Merge branch '5.2' into 5.x

* 5.2:
  add missing return type declaration
  Modernize func_get_args() calls to variadic parameters
  Use a lazyintertor to close files descriptors when no longer used

Filesystem.php

@@ -736,14 +736,16 @@ private function getSchemeAndHierarchy(string $filename): array
     }
 
     /**
+     * @param mixed ...$args
+     *
      * @return mixed
      */
-    private static function box(callable $func)
+    private static function box(callable $func, ...$args)
     {
         self::$lastError = null;
         set_error_handler(__CLASS__.'::handleError');
         try {
-            $result = $func(...\array_slice(\func_get_args(), 1));
+            $result = $func(...$args);
             restore_error_handler();
 
             return $result;