bug #23171 [Yaml] Fix linting yaml with constants as keys (chalasr)

This PR was merged into the 3.3 branch.

Discussion
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[Yaml] Fix linting yaml with constants as keys

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #23167
| License       | MIT
| Doc PR        | n/a

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Commits
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55a8d35 [Yaml] Fix linting yaml with constants as keys

src/Symfony/Component/Yaml/Command/LintCommand.php

@@ -18,6 +18,7 @@
 use Symfony\Component\Console\Style\SymfonyStyle;
 use Symfony\Component\Yaml\Exception\ParseException;
 use Symfony\Component\Yaml\Parser;
+use Symfony\Component\Yaml\Yaml;
 
 /**
  * Validates YAML files syntax and outputs encountered errors.
@@ -111,7 +112,7 @@ private function validate($content, $file = null)
         });
 
         try {
-            $this->getParser()->parse($content);
+            $this->getParser()->parse($content, Yaml::PARSE_CONSTANT);
         } catch (ParseException $e) {
             return array('file' => $file, 'valid' => false, 'message' => $e->getMessage());
         } finally {

src/Symfony/Component/Yaml/Tests/Command/LintCommandTest.php

@@ -51,6 +51,15 @@ public function testLintIncorrectFile()
         $this->assertContains('Unable to parse at line 3 (near "bar").', trim($tester->getDisplay()));
     }
 
+    public function testConstantAsKey()
+    {
+        $yaml = <<<YAML
+!php/const:Symfony\Component\Yaml\Tests\Command\Foo::TEST: bar
+YAML;
+        $ret = $this->createCommandTester()->execute(array('filename' => $this->createFile($yaml)), array('verbosity' => OutputInterface::VERBOSITY_VERBOSE, 'decorated' => false));
+        $this->assertSame(0, $ret, 'lint:yaml exits with code 0 in case of success');
+    }
+
     /**
      * @expectedException \RuntimeException
      */
@@ -105,3 +114,8 @@ protected function tearDown()
         rmdir(sys_get_temp_dir().'/framework-yml-lint-test');
     }
 }
+
+class Foo
+{
+    const TEST = 'foo';
+}