fix for Error: Attempt to assign property "step" on null closes issue #1036

changelog/1036.md

@@ -0,0 +1 @@
+- Fixed "Attempt to assign property step on null" error when using a {for} loop inside a block of an extended template [#1036](https://github.com/smarty-php/smarty/issues/1036)

src/Compile/Tag/ForTag.php

@@ -51,8 +51,9 @@ public function compile($args, \Smarty\Compiler\Template $compiler, $parameter =
 					$var = $_statement['var'];
 					$index = '';
 				}
-				$output .= "\$_smarty_tpl->assign($var, null);\n";
-				$output .= "\$_smarty_tpl->tpl_vars[$var]->value{$index} = {$_statement['value']};\n";
+				$itemVar = "\$_smarty_tpl->getVariable({$var})";
+				$output .= "\$_smarty_tpl->assign($var, []);\n";
+				$output .= "{$itemVar}->value{$index} = {$_statement['value']};\n";
 			}
 			if (is_array($_attr['var'])) {
 				$var = $_attr['var']['var'];
@@ -61,7 +62,8 @@ public function compile($args, \Smarty\Compiler\Template $compiler, $parameter =
 				$var = $_attr['var'];
 				$index = '';
 			}
-			$output .= "if ($_attr[ifexp]) {\nfor (\$_foo=true;$_attr[ifexp]; \$_smarty_tpl->tpl_vars[$var]->value{$index}$_attr[step]) {\n";
+			$itemVar = "\$_smarty_tpl->getVariable({$var})";
+			$output .= "if ($_attr[ifexp]) {\nfor (\$_foo=true;$_attr[ifexp]; {$itemVar}->value{$index}$_attr[step]) {\n";
 		} else {
 			$_statement = $_attr['start'];
 			if (is_array($_statement['var'])) {
@@ -71,21 +73,22 @@ public function compile($args, \Smarty\Compiler\Template $compiler, $parameter =
 				$var = $_statement['var'];
 				$index = '';
 			}
-			$output .= "\$_smarty_tpl->assign($var, null);";
+			$itemVar = "\$_smarty_tpl->getVariable({$var})";
+			$output .= "\$_smarty_tpl->assign($var, []);";
 			if (isset($_attr['step'])) {
-				$output .= "\$_smarty_tpl->tpl_vars[$var]->step = $_attr[step];";
+				$output .= "{$itemVar}->step = $_attr[step];";
 			} else {
-				$output .= "\$_smarty_tpl->tpl_vars[$var]->step = 1;";
+				$output .= "{$itemVar}->step = 1;";
 			}
 			if (isset($_attr['max'])) {
-				$output .= "\$_smarty_tpl->tpl_vars[$var]->total = (int) min(ceil((\$_smarty_tpl->tpl_vars[$var]->step > 0 ? $_attr[to]+1 - ($_statement[value]) : $_statement[value]-($_attr[to])+1)/abs(\$_smarty_tpl->tpl_vars[$var]->step)),$_attr[max]);\n";
+				$output .= "{$itemVar}->total = (int) min(ceil(({$itemVar}->step > 0 ? $_attr[to]+1 - ($_statement[value]) : $_statement[value]-($_attr[to])+1)/abs({$itemVar}->step)),$_attr[max]);\n";
 			} else {
-				$output .= "\$_smarty_tpl->tpl_vars[$var]->total = (int) ceil((\$_smarty_tpl->tpl_vars[$var]->step > 0 ? $_attr[to]+1 - ($_statement[value]) : $_statement[value]-($_attr[to])+1)/abs(\$_smarty_tpl->tpl_vars[$var]->step));\n";
+				$output .= "{$itemVar}->total = (int) ceil(({$itemVar}->step > 0 ? $_attr[to]+1 - ($_statement[value]) : $_statement[value]-($_attr[to])+1)/abs({$itemVar}->step));\n";
 			}
-			$output .= "if (\$_smarty_tpl->tpl_vars[$var]->total > 0) {\n";
-			$output .= "for (\$_smarty_tpl->tpl_vars[$var]->value{$index} = $_statement[value], \$_smarty_tpl->tpl_vars[$var]->iteration = 1;\$_smarty_tpl->tpl_vars[$var]->iteration <= \$_smarty_tpl->tpl_vars[$var]->total;\$_smarty_tpl->tpl_vars[$var]->value{$index} += \$_smarty_tpl->tpl_vars[$var]->step, \$_smarty_tpl->tpl_vars[$var]->iteration++) {\n";
-			$output .= "\$_smarty_tpl->tpl_vars[$var]->first = \$_smarty_tpl->tpl_vars[$var]->iteration === 1;";
-			$output .= "\$_smarty_tpl->tpl_vars[$var]->last = \$_smarty_tpl->tpl_vars[$var]->iteration === \$_smarty_tpl->tpl_vars[$var]->total;";
+			$output .= "if ({$itemVar}->total > 0) {\n";
+			$output .= "for ({$itemVar}->value{$index} = $_statement[value], {$itemVar}->iteration = 1;{$itemVar}->iteration <= {$itemVar}->total;{$itemVar}->value{$index} += {$itemVar}->step, {$itemVar}->iteration++) {\n";
+			$output .= "{$itemVar}->first = {$itemVar}->iteration === 1;";
+			$output .= "{$itemVar}->last = {$itemVar}->iteration === {$itemVar}->total;";
 		}
 		$output .= '?>';
 

tests/UnitTests/TemplateSource/TagTests/For/CompileForTest.php

@@ -197,4 +197,45 @@ public function dataTestSpacing()
                      array("{for \$x=-1;\$x>=0;\$x--}{\$x}{forelse}{\$buh}{/for}", "buh", 'T14', $i++),
         );
     }
+
+    /**
+     * Test {for} inside an inheritance (extends) template.
+     *
+     * The {for} tag pokes loop bookkeeping (step, total, value, ...) directly
+     * onto its loop Variable. In an extended template the child block renders
+     * with SCOPE_PARENT, so the loop variable is assigned to the parent and was
+     * not resolvable locally, causing 'assign property on null'.
+     *
+     * @see https://github.com/smarty-php/smarty/issues/1036
+     *
+     * @dataProvider dataForInheritance
+     */
+    public function testForInheritance($code, $result, $testName, $caching)
+    {
+        $this->smarty->caching = $caching;
+        $tpl = $this->smarty->createTemplate($code);
+        $this->assertEquals($result, $this->smarty->fetch($tpl), "test - {$testName}");
+    }
+
+    public function dataForInheritance()
+    {
+        $parent = 'extends:string:{block name="content"}{/block}';
+        $cases = array(
+            array('to',     '{for $i=0 to 3}{$i}{/for}',                      '0123'),
+            array('step',   '{for $i=0 to 3 step 2}{$i}{/for}',               '02'),
+            array('max',    '{for $i=0 to 30 max=3}{$i}{/for}',               '012'),
+            array('nested', '{for $i=0 to 1}{for $y=0 to 3}{$y}{/for}{/for}', '01230123'),
+            array('legacy', '{for $i=0; $i<4; $i++}{$i}{/for}',               '0123'),
+        );
+        $data = array();
+        foreach (array(false, true) as $caching) {
+            foreach ($cases as $case) {
+                $code = $parent . '|string:{block name="content"}' . $case[1] . '{/block}';
+                $name = $case[0] . ($caching ? ' (caching)' : '');
+                $data[] = array($code, $case[2], $name, $caching);
+            }
+        }
+        return $data;
+    }
+
 }