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- /* Copyright (C) 2001-2003, 2006-2008 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 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
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- 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, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
- #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'.
- 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
- #endif
- /* 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 || (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
- 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
- # else
- /* With this compiler, trust the _Bool type if the compiler has it. */
- # if !@HAVE__BOOL@
- 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. */
- #define false 0
- #define true 1
- #define __bool_true_false_are_defined 1
- #endif /* _GL_STDBOOL_H */
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