If Int32 is just an alias for int, how can the Int32 class use an int?

Question

Been browsing through .NET source code of .NET Framework Reference Source, just for fun of it. And found something I don\'t understand.

There is a Int32.cs

Answer 1

int is an alias for Int32, but the Int32 struct you are looking at is simply metadata, it is not a real object. The int m_value declaration is possibly there only to give the struct the appropriate size, because it is never actually referenced anywhere else (which is why it is allowed to be there).

So, in other words, the compiler kind of saves this from being a problem. There is a discussion on the topic in the MSDN Forums.

From the discussion, here is a quote from the chosen answer that helps to try to determine how the declaration is possible:

while it is true that the type contains an integer m_value field - the field is never referenced. In every supporting method (CompareTo, ToString, etc), "this" is used instead. It is possible that the m_value fields only exist to force the structures to have the appropriate size.

I suspect that when the compiler sees "int", it translates it into "a reference to System.Int32 in mscorlib.dll, to be resolved later", and since it's building mscorlib.dll, it does end up with a cyclical reference (but not one that can ever cause problems, because m_value is never used). If this assumption is correct, then this trick would only work for special compiler types.

Reading further, it can be determined that the struct is simply metadata, and not a real object, so it is not bound by the same recursive definiton restraints.