Comment last updated is wrong if authoring date is changed

This problem is still present in 6.12 as far as I can tell. If you edit the authored on date of a node with no comments, the last comment timestamp is not updated to match, so, for example topic list order in the forum module ends up being incorrect.

Bumping to D7 so that we fix that there first.

I've been trying to replicate this bug in D7, but have been unable to do so. It appears to have been fixed by a prior refactoring. Also, unless I'm mistaken, the relevant code is in the tracker module (tracker.pages.inc, lines 43-46):

    $result = db_query('SELECT n.nid, n.title, n.type, n.changed, n.uid, u.name, l.comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid INNER JOIN {users} u ON n.uid = u.uid WHERE n.nid IN (:nids)', array(':nids' => array_keys($nodes)), array('target' => 'slave'));
    foreach ($result as $node) {
      $node->last_activity = $nodes[$node->nid]->changed;
      $nodes[$node->nid] = $node;

Assuming I'm not missing something, ought this issue be marked fixed/closed, or the version switched back to 6.x-dev?

I tried to reproduce the problem using Tracker module in D6 and D7. I enabled Tracker and Comment, created a couple of nodes, waited a minute and then updated the Authored On date for one of the nodes by blanking-out the field. In both D6 and D7 /tracker shows the new time just fine.

However if I enable Views and use its version of tracker, I see the issue as originally described. This is because the view is displaying the last comment date whereas Tracker is showing the node's last edit date. So, the last_comment_timestamp is out of sync with the node's authored-on date.

I think the crux of the problem is here, in line 2335 of comment.module:

  else {
    // Comments do not exist.
    $node = db_query('SELECT uid, created FROM {node} WHERE nid = :nid', array(':nid' => $nid))->fetchObject();
    db_update('node_comment_statistics')
      ->fields(array(
        'cid' => 0,
        'comment_count' => 0,
        'last_comment_timestamp' => $node->created,
        'last_comment_name' => '',
        'last_comment_uid' => $node->uid,
      ))
      ->condition('nid', $nid)
      ->execute();
  }

...which supplies the node's creation date rather than its authored date if there are no comments.

Is it right that in addition to patching comment.module, we'd need to separately update node_comment_statistics for any existing comments to reflect this change?

Dug into this a little more, and the actual problem is that the comment_statistics are not updated when the node's creation date is changed. comment_statistics is filled in with the node creation date when the node is first created, but isn't updated again until a comment is added. So, if a post is created, then back-dated (or as in the OP, forward-dated), the last_comment_timestamp will be wrong until a comment is added. Seems like the only way to fix this would be to update comment_statistics on every node update, in case the date changed.

This issue is a duplicate of #55246: Node updates are not reflected in node_comment_statistics correctly which regards a similar issue which occurs when changing the node author.