bug symfony#58593 [Mime] fix encoding issue with UTF-8 addresses containing doubles spaces (0xb4lint)

This PR was submitted for the 7.2 branch but it was squashed and merged into the 5.4 branch instead.

Discussion
----------

[Mime] fix encoding issue with UTF-8 addresses containing doubles spaces

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#58592, Fix symfony#50345
| License       | MIT

Commits
-------

c6ed3c8 [Mime] fix encoding issue with UTF-8 addresses containing doubles spaces

Author: fabpot

src/Symfony/Component/Mime/Header/AbstractHeader.php

@@ -180,6 +180,20 @@ protected function getEncodableWordTokens(string $string): array
             $tokens[] = $encodedToken;
         }
 
+        foreach ($tokens as $i => $token) {
+            // whitespace(s) between 2 encoded tokens
+            if (
+                0 < $i
+                && isset($tokens[$i + 1])
+                && preg_match('~^[\t ]+$~', $token)
+                && $this->tokenNeedsEncoding($tokens[$i - 1])
+                && $this->tokenNeedsEncoding($tokens[$i + 1])
+            ) {
+                $tokens[$i - 1] .= $token.$tokens[$i + 1];
+                array_splice($tokens, $i, 2);
+            }
+        }
+
         return $tokens;
     }
 

src/Symfony/Component/Mime/Tests/Header/MailboxHeaderTest.php

@@ -62,6 +62,14 @@ public function testUtf8CharsInLocalPart()
     {
         $header = new MailboxHeader('Sender', new Address('fabïen@symfony.com'));
         $this->assertSame('fabïen@symfony.com', $header->getBodyAsString());
+
+        // name with single space
+        $header = new MailboxHeader('Sender', new Address('fabïen@symfony.com', 'Fabïen Pötencier'));
+        $this->assertSame('=?utf-8?Q?Fab=C3=AFen_P=C3=B6tencier?= <fabïen@symfony.com>', $header->getBodyAsString());
+
+        // name with double spaces
+        $header = new MailboxHeader('Sender', new Address('fabïen@symfony.com', 'Fabïen  Pötencier'));
+        $this->assertSame('=?utf-8?Q?Fab=C3=AFen__P=C3=B6tencier?= <fabïen@symfony.com>', $header->getBodyAsString());
     }
 
     public function testToString()