is_home() returns true for any component of an XML Sitemap

[MadtownLems]

It seems that any component of the core wp-sitemap.xml implementation returns true for the conditional tag is_home() (regardless even of if the homepage is set to display "Your Latest Posts" or "A static page").

For example, www.site.com/wp-sitemap-posts-page-1.xml will return true.

This can easily cause problems with themes and plugins that use filters and the is_home() conditional tag to control which posts appear on the homepage.

[swissspidy]

Possible duplicate of #51117

[RavanH]

Not sure this should be seen as a duplicate of #51117. Sure the default main query will set the is_home flag but when I modify the main query arguments (with query filter) to match the dedicated posts sitemap query, the is_home flag still gets set.

I checked and this is because of the following lines in wp-includes/class-wp-query.php starting at line 992:

if ( ! ( $this->is_singular || $this->is_archive || $this->is_search || $this->is_feed
                || ( defined( 'REST_REQUEST' ) && REST_REQUEST && $this->is_main_query() )
                || $this->is_trackback || $this->is_404 || $this->is_admin || $this->is_robots || $this->is_favicon ) ) {
        $this->is_home = true;
}

where the is_home flag is set when no others apply.

It seems to me we need a is_sitemap flag, in which case #51543 is more related :)

[RavanH]

This plugin should resolve the issue ​https://wordpress.org/plugins/xml-sitemaps-manager/
Please let me know if there are still problems after applying the fix.

[Cybr]

I think fixing any of #51542 (this ticket), #51543, or #51117 will resolve all these tickets.

[westonruter]

Will be fixed as part of ​https://github.com/WordPress/wordpress-develop/pull/12142 for #51543.

[westonruter]

There is an internal error currently blocking this from being closed as a duplicate of #51117. However, once that bug is fixed, this can be closed as such.

[westonruter]

Actually, #51117 is not a duplicate. The home query is still running needlessly.

[westonruter]

In 62664:

Sitemaps: Add the is_sitemap() conditional tag.

Introduce is_sitemap() as a conditional tag, mirroring the existing is_robots() and is_favicon() tags, and add the corresponding $is_sitemap property to WP_Query. The flag is set whenever the sitemap query variable is present, and a sitemap request is now excluded from being treated as the home page.

Developed in ​https://github.com/WordPress/wordpress-develop/pull/12142.
Follow-up to r47018, r48072.

Props masteradhoc, nimeshatxecurify, westonruter, mukesh27, madtownlems, ravanh, cybr, swissspidy.
See #51117.
Fixes #51542, #51543.