-- databasev2 2: the directions that are LEGAL, so WO-E224 cannot quietly
-- grow over-broad. Three shapes must all compile and run:
--   1. volatile -> durable ref: the referencing row is the one that
--      disappears, so nothing is left holding a stale id.
--   2. a backlink on a durable table whose referencer is volatile: a
--      backlink stores NO column, so after a restart it resolves to an
--      empty collection — a legal state, not a dangling id.
--   3. durable -> durable, the ordinary case.

@table(name: "users", index: [name])
class User {
  name: Text
  visits: backlink Visit.who
}

@table(name: "visits", durable: false, index: [who])
class Visit {
  who: ref User
  note: Text
}

@table(name: "audits", index: [who])
class Audit {
  who: ref User
  what: Text
}

fn main() -> Int {
  let u = insert User { name: "asha" };
  insert Visit { who: u, note: "scratch" };
  insert Audit { who: u, what: "kept" };
  for v in from x in Visit select x {
    print("visit ${v.note}");
  }
  for a in from x in Audit select x {
    print("audit ${a.what}");
  }
  return 0;
}