UPGRADE FROM 3.x to 4.0
=======================

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

 * Calling `get()` on a `ContainerBuilder` instance before compiling the
   container is not supported anymore and will throw an exception.

 * Using unsupported configuration keys in YAML configuration files raises an
   exception.

 * Using unsupported options to configure service aliases raises an exception.

Form
----

 * The `choices_as_values` option of the `ChoiceType` has been removed.

 * Support for data objects that implements both `Traversable` and
   `ArrayAccess` in `ResizeFormListener::preSubmit` method has been removed.

 * Using callable strings as choice options in ChoiceType is not supported
   anymore in favor of passing PropertyPath instances.

   Before:

   ```php
   'choice_value' => new PropertyPath('range'),
   'choice_label' => 'strtoupper',
   ```

   After:

   ```php
   'choice_value' => 'range',
   'choice_label' => function ($choice) {
       return strtoupper($choice);
   },
   ```

 * Caching of the loaded `ChoiceListInterface` in the `LazyChoiceList` has been removed,
   it must be cached in the `ChoiceLoaderInterface` implementation instead.

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

 * Support for absolute template paths has been removed.

 * The following form types registered as services have been removed; use their
   fully-qualified class name instead:

    - `"form.type.birthday"`
    - `"form.type.checkbox"`
    - `"form.type.collection"`
    - `"form.type.country"`
    - `"form.type.currency"`
    - `"form.type.date"`
    - `"form.type.datetime"`
    - `"form.type.email"`
    - `"form.type.file"`
    - `"form.type.hidden"`
    - `"form.type.integer"`
    - `"form.type.language"`
    - `"form.type.locale"`
    - `"form.type.money"`
    - `"form.type.number"`
    - `"form.type.password"`
    - `"form.type.percent"`
    - `"form.type.radio"`
    - `"form.type.range"`
    - `"form.type.repeated"`
    - `"form.type.search"`
    - `"form.type.textarea"`
    - `"form.type.text"`
    - `"form.type.time"`
    - `"form.type.timezone"`
    - `"form.type.url"`
    - `"form.type.button"`
    - `"form.type.submit"`
    - `"form.type.reset"`

 * The service `serializer.mapping.cache.apc` has been removed; use
   `serializer.mapping.cache.doctrine.apc` instead.

 * The `framework.serializer.cache` option has been removed. APCu should now
   be automatically used when available so you can remove this configuration key.

HttpKernel
----------

 * Possibility to pass objects as URI attributes to the ESI and SSI renderers
   has been removed. The inline fragment renderer should be used with object
   attributes.

 * The `ControllerResolver::getArguments()` method has been removed. If you
   have your own `ControllerResolverInterface` implementation, you should
   inject an `ArgumentResolverInterface` instance.

Serializer
----------

 * The ability to pass a Doctrine `Cache` instance to the `ClassMetadataFactory`
   class has been removed. You should use the `CacheClassMetadataFactory` class
   instead.

Translation
-----------

 * Removed the backup feature from the file dumper classes.

Yaml
----

 * Starting an unquoted string with `%` leads to a `ParseException`.

 * The `Dumper::setIndentation()` method was removed. Pass the indentation
   level to the constructor instead.

 * Removed support for passing `true`/`false` as the second argument to the
   `parse()` method to trigger exceptions when an invalid type was passed.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_EXCEPTION_ON_INVALID_TYPE);
   ```

 * Removed support for passing `true`/`false` as the third argument to the
   `parse()` method to toggle object support.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', false, true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_OBJECT);
   ```

 * Removed support for passing `true`/`false` as the fourth argument to the
   `parse()` method to parse objects as maps.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', false, false, true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_OBJECT_FOR_MAP);
   ```

 * Removed support for passing `true`/`false` as the fourth argument to the
   `dump()` method to trigger exceptions when an invalid type was passed.

   Before:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, true);
   ```

   After:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, Yaml::DUMP_EXCEPTION_ON_INVALID_TYPE);
   ```

 * Removed support for passing `true`/`false` as the fifth argument to the
   `dump()` method to toggle object support.

   Before:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, false, true);
   ```

   After:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, false, Yaml::DUMP_OBJECT);
   ```

 * The `!!php/object` tag to indicate dumped PHP objects was removed in favor of
   the `!php/object` tag.

Validator
---------

 * The `DateTimeValidator::PATTERN` constant was removed.

 * `Tests\Constraints\AbstractConstraintValidatorTest` has been removed in
   favor of `Test\ConstraintValidatorTestCase`.

   Before:

   ```php
   // ...
   use Symfony\Component\Validator\Tests\Constraints\AbstractConstraintValidatorTest;

   class MyCustomValidatorTest extends AbstractConstraintValidatorTest
   {
       // ...
   }
   ```

   After:

   ```php
   // ...
   use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;

   class MyCustomValidatorTest extends ConstraintValidatorTestCase
   {
       // ...
   }
   ```