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1 | /* Copyright (C) 2001-2003, 2006-2008 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 Lesser 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 Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser 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 _GL_STDBOOL_H | |
19 | #define _GL_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 | - Bit-fields of type 'bool' are not supported. Portable code | |
45 | should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'. | |
46 | ||
47 | - In C99, casts and automatic conversions to '_Bool' or 'bool' are | |
48 | performed in such a way that every nonzero value gets converted | |
49 | to 'true', and zero gets converted to 'false'. This doesn't work | |
50 | with this substitute. With this substitute, only the values 0 and 1 | |
51 | give the expected result when converted to _Bool' or 'bool'. | |
52 | ||
53 | Also, it is suggested that programs use 'bool' rather than '_Bool'; | |
54 | this isn't required, but 'bool' is more common. */ | |
55 | ||
56 | ||
57 | /* 7.16. Boolean type and values */ | |
58 | ||
59 | /* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same | |
60 | definitions below, but temporarily we have to #undef them. */ | |
61 | #if defined __BEOS__ && !defined __HAIKU__ | |
62 | # include <OS.h> /* defines bool but not _Bool */ | |
63 | # undef false | |
64 | # undef true | |
65 | #endif | |
66 | ||
67 | /* For the sake of symbolic names in gdb, we define true and false as | |
68 | enum constants, not only as macros. | |
69 | It is tempting to write | |
70 | typedef enum { false = 0, true = 1 } _Bool; | |
71 | so that gdb prints values of type 'bool' symbolically. But if we do | |
72 | this, values of type '_Bool' may promote to 'int' or 'unsigned int' | |
73 | (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int' | |
74 | (see ISO C 99 6.3.1.1.(2)). So we add a negative value to the | |
75 | enum; this ensures that '_Bool' promotes to 'int'. */ | |
76 | #if defined __cplusplus || (defined __BEOS__ && !defined __HAIKU__) | |
77 | /* A compiler known to have 'bool'. */ | |
78 | /* If the compiler already has both 'bool' and '_Bool', we can assume they | |
79 | are the same types. */ | |
80 | # if !@HAVE__BOOL@ | |
81 | typedef bool _Bool; | |
82 | # endif | |
83 | #else | |
84 | # if !defined __GNUC__ | |
85 | /* If @HAVE__BOOL@: | |
86 | Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when | |
87 | the built-in _Bool type is used. See | |
88 | http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html | |
89 | http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html | |
90 | http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html | |
91 | Similar bugs are likely with other compilers as well; this file | |
92 | wouldn't be used if <stdbool.h> was working. | |
93 | So we override the _Bool type. | |
94 | If !@HAVE__BOOL@: | |
95 | Need to define _Bool ourselves. As 'signed char' or as an enum type? | |
96 | Use of a typedef, with SunPRO C, leads to a stupid | |
97 | "warning: _Bool is a keyword in ISO C99". | |
98 | Use of an enum type, with IRIX cc, leads to a stupid | |
99 | "warning(1185): enumerated type mixed with another type". | |
100 | Even the existence of an enum type, without a typedef, | |
101 | "Invalid enumerator. (badenum)" with HP-UX cc on Tru64. | |
102 | The only benefit of the enum, debuggability, is not important | |
103 | with these compilers. So use 'signed char' and no enum. */ | |
104 | # define _Bool signed char | |
105 | # else | |
106 | /* With this compiler, trust the _Bool type if the compiler has it. */ | |
107 | # if !@HAVE__BOOL@ | |
108 | typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool; | |
109 | # endif | |
110 | # endif | |
111 | #endif | |
112 | #define bool _Bool | |
113 | ||
114 | /* The other macros must be usable in preprocessor directives. */ | |
115 | #define false 0 | |
116 | #define true 1 | |
117 | #define __bool_true_false_are_defined 1 | |
118 | ||
119 | #endif /* _GL_STDBOOL_H */ |