bug #35039 [DI] skip looking for config class when the extension clas…

…s is anonymous (nicolas-grekas)

This PR was merged into the 3.4 branch.

Discussion
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[DI] skip looking for config class when the extension class is anonymous

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #34613
| License       | MIT
| Doc PR        | -

Commits
-------

1c7eda4 [DI] skip looking for config class when the extension class is anonymous

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

@@ -80,6 +80,11 @@ public function getAlias()
     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);
         $constructor = $class ? $class->getConstructor() : null;