Merge branch '3.4'

* 3.4:
  fix merge
  fix merge
  [FORM] Prevent forms from extending itself as a parent
  fix merge
  Fix 7.2 compat layer
  [DI] Prefixed env vars and load time inlining are incompatible
  bug #24499 [Bridge\PhpUnit] Fix infinite loop when running isolated method (bis) (nicolas-grekas)
  Fix PHP 7.2 support
  [HttpFoundation] Add missing session.lazy_write config option
  [DI] Exclude inline services declared in XML from autowiring candidates
  [HttpFoundation] Combine Cache-Control headers
  [Form] fix parsing invalid floating point numbers
  Escape command usage when displaying it in the text descriptor
  [DI] Throw accurate failures when accessing removed services
  [DI] Turn private defs to non-public ones before removing passes
  Use for=ID on radio/checkbox label.

Author: nicolas-grekas

Tests/Command/CacheClearCommand/CacheClearCommandTest.php

@@ -55,7 +55,7 @@ public function testCacheIsFreshAfterCacheClearedWithWarmup()
         $finder = new Finder();
         $metaFiles = $finder->files()->in($this->kernel->getCacheDir())->name('*.php.meta');
         // simply check that cache is warmed up
-        $this->assertGreaterThanOrEqual(1, count($metaFiles));
+        $this->assertNotEmpty($metaFiles);
         $configCacheFactory = new ConfigCacheFactory(true);
 
         foreach ($metaFiles as $file) {

Tests/Controller/ControllerTraitTest.php

@@ -373,6 +373,9 @@ public function testRedirectToRoute()
         $this->assertSame(302, $response->getStatusCode());
     }
 
+    /**
+     * @runInSeparateProcess
+     */
     public function testAddFlash()
     {
         $flashBag = new FlashBag();

Tests/Fixtures/Validation/Article.php

@@ -2,7 +2,9 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\Fixtures\Validation;
 
-class Article implements NotExistingInterface
-{
-    public $category;
+if (!function_exists('__phpunit_run_isolated_test')) {
+    class Article implements NotExistingInterface
+    {
+        public $category;
+    }
 }