wp-includes/post.php:7346Checks for changed slugs for published post objects and save the old slug.
$post_idint$postWP_Post$post_beforeWP_Postfunction wp_check_for_changed_slugs( $post_id, $post, $post_before ) { // Don't bother if it hasn't changed. if ( $post->post_name === $post_before->post_name ) { return; } // We're only concerned with published, non-hierarchical objects. if ( ! ( 'publish' === $post->post_status || ( 'attachment' === $post->post_type && 'inherit' === $post->post_status ) ) || is_post_type_hierarchical( $post->post_type ) ) { return; } $old_slugs = (array) get_post_meta( $post_id, '_wp_old_slug' ); // If we haven't added this old slug before, add it now. if ( ! empty( $post_before->post_name ) && ! in_array( $post_before->post_name, $old_slugs, true ) ) { add_post_meta( $post_id, '_wp_old_slug', $post_before->post_name ); } // If the new slug was used previously, delete it from the list. if ( in_array( $post->post_name, $old_slugs, true ) ) { delete_post_meta( $post_id, '_wp_old_slug', $post->post_name ); }}Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/post.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.