Symfony version(s) affected: 4.4, 5.3, 5.4, 6.0

Description

In November, PHP 8.1 will be released and we should be prepared. In this PR, I'd like to track the efforts necessary to make all actively maintained branches ready for that release.

Ready means: if an application uses features of PHP 8.1, Symfony must not blow up.

We do already have a GitHub action that tests all branches with PHP 8.1. This action will always pass, but the output will show us if we're compatible yet: https://github.com/symfony/symfony/runs/2752054643

I will update this issue as we progress.

How to Contribute

If you want to join the effort, please start with the components and bridges. Fixing those will also fix many broken bundle tests. Reminder: We treat compatibility issues as bugs. As always, please fix bugs on the lowest maintained branch that suffers from the bug.

Progress

Components

• Asset
  • [Asset] Don't pass null to strpos() #41559
• BrowserKit
• Cache
  • Add ReturnTypeWillChange to PDO implementations doctrine/dbal#4662
  • Add ReturnTypeWillChange predis/predis#706
  • Fix tests failing with DBAL 3 #42819
• Config
  • [Config] Reflection failure when using new in initializers in PHP 8.1 #43260
• Console
  • Fix incompatible implicit float-to-int conversions #41555
  • Failing test: ApplicationTest::testRenderExceptionWithDoubleWidthCharacters
  • Failing test: Symfony\Component\Console\Tests\Style\SymfonyStyleTest::testOutputs
• CssSelector
• Debug
• DependencyInjection
  • ContainerBuilder::hash() is unstable when switching from PHP 8.0 to 8.1 #41592
  • [DependencyInjection] Fix testServiceSubscriber for PHP 8.1 #41603
  • Support for PHP 8.1 laminas/laminas-code#86
  • [DependencyInjection] fix support for "new" in initializers on PHP 8.1 #43277
  • [DependencyInjection] Cast tag attribute value to string #44639
• DomCrawler
  • Fix PHP 8.1 deprecations Masterminds/html5-php#207
• Dotenv
• ErrorHandler
  • [ErrorHandler] Fix test fatal_with_nested_handlers for PHP 8.1 #42761
• EventDispatcher
• ExpressionLanguage
• Filesystem
• Finder
• Form
  • Add ReturnTypeWillChange where necessary doctrine/collections#277
  • Failing test: NumberToLocalizedStringTransformerTest
  • [Form] Remove broken test case #42630
• HttpClient
  • NativeHttpClient thows Invalid IP Address: 0 on PHP 8.1 #41622
  • [HttpClient] Revert bindto workaround for unaffected PHP versions #41624
  • [HttpClient] Don't pass float to usleep() #42769
• HttpFoundation
  • [HttpFoundation] Handle new tentative return types #41626
  • "false" pseudo type is not handled properly sebastianbergmann/type#15
  • Add return types to JsonSerializable implementations #41556
  • Failing test: BinaryFileResponseTest::testSetContentDispositionGeneratesSafeFallbackFilename
  • [HttpFoundation] Don't pass null to strpos() #42380
  • [HttpFoundation] Remove implicit float to int cast #42783
  • [HttpFoundation] Fix PHP 8.1 deprecation notice in IpUtils::checkIp() #43357
• HttpKernel
  • Fix SplFileInfo mock in HttpKernelBrowserTest #42618
• Inflector
• Intl
• Ldap
• Lock
  • Add ReturnTypeWillChange to PDO implementations doctrine/dbal#4662
  • Failing test: SemaphoreStoreTest::testBlockingLocks
  • Fix incompatible implicit float-to-int conversions #41555
  • Add ReturnTypeWillChange predis/predis#706
• Mailer
• Messenger
  • Add ReturnTypeWillChange to PDO implementations doctrine/dbal#4662
  • [Messenger] Fix broken mock #41558
• Mime
  • [Mime] Fix CSV file mime type guess test for PHP 8.1 #41614
• Notifier
• OptionsResolver
• PasswordHasher
• Process
• PropertyAccess
• PropertyInfo
• RateLimiter
• Routing
• SecurityCore
  • Fix Serializable deprecations triggered by token mocks #41554
  • [Security] Fix SerializableUser fixture #41567
• SecurityCsrf
• SecurityGuard
  • Fix Serializable deprecations triggered by token mocks #41554
• SecurityHttp
  • Fix Serializable deprecations triggered by token mocks #41554
• Serializer
  • Add return types to JsonSerializable implementations #41556
  • [Serializer] Don't pass null to preg_match() #43062
• Semaphore
• Stopwatch
• String
  • [String] Fix implicit float-to-int casts #41561
• Templating
• Translation
  • [Translation] Don't pass null to strtoupper() #41562
  • Failing test: PseudoLocalizationTranslatorTest::testTrans
• Uid
• Validator
  • [Validator] Fix tests by making constraint options dumps order consistent #41636
• VarDumper
  • [VarDumper] Fix tests for PHP 8.1 #41701
  • Fix incompatible implicit float-to-int conversions #41555
  • [VarDumper] Fix handling of "new" in initializers on PHP 8.1 #43270
• VarExporter
  • [VarExporter] Fix test on PHP 8.1 #41627
  • [VarExporter] Suppress deprecations for legacy fixtures #42782
• WebLink
• Workflow
• Yaml
  • Fix incompatible implicit float-to-int conversions #41555

Bridges

• Doctrine
  • Add ReturnTypeWillChange to PDO implementations doctrine/dbal#4662
  • Add ReturnTypeWillChange to core interface implementations doctrine/dbal#4734
  • Add ReturnTypeWillChange to ReflectionEmbeddedProperty doctrine/orm#8742
  • Add ReturnTypeWillChange to extended reflection classes doctrine/persistence#189
  • Add ReturnTypeWillChange where necessary doctrine/collections#277
• Monolog
  • Fix deprecation warning on PHP 8.1 Seldaek/monolog#1554
• PhpUnit
• ProxyManager
  • Support for PHP 8.1 laminas/laminas-code#86
• Twig
  • Fix Serializable deprecations triggered by token mocks #41554

Bundles

• DebugBundle
• FrameworkBundle
  • [FrameworkBundle][WebProfilerBundle] Don't pass null to string parameters #41565
  • Fix PHP 8.1 deprecations Masterminds/html5-php#207
  • Fix Serializable deprecations triggered by token mocks #41554
  • [DependencyInjection] Don't pass null to trim() #41557
  • [DomCrawler] Don't pass null to trim() #42768
  • [Cache] Fix implicit float to int cast #42835
• SecurityBundle
  • Fix PHP 8.1 deprecations Masterminds/html5-php#207
  • Fix Serializable deprecations triggered by token mocks #41554
  • [DependencyInjection] Don't pass null to trim() #41557
  • [SecurityBundle] Fix broken mock #42770
• TwigBundle
  • [DependencyInjection] Don't pass null to trim() #41557
• WebProfilerBundle
  • Fix PHP 8.1 deprecations Masterminds/html5-php#207
  • [FrameworkBundle][WebProfilerBundle] Don't pass null to string parameters #41565
  • Add ReturnTypeWillChange to JsonSerializable implementation twigphp/Twig#3536
  • [DependencyInjection] Don't pass null to trim() #41557
• WebServerBundle