这就是解决方案：

add_action(\'pre_post_update\', function($post_id, $post_data) {
    global $original_post;

    $original_post = get_post($post_id);
}, 10, 2);

add_action( \'save_post_\', function($post_id, $post, $update) {
    global $original_post;

    $original_post->post_title; // original post title
    $post->post_title; // new post title
}, 10, 3);