From afab34d8ed9050878d209946f68a645d18b91bbc Mon Sep 17 00:00:00 2001
From: Nicolas Grekas <nicolas.grekas@gmail.com>
Date: Wed, 1 Dec 2021 15:17:12 +0100
Subject: [PATCH] [HttpKernel] fix sending Vary: Accept-Language when
 appropriate

---
 .../Component/HttpKernel/EventListener/LocaleListener.php      | 1 +
 .../Component/HttpKernel/EventListener/ResponseListener.php    | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/src/Symfony/Component/HttpKernel/EventListener/LocaleListener.php b/src/Symfony/Component/HttpKernel/EventListener/LocaleListener.php
index 5d77377c6046b..f19e13649e988 100644
--- a/src/Symfony/Component/HttpKernel/EventListener/LocaleListener.php
+++ b/src/Symfony/Component/HttpKernel/EventListener/LocaleListener.php
@@ -70,6 +70,7 @@ private function setLocale(Request $request)
             $request->setLocale($locale);
         } elseif ($this->useAcceptLanguageHeader && $this->enabledLocales && ($preferredLanguage = $request->getPreferredLanguage($this->enabledLocales))) {
             $request->setLocale($preferredLanguage);
+            $request->attributes->set('_vary_by_language', true);
         }
     }
 
diff --git a/src/Symfony/Component/HttpKernel/EventListener/ResponseListener.php b/src/Symfony/Component/HttpKernel/EventListener/ResponseListener.php
index bb51c6dc0dbda..a4090159bb751 100644
--- a/src/Symfony/Component/HttpKernel/EventListener/ResponseListener.php
+++ b/src/Symfony/Component/HttpKernel/EventListener/ResponseListener.php
@@ -50,6 +50,9 @@ public function onKernelResponse(ResponseEvent $event)
 
         if ($this->addContentLanguageHeader && !$response->isInformational() && !$response->isEmpty() && !$response->headers->has('Content-Language')) {
             $response->headers->set('Content-Language', $event->getRequest()->getLocale());
+        }
+
+        if ($event->getRequest()->attributes->get('_vary_by_language')) {
             $response->setVary('Accept-Language', false);
         }