[galangalalgol]

You are right! As of 5.1.1 at least it catches the cross domain access I was using to smash things. From what I am reading it sounds like it didn't work in 5.1 I could go try it in godbolt to find out when it was fixed, but I kind of don't care. Very exciting, I like ocaml and was lamenting the changes.

[debugnik]

That makes a lot more sense: The earliest 5.x releases weren't stable at all despite the non-prerelease version numbers. I waited for longer than I wanted to before upgrading from the LTS to 5, but right now it should be ok to switch as long as the few regressions, like the GC pacing issue, don't affect you workload.