-- probe: Text interpolation of a borrowed field inside a loop.
-- If the interpolation segment drops the field it only borrows, repeated
-- calls corrupt the arena and the third-ish call crashes in release.

class Row {
  method: Text
}

class Tab {
  rows: multi Row

  fn scan() -> Text {
    let out = "";
    for r in self.rows {
      if out == "" { out = "${r.method}"; } else { out = "${out}, ${r.method}"; }
    }
    return out;
  }

  -- the RETURN flavor: an interpolation of a borrowed field handed straight
  -- to the caller must be the caller's own copy, not the row's string
  fn first() -> Text {
    for r in self.rows {
      return "${r.method}";
    }
    return "";
  }
}

fn main() -> Int {
  let t = Tab { rows: [] };
  push(t.rows, Row { method: "GET" });
  push(t.rows, Row { method: "POST" });
  let i = 0;
  while i < 50 {
    let s = t.scan();
    if s != "GET, POST" { print("bad: ${s} at ${i}"); return 1; }
    let h = t.first();
    if h != "GET" { print("bad first: ${h} at ${i}"); return 1; }
    i = i + 1;
  }
  print("ok");
  return 0;
}