public function all() {
		if ( $this->void_query ) {
			return array();
		}

		$query = $this->build_query();

		$return_ids = 'ids' === $query->get( 'fields', '' );

		/**
		 * Do not skip counting the rows if we have some filtering to do on
		 * `found_posts`.
		 */
		$query->set( 'no_found_rows', $this->skip_found_rows );
		// we'll let the class build the items later
		$query->set( 'fields', 'ids' );

		/**
		 * Filters the query object by reference before getting the posts.
		 *
		 * @since 4.7.19
		 *
		 * @param WP_Query $query
		 */
		do_action_ref_array( "{$this->filter_name}_pre_get_posts", array( &$query ) );

		$results = $query->get_posts();

		/**
		 * Allow extending classes to customize the return value.
		 * Since we are filtering the array returning empty values while formatting
		 * the item will exclude it from the return values.
		 */
		return $return_ids
			? $results
			: array_filter( array_map( array( $this, 'format_item' ), $results ) );
	}