Language selector is immune to hook_entity_field_access in entity forms.

Looks good to me. Thanks!

Nice bug fix and great test coverage.

Committed and pushed f6674fa417 to 8.7.x and efefc9236c to 8.6.x. Thanks!

+++ b/core/modules/language/tests/language_entity_field_access_test/language_entity_field_access_test.module
@@ -0,0 +1,18 @@
+function language_entity_field_access_test_entity_field_access($operation, FieldDefinitionInterface $field_definition, AccountInterface $account, FieldItemListInterface $items = NULL) {
+  return AccessResult::forbidden();
+}

Quite extreme to deny access to everything but it works within the context of the test. I think we could file a follow-up to make field_test_boolean_access_denied_entity_field_access() more generic and rename its module and use it here.

This if statement in language.module was throwing warnings when i form i had didn't have #access set inside $form['langcode'].

    if (isset($form[$langcode_key]) && $form[$langcode_key]['#access'] !== FALSE) {
      $language_configuration = ContentLanguageSettings::loadByEntityTypeBundle($entity->getEntityTypeId(), $entity->bundle());
      $form[$langcode_key]['#access'] = $language_configuration->isLanguageAlterable();
    }

I have attached a small patch that checks if #access is not set or is false.

This was committed to 8.6. It was re-opened due to a problem when #access is not defined on the form. Instead, lets made a follow up to explore that problem,

Follow up creates #3270660: Warning if #access not defined on form. Restoring meta data to the time this was committed.

Cheers.

Moved patch and credit to new issue.