How's Roslyn C# compiler bootstrapped?

Question

I've started reading about "Roslyn" the new C# compiler and was wondering how was the Roslyn compiler compiled?
I understand that boostrapping is needed in order to have "self hosting compiler", and I wondered how was the Roslyn compiler "bootstrapped"?

Answer 1

Bootstrapping is only a problem if there isn't already an existing implementation of the language. In this case there was, so it's easy.

1. Compile the first version of Roslyn using the existing C# compiler
2. Then re-compile it using the freshly compiled Roslyn build.
3. Done.