1 /* Copyright (C) 2001-2003, 2006-2012 Free Software Foundation, Inc. 2 Written by Bruno Haible <haible (at) 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@ 78 typedef 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'. */ 114 typedef 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
