From 34763ae316e2a32defe9beef96769e10c605f9c0 Mon Sep 17 00:00:00 2001
From: Simon Wisselink <s.wisselink@iwink.nl>
Date: Mon, 27 Jan 2020 17:54:45 +0100
Subject: [PATCH] This appears to fix #453, #498, #499 and possibly more
 issues. Will need further testing and unit tests.

---
 .../smarty_internal_templatecompilerbase.php         | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/libs/sysplugins/smarty_internal_templatecompilerbase.php b/libs/sysplugins/smarty_internal_templatecompilerbase.php
index a72f3a4a..a376ecc6 100644
--- a/libs/sysplugins/smarty_internal_templatecompilerbase.php
+++ b/libs/sysplugins/smarty_internal_templatecompilerbase.php
@@ -627,16 +627,8 @@ abstract class Smarty_Internal_TemplateCompilerBase
                     if (count($parameter) === 0) {
                         $this->trigger_template_error('Illegal number of parameter in "isset()"');
                     }
-                    if ($parHasFuction) {
-                        $pa = array();
-                        foreach ($parameter as $p) {
-                            $pa[] = (strpos($p, '(') === false) ? ('isset(' . $p . ')') : ('(' . $p . ' !== null )');
-                        }
-                        return '(' . implode(' && ', $pa) . ')';
-                    } else {
-                        $isset_par = str_replace("')->value", "',null,true,false)->value", $par);
-                    }
-                    return $name . '(' . $isset_par . ')';
+	                $isset_par = str_replace("')->value", "',null,true,false)->value", $par);
+                    return '@!is_null(' . $isset_par . ')';
                 } elseif (in_array(
                     $func_name,
                     array(