| 1 | /* Copyright (C) 2001-2003, 2006-2020 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, see <https://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 | https://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html |
| 86 | https://lists.gnu.org/r/bug-coreutils/2005-11/msg00161.html |
| 87 | https://lists.gnu.org/r/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 */ |