Source

File: wp-includes/link-template.php

function get_next_posts_page_link( $max_page = 0 ) {
	global $paged;

	if ( ! is_single() ) {
		if ( ! $paged ) {
			$paged = 1;
		}
		$nextpage = intval( $paged ) + 1;
		if ( ! $max_page || $max_page >= $nextpage ) {
			return get_pagenum_link( $nextpage );
		}
	}
}