1/* Copyright (C) 2001, 2002, 2003, 2006, 2007, 2008, 2009 Free Software 2 Foundation, Inc. 3 Written by Bruno Haible <haible@clisp.cons.org>, 2001. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3, or (at your option) 8 any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program; if not, write to the Free Software Foundation, 17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 18 19#ifndef _GL_STDBOOL_H 20#define _GL_STDBOOL_H 21 22/* ISO C 99 <stdbool.h> for platforms that lack it. */ 23 24/* Usage suggestions: 25 26 Programs that use <stdbool.h> should be aware of some limitations 27 and standards compliance issues. 28 29 Standards compliance: 30 31 - <stdbool.h> must be #included before 'bool', 'false', 'true' 32 can be used. 33 34 - You cannot assume that sizeof (bool) == 1. 35 36 - Programs should not undefine the macros bool, true, and false, 37 as C99 lists that as an "obsolescent feature". 38 39 Limitations of this substitute, when used in a C89 environment: 40 41 - <stdbool.h> must be #included before the '_Bool' type can be used. 42 43 - You cannot assume that _Bool is a typedef; it might be a macro. 44 45 - Bit-fields of type 'bool' are not supported. Portable code 46 should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'. 47 48 - In C99, casts and automatic conversions to '_Bool' or 'bool' are 49 performed in such a way that every nonzero value gets converted 50 to 'true', and zero gets converted to 'false'. This doesn't work 51 with this substitute. With this substitute, only the values 0 and 1 52 give the expected result when converted to _Bool' or 'bool'. 53 54 Also, it is suggested that programs use 'bool' rather than '_Bool'; 55 this isn't required, but 'bool' is more common. */ 56 57 58/* 7.16. Boolean type and values */ 59 60/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same 61 definitions below, but temporarily we have to #undef them. */ 62#if defined __BEOS__ && !defined __HAIKU__ 63# include <OS.h> /* defines bool but not _Bool */ 64# undef false 65# undef true 66#endif 67 68/* For the sake of symbolic names in gdb, we define true and false as 69 enum constants, not only as macros. 70 It is tempting to write 71 typedef enum { false = 0, true = 1 } _Bool; 72 so that gdb prints values of type 'bool' symbolically. But if we do 73 this, values of type '_Bool' may promote to 'int' or 'unsigned int' 74 (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int' 75 (see ISO C 99 6.3.1.1.(2)). So we add a negative value to the 76 enum; this ensures that '_Bool' promotes to 'int'. */ 77#if defined __cplusplus || (defined __BEOS__ && !defined __HAIKU__) 78 /* A compiler known to have 'bool'. */ 79 /* If the compiler already has both 'bool' and '_Bool', we can assume they 80 are the same types. */ 81# if !@HAVE__BOOL@ 82typedef bool _Bool; 83# endif 84#else 85# if !defined __GNUC__ 86 /* If @HAVE__BOOL@: 87 Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when 88 the built-in _Bool type is used. See 89 http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html 90 http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html 91 http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html 92 Similar bugs are likely with other compilers as well; this file 93 wouldn't be used if <stdbool.h> was working. 94 So we override the _Bool type. 95 If !@HAVE__BOOL@: 96 Need to define _Bool ourselves. As 'signed char' or as an enum type? 97 Use of a typedef, with SunPRO C, leads to a stupid 98 "warning: _Bool is a keyword in ISO C99". 99 Use of an enum type, with IRIX cc, leads to a stupid 100 "warning(1185): enumerated type mixed with another type". 101 Even the existence of an enum type, without a typedef, 102 "Invalid enumerator. (badenum)" with HP-UX cc on Tru64. 103 The only benefit of the enum, debuggability, is not important 104 with these compilers. So use 'signed char' and no enum. */ 105# define _Bool signed char 106# else 107 /* With this compiler, trust the _Bool type if the compiler has it. */ 108# if !@HAVE__BOOL@ 109typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool; 110# endif 111# endif 112#endif 113#define bool _Bool 114 115/* The other macros must be usable in preprocessor directives. */ 116#define false 0 117#define true 1 118#define __bool_true_false_are_defined 1 119 120#endif /* _GL_STDBOOL_H */ 121