Curious C# using statement expansion

Question

I\'ve run ildasm to find that this:

    using(Simple simp = new Simple())
    {
        Console.WriteLine(\"here\");
    }

generates IL cod

Answer 1

The code must be translated this way to avoid possible NullReferenceException when disposing the object. As per C# language reference, the using statement accepts not only a local variable declaration as its first nonterminal resource_acquisition symbol, but any expression. Consider the following code:

DisposableType @object = null;
using(@object) {
    // whatever
}

Clearly, unless null-conditional @object?.Dispose() in the finnaly block, an exception would ensue. The null check is superfluous only when the expression is of a non-nullable value type (non-nullable struct). And indeed, according to the aforementioned language reference it is absent in such case.