InsertComment about apply-refact

[mpickering]

To answer your question directly, you need to provide the SrcSpan of the expression to attach the comment to. For two reasons,

1. The only way to insert comments is by attaching them to something. (and placing them in the annotations map)
2. The SrcSpan might not be the actual location of the expression, it is used as a key so we can continue to refer to the same expression as it moves around.

So saying that, it doesn't make sense to provide an operation which allows you to insert a comment at a specific location because at the transformation stage all that information is lost.

I will answer more about comments on the other issue you opened.