Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

Permissions are now defined in $module.permissions.yml file instead of using hook_permission().

Static permissions

Drupal 7

// in views. module file.

function views_permission() {
  $permissions = array(
    'access all views' => array(
      'title' => t('Bypass views access control'),
      'description' => t('Bypass access control when accessing views.'),
    ),
  );

  return $permissions;
}

Drupal 8

# In views.permissions.yml file.
access all views:
  title: 'Bypass views access control'
  description: 'Bypass access control when accessing views.'
  restrict access: TRUE

Dynamic permissions

In https://www.drupal.org/node/2329485 , this mechanism was extended to support dynamic permissions.

Drupal 7

// In filter.module file.
function filter_permission() {
  $perms['administer filters'] = array(
    'title' => t('Administer text formats and filters'),
    'restrict access' => TRUE,
  );

  // Generate permissions for each text format. Warn the administrator that any
  // of them are potentially unsafe.
  foreach (filter_formats() as $format) {
    $permission = filter_permission_name($format);
    if (!empty($permission)) {
      // Only link to the text format configuration page if the user who is
      // viewing this will have access to that page.
      $format_name_replacement = user_access('administer filters') ? l($format->name, 'admin/config/content/formats/' . $format->format) : drupal_placeholder($format->name);
      $perms[$permission] = array(
        'title' => t("Use the !text_format text format", array('!text_format' => $format_name_replacement,)),
        'description' => drupal_placeholder(t('Warning: This permission may have security implications depending on how the text format is configured.')),
      );
    }
  }
  return $perms;
}

Drupal 8

In Drupal 8, you can support dynamic permissions by referencing a function that will dynamically define those permissions. This callback defines the permissions for core's filter module.

// in filter.permissions.yml


permission_callbacks:
  - Drupal\filter\FilterPermissions::permissions
// in FilterPermissions.php

class FilterPermissions {
  public function permissions() {
    $permissions = [];
    // Generate permissions for each text format. Warn the administrator that any
    // of them are potentially unsafe.
    /** @var \Drupal\filter\FilterFormatInterface[] $formats */
    $formats = $this->entityManager->getStorage('filter_format')->loadByProperties(['status' => TRUE]);
    uasort($formats, 'Drupal\Core\Config\Entity\ConfigEntityBase::sort');
    foreach ($formats as $format) {
      if ($permission = $format->getPermissionName()) {
        $permissions[$permission] = [
          'title' => $this->t('Use the @label text format', ['@url' => $format->url(), '@label' => $format->label()]),
          'description' => String::placeholder($this->t('Warning: This permission may have security implications depending on how the text format is configured.')),
        ];
      }
    }
    return $permissions;
  }
}

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done