derived*   GetEditObject; };        virtual NestedDerived*        Edit  ; }; You receive the following error message:

nest.cpp(21) : error C2555: 'Dervied::NestedDerived::GetEditObject': overriding virtual function return type differs and is not covariant from 'Base::NestedBase ::GetEditObject' nest.cpp(9) : see declaration of 'Base::NestedBase::GetEditObject'

For additional information about the terminology that is used to describe Microsoft product updates, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Keywords: kbbug kbfix kbqfe kbvsnet2003presp1fix kbhotfixserver KB839998

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