9 files declare their use of RfcLogLevel in Zircon Profile 8

bootstrap.inc in core/includes/bootstrap.inc

Functions that need to be loaded on every Drupal request.

dblog.admin.inc in core/modules/dblog/dblog.admin.inc

Administrative page callbacks for the Database Logging module.

DbLogController.php in core/modules/dblog/src/Controller/DbLogController.php

Contains \Drupal\dblog\Controller\DbLogController.

DbLogTest.php in core/modules/dblog/src/Tests/DbLogTest.php

Contains \Drupal\dblog\Tests\DbLogTest.

errors.inc in core/includes/errors.inc

Functions for error handling.

InstallUninstallTest.php in core/modules/system/src/Tests/Module/InstallUninstallTest.php

Contains \Drupal\system\Tests\Module\InstallUninstallTest.

MigrateMessage.php in core/modules/migrate/src/MigrateMessage.php

Contains \Drupal\migrate\MigrateMessage.

ModuleTestBase.php in core/modules/system/src/Tests/Module/ModuleTestBase.php

Contains \Drupal\system\Tests\Module\ModuleTestBase.

ViewsIntegrationTest.php in core/modules/dblog/src/Tests/Views/ViewsIntegrationTest.php

Contains \Drupal\dblog\Tests\Views\ViewsIntegrationTest.