As well as showing future posts, this plugin will also show posts which are draft or in the trash.

The correct code for the plugin should be

add_action('pre_get_posts', 'show_future_posts');

function show_future_posts($query)
{
  if ($query->is_single()) {
    $query->set('post_status', array('publish', 'future'));
  }
}

https://www.ads-software.com/plugins/show-future-posts-on-single-post/

Hello someone know why doesn’t work on new release of wordpress?

https://www.ads-software.com/plugins/show-future-posts-on-single-post/

Just to let others know:

The plugin “Show Future Posts on Single Post” kills the_excerpt on WP 3.4.1

https://www.ads-software.com/extend/plugins/show-future-posts-on-single-post/