wp-includes/link-template.php:2201Retrieves the boundary post.
$in_same_termbooloptionalfalse$excluded_termsint[]|stringoptional''$startbooloptionaltrue$taxonomystringoptional'category'array|nullfunction get_boundary_post( $in_same_term = false, $excluded_terms = '', $start = true, $taxonomy = 'category' ) { $post = get_post(); if ( ! $post || ! is_single() || is_attachment() || ! taxonomy_exists( $taxonomy ) ) { return null; } $query_args = array( 'posts_per_page' => 1, 'order' => $start ? 'ASC' : 'DESC', 'update_post_term_cache' => false, 'update_post_meta_cache' => false, ); $term_array = array(); if ( ! is_array( $excluded_terms ) ) { if ( ! empty( $excluded_terms ) ) { $excluded_terms = explode( ',', $excluded_terms ); } else { $excluded_terms = array(); } } if ( $in_same_term || ! empty( $excluded_terms ) ) { if ( $in_same_term ) { $term_array = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) ); } if ( ! empty( $excluded_terms ) ) { $excluded_terms = array_map( 'intval', $excluded_terms ); $excluded_terms = array_diff( $excluded_terms, $term_array ); $inverse_terms = array(); foreach ( $excluded_terms as $excluded_term ) { $inverse_terms[] = $excluded_term * -1; } $excluded_terms = $inverse_terms; } $query_args['tax_query'] = array( array( 'taxonomy' => $taxonomy, 'terms' => array_merge( $term_array, $excluded_terms ), ), ); } return get_posts( $query_args );}Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/link-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.