How does he do that? Sue himself?
Cruz should call on Trump to sue him ASAP.
Trump will help Cruz in any way he can.
If Cruz doesn't ask for the case to be dismissed on standing or similar grounds, the court might consider the question on the merits.
It's likely that the court won't render a decision anyway. Too much controversy, and no matter what a court decides (even the right way), the court will take a credibility hit. Better to just say "not my job." It would be different, by the way, in any case but a presidential election case. How many "naturalized vs. not naturalized cases" do you think exist? THOUSANDS. But none of them in the context of an election.
Cruz can also submit to adversarial process in an informal way, such as within the GOP (I am going to ream my GOP party hacks who allow an unqualified name to appear on the primary ballot - that is fraud, and should be prosecuted as such). I've thought of a few other ways that the argument can be made "more public." Cruz's mission is to make the issue "less public," and avoid an adversarial hearing on the merits.
He's naturalized. Of that I have no doubt. None.
It is likely that no Federal court has jurisdiction in the matter anyway, so getting a "summary judgment" from a court on this matter would be no different than getting a judgment from your local animal control officer.
How does he do that? Sue himself?
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Good question. If Cruz is the plaintiff then who is the defendant? I don’t think you can be both. If Cruz is the defendant, which is possible of course, then the plaintiff needs to claim personal damage to himself/herself. What would that damage be?