Symfony 2.8.1 error after installation

I am using Symfony 2.8.1 and work on Windows 8 with WAMP Server 2, Apache 2.4.2 and PHP 5.4.3 I have installed Symfony with the command tool with success, but when I try to access the url http://localhost/Symfony/web/app_dev.php/ I get this error message :

FatalErrorException in ProxyGenerator.php line 62: Parse Error: syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING)

Then this list of errors :

in ProxyGenerator.php line 62
at DebugClassLoader->loadClass() in EntityManager.php line 0
at ProxyFactory->__construct() in EntityManager.php line 166
at EntityManager->__construct() in EntityManager.php line 850
at EntityManager::create() in appDevDebugProjectContainer.php line 605
at appDevDebugProjectContainer->getDoctrine_Orm_DefaultEntityManagerService() in Container.php line 312
at Container->get() in classes.php line 6695
at ManagerRegistry->getService() in classes.php line 6665
at AbstractManagerRegistry->getManagers() in DoctrineDataCollector.php line 65
at DoctrineDataCollector->collect() in Profiler.php line 218
at Profiler->collect() in ProfilerListener.php line 128
at ProfilerListener->onKernelResponse() in WrappedListener.php line 61
at call_user_func() in WrappedListener.php line 61
at WrappedListener->__invoke() in classes.php line 1853
at call_user_func() in classes.php line 1853
at EventDispatcher->doDispatch() in classes.php line 1771
at EventDispatcher->dispatch() in TraceableEventDispatcher.php line 132
at TraceableEventDispatcher->dispatch() in HttpKernel.php line 179
at HttpKernel->filterResponse() in HttpKernel.php line 161
at HttpKernel->handleRaw() in HttpKernel.php line 62
at HttpKernel->handle() in ContainerAwareHttpKernel.php line 69
at ContainerAwareHttpKernel->handle() in Kernel.php line 185
at Kernel->handle() in app_dev.php line 30
at {main}() in app_dev.php line 0

On line 62 of ProxyGenerator.php :

protected $placeholders = [
    'baseProxyInterface'   => Proxy::class,
    'additionalProperties' => '',
];

The issue seems to be this :

Proxy::class

When I change it into that :

'Doctrine\Common\Proxy\Proxy'

It works !

I'd like to know what's happening and if the change I made is a solution for real.

Any thoughts ? Thanks.