What is allowed in Visual Basic that's prohibited in C# (or vice versa)?

Question

This is code-related as in what the compiler will allow you to do in one language, but not allow you to do in another language (e.g. optional parameters in

Answer 1

VB allows nonvirtual calls to virtual instance methods (call in IL), whereas C# only allows virtual calls (callvirt in IL). Consider the following code:

Class Base
    Public Overridable Sub Foo()
        Console.WriteLine("Base")
    End Sub

    Public Sub InvokeFoo()
        Me.Foo()
        MyClass.Foo()
    End Sub
End Class

Class Derived : Inherits Base
    Public Overrides Sub Foo()
        Console.WriteLine("Derived")
    End Sub
End Class

Dim d As Base = New Derived()
d.InvokeFoo()

The output is:

Derived
Base

That's not possible in C# (without resorting to Reflection.Emit).