Cumulative Drupal 9 Compatibility Patches

Cumulative Drupal 9 Readiness Patches.

This MR applies the Drupal 9 compatibility patches from

https://www.drupal.org/files/issues/2020-06-20/Drupal_9_Compatibility_Issue-3153442-2.patch

and uses dependency injection to provide the \Drupal::messenger service.

It is useful to have an issue fork for Drupal 9 compatibility, rather than simply a patch, because:

In short, you can't use a patch to tell Composer that a Drupal 8 module is compatible with Drupal 9.

Source: https://www.mediacurrent.com/blog/how-fix-catch-22-problem-drupal-9-fixes-composer/

Adding Issue Fork as a Composer repository:

To use this issue fork as a transitional D9-compatible package in your project, modify your composer.json:

    "repositories": {
        "drupal/fapi_validation": {
            "type": "vcs",
            "url": "https://git.drupalcode.org/issue/fapi_validation-3153442"
        },
        "drupal": {
          "type": "composer",
          "url": "https://packages.drupal.org/8",
          "exclude": ["drupal/fapi_validation"]
        },

Requiring the patched package from the Issue Fork:

Execute the following command in a terminal:

$ composer require drupal/fapi_validation:dev-3153442-drupal-check--

or manually add the requirement to composer.json:

    "require": {
        "drupal/fapi_validation": "dev-3153442-drupal-check--",

Credit due, mainly, to Benji Fisher via: https://www.drupal.org/project/views_url_alias/issues/3142138#comment-14177409

NOTE: Tested with Drupal 8. Transitional D8 / D9 module now passes Upgrade Status D9 compatibility tests.

NOTE: Not yet tested with Drupal 9. You can help the Drupal community by testing this!

Closes #3153442

fapiv_example/src/Form/SimpleForm.php

@@ -4,6 +4,7 @@ namespace Drupal\fapiv_example\Form;
 
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Messenger\MessengerInterface;
 
 /**
  * Implements the SimpleForm form controller.
@@ -15,6 +16,23 @@ use Drupal\Core\Form\FormStateInterface;
  */
 class SimpleForm extends FormBase {
 
+  /**
+   * Protected member variable.
+   *
+   * @var \Drupal\Component\Utility\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Constructs a new SimpleForm.
+   *
+   * @param \Drupal\Component\Utility\MessengerInterface $messenger
+   *   The messenger service.
+   */
+  public function __construct(MessengerInterface $messenger) {
+    $this->messenger = $messenger;
+  }
+
   /**
    * Build the simple form.
    *
@@ -97,7 +115,7 @@ class SimpleForm extends FormBase {
      * with the title.
      */
     $title = $form_state->getValue('title');
-    drupal_set_message($this->t('You specified a title of %title.', ['%title' => $title]));
+    $this->messenger()->addMessage($this->t('You specified a title of %title.', ['%title' => $title]));
   }
 
 }