--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libobjc/nil_method.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,55 @@
+/* GNU Objective C Runtime nil receiver function
+   Copyright (C) 1993-2017 Free Software Foundation, Inc.
+   Contributed by Kresten Krab Thorup
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation; either version 3, or (at your option) any later version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+
+/* This is the nil method, the function that is called when the receiver
+   of a method is nil */
+
+#include "objc-private/common.h"
+#include "objc/objc.h"
+
+/* When the receiver of a method invocation is nil, the runtime
+   returns nil_method() as the method implementation.  This function
+   will be casted to whatever function was supposed to be executed to
+   execute that method (that function will take an id, followed by a
+   SEL, followed by who knows what arguments, depends on the method),
+   and executed.
+   
+   For this reason, nil_method() should be a function which can be
+   called in place of any function taking an 'id' argument followed by
+   a 'SEL' argument, followed by zero, or one, or any number of
+   arguments (both a fixed number, or a variable number !).
+   
+   There is no "proper" implementation of such a nil_method function
+   in C, however in all existing implementations it does not matter
+   when extra arguments are present, so we can simply create a function
+   taking a receiver and a selector, and all other arguments will be
+   ignored. :-)
+*/
+
+id
+nil_method (id receiver, SEL op __attribute__ ((__unused__)))
+{
+  return receiver;
+}