How to introduce Permalinks into pop-u-lar widget?

I am using the pop-u-lar widget on my blog, which is linking to the selected posts by their “guid”s.
However, the site itself is using human-readable links instead and I want the widget to do the same.

The widget uses a “for each” loop with the variable $post, so I thought get_the_permalink($post) would do the job, but it seems the refer to the site url instead.
Basically it is about this line of code:

<a href="https://wordpress.stackexchange.com/questions/261480/<?php echo $post->guid ?>"><?php echo $post->post_title ?></a>

Where is the knot in my reasoning?

Here is the widget code:

<ol class="f">
        <?php
            $rows = (isset($instance['num_of_posts']))?$instance['num_of_posts']:3;
            $ptype = (isset($instance['ptype_select']))?$instance['ptype_select']:'any';
            $pop_tax = (isset($instance['pop_tax']))?$instance['pop_tax']:'';
            $pop_tax_val = (isset($instance['pop_tax_val']))?$instance['pop_tax_val']:'';
            if(false !== ($posts = get_transient($this->id))){

            }else{
                switch ($instance['select_by']) {
                    case 'views':
                        $posts = yg_popular::yg_getPopularPosts($rows,$instance['dur_select'],$ptype,$pop_tax,$pop_tax_val);
                        break;
                    case 'comments':
                        $posts = yg_popular::yg_getPopularPostsComments($rows,$ptype,$instance['dur_select'],$pop_tax,$pop_tax_val);
                        break;
                    case 'tags':
                        $posts = yg_popular::yg_getPopularPostsTags($rows,$ptype);
                        break;
                    case 'most recent':
                        $posts = yg_popular::yg_getPopularPosts($rows,'recent',$ptype,$pop_tax,$pop_tax_val);
                        break;
                    default:
                        $posts = yg_popular::yg_getPopularPosts($rows,false,$instance['dur_select'],$ptype,$pop_tax,$pop_tax_val);
                        break;
                }
                $cacheDur = yg_popular::yg_getCacheDuration();
                if($cacheDur!=0)
                    set_transient($this->id,$posts, $cacheDur * 60);
            }
            foreach ($posts as $post){
        ?>
            <li class="l">
                <a href="https://wordpress.stackexchange.com/questions/261480/<?php echo $post->guid ?>"><?php echo $post->post_title ?></a>
            </li  class="l">
        <?php
        }
        ?>
        </ol>