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1 | /* GNU Objective C Runtime nil receiver function | |
2 | Copyright (C) 1993-2021 Free Software Foundation, Inc. | |
3 | Contributed by Kresten Krab Thorup | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under the | |
8 | terms of the GNU General Public License as published by the Free Software | |
9 | Foundation; either version 3, or (at your option) any later version. | |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | |
14 | details. | |
15 | ||
16 | Under Section 7 of GPL version 3, you are granted additional | |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | You should have received a copy of the GNU General Public License and | |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
24 | ||
25 | ||
26 | /* This is the nil method, the function that is called when the receiver | |
27 | of a method is nil */ | |
28 | ||
29 | #include "objc-private/common.h" | |
30 | #include "objc/objc.h" | |
31 | ||
32 | /* When the receiver of a method invocation is nil, the runtime | |
33 | returns nil_method() as the method implementation. This function | |
34 | will be casted to whatever function was supposed to be executed to | |
35 | execute that method (that function will take an id, followed by a | |
36 | SEL, followed by who knows what arguments, depends on the method), | |
37 | and executed. | |
38 | ||
39 | For this reason, nil_method() should be a function which can be | |
40 | called in place of any function taking an 'id' argument followed by | |
41 | a 'SEL' argument, followed by zero, or one, or any number of | |
42 | arguments (both a fixed number, or a variable number !). | |
43 | ||
44 | There is no "proper" implementation of such a nil_method function | |
45 | in C, however in all existing implementations it does not matter | |
46 | when extra arguments are present, so we can simply create a function | |
47 | taking a receiver and a selector, and all other arguments will be | |
48 | ignored. :-) | |
49 | */ | |
50 | ||
51 | id | |
52 | nil_method (id receiver, SEL op __attribute__ ((__unused__))) | |
53 | { | |
54 | return receiver; | |
55 | } |