minor symfony#58089 [Uid] Rework internal format conversion (alexandre-daubois)

This PR was merged into the 7.2 branch.

Discussion
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[Uid] Rework internal format conversion

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

On a second look, the control flow is a bit confusing so I propose this refactor to clear things up.

Commits
-------

736c5a6 [Uid] Rework internal format conversion

Author: nicolas-grekas

src/Symfony/Component/Uid/Uuid.php

@@ -124,15 +124,17 @@ final public static function v8(string $uuid): UuidV8
     /**
      * @param int-mask-of<Uuid::FORMAT_*> $format
      */
-    public static function isValid(string $uuid /*, int $format = self::FORMAT_RFC_4122 */): bool
+    public static function isValid(string $uuid /* , int $format = self::FORMAT_RFC_4122 */): bool
     {
         $format = 1 < \func_num_args() ? func_get_arg(1) : self::FORMAT_RFC_4122;
 
         if (36 === \strlen($uuid) && !($format & self::FORMAT_RFC_4122)) {
             return false;
         }
 
-        $uuid = self::transformToRfc4122($uuid, $format);
+        if (false === $uuid = self::transformToRfc4122($uuid, $format)) {
+            return false;
+        }
 
         if (self::NIL === $uuid && \in_array(static::class, [__CLASS__, NilUuid::class], true)) {
             return true;
@@ -190,10 +192,11 @@ private static function format(string $uuid, string $version): string
      *
      * @param int-mask-of<Uuid::FORMAT_*> $format
      *
-     * @return non-empty-string
+     * @return string|false The RFC4122 string or false if the format doesn't match the input
      */
-    private static function transformToRfc4122(string $uuid, int $format): string
+    private static function transformToRfc4122(string $uuid, int $format): string|false
     {
+        $inputUuid = $uuid;
         $fromBase58 = false;
         if (22 === \strlen($uuid) && 22 === strspn($uuid, BinaryUtil::BASE58['']) && $format & self::FORMAT_BASE_58) {
             $uuid = str_pad(BinaryUtil::fromBase($uuid, BinaryUtil::BASE58), 16, "\0", \STR_PAD_LEFT);
@@ -214,6 +217,11 @@ private static function transformToRfc4122(string $uuid, int $format): string
             $uuid = $ulid->toRfc4122();
         }
 
+        if ($inputUuid === $uuid && !($format & self::FORMAT_RFC_4122)) {
+            // input format doesn't match the input string
+            return false;
+        }
+
         return $uuid;
     }
 }