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1/* Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
2 Written by Bruno Haible <haible@clisp.cons.org>, 2001.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
17
18#ifndef _STDBOOL_H
19#define _STDBOOL_H
20
21/* ISO C 99 <stdbool.h> for platforms that lack it. */
22
23/* Usage suggestions:
24
25 Programs that use <stdbool.h> should be aware of some limitations
26 and standards compliance issues.
27
28 Standards compliance:
29
30 - <stdbool.h> must be #included before 'bool', 'false', 'true'
31 can be used.
32
33 - You cannot assume that sizeof (bool) == 1.
34
35 - Programs should not undefine the macros bool, true, and false,
36 as C99 lists that as an "obsolescent feature".
37
38 Limitations of this substitute, when used in a C89 environment:
39
40 - <stdbool.h> must be #included before the '_Bool' type can be used.
41
42 - You cannot assume that _Bool is a typedef; it might be a macro.
43
44 - In C99, casts and automatic conversions to '_Bool' or 'bool' are
45 performed in such a way that every nonzero value gets converted
46 to 'true', and zero gets converted to 'false'. This doesn't work
47 with this substitute. With this substitute, only the values 0 and 1
48 give the expected result when converted to _Bool' or 'bool'.
49
50 Also, it is suggested that programs use 'bool' rather than '_Bool';
51 this isn't required, but 'bool' is more common. */
52
53
54/* 7.16. Boolean type and values */
55
56/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same
57 definitions below, but temporarily we have to #undef them. */
58#ifdef __BEOS__
59# include <OS.h> /* defines bool but not _Bool */
60# undef false
61# undef true
62#endif
63
64/* For the sake of symbolic names in gdb, we define true and false as
65 enum constants, not only as macros.
66 It is tempting to write
67 typedef enum { false = 0, true = 1 } _Bool;
68 so that gdb prints values of type 'bool' symbolically. But if we do
69 this, values of type '_Bool' may promote to 'int' or 'unsigned int'
70 (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
71 (see ISO C 99 6.3.1.1.(2)). So we add a negative value to the
72 enum; this ensures that '_Bool' promotes to 'int'. */
73#if defined __cplusplus || defined __BEOS__
74 /* A compiler known to have 'bool'. */
75 /* If the compiler already has both 'bool' and '_Bool', we can assume they
76 are the same types. */
77# if !@HAVE__BOOL@
78typedef bool _Bool;
79# endif
80#else
81# if !defined __GNUC__
82 /* If @HAVE__BOOL@:
83 Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when
84 the built-in _Bool type is used. See
85 http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
86 http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
87 http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
88 Similar bugs are likely with other compilers as well; this file
89 wouldn't be used if <stdbool.h> was working.
90 So we override the _Bool type.
91 If !@HAVE__BOOL@:
92 Need to define _Bool ourselves. As 'signed char' or as an enum type?
93 Use of a typedef, with SunPRO C, leads to a stupid
94 "warning: _Bool is a keyword in ISO C99".
95 Use of an enum type, with IRIX cc, leads to a stupid
96 "warning(1185): enumerated type mixed with another type".
97 The only benefit of the enum type, debuggability, is not important
98 with these compilers. So use 'signed char' and no typedef. */
99# define _Bool signed char
100enum { false = 0, true = 1 };
101# else
102 /* With this compiler, trust the _Bool type if the compiler has it. */
103# if !@HAVE__BOOL@
104typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
105# endif
106# endif
107#endif
108#define bool _Bool
109
110/* The other macros must be usable in preprocessor directives. */
111#define false 0
112#define true 1
113#define __bool_true_false_are_defined 1
114
115#endif /* _STDBOOL_H */