…ices (nicolas-grekas)This PR was merged into the 3.3-dev branch.Discussion----------[DI] Allow extensions to create ServiceLocator as services| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets | -| License       | MIT| Doc PR        | -https://github.com/symfony/symfony/pull/21770/files?w=1With this PR, DI extensions are able to create "service locator" services.They are easily created as such:```php$container->register('my_service_locator', ServiceLocator::class)    ->addArgument(array(        'exposed_id' => new ServiceClosureArgument(new Reference('internal_id')),    ))```I already need this in two different PRs to come.Commits-------1d96633 [DI] Allow creating ServiceLocator-based services in extensions

…s" tag to inject services into actions (nicolas-grekas)This PR was merged into the 3.3-dev branch.Discussion----------[FrameworkBundle] Add new "controller.service_arguments" tag to inject services into actions| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | (no test yet)| Fixed tickets | -| License       | MIT| Doc PR        | -Talking with@simensen and@weaverryan, we wondered if we could leverage the `ArgumentResolver` mechanism to make it inject services on demand, using e.g. autowiring.```phpclass PostController{  public function indexAction(Request $request, PostRepository $postRepository)  {    // PostRepository comes from the container    $postRepository->findAll(); // ...  }}```This PR achieves that, using a new "controller.service_arguments" tag. Typically:```yamlservices:    AppBundle\Controller\PostController:        autowire: true        tags:            - name: controller.service_arguments```It also supports with explicit wiring (thus doesn't necessarily require autowiring if you don't want to use it):```yamlservices:    AppBundle\Controller\PostController:        tags:            - name: controller.service_arguments              action: fooAction              argument: logger              id: my_logger```~~The attached diff is bigger than strictly required for now, until#21770 is merged.~~Todo:- [x] rebase on top of#21770 when merged- [x] add tests- [x] add cleaning pass to remove empty service locatorsCommits-------9c6e672 [FrameworkBundle] Add new "controller.service_arguments" tag to inject services into actions

…es (HypeMC)This PR was merged into the 5.4 branch.Discussion----------[DependencyInjection] Add section about Service ClosuresDocuments service closures added insymfony/symfony#21770 andsymfony/symfony#41176, and the `service_closure()` PHP-DSL function added insymfony/symfony#42625 .Commits-------f2b2fdb [DI] Add section about Service Closures