Source

File: wp-includes/class-wp-query.php

public function have_posts() {
		if ( $this->current_post + 1 < $this->post_count ) {
			return true;
		} elseif ( $this->current_post + 1 == $this->post_count && $this->post_count > 0 ) {
			/**
			 * Fires once the loop has ended.
			 *
			 * @since 2.0.0
			 *
			 * @param WP_Query $this The WP_Query instance (passed by reference).
			 */
			do_action_ref_array( 'loop_end', array( &$this ) );
			// Do some cleaning up after the loop.
			$this->rewind_posts();
		} elseif ( 0 === $this->post_count ) {
			/**
			 * Fires if no results are found in a post query.
			 *
			 * @since 4.9.0
			 *
			 * @param WP_Query $this The WP_Query instance.
			 */
			do_action( 'loop_no_results', $this );
		}

		$this->in_the_loop = false;
		return false;
	}