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/* Copyright (C) 2001-2003, 2006-2009 Free Software Foundation, Inc.
Written by Bruno Haible <haible@clisp.cons.org>, 2001.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2, 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
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>. */
#ifndef _UNISTRING_STDBOOL_H
#define _UNISTRING_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'.
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 */
/* For the sake of symbolic names in gdb, we 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 if we do
this, values of type '_Bool' may promote to 'int' or 'unsigned int'
(see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
(see ISO C 99 6.3.1.1.(2)). So we add a negative value to the
enum; this ensures that '_Bool' promotes to 'int'. */
#if defined __cplusplus
/* Assume the compiler has 'bool' and '_Bool'. */
#else
/* 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
http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
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.
If !@HAVE__BOOL@:
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
#endif
#define bool _Bool
/* The other macros must be usable in preprocessor directives. */
#define false 0
#define true 1
#define __bool_true_false_are_defined 1
#endif /* _UNISTRING_STDBOOL_H */
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