Does casting an IList<T> to an array of type T[] cause enumeration?

Question

I have a method that looks like:

T[] field;

public Method(IList<T> argument)
{
    this.field = (T[])argument;
}

When the body of the method is executed does enumeration take place during the cast? Would that change if the underlying type was different?

Answer 1

No, it won't enumerate anything. It will either succeed if argument actually is a T[], or throw an InvalidCastException exception if it isn't. (Or return null if argument is null.)

Answer 2

If argument is a reference to an array (of type T), then there is no enumeration — it is a simple cast.

If argument is a reference to a List<T> or another class that implements IList then there will potentially be a casting exception. (I say potenially as there may be an implict or explict conversion to T[] — most likely there won't be).

Edit: as pointed out by Jon, a conversion won't be made in the generic method, so the above parenthesis is incorrect.