…licit service locators (nicolas-grekas)This PR was squashed before being merged into the 3.3-dev branch (closes#21708).Discussion----------[DI] Add and wire ServiceSubscriberInterface - aka explicit service locators| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | no test yet| Fixed tickets |#20658| License       | MIT| Doc PR        | -This PR implements the second and missing part of#20658: it enables objects to declare their service dependencies in a similar way than we do for EventSubscribers: via a static method. Here is the interface and its current description:```phpnamespace Symfony\Component\DependencyInjection;/** * A ServiceSubscriber exposes its dependencies via the static {@link getSubscribedServices} method. * * The getSubscribedServices method returns an array of service types required by such instances, * optionally keyed by the service names used internally. Service types that start with an interrogation * mark "?" are optional, while the other ones are mandatory service dependencies. * * The injected service locators SHOULD NOT allow access to any other services not specified by the method. * * It is expected that ServiceSubscriber instances consume PSR-11-based service locators internally. * This interface does not dictate any injection method for these service locators, although constructor * injection is recommended. * *@author Nicolas Grekas <p@tchwork.com> */interface ServiceSubscriberInterface{    /**     * Returns an array of service types required by such instances, optionally keyed by the service names used internally.     *     * For mandatory dependencies:     *     *  * array('logger' => 'Psr\Log\LoggerInterface') means the objects use the "logger" name     *    internally to fetch a service which must implement Psr\Log\LoggerInterface.     *  * array('Psr\Log\LoggerInterface') is a shortcut for     *  * array('Psr\Log\LoggerInterface' => 'Psr\Log\LoggerInterface')     *     * otherwise:     *     *  * array('logger' => '?Psr\Log\LoggerInterface') denotes an optional dependency     *  * array('?Psr\Log\LoggerInterface') is a shortcut for     *  * array('Psr\Log\LoggerInterface' => '?Psr\Log\LoggerInterface')     *     *@return array The required service types, optionally keyed by service names     */    public static function getSubscribedServices();}```We could then have eg a controller-as-a-service implement this interface, and be auto or manually wired according to the return value of this method - using the "kernel.service_subscriber" tag to do so.eg:```yamlservices:  App\Controller\FooController:    arguments: [service_container]    tags:      - name: kernel.service_subscriber        key: logger        service: monolog.logger.foo_channel```The benefits are:- it keeps the lazy-behavior gained by service locators / container injection- it allows the referenced services to be made private from the pov of the main Symfony DIC - thus enables some compiler optimizations- it makes dependencies autowirable (while keeping manual wiring possible)- it does not add any strong coupling at the architecture level- and most importantly and contrary to regular container injection, *it makes dependencies explicit* - each classes declaring which services it consumes.Some might argue that:- it requires to be explicit - thus more verbose. Yet many others think it's a good thing - ie it's worth it.- some coupling happens at the dependency level, since you need to get the DI component to get the interface definition. This is something that the PHP-FIG could address at some point.Commits-------c5e80a2 implement ServiceSubscriberInterface where applicable9b7df39 [DI] Add and wire ServiceSubscriberInterface

…ing ControllerTrait (nicolas-grekas)This PR was merged into the 3.3-dev branch.Discussion----------[FrameworkBundle] Introduce AbstractController, replacing ControllerTrait| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no (master only)| Deprecations? | yes| Tests pass?   | yes| Fixed tickets | -| License       | MIT| Doc PR        | -Basically reverts and replaces#18193.Instead of using getter injection to provide our controller helpers, let's leverage the new `ServiceSubscriberInterface` (see#21708).This is what the proposed `AbstractController` class provides.So, instead of extending `Controller`, this would encourage extending `AbstractController`.This provides almost the same experience, but makes the container private, thus not usable by userland (this safeguard was already provided by `ControllerTrait`).I did not deprecate `Controller`, but I think we should. Now that we also have "controller.service_arguments" (see#21771), we have everything in place to encourage *not* using the container in controllers directly anymore.My target in doing so is removing getter injection, which won't have any use case in core anymore.The wiring for this could be:```yamlservices:    _instanceof:        Symfony\Bundle\FrameworkBundle\Controller\AbstractController:            calls: [ [ setContainer, [ '@container' ] ] ]            tags: [ container.service_subscriber ]````But this is optional, because we don't really need to inject a scoped service locator: injecting the real container is fine also, since everything is private. And this is done automatically on ControllerResolver.Commits-------a93f059 [FrameworkBundle] Introduce AbstractController, replacing ControllerTrait

…las-grekas)" (nicolas-grekas)This PR was merged into the 3.3-dev branch.Discussion----------Revert "feature#20973 [DI] Add getter injection (nicolas-grekas)"This reverts commit2183f98, reversingchanges made tob465634.| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no (master only)| Deprecations? | no| Tests pass?   | yes| Fixed tickets | -| License       | MIT| Doc PR        | -Let's remove getter injection, we now have enough alternative mechanisms to achieve almost the same results (e.g. `ServiceSubscriberInterface`, see#21708)., and I'm tired being called by names because of it.The only use case in core is `ControllerTrait`, but this should be gone if#22157 is merged.Commits-------23fa3a0 Revert "feature#20973 [DI] Add getter injection (nicolas-grekas)"