Subject: Re: "blatantly" unconstitutional
Exactly. It had to do with slaves born in this country and/or people who were brought here legally (via the law structure of the time, while allowed slavery).

What does it say about illegal immigration?

It doesn't. There is no exception carved out for illegal immigration. Only for those not subject to the jurisdiction of the US government (like diplomats, occupying armies, etc). Nor does it specify (or restrict itself) to slaves. Therefore, a child born of a migrant (legal or otherwise) is a citizen. QED.