1 /* Copyright (C) 2001-2003, 2006-2017, 2019 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, see <https://www.gnu.org/licenses/>. */ 16 17 #ifndef _TEXTSTYLE_STDBOOL_H 18 #define _TEXTSTYLE_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 #ifdef __cplusplus 62 /* Assume the compiler has 'bool' and '_Bool'. */ 63 #else 64 /* <stdbool.h> is known to exist and work with the following compilers: 65 - GNU C 3.0 or newer, on any platform, 66 - Intel C, 67 - MSVC 12 (Visual Studio 2013) or newer, 68 - Sun C, on Solaris, if _STDC_C99 is defined, 69 - AIX xlc, if _ANSI_C_SOURCE is defined, 70 - HP C, on HP-UX 11.31 or newer. 71 It is know not to work with: 72 - Sun C, on Solaris, if __C99FEATURES__ is defined but _STDC_C99 is not, 73 - MIPSpro C 7.30, on IRIX. */ 74 # if (__GNUC__ >= 3) \ 75 || defined __INTEL_COMPILER \ 76 || (_MSC_VER >= 1800) \ 77 || (defined __SUNPRO_C && defined _STDC_C99) \ 78 || (defined _AIX && !defined __GNUC__ && defined _ANSI_C_SOURCE) \ 79 || defined __HP_cc 80 /* Assume the compiler has <stdbool.h>. */ 81 # include <stdbool.h> 82 # else 83 /* Need to define _Bool ourselves. As 'signed char' or as an enum type? 84 Use of a typedef, with SunPRO C, leads to a stupid 85 "warning: _Bool is a keyword in ISO C99". 86 Use of an enum type, with IRIX cc, leads to a stupid 87 "warning(1185): enumerated type mixed with another type". 88 Even the existence of an enum type, without a typedef, 89 "Invalid enumerator. (badenum)" with HP-UX cc on Tru64. 90 The only benefit of the enum, debuggability, is not important 91 with these compilers. So use 'signed char' and no enum. */ 92 # define _Bool signed char 93 # define bool _Bool 94 # endif 95 #endif 96 97 /* The other macros must be usable in preprocessor directives. */ 98 #ifdef __cplusplus 99 # define false false 100 # define true true 101 #else 102 # undef false 103 # define false 0 104 # undef true 105 # define true 1 106 #endif 107 108 #define __bool_true_false_are_defined 1 109 110 #endif /* _TEXTSTYLE_STDBOOL_H */ 111