1/* Copyright (C) 2001-2003, 2006-2012 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 3, 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, see <http://www.gnu.org/licenses/>.  */
16
17#ifndef _GL_STDBOOL_H
18#define _GL_STDBOOL_H
19
20/* ISO C 99 <stdbool.h> for platforms that lack it.  */
21
22/* Usage suggestions:
23
24   Programs that use <stdbool.h> should be aware of some limitations
25   and standards compliance issues.
26
27   Standards compliance:
28
29       - <stdbool.h> must be #included before 'bool', 'false', 'true'
30         can be used.
31
32       - You cannot assume that sizeof (bool) == 1.
33
34       - Programs should not undefine the macros bool, true, and false,
35         as C99 lists that as an "obsolescent feature".
36
37   Limitations of this substitute, when used in a C89 environment:
38
39       - <stdbool.h> must be #included before the '_Bool' type can be used.
40
41       - You cannot assume that _Bool is a typedef; it might be a macro.
42
43       - Bit-fields of type 'bool' are not supported.  Portable code
44         should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'.
45
46       - In C99, casts and automatic conversions to '_Bool' or 'bool' are
47         performed in such a way that every nonzero value gets converted
48         to 'true', and zero gets converted to 'false'.  This doesn't work
49         with this substitute.  With this substitute, only the values 0 and 1
50         give the expected result when converted to _Bool' or 'bool'.
51
52       - C99 allows the use of (_Bool)0.0 in constant expressions, but
53         this substitute cannot always provide this property.
54
55   Also, it is suggested that programs use 'bool' rather than '_Bool';
56   this isn't required, but 'bool' is more common.  */
57
58
59/* 7.16. Boolean type and values */
60
61/* BeOS <sys/socket.h> already #defines false 0, true 1.  We use the same
62   definitions below, but temporarily we have to #undef them.  */
63#if defined __BEOS__ && !defined __HAIKU__
64# include <OS.h> /* defines bool but not _Bool */
65# undef false
66# undef true
67#endif
68
69#ifdef __cplusplus
70# define _Bool bool
71# define bool bool
72#else
73# if defined __BEOS__ && !defined __HAIKU__
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        Even the existence of an enum type, without a typedef,
98          "Invalid enumerator. (badenum)" with HP-UX cc on Tru64.
99        The only benefit of the enum, debuggability, is not important
100        with these compilers.  So use 'signed char' and no enum.  */
101#   define _Bool signed char
102#  else
103   /* With this compiler, trust the _Bool type if the compiler has it.  */
104#   if !@HAVE__BOOL@
105   /* For the sake of symbolic names in gdb, define true and false as
106      enum constants, not only as macros.
107      It is tempting to write
108         typedef enum { false = 0, true = 1 } _Bool;
109      so that gdb prints values of type 'bool' symbolically.  But then
110      values of type '_Bool' might promote to 'int' or 'unsigned int'
111      (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
112      (see ISO C 99 6.3.1.1.(2)).  So add a negative value to the
113      enum; this ensures that '_Bool' promotes to 'int'.  */
114typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
115#   endif
116#  endif
117# endif
118# define bool _Bool
119#endif
120
121/* The other macros must be usable in preprocessor directives.  */
122#ifdef __cplusplus
123# define false false
124# define true true
125#else
126# define false 0
127# define true 1
128#endif
129
130#define __bool_true_false_are_defined 1
131
132#endif /* _GL_STDBOOL_H */
133