Microsoft KB Archive/940164

= 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

Article Last Modified on 7/30/2007

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APPLIES TO


 * Microsoft .NET Framework 2.0
 * Microsoft Visual Studio 2005 Standard Edition
 * Microsoft Visual Studio 2005 Professional Edition
 * Microsoft Visual Studio 2005 Express Edition

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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.



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



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

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

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

Existing code
public static E GetClass where E : class, new

Replacement code
public static E GetClass where E : new



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



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

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 where E : AbstractClass1, new { }

public class Class1 : AbstractClass1 { }

public class Class2 where E : AbstractClass1, 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(&quot;Hit enter to continue..&quot;); Console.ReadLine; Class2<Class1> c2 = new Class2<Class1>; c2.GetClass1; Console.WriteLine(&quot;Hi&quot;); } } </li> <li>Compile the program, and then run the program. The BadImageFormatException exception occurs at run time when the c2.GetClass1 method is called.</li></ol>

Keywords: kbtshoot kbbug KB940164

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