Add a request_stack service and use it for the http kernel.

definitely +1. this will make things a lot saner

+++ b/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/DependencyInjection/ContainerAwareHttpKernel.php
@@ -35,12 +35,12 @@ class ContainerAwareHttpKernel extends HttpKernel
      * @param ContainerInterface          $container          A ContainerInterface instance
-     * @param ControllerResolverInterface $controllerResolver A ControllerResolverInterface instance
+     * @param ControllerResolverInterface $controller_resolver A ControllerResolverInterface instance
      * @param RequestStack                $requestStack       A stack for master/sub requests
      */
-    public function __construct(EventDispatcherInterface $dispatcher, ContainerInterface $container, ControllerResolverInterface $controllerResolver, RequestStack $requestStack = null)
+    public function __construct(EventDispatcherInterface $dispatcher, ContainerInterface $container, ControllerResolverInterface $controller_resolver, RequestStack $requestStack = null)
     {
-        parent::__construct($dispatcher, $controllerResolver, $requestStack);
+        parent::__construct($dispatcher, $controller_resolver, $requestStack);
 
         $this->container = $container;
 

Why are we changing symfony here? :) I guess you renamed it in our own HttpKernel and the parent got changed too?

Not sure if we should follow our own naming or that of symfony in cases like this...

Just to follow the same constructor as theirs, marking it optional.

Confession: I'm not sure what this actually accomplishes for us, since this code was already running in HEAD (in their upstream version of HttpKernel):
$this->requestStack = $requestStack ?: new RequestStack();

So we have it in core.services.yml now, but that's it? What else is in scope for this issue?

next steps would be replacing @request with @request_stack in core.services.yml, probably most important would be to make FormBase use that instead of the @request service

The issue title sounds scary, but really we're just expanding the constructor with an extra param to match what Symfony is doing, so this is pretty straight-forward.

Committed and pushed to 8.x. Thanks!