User feedback if commenting on a closed node

I'm not 100% sure about this patch. We don't normally cater to inaccessible forms. I suppose the comment form is a candidate, when a moderator disables commenting on a (heated?) topic while people are still typing replies.
But are there more probably situations like this out there?

I don't think this needs fixing.

+1

Although it is a rare case, this is a really simple fix that might as well go in.

+1 from me too... although with one minor complaint: we want to say "post" rather than "posts" in the error message.

Although this is a rare case, it is one users may sometimes encounter... and a total lack of feedback as we have now is bad.

There appears to be a similar message in core already now.

Err no:

    $txt = t('Comment: unauthorized comment submitted or comment submitted to a closed node %subject.', array('%subject' => theme('placeholder', $edit['subject'])));
    watchdog('content', $txt, WATCHDOG_WARNING);
    drupal_set_message($txt, 'error');

Note the drupal_set_message(). Granted, the text is quite user-hostile.