UPGRADE FROM 3.3 to 3.4
=======================

DependencyInjection
-------------------

 * Top-level anonymous services in XML are deprecated and will throw an exception in Symfony 4.0.

Finder
------

 * The `Symfony\Component\Finder\Iterator\FilterIterator` class has been
   deprecated and will be removed in 4.0 as it used to fix a bug which existed 
   before version 5.5.23/5.6.7.

FrameworkBundle
---------------

 * The `doctrine/cache` dependency has been removed; require it via `composer
   require doctrine/cache` if you are using Doctrine cache in your project.

 * The `validator.mapping.cache.doctrine.apc` service has been deprecated.

 * Using the `KERNEL_DIR` environment variable or the automatic guessing based
   on the `phpunit.xml` / `phpunit.xml.dist` file location is deprecated since 3.4. 
   Set the `KERNEL_CLASS` environment variable to the fully-qualified class name
   of your Kernel instead. Not setting the `KERNEL_CLASS` environment variable 
   will throw an exception on 4.0 unless you override the `KernelTestCase::createKernel()` 
   or `KernelTestCase::getKernelClass()` method.
   
 * The `KernelTestCase::getPhpUnitXmlDir()` and `KernelTestCase::getPhpUnitCliConfigArgument()` 
   methods are deprecated since 3.4 and will be removed in 4.0.

Process
-------

 * The `Symfony\Component\Process\ProcessBuilder` class has been deprecated,
   use the `Symfony\Component\Process\Process` class directly instead.

SecurityBundle
--------------

 * `FirewallContext::getListeners()` now returns `\Traversable|array`

Validator
---------

 * Not setting the `strict` option of the `Choice` constraint to `true` is
   deprecated and will throw an exception in Symfony 4.0.