[HttpKernel] Remove magic on MapSessionContext and store the object i…

…tself in session

src/Symfony/Component/HttpKernel/CHANGELOG.md

@@ -8,7 +8,7 @@ CHANGELOG
  * Add `HttpException::fromStatusCode()`
  * Add `$validationFailedStatusCode` argument to `#[MapQueryParameter]` that allows setting a custom HTTP status code when validation fails
  * Add `NearMissValueResolverException` to let value resolvers report when an argument could be under their watch but failed to be resolved
- * Add `MapSessionContext` to map multiple session value to an object
+ * Add `MapSessionContext` to map an object to the session
 
 7.0
 ---

src/Symfony/Component/HttpKernel/Controller/ArgumentResolver/SessionContextValueResolver.php

@@ -39,18 +39,17 @@ public function resolve(Request $request, ArgumentMetadata $argument): array
             throw new \LogicException(sprintf('#[MapSessionContext] cannot be used on controller argument "$%s" of type "%s"; a class must be provided.', $argument->getName(), $type));
         }
 
-        $class = eval(<<<SUBCLASS
-                return (
-                    new class() extends $type {
-                        use Symfony\Component\HttpKernel\Controller\SessionContextTrait;
-                    }
-                );
-            SUBCLASS
-        );
-        $class->initSessionContext($request->getSession(), new $type());
+        if ($request->getSession()->has($type)) {
+            return [
+                $request->getSession()->get($type),
+            ];
+        }
+
+        $object = new $type();
+        $request->getSession()->set($type, $object);
 
         return [
-            $class,
+            $object,
         ];
     }
 }

src/Symfony/Component/HttpKernel/Tests/Controller/ArgumentResolver/SessionContextValueResolverTest.php

@@ -68,7 +68,6 @@ public function testResolvingSuccessfully(ArgumentMetadata $metadata, string $ex
         $result = $this->resolver->resolve($this->request, $metadata);
         $this->assertCount(1, $result);
 
-        $this->assertTrue((new \ReflectionClass($result[0]))->isAnonymous());
         $this->assertInstanceOf($expectedType, $result[0]);
     }