minor #39769 [Yaml] quote all dumped unicode spaces (xabbuh)

This PR was merged into the 4.4 branch.

Discussion
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[Yaml] quote all dumped unicode spaces

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #39767
| License       | MIT
| Doc PR        |

Commits
-------

0028efe8f8 quote all dumped unicode spaces

src/Symfony/Component/Yaml/Escaper.php

@@ -86,7 +86,7 @@ class Escaper
 
         // Determines if the PHP value contains any single characters that would
         // cause it to require single quoting in YAML.
-        return 0 < preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` ]/x', $value);
+        return 0 < preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` \p{Zs}]/xu', $value);
     }
 
     /**

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

@@ -635,6 +635,21 @@ YAML;
     {
         $this->assertSame('{ foo: ~ }', $this->dumper->dump(['foo' => null], 0, 0, Yaml::DUMP_NULL_AS_TILDE));
     }
+
+    public function testDumpIdeographicSpaces()
+    {
+        $expected = <<<YAML
+alone: '　'
+within_string: 'a　b'
+regular_space: 'a b'
+
+YAML;
+        $this->assertSame($expected, $this->dumper->dump([
+            'alone' => '　',
+            'within_string' => 'a　b',
+            'regular_space' => 'a b',
+        ], 2));
+    }
 }
 
 class A

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

@@ -511,6 +511,10 @@ class InlineTest extends TestCase
             ['"0123\r"', "0123\r"],
             ['"0123\t"', "0123\t"],
             ['"0123\v"', "0123\v"],
+
+            // whitespaces
+            'ideographic space' => ["'　'", '　'],
+            'ideographic space surrounded by characters' => ["'a　b'", 'a　b'],
         ];
     }