Question

See the following code:

public abstract class Base
{
    public virtual void Foo<T>() where T : class
    {
        Console.WriteLine("base");
    }
}

public class Derived : Base
{
    public override void Foo<T>()
    {
        Console.WriteLine("derived");
    }

    public void Bang()
    {
        Action bang = new Action(delegate { base.Foo<string>(); });
        bang();    //VerificationException is thrown
    }
}

new Derived().Bang(); throws an exception. Inside the generated CIL of the method Bang I got:

call instance void ConsoleApp.Derived::'<>n__FabricatedMethod1'<string>()

and the signature of the compiler generated method:

method private hidebysig 
    instance void '<>n__FabricatedMethod1'<T> () cil managed 
{
    .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = (
        01 00 00 00
    )       
    .maxstack 8

    IL_0000: ldarg.0
    IL_0001: call instance void ConsoleApp.Base::Foo<!!T>()
    IL_0006: ret
}

I think the correct code should be '<>n__FabricatedMethod1'<class T>. Is it a bug?
By the way, without using delegate{ }(lambda expression is the same), the code works fine with syntax sugars.

Action good = new Action(base.Foo<string>());
good();  //fine

EDIT I’m using VS2012 RTMRel in windows8 RTM, .net framework 4.5

EDIT This bug is now fixed.

Answer 1

It is confirmed as a bug and now fixed

Update: the Connect article no longer exists. The bug is fixed.