From a3eb1bc4577c9ca64e2a8677b8a910512fe6c428 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kuba=20Wer=C5=82os?= <werlos@gmail.com>
Date: Sat, 28 Jun 2025 13:05:38 +0200
Subject: [PATCH] `PromotedConstructorPropertyFixer` - do not promote when type
 of property is not nullable and type of parameter is nullable

---
 README.md                                          |  2 +-
 src/Fixer/PromotedConstructorPropertyFixer.php     | 11 +++++++++--
 .../Fixer/PromotedConstructorPropertyFixerTest.php | 14 ++++++++++++--
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 937bce4b..639752a9 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
 [![Latest stable version](https://img.shields.io/packagist/v/kubawerlos/php-cs-fixer-custom-fixers.svg?label=current%20version)](https://packagist.org/packages/kubawerlos/php-cs-fixer-custom-fixers)
 [![PHP version](https://img.shields.io/packagist/php-v/kubawerlos/php-cs-fixer-custom-fixers.svg)](https://php.net)
 [![License](https://img.shields.io/github/license/kubawerlos/php-cs-fixer-custom-fixers.svg)](LICENSE)
-![Tests](https://img.shields.io/badge/tests-3795-brightgreen.svg)
+![Tests](https://img.shields.io/badge/tests-3796-brightgreen.svg)
 [![Downloads](https://img.shields.io/packagist/dt/kubawerlos/php-cs-fixer-custom-fixers.svg)](https://packagist.org/packages/kubawerlos/php-cs-fixer-custom-fixers)
 
 [![CI status](https://github.com/kubawerlos/php-cs-fixer-custom-fixers/actions/workflows/ci.yaml/badge.svg)](https://github.com/kubawerlos/php-cs-fixer-custom-fixers/actions/workflows/ci.yaml)
diff --git a/src/Fixer/PromotedConstructorPropertyFixer.php b/src/Fixer/PromotedConstructorPropertyFixer.php
index 140f8f1b..2198edc4 100644
--- a/src/Fixer/PromotedConstructorPropertyFixer.php
+++ b/src/Fixer/PromotedConstructorPropertyFixer.php
@@ -275,11 +275,18 @@ private function typesAllowPromoting(string $propertyType, string $parameterType
             return true;
         }
 
-        if (\substr($propertyType, 0, 1) === '?') {
+        $isPropertyNullable = \substr($propertyType, 0, 1) === '?';
+        $isParameterNullable = \substr($parameterType, 0, 1) === '?';
+
+        if ($isParameterNullable && !$isPropertyNullable) {
+            return false;
+        }
+
+        if ($isPropertyNullable) {
             $propertyType = \substr($propertyType, 1);
         }
 
-        if (\substr($parameterType, 0, 1) === '?') {
+        if ($isParameterNullable) {
             $parameterType = \substr($parameterType, 1);
         }
 
diff --git a/tests/Fixer/PromotedConstructorPropertyFixerTest.php b/tests/Fixer/PromotedConstructorPropertyFixerTest.php
index bf2eb390..be55577b 100644
--- a/tests/Fixer/PromotedConstructorPropertyFixerTest.php
+++ b/tests/Fixer/PromotedConstructorPropertyFixerTest.php
@@ -100,6 +100,16 @@ public function __construct(string $x) {
             ',
         ];
 
+        yield 'do not promote when type of property is not nullable and type of parameter is nullable' => [
+            '<?php class Foo {
+                private int $x;
+                public function __construct(?int $x) {
+                    $this->x = $x;
+                }
+            }
+            ',
+        ];
+
         yield 'do not promote when not simple assignment' => [
             '<?php class Foo {
                 private int $x;
@@ -919,7 +929,8 @@ public function __construct(int $x, int $y, int $z, bool $condition)
 
         yield 'promote nullable types' => [
             '<?php class Foo {
-                public function __construct(private ?int $x, private ?int $y, private ?int $z)
+                private int $z;
+                public function __construct(private ?int $x, private ?int $y, ?int $z)
                 {
                 }
             }
@@ -932,7 +943,6 @@ public function __construct(int $x, ?int $y, ?int $z)
                 {
                     $this->x = $x;
                     $this->y = $y;
-                    $this->z = $z;
                 }
             }
             ',