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Diffstat (limited to 'gl/stdbool.in.h')
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1 | /* Copyright (C) 2001, 2002, 2003, 2006, 2007 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, 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 | #ifdef __BEOS__ | ||
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__ | ||
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 */ | ||