Consider using IOperation

[333fred]

By only looking for CastExpressionSyntaxes, you're missing the implicit 0 conversion case. Consider using IOperation to avoid missing this case and not having to deal with syntax.

[agocke]

https://github.com/agocke/static-cs/blob/d9ba7fcdfcb51850a8665e1442d8cf1bafb2a655/test/Program.cs#L20-L22

Haven't gotten around to fixing it yet :)