do_action() in wp_die() doesn’t pass parameter

I am working on a plugin to ajaxify commens as wpmu-plugin. It’s almost done, with a weird little problem remaining.

I added a new hook in wp_die() to catch error messages. I added it this way:

1244: do_action('wp_abort', $message);

(line 1244 is right after $message is processed)

Good so far. So I hooked my function on:

add_action('wp_abort', 'ajax_comments_send');

The function, which doesn’t do much more than this:

function ajax_comments_send () {
    $passed = func_get_arg();
    $comment = @get_comment($passed);

    if (!is_object($comment)) {
        header('HTTP/1.0 406 Not Acceptable');
        die($passed);
    }

    // code for sending the comment on success

The problem is: Whatever I do, the $message isn’t passed to ajax_comments_send. I tried to add the die($passed); as first statement, but it doesn’t output anything.

Furthermore I digged into the code and did a little debugging. My results:

• do_action() is being executed as expected
• in plugin.php, do_action(), the parameter is there and is being passed to call_user_func_array() correctly
• ajax_comments_send works, the correct header is being sent
• ajax_comments_send works, on success the comment is successfully being transmitted

Further investigation showed that I also can’t call the function directly in do_action:

if ($tag == 'wp_abort') {
    ajax_comments_send('test');
}

After a sleepless night I’m left with a big what the heck?