From 35deb66f096644eb4eb9e428b2888fd3cca34175 Mon Sep 17 00:00:00 2001
From: Tomas Votruba <tomas.vot@gmail.com>
Date: Tue, 30 Jun 2026 11:01:36 +0200
Subject: [PATCH] [Php81] Skip ReadOnlyPropertyRector on property changed via
 reference in foreach

---
 .../skip_changed_by_ref_in_foreach.php.inc    | 16 ++++++++++
 .../Property/ReadOnlyPropertyRector.php       | 31 +++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 rules-tests/Php81/Rector/Property/ReadOnlyPropertyRector/Fixture/skip_changed_by_ref_in_foreach.php.inc

diff --git a/rules-tests/Php81/Rector/Property/ReadOnlyPropertyRector/Fixture/skip_changed_by_ref_in_foreach.php.inc b/rules-tests/Php81/Rector/Property/ReadOnlyPropertyRector/Fixture/skip_changed_by_ref_in_foreach.php.inc
new file mode 100644
index 00000000000..0971532f612
--- /dev/null
+++ b/rules-tests/Php81/Rector/Property/ReadOnlyPropertyRector/Fixture/skip_changed_by_ref_in_foreach.php.inc
@@ -0,0 +1,16 @@
+<?php
+
+namespace Rector\Tests\Php81\Rector\Property\ReadOnlyPropertyRector\Fixture;
+
+final class SkipChangedByRefInForeach
+{
+    private array $relativeDateStrings;
+
+    public function __construct()
+    {
+        $this->relativeDateStrings = ['yesterday', 'today'];
+        foreach ($this->relativeDateStrings as &$string) {
+            $string = strtoupper($string);
+        }
+    }
+}
diff --git a/rules/Php81/Rector/Property/ReadOnlyPropertyRector.php b/rules/Php81/Rector/Property/ReadOnlyPropertyRector.php
index 31a4fd1c300..38b33743a35 100644
--- a/rules/Php81/Rector/Property/ReadOnlyPropertyRector.php
+++ b/rules/Php81/Rector/Property/ReadOnlyPropertyRector.php
@@ -13,6 +13,7 @@
 use PhpParser\Node\Param;
 use PhpParser\Node\Stmt\Class_;
 use PhpParser\Node\Stmt\ClassMethod;
+use PhpParser\Node\Stmt\Foreach_;
 use PhpParser\Node\Stmt\Property;
 use PhpParser\Node\Stmt\Return_;
 use PhpParser\NodeVisitor;
@@ -180,6 +181,11 @@ private function refactorProperty(Class_ $class, Property $property, Scope $scop
             return null;
         }
 
+        // changed via reference in foreach, e.g. foreach ($this->items as &$item), so it cannot be readonly
+        if ($this->isPropertyChangedInByRefForeach($class, (string) $this->getName($property))) {
+            return null;
+        }
+
         $this->visibilityManipulator->makeReadonly($property);
         $this->removeReadOnlyDoc($property);
 
@@ -247,6 +253,11 @@ private function refactorParam(Class_ $class, ClassMethod $classMethod, Param $p
             return null;
         }
 
+        // changed via reference in foreach, e.g. foreach ($this->items as &$item), so it cannot be readonly
+        if ($this->isPropertyChangedInByRefForeach($class, (string) $this->getName($param))) {
+            return null;
+        }
+
         $this->visibilityManipulator->makeReadonly($param);
 
         $this->removeReadOnlyDoc($param);
@@ -283,6 +294,26 @@ private function isPropertyReturnedByRef(Class_ $class, string $propertyName): b
         return false;
     }
 
+    private function isPropertyChangedInByRefForeach(Class_ $class, string $propertyName): bool
+    {
+        return (bool) $this->betterNodeFinder->findFirst($class, function (Node $node) use ($propertyName): bool {
+            if (! $node instanceof Foreach_) {
+                return false;
+            }
+
+            if (! $node->byRef) {
+                return false;
+            }
+
+            if (! $node->expr instanceof PropertyFetch) {
+                return false;
+            }
+
+            return $this->isName($node->expr->var, 'this')
+                && $this->isName($node->expr, $propertyName);
+        });
+    }
+
     private function isPromotedPropertyAssigned(Class_ $class, Param $param): bool
     {
         $constructClassMethod = $class->getMethod(MethodName::CONSTRUCT);