Temporarily provide (and autoload) old symfony translator interface

composer.json

@@ -75,7 +75,8 @@
             "Flarum\\": "src/"
         },
         "files": [
-            "src/helpers.php"
+            "src/helpers.php",
+            "src/TranslatorInterface.php"
         ]
     },
     "autoload-dev": {

src/Locale/Translator.php

@@ -12,8 +12,9 @@
 use Illuminate\Contracts\Translation\Translator as TranslatorContract;
 use Symfony\Component\Translation\MessageCatalogueInterface;
 use Symfony\Component\Translation\Translator as BaseTranslator;
+use Symfony\Component\Translation\TranslatorInterface;  // Defined locally as BC layer
 
-class Translator extends BaseTranslator implements TranslatorContract
+class Translator extends BaseTranslator implements TranslatorContract, TranslatorInterface
 {
     const REFERENCE_REGEX = '/^=>\s*([a-z0-9_\-\.]+)$/i';
 

src/TranslatorInterface.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Symfony\Component\Translation;
+
+/**
+ * @deprecated beta 16, remove beta 17.
+ * This is here to provide a graceful transition for classes typehinting the old interface.
+ * Temporarily, `Flarum\Locale\Translator` will implement this to avoid breaking that typehint.
+ * Before beta 17, this should be removed from autoload.
+ */
+interface TranslatorInterface{}