[Mono-list] why does gmcs let me assign null to a value type?

[Eric Slosser]

<csharp newbie>

I have a C# struct that's defined as
	
	public struct Field : IComparable, IComparable<Field>, IEquatable<Field> 
	{
	}

When I do this:

	Field f = null;

I'd expect error CS0037 (can't convert null to 'Field' because it is a value type.

But when Field is defined in an assembly that was compiled by VisStudio, gmcs (v2.8.1.0) is happy to let me assign null to it.  

Why?