Homepage missing in the sitemap

[Chouby]

On a fresh install,

1. Unpublish the sample page to make sure that no page is published.
2. Go to the sitemaps index.

There is no entry for pages as we could expect. But as the hompepage is listed in the list of pages, that means that the homepage is not indexed.

The issue is because the method WP_Sitemaps_Posts::get_max_num_pages() returns 0 when there are no pages.

[pacifika]

Minimum 1 sitemap for pages.

[pacifika]

Formatted version of the previous attachment.

[swissspidy]

My initial thought was more like this:

$min_num_pages =  ( 'page' === $post_type && 1 === $page_num && 'posts' === get_option( 'show_on_front' ) ) ? 1 : 0;

[elrae]

sets minimum pages to 1 on pages

[elrae]

I've added a patch with your approach @swissspidy but I excluded the 1 === $pagenum as that variable isn't available in this function. There's also no $paged in there to know if we're on the first page. However, the check against 'page' === $post_type and the max($min_num_pages, $query->max_num_pages) should cover us

[swissspidy]

In 48476:

Sitemaps: Ensure entry for ‘page’ post type sitemap in index.

If there are no pages and no static homepage, there will still be one sitemap including the homepage URL.

This change ensures that this sitemap is correctly listed in the sitemap index.

Props Chouby, pacifika, elrae.
Fixes #50571.