bug symfony#61520 [Yaml] Fix scope resolution operator in flow mapping keys (MatTheCat)

This PR was merged into the 6.4 branch.

Discussion
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[Yaml] Fix scope resolution operator in flow mapping keys

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#61082
| License       | MIT

Instead of splitting flow mapping keys by colon after `!php/const` or `!php/enum`, this PR splits by “lone” colon so that the `::` operator can be used.

Commits
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b09d67b [Yaml] Fix scope resolution operator in flow mapping keys

Author: nicolas-grekas

src/Symfony/Component/Yaml/Inline.php

@@ -453,7 +453,7 @@ private static function parseMapping(string $mapping, int $flags, int &$i = 0, a
             }
 
             if ('!php/const' === $key || '!php/enum' === $key) {
-                $key .= ' '.self::parseScalar($mapping, $flags, [':'], $i, false);
+                $key .= ' '.self::parseScalar($mapping, $flags, ['(?<!:):(?!:)'], $i, false);
                 $key = self::evaluateScalar($key, $flags);
             }
 

src/Symfony/Component/Yaml/Tests/InlineTest.php

@@ -63,6 +63,7 @@ public static function getTestsForParsePhpConstants()
             ['{ foo: !php/const PHP_INT_MAX }', ['foo' => \PHP_INT_MAX]],
             ['{ !php/const PHP_INT_MAX: foo }', [\PHP_INT_MAX => 'foo']],
             ['!php/const NULL', null],
+            ['{ !php/const Symfony\Component\Yaml\Yaml::PARSE_CONSTANT: foo }', [Yaml::PARSE_CONSTANT => 'foo']],
         ];
     }