Instead of hard-coding a specific context window,
it seemed prudent to make this configurable. That
makes it easier to test different context window
sizes as well.
I am not totally convinced that this is the right
place for this configuration. I could see the context
window size being a property of `Diagnostic` instead,
since we might want to change the context window
size based not just on some end user configuration,
but perhaps also the specific diagnostic.
But for now, I think it's fine for it to live here,
and all of the rendering logic doesn't care where
it lives. So it should be relatively easy to change
in the future.
This adds a new configuration knob to diagnostic rendering that, when
enabled, will make diagnostic rendering much more terse. Specifically,
it will guarantee that each diagnostic will only use one line.
This doesn't actually hook the concise output option up to anything.
We'll do that plumbing in the next commit.
... with supporting types. This is meant to give us a base to work with
in terms of our new diagnostic data model. I expect the representations
to be tweaked over time, but I think this is a decent start.
I would also like to add doctest examples, but I think it's better if we
wait until an initial version of the renderer is done for that.
This puts them out of the way so that they can hopefully be removed more
easily in the (near) future, and so that they don't get in the way of
the new types. This also makes the intent of the migration a bit clearer
in the code and hopefully results in less confusion.
Andrew Gallant