From b909acf2eecc36624cd1277c1aa863bf4cb01b52 Mon Sep 17 00:00:00 2001
From: HypeMC <hypemc@gmail.com>
Date: Fri, 4 Mar 2022 07:24:56 +0100
Subject: [PATCH] [HttpFoundation] Fix PHP 8.1 deprecation in isNotModified

---
 src/Symfony/Component/HttpFoundation/Response.php  |  3 +--
 .../HttpFoundation/Tests/ResponseTest.php          | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index bd990e9c04ae7..bfdc1b24a789a 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -1079,8 +1079,7 @@ public function isNotModified(Request $request): bool
         $lastModified = $this->headers->get('Last-Modified');
         $modifiedSince = $request->headers->get('If-Modified-Since');
 
-        if ($ifNoneMatchEtags = $request->getETags()) {
-            $etag = $this->getEtag();
+        if (($ifNoneMatchEtags = $request->getETags()) && (null !== $etag = $this->getEtag())) {
             if (0 == strncmp($etag, 'W/', 2)) {
                 $etag = substr($etag, 2);
             }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
index 473406287dd09..734961b80e88b 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
@@ -284,6 +284,20 @@ public function testIsNotModifiedIfModifiedSinceAndEtagWithoutLastModified()
         $this->assertFalse($response->isNotModified($request));
     }
 
+    public function testIfNoneMatchWithoutETag()
+    {
+        $request = new Request();
+        $request->headers->set('If-None-Match', 'randomly_generated_etag');
+
+        $this->assertFalse((new Response())->isNotModified($request));
+
+        // Test wildcard
+        $request = new Request();
+        $request->headers->set('If-None-Match', '*');
+
+        $this->assertFalse((new Response())->isNotModified($request));
+    }
+
     public function testIsValidateable()
     {
         $response = new Response('', 200, ['Last-Modified' => $this->createDateTimeOneHourAgo()->format(\DATE_RFC2822)]);