How does the assignment of the null literal to a System.Nullable type get handled by .Net (C#)?

Question

I was wondering if anyone knows how the C# compiler handles the following assignment:

int? myInt = null;

My assumption is that there is an

Answer 1

C# is a high-level language that get's compiled to IL.

With the introduction of nullable types, the C# standard changed, so the behavior of the C# compiler had to change to handle a new rule like "no struct, except Nullable, can be assigned a value of null".

Assigning null to a struct is generally disallowed, but that's just a rule the compiler enforces when generating the IL. Since the compiler parses all your code and figures out what it means, it can recognize all kinds of rules, even ones that, to you, may appear to be exceptions.

Basically, if the compiler parses your C# code and finds that you're assigning null to a struct, it outputs an error. If it finds that your assigning null to a Nullable struct, then it knows how to handle it and generates the appropriate IL.

From the C# standard:

13.7.1 Null type conversions: "An implicit conversion exists from the null type (§11.2.7) to any nullable type. This conversion produces the null value (§12.2) of the given nullable type."

12.2 Default values: "The default value of a nullable type is an instance for which the HasValue property is false. Referencing the Value property of a default value of a nullable type results in an exception of type System.InvalidOperationException. The default value is also known as the null value of the nullable type. An implicit conversion exists from the null type (§11.2.7) to any nullable type, and this conversion produces the null value of the type."