Fix array access with a Stringable key on ArrayAccess objects using object keys

CHANGELOG

@@ -1,5 +1,6 @@
 # 3.28.1 (2026-XX-XX)
 
+ * Fix array access with a `Stringable` key coercing the key to string for `ArrayAccess` objects that use object keys (such as `SplObjectStorage`)
  * Fix duplicated macro argument names triggering a PHP fatal error instead of a `SyntaxError`
 
 # 3.28.0 (2026-07-03)

src/Node/Expression/GetAttrExpression.php

@@ -74,7 +74,7 @@ class GetAttrExpression extends AbstractExpression implements SupportDefinedTest
                     ->raw($var)
                     ->raw('[')
                 ;
-                $this->compileArrayKey($compiler);
+                $this->compileArrayKey($compiler, $var);
                 $compiler->raw('] ?? null) : null)');
 
                 return;
@@ -91,7 +91,7 @@ class GetAttrExpression extends AbstractExpression implements SupportDefinedTest
                 ->raw($var)
                 ->raw('[')
             ;
-            $this->compileArrayKey($compiler);
+            $this->compileArrayKey($compiler, $var);
             $compiler->raw('] ?? null) : ');
         }
 
@@ -177,9 +177,11 @@ class GetAttrExpression extends AbstractExpression implements SupportDefinedTest
 
     /**
      * Coerces a Stringable array key to string so the optimized path matches
-     * CoreExtension::getAttribute(); scalars are left to PHP's native offset coercion.
+     * CoreExtension::getAttribute(): only arrays coerce the key, while ArrayAccess
+     * objects (e.g. SplObjectStorage) receive it untouched. Scalars are left to
+     * PHP's native offset coercion.
      */
-    private function compileArrayKey(Compiler $compiler): void
+    private function compileArrayKey(Compiler $compiler, string $var): void
     {
         $attribute = $this->getNode('attribute');
 
@@ -193,7 +195,7 @@ class GetAttrExpression extends AbstractExpression implements SupportDefinedTest
         $compiler
             ->raw('(('.$key.' = ')
             ->subcompile($attribute)
-            ->raw(') instanceof \Stringable ? (string) '.$key.' : '.$key.')')
+            ->raw(') instanceof \Stringable && is_array('.$var.') ? (string) '.$key.' : '.$key.')')
         ;
     }
 

tests/TemplateTest.php

@@ -284,6 +284,29 @@ class TemplateTest extends TestCase
         yield 'strict' => [true];
     }
 
+    /**
+     * @dataProvider getStrictVariablesModes
+     */
+    #[DataProvider('getStrictVariablesModes')]
+    public function testArrayAccessWithObjectKeyKeepsTheObjectKey(bool $strict)
+    {
+        $twig = new Environment(new ArrayLoader(['index' => '{{ data[object] }}']), [
+            'strict_variables' => $strict,
+            'autoescape' => false,
+        ]);
+
+        $object = new class implements \Stringable {
+            public function __toString(): string
+            {
+                return 'string';
+            }
+        };
+        $data = new \SplObjectStorage();
+        $data[$object] = 'value';
+
+        $this->assertSame('value', $twig->render('index', ['data' => $data, 'object' => $object]));
+    }
+
     public function testArrayAccessWithStringableKeyIsCheckedBySandbox()
     {
         $object = new class implements \Stringable {