How to add post_distinct filter to WP_Comment_Query?

Okay, I understood by now, that get_comments() is only for … well comments. The following is not very elegant, but it does work at least.

$i = 0;
while (count($comments) < $number) {
    $comment = get_comments(
        apply_filters(
            'widget_comments_args', array(
                'number'      => 1,
                'status'      => 'approve',
                'post_status' => 'publish',
                'offset'      => $i
            )
        )
    );

    if (!isset($comment[0]))
        break;

    $comment = $comment[0]; // unwrap
    $comments[$comment->comment_post_ID] = $comment;

    $i++;
}

// Sort by date
// @ to avoid this bug: https://bugs.php.net/bug.php?id=50688
@usort($comments, function ($a, $b) {
    return get_the_date('U', $a->comment_post_ID) < get_the_date('U', $b->comment_post_ID);
});