[FrameworkBundle] Deprecate flashbag and attributebag services

Author: warslett

CHANGELOG.md

@@ -17,6 +17,7 @@ CHANGELOG
  * Added `debug:container --deprecations` option to see compile-time deprecations.
  * Made `BrowserKitAssertionsTrait` report the original error message in case of a failure
  * Added ability for `config:dump-reference` and `debug:config` to dump and debug kernel container extension configuration.
+ * Deprecated `session.attribute_bag` service and `session.flash_bag` service.
 
 5.0.0
 -----

Resources/config/session.xml

@@ -43,11 +43,13 @@
 
         <service id="session.flash_bag" class="Symfony\Component\HttpFoundation\Session\Flash\FlashBag">
             <factory service="session" method="getFlashBag" />
+            <deprecated package="symfony/framework-bundle" version="5.1">The "%service_id%" service is deprecated, use "$session->getFlashBag()" instead.</deprecated>
         </service>
         <service id="Symfony\Component\HttpFoundation\Session\Flash\FlashBagInterface" alias="session.flash_bag" />
 
         <service id="session.attribute_bag" class="Symfony\Component\HttpFoundation\Session\Attribute\AttributeBag">
             <factory service="session" method="getAttributeBag" />
+            <deprecated package="symfony/framework-bundle" version="5.1">The "%service_id%" service is deprecated, use "$session->getAttributeBag()" instead.</deprecated>
         </service>
 
         <service id="session.storage.mock_file" class="Symfony\Component\HttpFoundation\Session\Storage\MockFileSessionStorage">

Tests/Functional/SessionTest.php

@@ -11,8 +11,12 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\Functional;
 
+use Symfony\Bridge\PhpUnit\ExpectDeprecationTrait;
+
 class SessionTest extends AbstractWebTestCase
 {
+    use ExpectDeprecationTrait;
+
     /**
      * Tests session attributes persist.
      *
@@ -72,10 +76,13 @@ public function testFlash($config, $insulate)
     /**
      * Tests flash messages work when flashbag service is injected to the constructor.
      *
+     * @group legacy
      * @dataProvider getConfigs
      */
     public function testFlashOnInjectedFlashbag($config, $insulate)
     {
+        $this->expectDeprecation('Since symfony/framework-bundle 5.1: The "session.flash_bag" service is deprecated, use "$session->getFlashBag()" instead.');
+
         $client = $this->createClient(['test_case' => 'Session', 'root_config' => $config]);
         if ($insulate) {
             $client->insulate();