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/* Copyright (C) 2001-2003, 2006-2021 Free Software Foundation, Inc.
Written by Bruno Haible <>, 2001.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <>. */
#ifndef _GL_STDBOOL_H
#define _GL_STDBOOL_H
/* ISO C 99 <stdbool.h> for platforms that lack it. */
/* Usage suggestions:
Programs that use <stdbool.h> should be aware of some limitations
and standards compliance issues.
Standards compliance:
- <stdbool.h> must be #included before 'bool', 'false', 'true'
can be used.
- You cannot assume that sizeof (bool) == 1.
- Programs should not undefine the macros bool, true, and false,
as C99 lists that as an "obsolescent feature".
Limitations of this substitute, when used in a C89 environment:
- <stdbool.h> must be #included before the '_Bool' type can be used.
- You cannot assume that _Bool is a typedef; it might be a macro.
- Bit-fields of type 'bool' are not supported. Portable code
should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'.
- In C99, casts and automatic conversions to '_Bool' or 'bool' are
performed in such a way that every nonzero value gets converted
to 'true', and zero gets converted to 'false'. This doesn't work
with this substitute. With this substitute, only the values 0 and 1
give the expected result when converted to _Bool' or 'bool'.
- C99 allows the use of (_Bool)0.0 in constant expressions, but
this substitute cannot always provide this property.
Also, it is suggested that programs use 'bool' rather than '_Bool';
this isn't required, but 'bool' is more common. */
/* 7.16. Boolean type and values */
/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same
definitions below, but temporarily we have to #undef them. */
#if defined __BEOS__ && !defined __HAIKU__
# include <OS.h> /* defines bool but not _Bool */
# undef false
# undef true
#ifdef __cplusplus
# define _Bool bool
# define bool bool
# if defined __BEOS__ && !defined __HAIKU__
/* A compiler known to have 'bool'. */
/* If the compiler already has both 'bool' and '_Bool', we can assume they
are the same types. */
# if !@HAVE__BOOL@
typedef bool _Bool;
# endif
# else
# if !defined __GNUC__
/* If @HAVE__BOOL@:
Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when
the built-in _Bool type is used. See
Similar bugs are likely with other compilers as well; this file
wouldn't be used if <stdbool.h> was working.
So we override the _Bool type.
Need to define _Bool ourselves. As 'signed char' or as an enum type?
Use of a typedef, with SunPRO C, leads to a stupid
"warning: _Bool is a keyword in ISO C99".
Use of an enum type, with IRIX cc, leads to a stupid
"warning(1185): enumerated type mixed with another type".
Even the existence of an enum type, without a typedef,
"Invalid enumerator. (badenum)" with HP-UX cc on Tru64.
The only benefit of the enum, debuggability, is not important
with these compilers. So use 'signed char' and no enum. */
# define _Bool signed char
# else
/* With this compiler, trust the _Bool type if the compiler has it. */
# if !@HAVE__BOOL@
/* For the sake of symbolic names in gdb, define true and false as
enum constants, not only as macros.
It is tempting to write
typedef enum { false = 0, true = 1 } _Bool;
so that gdb prints values of type 'bool' symbolically. But then
values of type '_Bool' might promote to 'int' or 'unsigned int'
(see ISO C 99; however, '_Bool' must promote to 'int'
(see ISO C 99 So add a negative value to the
enum; this ensures that '_Bool' promotes to 'int'. */
typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
# endif
# endif
# endif
# define bool _Bool
/* The other macros must be usable in preprocessor directives. */
#ifdef __cplusplus
# define false false
# define true true
# define false 0
# define true 1
#define __bool_true_false_are_defined 1
#endif /* _GL_STDBOOL_H */