Merge branch '4.3' into 4.4

* 4.3:
  [ProxyManager] fix generating proxies for root-namespaced classes
  [DI] skip looking for config class when the extension class is anonymous
  Fix typo
  [Dotenv] FIX missing getenv
  [HttpClient][Psr18Client] Remove Psr18ExceptionTrait

src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php

@@ -85,6 +85,7 @@ EOF;
     public function getProxyCode(Definition $definition): string
     {
         $code = $this->classGenerator->generate($this->generateProxyClass($definition));
+        $code = preg_replace('/^(class [^ ]++ extends )([^\\\\])/', '$1\\\\$2', $code);
 
         if (version_compare(self::getProxyManagerVersion(), '2.2', '<')) {
             $code = preg_replace(

src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/Fixtures/php/lazy_service_structure.txt

@@ -21,5 +21,5 @@ class LazyServiceProjectServiceContainer extends Container
     }
 }
 
-class stdClass_%s extends %SstdClass implements \ProxyManager\%s
+class stdClass_%s extends \stdClass implements \ProxyManager\%s
 {%a}%A

src/Symfony/Component/DependencyInjection/Extension/Extension.php

@@ -80,6 +80,11 @@ abstract class Extension implements ExtensionInterface, ConfigurationExtensionIn
     public function getConfiguration(array $config, ContainerBuilder $container)
     {
         $class = \get_class($this);
+
+        if (false !== strpos($class, "\0")) {
+            return null; // ignore anonymous classes
+        }
+
         $class = substr_replace($class, '\Configuration', strrpos($class, '\\'));
         $class = $container->getReflectionClass($class);
 

src/Symfony/Component/Dotenv/Dotenv.php

@@ -463,7 +463,7 @@ final class Dotenv
             } elseif (isset($this->values[$name])) {
                 $value = $this->values[$name];
             } else {
-                $value = '';
+                $value = (string) getenv($name);
             }
 
             if ('' === $value && isset($matches['default_value']) && '' !== $matches['default_value']) {

src/Symfony/Component/Dotenv/Tests/DotenvTest.php

@@ -443,6 +443,17 @@ class DotenvTest extends TestCase
         }
     }
 
+    public function testGetVariablesValueFromGetenv()
+    {
+        putenv('Foo=Bar');
+
+        $dotenv = new Dotenv(true);
+        $values = $dotenv->parse('Foo=${Foo}');
+        $this->assertSame('Bar', $values['Foo']);
+
+        putenv('Foo');
+    }
+
     /**
      * @group legacy
      * @expectedDeprecation The default value of "$usePutenv" argument of "%s" will be changed from "true" to "false" in Symfony 5.0. You should define its value explicitly.

src/Symfony/Component/HttpClient/Psr18Client.php

@@ -190,7 +190,7 @@ final class Psr18Client implements ClientInterface, RequestFactoryInterface, Str
 /**
  * @internal
  */
-trait Psr18ExceptionTrait
+class Psr18NetworkException extends \RuntimeException implements NetworkExceptionInterface
 {
     private $request;
 
@@ -206,18 +206,21 @@ trait Psr18ExceptionTrait
     }
 }
 
-/**
- * @internal
- */
-class Psr18NetworkException extends \RuntimeException implements NetworkExceptionInterface
-{
-    use Psr18ExceptionTrait;
-}
-
 /**
  * @internal
  */
 class Psr18RequestException extends \InvalidArgumentException implements RequestExceptionInterface
 {
-    use Psr18ExceptionTrait;
+    private $request;
+
+    public function __construct(TransportExceptionInterface $e, RequestInterface $request)
+    {
+        parent::__construct($e->getMessage(), 0, $e);
+        $this->request = $request;
+    }
+
+    public function getRequest(): RequestInterface
+    {
+        return $this->request;
+    }
 }

src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php

@@ -401,13 +401,11 @@ class NativeSessionStorage implements SessionStorageInterface
      *     ini_set('session.save_path', '/tmp');
      *
      * or pass in a \SessionHandler instance which configures session.save_handler in the
-     * constructor, for a template see NativeFileSessionHandler or use handlers in
+     * constructor, for a template see NativeFileSessionHandler.
-     * composer package drak/native-session
      *
      * @see https://php.net/session-set-save-handler
      * @see https://php.net/sessionhandlerinterface
      * @see https://php.net/sessionhandler
-     * @see https://github.com/zikula/NativeSession
      *
      * @param AbstractProxy|\SessionHandlerInterface|null $saveHandler
      *