Replace direct access to inheritance property on Template object by proper getter.

src/Compile/Tag/BlockClose.php

@@ -84,9 +84,9 @@ class BlockClose extends Inheritance {
 		$compiler->parser->current_buffer = $_buffer;
 		$output = "<?php \n";
 		if ($compiler->_cache['blockNesting'] === 1) {
-			$output .= "\$_smarty_tpl->inheritance->instanceBlock(\$_smarty_tpl, '$_className', $_name);\n";
+			$output .= "\$_smarty_tpl->getInheritance()->instanceBlock(\$_smarty_tpl, '$_className', $_name);\n";
 		} else {
-			$output .= "\$_smarty_tpl->inheritance->instanceBlock(\$_smarty_tpl, '$_className', $_name, \$this->tplIndex);\n";
+			$output .= "\$_smarty_tpl->getInheritance()->instanceBlock(\$_smarty_tpl, '$_className', $_name, \$this->tplIndex);\n";
 		}
 		$output .= "?>\n";
 		--$compiler->_cache['blockNesting'];

src/Compile/Tag/Child.php

@@ -71,7 +71,7 @@ class Child extends Base {
 		if (isset($_assign)) {
 			$output .= "ob_start();\n";
 		}
-		$output .= '$_smarty_tpl->inheritance->call' . $this->blockType . '($_smarty_tpl, $this' .
+		$output .= '$_smarty_tpl->getInheritance()->call' . $this->blockType . '($_smarty_tpl, $this' .
 			($this->blockType === 'Child' ? '' : ", {$tag}") . ");\n";
 		if (isset($_assign)) {
 			$output .= "\$_smarty_tpl->assign({$_assign}, ob_get_clean());\n";

src/Compile/Tag/ExtendsTag.php

@@ -109,7 +109,7 @@ class ExtendsTag extends Inheritance {
 		}
 		$compiler->parser->template_postfix[] = new \Smarty\ParseTree\Tag(
 			$compiler->parser,
-			'<?php $_smarty_tpl->inheritance->endChild($_smarty_tpl' .
+			'<?php $_smarty_tpl->getInheritance()->endChild($_smarty_tpl' .
 			(isset($template) ?
 				", {$template}{$inlineUids}" :
 				'') . ");\n?>"

src/Compile/Tag/IncludeTag.php

@@ -287,9 +287,6 @@ class IncludeTag extends Base {
 		$uid = $tpl->source->type . $tpl->source->uid;
 		if ($tpl->source->exists) {
 			$compiler->parent_compiler->mergedSubTemplatesData[$uid][$t_hash]['uid'] = $tpl->source->uid;
-			if (isset($compiler->template->inheritance)) {
-				$tpl->inheritance = clone $compiler->template->inheritance;
-			}
 			$tpl->compiled = new Compiled();
 			$tpl->compiled->nocache_hash = $compiler->parent_compiler->template->compiled->nocache_hash;
 			$tpl->loadCompiler();

src/Compile/Tag/Inheritance.php

@@ -29,7 +29,7 @@ abstract class Inheritance extends Base
      */
     public static function postCompile(\Smarty\Compiler\Template $compiler, $initChildSequence = false)
     {
-        $compiler->prefixCompiledCode .= "<?php \$_smarty_tpl->_loadInheritance();\n\$_smarty_tpl->inheritance->init(\$_smarty_tpl, " .
+        $compiler->prefixCompiledCode .= "<?php \$_smarty_tpl->getInheritance()->init(\$_smarty_tpl, " .
                                          var_export($initChildSequence, true) . ");\n?>\n";
     }
 

src/Runtime/InheritanceRuntime.php

@@ -71,8 +71,7 @@ class InheritanceRuntime {
 	public function init(Template $tpl, $initChild, $blockNames = []) {
 		// if called while executing parent template it must be a sub-template with new inheritance root
 		if ($initChild && $this->state === 3 && (strpos($tpl->template_resource, 'extendsall') === false)) {
-			$tpl->inheritance = new InheritanceRuntime();
+			$tpl->getInheritance()->init($tpl, $initChild, $blockNames);
-			$tpl->inheritance->init($tpl, $initChild, $blockNames);
 			return;
 		}
 		++$this->tplIndex;
@@ -227,7 +226,8 @@ class InheritanceRuntime {
 		if (isset($block->parent)) {
 			$this->callBlock($block->parent, $tpl);
 		} else {
-			throw new Exception("inheritance: illegal '{$tag}' used in child template '{$tpl->inheritance->sources[$block->tplIndex]->filepath}' block '{$block->name}'");
+			throw new Exception("inheritance: illegal '{$tag}' used in child template '" .
+				"{$tpl->getInheritance()->sources[$block->tplIndex]->filepath}' block '{$block->name}'");
 		}
 	}
 

src/Template.php

@@ -33,13 +33,6 @@ class Template extends TemplateBase {
 	 */
 	public $source = null;
 
-	/**
-	 * Inheritance runtime extension
-	 *
-	 * @var InheritanceRuntime
-	 */
-	public $inheritance = null;
-
 	/**
 	 * Template resource
 	 *
@@ -479,21 +472,21 @@ class Template extends TemplateBase {
 	}
 
 	/**
-	 * Load inheritance object
+	 * Helper function for InheritanceRuntime object
+	 *
+	 * @return InheritanceRuntime
+	 * @throws Exception
 	 */
-	public function _loadInheritance() {
+	public function getInheritance(): InheritanceRuntime {
-		if (!isset($this->inheritance)) {
+		return $this->_getSmartyObj()->getRuntime('Inheritance');
-			$this->inheritance = new InheritanceRuntime();
-		}
 	}
 
 	/**
-	 * Unload inheritance object
+	 * Unload event callbacks
 	 */
 	private function _cleanUp() {
 		$this->startRenderCallbacks = [];
 		$this->endRenderCallbacks = [];
-		$this->inheritance = null;
 	}
 
 	/**