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BUG: A BadImageFormatException exception may occur when you use a recursively defined constraint of a generic type in a .NET Framework 2.0-based application

Article ID: 940164 - View products that this article applies to.

SYMPTOMS

In a Microsoft .NET Framework 2.0-based application, you use a recursively defined constraint of a generic type. When you do this, a BadImageFormatException exception may occur at run time. This problem occurs only in certain scenarios.

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CAUSE

This problem occurs because of an issue in the Microsoft Visual Studio 2005 common language runtime (CLR 2.0) components.

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WORKAROUND

To work around this problem, remove the class constraint from the public static E GetClass<E> method.

Note Constraints are limits that are put on generic-type parameters.

To remove the class constraint from the public static E GetClass<E> method, change the method signature as follows.

Existing code

public static E GetClass<E>() where E : class, new()

Replacement code

public static E GetClass<E>() where E : new()

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STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section.

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MORE INFORMATION

For more information about generics in the CLR, visit the following Microsoft Developer Network (MSDN) Web site:

http://msdn.microsoft.com/msdnmag/issues/06/00/NET/default.aspx

(http://msdn.microsoft.com/msdnmag/issues/06/00/NET/default.aspx)

Steps to reproduce the problem

On a computer that has Visual Studio 2005 installed, create the following C# program.

using System;

public abstract class AbstractClass1<E> where E : AbstractClass1<E>, new()
{ }

public class Class1 : AbstractClass1<Class1>
{ }

public class Class2<E> where E : AbstractClass1<E>, new()
{
    public E GetClass1()
    {
        return Factory.GetClass<E>();
    }
}

public class Factory
{
    public static E GetClass<E>() where E : class, new()
    {
        return new E();
    }
}

public class Program
{
    static void Main()
    {
        Console.WriteLine("Hit enter to continue..");
        Console.ReadLine();
        Class2<Class1> c2 = new Class2<Class1>();
        c2.GetClass1();
        Console.WriteLine("Hi");
    }
}

Compile the program, and then run the program. The BadImageFormatException exception occurs at run time when the c2.GetClass1 method is called.

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