From 0197736dfc22adbe441ec50c16cf5c69c2655e76 Mon Sep 17 00:00:00 2001
From: Fabien Potencier <fabien@potencier.org>
Date: Sat, 6 Jun 2026 09:31:56 +0200
Subject: [PATCH] Reduce memory usage of the context restoration compiled at
 the end of for loops

---
 CHANGELOG              |  1 +
 src/Node/ForNode.php   |  5 ++++-
 tests/Node/ForTest.php | 12 ++++++++----
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index e89fde984..972517c8c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,6 @@
 # 3.28.0 (2026-XX-XX)
 
+ * Reduce memory usage and speed up the context restoration compiled at the end of `for` loops
  * Report the column number in syntax errors and expose it via `Error::getTemplateColumn()`
  * Track the source offset of each token and expose it via `Token::getOffset()`
  * Fix nested `block()` calls to resolve against the overriding template when a block rendered through `block(name, template)` calls `parent()`
diff --git a/src/Node/ForNode.php b/src/Node/ForNode.php
index 2c86622d4..fda40719f 100644
--- a/src/Node/ForNode.php
+++ b/src/Node/ForNode.php
@@ -115,6 +115,9 @@ class ForNode extends Node
         $compiler->raw(");\n");
 
         // keep the values set in the inner context for variables defined in the outer context
-        $compiler->write("\$context = array_intersect_key(\$context, \$_parent) + \$_parent;\n");
+        $compiler
+            ->write("\$context = array_intersect_key(\$context, \$_parent);\n")
+            ->write("\$context += \$_parent;\n")
+        ;
     }
 }
diff --git a/tests/Node/ForTest.php b/tests/Node/ForTest.php
index 2fcf0fa7c..9a642073c 100644
--- a/tests/Node/ForTest.php
+++ b/tests/Node/ForTest.php
@@ -77,7 +77,8 @@ foreach (\$context['_seq'] as \$context["key"] => \$context["item"]) {
 }
 \$_parent = \$context['_parent'];
 unset(\$context['_seq'], \$context['key'], \$context['item'], \$context['_parent']);
-\$context = array_intersect_key(\$context, \$_parent) + \$_parent;
+\$context = array_intersect_key(\$context, \$_parent);
+\$context += \$_parent;
 EOF
         ];
 
@@ -119,7 +120,8 @@ foreach (\$context['_seq'] as \$context["k"] => \$context["v"]) {
 }
 \$_parent = \$context['_parent'];
 unset(\$context['_seq'], \$context['k'], \$context['v'], \$context['_parent'], \$context['loop']);
-\$context = array_intersect_key(\$context, \$_parent) + \$_parent;
+\$context = array_intersect_key(\$context, \$_parent);
+\$context += \$_parent;
 EOF
         ];
 
@@ -161,7 +163,8 @@ foreach (\$context['_seq'] as \$context["k"] => \$context["v"]) {
 }
 \$_parent = \$context['_parent'];
 unset(\$context['_seq'], \$context['k'], \$context['v'], \$context['_parent'], \$context['loop']);
-\$context = array_intersect_key(\$context, \$_parent) + \$_parent;
+\$context = array_intersect_key(\$context, \$_parent);
+\$context += \$_parent;
 EOF
         ];
 
@@ -210,7 +213,8 @@ if (!\$context['_iterated']) {
 }
 \$_parent = \$context['_parent'];
 unset(\$context['_seq'], \$context['k'], \$context['v'], \$context['_parent'], \$context['_iterated'], \$context['loop']);
-\$context = array_intersect_key(\$context, \$_parent) + \$_parent;
+\$context = array_intersect_key(\$context, \$_parent);
+\$context += \$_parent;
 EOF
         ];