Get rid of field_behaviors_widget()

tagging

and tagging

+++ b/core/modules/entity/lib/Drupal/entity/EntityFormDisplayInterface.phpundefined
@@ -14,4 +14,17 @@
+  /**
+   * Returns the definition of a renderer plugin for the given field (e.g.
+   * widget, formatter).
+   *
+   * @param string $field_name
+   *   The name of the field.
+   *
+   * @return array|null
+   *   The widget or formatter plugin, or NULL if the field does not exist.

The first line of functions/methods phpdoc should fit in 80 chars if possible.

Maybe "Returns the definition of the renderer plugin used for a component" ?
Then the @return section could be:
"The definition of the renderer plugin (e.g. widget, formatter), or NULL if the component is not set."

+++ b/core/modules/entity/lib/Drupal/entity/EntityFormDisplayInterface.phpundefined
@@ -14,4 +14,17 @@
+  public function getRendererDefinition($field_name);

As a replacement of field_behaviors_widget(), we need the method to exist on EntityFormDisplay, true.
But generally speaking, the method would also make sense on EntityDisplay objects.
So I'd suggest adding it to EntityDisplayBaseInterface & EntityDisplayBase

+++ b/core/modules/entity/lib/Drupal/entity/Plugin/Core/Entity/EntityFormDisplay.phpundefined
@@ -45,6 +45,14 @@ public function __construct(array $values, $entity_type) {
+    $options = getComponent($field_name);

Should be $this->getComponent($field_name) :-)
(probably explains that patch fails to install)

Also, it should be wrapped in an if() because the field might be hidden, in which case getComponent() will return NULL:

if ($options = $this->getComponent($field_name)) {
  return $this->pluginManager->...
}

I'm fine with keeping the function around as @deprecated, but:

- This function makes very very little sense in D8. "Give me this property from the plugin definition of the widget used by this field".
But now that we have "form modes", there is no such thing as "the (one and only) widget used by this field". Just like "what's the formatter used by this field" makes no sense - in which view mode ?
The function currently uses the widget used in the 'default' form mode, but this makes no special sense.
- It's really a remnant from CCK D6 where widget info definitions had a 'behaviors' entry, which doesn't exist anymore. Its only possible remaining use is for "default values", and it's a sick use, that we need to get rid of anyway : #2056405: Let field types provide their support for "default values" and associated input UI

Now that #2056405: Let field types provide their support for "default values" and associated input UI is in and the 'default_value' entry in widget plugin definitions is not supported anymore, we have no reason whatsoever to keep field_behaviors_widget().
We should really just remove it.

 + if (!isset($instance['default_value'])) {
+  $instance['default_value'] = NULL;
+} 

This looks like this might be useless now ?

Looks good if green

Created https://drupal.org/node/2102175