Use strings to represent wildcard characters

A string is made of characters, an array might contain anything.

lib/Doctrine/DBAL/Platforms/AbstractPlatform.php

@@ -43,7 +43,6 @@ use Doctrine\DBAL\TransactionIsolationLevel;
 use Doctrine\DBAL\Types;
 use Doctrine\DBAL\Types\Type;
 use function addcslashes;
-use function implode;
 use function preg_quote;
 use function preg_replace;
 use function sprintf;
@@ -3596,17 +3595,14 @@ abstract class AbstractPlatform
     final public function escapeStringForLike(string $inputString, string $escapeChar) : string
     {
         return preg_replace(
-            '~([' . preg_quote(implode('', $this->getLikeWildcardCharacters()) . $escapeChar, '~') . '])~u',
+            '~([' . preg_quote($this->getLikeWildcardCharacters() . $escapeChar, '~') . '])~u',
             addcslashes($escapeChar, '\\') . '$1',
             $inputString
         );
     }
 
-    /**
-     * @return string[]
-     */
-    protected function getLikeWildcardCharacters() : array
+    protected function getLikeWildcardCharacters() : string
     {
-        return ['%', '_'];
+        return '%_';
     }
 }

lib/Doctrine/DBAL/Platforms/SQLServer2008Platform.php

@@ -117,11 +117,8 @@ class SQLServer2008Platform extends SQLServer2005Platform
         return Keywords\SQLServer2008Keywords::class;
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    protected function getLikeWildcardCharacters() : array
+    protected function getLikeWildcardCharacters() : string
     {
-        return array_merge(parent::getLikeWildcardCharacters(), ['[', ']', '^']);
+        return parent::getLikeWildcardCharacters() . '[]^';
     }
 }