Issue #2937543 by alexpott, Berdir, larowlan: Using the...

Issue #2937543 by alexpott, Berdir, larowlan: Using the Yaml::PARSE_KEYS_AS_STRINGS flag is deprecated since Symfony 3.4 as it will be removed in 4.0

core/lib/Drupal/Component/Serialization/YamlSymfony.php

@@ -34,7 +34,7 @@ public static function decode($raw) {
       $yaml = new Parser();
       // Make sure we have a single trailing newline. A very simple config like
       // 'foo: bar' with no newline will fail to parse otherwise.
-      return $yaml->parse($raw, SymfonyYaml::PARSE_EXCEPTION_ON_INVALID_TYPE | SymfonyYaml::PARSE_KEYS_AS_STRINGS);
+      return $yaml->parse($raw, SymfonyYaml::PARSE_EXCEPTION_ON_INVALID_TYPE);
     }
     catch (\Exception $e) {
       throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);

core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php

@@ -185,7 +185,6 @@ public static function getSkippedDeprecations() {
       'The Symfony\Component\HttpFoundation\Session\Storage\Handler\WriteCheckSessionHandler class is deprecated since Symfony 3.4 and will be removed in 4.0. Implement `SessionUpdateTimestampHandlerInterface` or extend `AbstractSessionHandler` instead.',
       'The "session_handler.write_check" service relies on the deprecated "Symfony\Component\HttpFoundation\Session\Storage\Handler\WriteCheckSessionHandler" class. It should either be deprecated or its implementation upgraded.',
       'Not setting the strict option of the Choice constraint to true is deprecated since Symfony 3.4 and will throw an exception in 4.0.',
-      'Using the Yaml::PARSE_KEYS_AS_STRINGS flag is deprecated since Symfony 3.4 as it will be removed in 4.0. Quote your keys when they are evaluable instead.',
       'Drupal\node\Plugin\Action\DeleteNode is deprecated in Drupal 8.6.x, will be removed before Drupal 9.0.0. Use \Drupal\Core\Action\Plugin\Action\DeleteAction instead. See https://www.drupal.org/node/2934349.',
       'Drupal\comment\Plugin\Action\DeleteComment is deprecated in Drupal 8.6.x, will be removed before Drupal 9.0.0. Use \Drupal\Core\Action\Plugin\Action\DeleteAction instead. See https://www.drupal.org/node/2934349.',
     ];