From 4b13b4fb9d3dca4c9f99718e220936dcfd9c9c95 Mon Sep 17 00:00:00 2001
From: Sander Muller <github@scode.nl>
Date: Sat, 17 Oct 2026 17:16:37 +0200
Subject: [PATCH] Skip PhpParser\NodeTraverser in preload.php when it is
 already declared

PHPStan Turbo declares a native PhpParser\NodeTraverser when it is
activated. preload.php then fails with "Cannot redeclare class". Without
Turbo, the class is not declared yet and preload.php loads it as before.
---
 build/build-preload.php | 10 ++++++++++
 preload.php             |  6 +++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/build/build-preload.php b/build/build-preload.php
index 47630502cdf..a2216797532 100755
--- a/build/build-preload.php
+++ b/build/build-preload.php
@@ -48,6 +48,7 @@ final class PreloadBuilder
 declare(strict_types=1);
 
 use PhpParser\Node;
+use PhpParser\NodeTraverser;
 use PHPStan\Testing\PHPStanTestCase;
 
 if (defined('__PHPSTAN_RUNNING__')) {
@@ -230,6 +231,15 @@ private function createRequireOnceFilePathLine(string $realPath): string
         }
 
         $filePath = '/vendor/' . Strings::after($realPath, 'vendor/');
+
+        // PHPStan Turbo declares its native NodeTraverser before this file runs
+        if ($filePath === '/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php') {
+            return 'if (! class_exists(NodeTraverser::class, false)) {' . PHP_EOL
+                . "    require_once __DIR__ . '" . $filePath . "';" . PHP_EOL
+                . '}' . PHP_EOL
+                . PHP_EOL;
+        }
+
         return "require_once __DIR__ . '" . $filePath . "';" . PHP_EOL;
     }
 
diff --git a/preload.php b/preload.php
index b0e5eeaa067..7a108f6bd79 100644
--- a/preload.php
+++ b/preload.php
@@ -3,6 +3,7 @@
 declare(strict_types=1);
 
 use PhpParser\Node;
+use PhpParser\NodeTraverser;
 use PHPStan\Testing\PHPStanTestCase;
 
 if (defined('__PHPSTAN_RUNNING__')) {
@@ -274,7 +275,10 @@ function isPHPStanTestPreloaded(): bool
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/Node/VariadicPlaceholder.php';
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeDumper.php';
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeFinder.php';
-require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php';
+if (! class_exists(NodeTraverser::class, false)) {
+    require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php';
+}
+
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeVisitor/CloningVisitor.php';
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeVisitor/CommentAnnotatingVisitor.php';
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeVisitor/FindingVisitor.php';