Stop the escaping safe analysis from retaining every analyzed node

CHANGELOG

@@ -1,5 +1,6 @@
 # 3.30.0 (2026-XX-XX)
 
+ * Fix the escaping safe analysis retaining every compiled template node for the lifetime of the environment
  * Fix `IntlExtension` letting the pattern derived from a date formatter prototype override an explicit locale
  * Fix `IntlExtension` not honoring the locale of a date formatter prototype configured with no date and time styles
  * Speed up macro calls

src/NodeVisitor/SafeAnalysisNodeVisitor.php

@@ -29,9 +29,17 @@ use Twig\Node\Node;
  */
 final class SafeAnalysisNodeVisitor implements NodeVisitorInterface
 {
-    private $data = [];
+    /**
+     * @var \WeakMap<Node, array>
+     */
+    private \WeakMap $data;
     private $safeVars = [];
 
+    public function __construct()
+    {
+        $this->data = new \WeakMap();
+    }
+
     public function setSafeVars(array $safeVars): void
     {
         $this->safeVars = $safeVars;
@@ -42,47 +50,23 @@ final class SafeAnalysisNodeVisitor implements NodeVisitorInterface
      */
     public function getSafe(Node $node)
     {
-        $hash = spl_object_id($node);
-        if (!isset($this->data[$hash])) {
-            return [];
+        $safe = $this->data[$node] ?? [];
+
+        if (\in_array('html_attr', $safe, true)) {
+            $safe[] = 'html';
+            $safe[] = 'html_attr_relaxed';
         }
 
-        foreach ($this->data[$hash] as $bucket) {
-            if ($bucket['key'] !== $node) {
-                continue;
-            }
-
-            if (\in_array('html_attr', $bucket['value'], true)) {
-                $bucket['value'][] = 'html';
-                $bucket['value'][] = 'html_attr_relaxed';
-            }
-
-            if (\in_array('html_attr_relaxed', $bucket['value'], true)) {
-                $bucket['value'][] = 'html';
-            }
-
-            return $bucket['value'];
+        if (\in_array('html_attr_relaxed', $safe, true)) {
+            $safe[] = 'html';
         }
 
-        return [];
+        return $safe;
     }
 
     private function setSafe(Node $node, array $safe): void
     {
-        $hash = spl_object_id($node);
-        if (isset($this->data[$hash])) {
-            foreach ($this->data[$hash] as &$bucket) {
-                if ($bucket['key'] === $node) {
-                    $bucket['value'] = $safe;
-
-                    return;
-                }
-            }
-        }
-        $this->data[$hash][] = [
-            'key' => $node,
-            'value' => $safe,
-        ];
+        $this->data[$node] = $safe;
     }
 
     public function enterNode(Node $node, Environment $env): Node

tests/NodeVisitor/SafeAnalysisTest.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Tests\NodeVisitor;
+
+use PHPUnit\Framework\TestCase;
+use Twig\Environment;
+use Twig\Loader\ArrayLoader;
+use Twig\Node\Node;
+use Twig\Source;
+
+class SafeAnalysisTest extends TestCase
+{
+    public function testCompilingDoesNotRetainTheAst()
+    {
+        $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => 'html']);
+        $source = new Source('{{ "a"|upper }}{{ foo.bar }}{{ [1, 2]|join("-") }}{{ b ? "y" : "n" }}', 'index');
+
+        $ast = $env->parse($env->tokenize($source));
+
+        $refs = [];
+        $collect = static function (Node $node) use (&$collect, &$refs) {
+            $refs[] = \WeakReference::create($node);
+            foreach ($node as $child) {
+                $collect($child);
+            }
+        };
+        $collect($ast);
+        $this->assertNotEmpty($refs);
+
+        unset($ast, $collect);
+        gc_collect_cycles();
+
+        $retained = 0;
+        foreach ($refs as $ref) {
+            if (null !== $ref->get()) {
+                ++$retained;
+            }
+        }
+
+        $this->assertSame(0, $retained, \sprintf('%d of %d AST nodes are still referenced after compilation.', $retained, \count($refs)));
+    }
+}