A timeout (or recursion/expansion depth limit) could be useful to give the human some specifics about what went wrong. But humans generally kill compilations t

A timeout (or recursion/expansion depth limit) could be useful to give the human some specifics about what went wrong. But humans generally kill compilations that take much longer than usual. If it took 20 seconds before, and now it's run for 10 minutes and hasn't finished, I'm probably going to control-C it (or whatever), and then diff against the previous code to try to figure out what went wrong.