diff -u b/core/modules/field/field.attach.inc b/core/modules/field/field.attach.inc
--- b/core/modules/field/field.attach.inc
+++ b/core/modules/field/field.attach.inc
@@ -113,34 +113,34 @@
  * @todo Remove _field_invoke() and friends when field types and formatters are
  * turned into plugins.
  *
- * @param $method
+ * @param string $method
  *   The name of the method to invoke.
- * @param $target
+ * @param Closure $target
  *   A closure that receives an $instance object and returns the object on
  *   which the method should be invoked.
  * @param Drupal\Core\Entity\EntityInterface $entity
  *   The fully formed $entity_type entity.
- * @param $a
- *   A parameter for the invoked method.
- * @param $b
- *   A parameter for the invoked method.
- * @param $options
+ * @param mixed $a
+ *   A parameter for the invoked method. Defaults to NULL.
+ * @param mixed $b
+ *   A parameter for the invoked method. Defaults to NULL.
+ * @param array $options
  *   An associative array of additional options, with the following keys:
- *  - 'field_name': The name of the field whose operation should be invoked. By
+ *    - field_name: The name of the field whose operation should be invoked. By
  *    default, the operation is invoked on all the fields in the entity's
- *    bundle. NOTE: This option is not compatible with the 'deleted' option; the
- *    'field_id' option should be used instead.
- *  - 'field_id': The id of the field whose operation should be invoked. By
+ *    bundle. NOTE: This option is not compatible with the 'deleted' option;
+ *    the 'field_id' option should be used instead.
+ *    - field_id: The id of the field whose operation should be invoked. By
  *    default, the operation is invoked on all the fields in the entity's'
  *    bundles.
- *  - 'deleted': If TRUE, the function will operate on deleted fields as well as
- *    non-deleted fields. If unset or FALSE, only non-deleted fields are
+ *    - deleted: If TRUE, the function will operate on deleted fields as well
+ *    as non-deleted fields. If unset or FALSE, only non-deleted fields are
  *    operated on.
- *  - 'langcode': A language code or an array of language codes keyed by field
+ *    - langcode: A language code or an array of language codes keyed by field
  *    name. It will be used to narrow down to a single value the available
  *    languages to act on.
  */
-function field_invoke_method($method, Closure $target_closure, EntityInterface $entity, &$a = NULL, &$b = NULL, $options = array()) {
+function field_invoke_method($method, \Closure $target_closure, EntityInterface $entity, &$a = NULL, &$b = NULL, $options = array()) {
   // Merge default options.
   $default_options = array(
     'deleted' => FALSE,