> Do you think for something to be a JIT it must only compile code immediately before it's used?

I mean, that's more or less what the name "just-in-time compiler" implies. I'm aware that the name is not necessarily a precise definition, but I'm not sure how far the definition stretches. Does JIT have a precise agreed-upon definition, or is it somewhat more vaguely defined?

No these terms never have precise meanings, and trying to debate them too much doesn't achieve much. But if your definition doesn't actually work for any examples of the thing you're defining at all except one then it's probably wrong.

Ok, fair enough. I was worried that there was some precise definition I had missed, but if that's not the case, I agree there's no point in debating it.

Well, there's at least one definition that's pretty noncontroversial, if not terribly satisfying or precise: it's not a JIT if you compile well in advance of any indication the program needs to be run.

Whether that lazy-compilation strategy is fine-grained or not isn't clearcut, I believe. I think if you distribute a C program with a bash bootstrapper calling plain old gcc to compile and run the C code only when needed, even gcc might be considered a (coarse-grained, rather rudimentary) JIT in that context.

Like TCCBoot? https://bellard.org/tcc/tccboot.html