Permission providers are now implemented as tagged services, permission_callbacks in .permissions.yml deprecated

Before

.permissions.yml

permission_callbacks:
  - \Drupal\my_module\MyPermissions::myPermissions

Permissions class

declare(strict_types=1);

namespace Drupal\my_module;

use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\StringTranslation\TranslationInterface;

final class MyPermissions {

  use StringTranslationTrait;

  public function __construct(
    private readonly \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager,
    TranslationInterface $translation,
  ) {
    $this->setStringTranslation($translation);
  }

  public function myPermissions(): array {
    return [
      'my_module permission' => [
        'title' => $this->t('My Permission'),
      ],
    ];
  }

}

After

User permission providers are now created as entries in a.services.yml file, with no changes to how provider classes are constructed:

services:
  my_permission_provider:
    class: Drupal\my_module\MyPermissions
    autowire: true
    tags:
      - { name: 'user.permission_provider', method: 'myPermissions', provider: 'my_module' }
  Drupal\my_module\MyPermissions: '@my_permission_provider'

Deprecations

Existing implementations of permission_callbacks have been removed from core, while associated permission classes have been updated.

• They remove \Drupal\Core\DependencyInjection\ContainerInjectionInterface, instead relying on autowiring for dependency injection.
• Parameters have been updated, such that they are renamed to camelcase, and use contructor promotion, with associated parameter documentation in constructor removed. Parameter position and typing has not changed.
• Most explicit property definitions have been removed, in favor of constructor promotion.