gen_stub: set up PHP 8.6 support

Add the new known string from #20951

Author: DanielEScherzer

build/gen_stub.php

@@ -26,6 +26,7 @@
 const PHP_83_VERSION_ID = 80300;
 const PHP_84_VERSION_ID = 80400;
 const PHP_85_VERSION_ID = 80500;
+const PHP_86_VERSION_ID = 80600;
 const ALL_PHP_VERSION_IDS = [
     PHP_70_VERSION_ID,
     PHP_80_VERSION_ID,
@@ -34,6 +35,7 @@
     PHP_83_VERSION_ID,
     PHP_84_VERSION_ID,
     PHP_85_VERSION_ID,
+    PHP_86_VERSION_ID,
 ];
 
 // file_put_contents() but with a success message printed after saving
@@ -2900,6 +2902,11 @@ class StringBuilder {
         '8.5' => 'ZEND_STR_8_DOT_5',
     ];
 
+    // NEW in 8.6
+    private const PHP_86_KNOWN = [
+        "arguments" => "ZEND_STR_ARGUMENTS",
+    ];
+
     /**
      * Get an array of three strings:
      *   - declaration of zend_string, if needed, or empty otherwise
@@ -2938,6 +2945,10 @@ public static function getString(
         }
         $include = self::PHP_80_KNOWN;
         switch ($minPhp) {
+            case PHP_86_VERSION_ID:
+                $include = array_merge($include, self::PHP_86_KNOWN);
+                // Intentional fall through
+
             case PHP_85_VERSION_ID:
                 $include = array_merge($include, self::PHP_85_KNOWN);
                 // Intentional fall through
@@ -4127,7 +4138,8 @@ public function __construct(array $fileTags) {
                     throw new Exception(
                         "Legacy PHP version must be one of: \"" . PHP_70_VERSION_ID . "\" (PHP 7.0), \"" . PHP_80_VERSION_ID . "\" (PHP 8.0), " .
                         "\"" . PHP_81_VERSION_ID . "\" (PHP 8.1), \"" . PHP_82_VERSION_ID . "\" (PHP 8.2), \"" . PHP_83_VERSION_ID . "\" (PHP 8.3), " .
-                        "\"" . PHP_84_VERSION_ID . "\" (PHP 8.4), \"" . PHP_85_VERSION_ID . "\" (PHP 8.5), \"" . $tag->value . "\" provided"
+                        "\"" . PHP_84_VERSION_ID . "\" (PHP 8.4), \"" . PHP_85_VERSION_ID . "\" (PHP 8.5), \"" . PHP_86_VERSION_ID . "\" (PHP 8.6), " .
+                        $tag->value . "\" provided"
                     );
                 }