bug #18596 [DI] Fix internal caching in AutowirePass (nicolas-grekas)

This PR was merged into the 2.8 branch.

Discussion
----------

[DI] Fix internal caching in AutowirePass

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

ping @dunglas

Commits
-------

ed2e236 [DI] Fix internal caching in AutowirePass

src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php

@@ -228,7 +228,7 @@ private function createAutowiredDefinition(\ReflectionClass $typeHint, $id)
      * @param string     $id
      * @param Definition $definition
      *
-     * @return \ReflectionClass|null
+     * @return \ReflectionClass|false
      */
     private function getReflectionClass($id, Definition $definition)
     {
@@ -238,15 +238,17 @@ private function getReflectionClass($id, Definition $definition)
 
         // Cannot use reflection if the class isn't set
         if (!$class = $definition->getClass()) {
-            return;
+            return false;
         }
 
         $class = $this->container->getParameterBag()->resolveValue($class);
 
         try {
-            return $this->reflectionClasses[$id] = new \ReflectionClass($class);
+            $reflector = new \ReflectionClass($class);
         } catch (\ReflectionException $reflectionException) {
-            // return null
+            $reflector = false;
         }
+
+        return $this->reflectionClasses[$id] = $reflector;
     }
 }