[Form] Add choice_translation_parameters option

reference/forms/types/choice.rst

@@ -18,6 +18,7 @@ To use this field, you must specify *either* ``choices`` or ``choice_loader`` op
 |             | - `choice_label`_                                                            |
 |             | - `choice_loader`_                                                           |
 |             | - `choice_name`_                                                             |
+|             | - `choice_translation_parameters`_                                           |
 |             | - `choice_translation_domain`_                                               |
 |             | - `choice_value`_                                                            |
 |             | - `expanded`_                                                                |
@@ -225,6 +226,8 @@ correct types will be assigned to the model.
 
 .. include:: /reference/forms/types/options/choice_name.rst.inc
 
+.. include:: /reference/forms/types/options/choice_translation_parameters.rst.inc
+
 .. include:: /reference/forms/types/options/choice_translation_domain.rst.inc
 
 .. include:: /reference/forms/types/options/choice_value.rst.inc

reference/forms/types/options/choice_translation_parameters.rst.inc

@@ -0,0 +1,52 @@
+choice_translation_parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**type**: ``array``, ``callable``, ``string`` or :class:`Symfony\\Component\\PropertyAccess\\PropertyPath` **default**: ``[]``
+
+The choice values are translated before displaying it, so it can contain
+:ref:`translation placeholders <component-translation-placeholders>`.
+This option defines the values used to replace those placeholders. This can be
+an associative array where the keys match the choice keys and the values
+are the attributes for each choice, a callable or a property path
+(just like `choice_label`_).
+
+Given this translation message:
+
+.. code-block:: yaml
+
+    # translations/messages.en.yaml
+    form.order.yes: 'I confirm my order to the company %company%'
+    form.order.no: 'I cancel my order'
+
+You can specify the placeholder values as follows::
+
+    $builder->add('id', null, [
+        'choice' => [
+            'form.order.yes' => true,
+            'form.order.no' => false,
+        ],
+        'choice_translation_parameters' => function ($choice, $key, $value) {
+            if (false === $choice) {
+                return [];
+            }
+
+            return ['%company%' => 'ACME Inc.']
+        },
+    ]);
+
+If an array, the keys of the ``choices`` array must be used as keys::
+
+    $builder->add('id', null, [
+        'choice' => [
+            'form.order.yes' => true,
+            'form.order.no' => false,
+        ],
+        'choice_translation_parameters' => [
+            'form.order.yes' => ['%company%' => 'ACME Inc.'],
+            'form.order.no' => [],
+        ],
+    ]);
+
+The ``choice_translation_parameters`` option of children fields is merged with
+the same option of their parents, so children can reuse and/or override any of
+the parent placeholders.