[String] Fix AsciiSlugger with emojis

Author: fancyweb

Slugger/AsciiSlugger.php

@@ -113,10 +113,8 @@ public function slug(string $string, string $separator = '-', string $locale = n
             $transliterator = (array) $this->createTransliterator($locale);
         }
 
-        if (\is_string($this->emoji)) {
-            $transliterator[] = EmojiTransliterator::create("emoji-{$this->emoji}");
-        } elseif ($this->emoji && null !== $locale) {
-            $transliterator[] = EmojiTransliterator::create("emoji-{$locale}");
+        if ($emojiTransliterator = $this->createEmojiTransliterator($locale)) {
+            $transliterator[] = $emojiTransliterator;
         }
 
         if ($this->symbolsMap instanceof \Closure) {
@@ -177,6 +175,25 @@ private function createTransliterator(string $locale): ?\Transliterator
         return $this->transliterators[$locale] = $this->transliterators[$parent] = $transliterator ?? null;
     }
 
+    private function createEmojiTransliterator(?string $locale): ?EmojiTransliterator
+    {
+        if (\is_string($this->emoji)) {
+            $locale = $this->emoji;
+        } elseif (!$this->emoji) {
+            return null;
+        }
+
+        while (null !== $locale) {
+            try {
+                return EmojiTransliterator::create("emoji-$locale");
+            } catch (\IntlException) {
+                $locale = self::getParentLocale($locale);
+            }
+        }
+
+        return null;
+    }
+
     private static function getParentLocale(?string $locale): ?string
     {
         if (!$locale) {

Tests/Slugger/AsciiSluggerTest.php

@@ -49,6 +49,7 @@ public function provideSlugTests(): iterable
 
     /**
      * @dataProvider provideSlugEmojiTests
+     *
      * @requires extension intl
      */
     public function testSlugEmoji(string $expected, string $string, ?string $locale, string|bool $emoji = true)
@@ -94,5 +95,15 @@ public function provideSlugEmojiTests(): iterable
             'en',
             'github',
         ];
+        yield [
+            'un-chat-qui-sourit-chat-noir-et-un-tete-de-lion-vont-au-parc-national',
+            'un 😺, 🐈‍⬛, et un 🦁 vont au 🏞️',
+            'fr_XX', // Fallback on parent locale
+        ];
+        yield [
+            'un-et-un-vont-au',
+            'un 😺, 🐈‍⬛, et un 🦁 vont au 🏞️',
+            'undefined_locale', // Behaves the same as if emoji support is disabled
+        ];
     }
 }