url_to_postid does not return post id for static Posts page

[nextendweb]

Steps to reproduce:

• Create a page called "Blog", slug: blog. ID: 10 permalink: ​https://a.com/blog/
• Go to WordPress->Settings->Reading-> Your homepage displays -> A static page -> Posts page -> set the previously created "Blog" page.
• Call ->

<?php
var_dump(url_to_postid('https://a.com/blog/'));

Result: 0
Expected result: 10

The cause is that this query is not for a singular page, so $query->is_singular will return false.

The following code would solve this issue:

<?php
// Do the query.
// Do the query.
$query = new \WP_Query($query);
if (!empty($query->posts) && $query->is_singular) {
        return $query->post->ID;
} else {
        if ($query->get_queried_object() instanceof WP_POST) {
                return $query->queried_object_id;
        }

        return 0;
}

Fixes: https://core.trac.wordpress.org/ticket/58516