When I declare a class as internal, why does the IL show it as private?

Question

If I declare a class as internal, why does the IL show it as private?

internal class Thing

.class private auto ansi beforefieldinit Thing.Thing
       exten         


        

Answer 1

The mapping of C# keywords to IL keywords isn't always a logical one. Ecma-335, section II.23.1.15 shows what flags are valid for a type. You'll see that it only defines Public, NotPublic and a set of NestedXxx flags. Nothing similar to "internal". So your class is actually NotPublic, displayed as "private" in ildasm.

It is easy to see a side-effect of this: try this declaration in your C# code:

private class DoesNotWork {
}

You'll get:

error CS1527: Elements defined in a namespace cannot be explicitly declared as private, protected, or protected internal