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Annotation of embedaddon/libiconv/srclib/stdbool.in.h, revision 1.1.1.2

1.1.1.2 ! misho       1: /* Copyright (C) 2001-2003, 2006-2011 Free Software Foundation, Inc.
1.1       misho       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, write to the Free Software Foundation,
                     16:    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
                     17: 
                     18: #ifndef _GL_STDBOOL_H
                     19: #define _GL_STDBOOL_H
                     20: 
                     21: /* ISO C 99 <stdbool.h> for platforms that lack it.  */
                     22: 
                     23: /* Usage suggestions:
                     24: 
                     25:    Programs that use <stdbool.h> should be aware of some limitations
                     26:    and standards compliance issues.
                     27: 
                     28:    Standards compliance:
                     29: 
                     30:        - <stdbool.h> must be #included before 'bool', 'false', 'true'
                     31:          can be used.
                     32: 
                     33:        - You cannot assume that sizeof (bool) == 1.
                     34: 
                     35:        - Programs should not undefine the macros bool, true, and false,
                     36:          as C99 lists that as an "obsolescent feature".
                     37: 
                     38:    Limitations of this substitute, when used in a C89 environment:
                     39: 
                     40:        - <stdbool.h> must be #included before the '_Bool' type can be used.
                     41: 
                     42:        - You cannot assume that _Bool is a typedef; it might be a macro.
                     43: 
                     44:        - Bit-fields of type 'bool' are not supported.  Portable code
                     45:          should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'.
                     46: 
                     47:        - In C99, casts and automatic conversions to '_Bool' or 'bool' are
                     48:          performed in such a way that every nonzero value gets converted
                     49:          to 'true', and zero gets converted to 'false'.  This doesn't work
                     50:          with this substitute.  With this substitute, only the values 0 and 1
                     51:          give the expected result when converted to _Bool' or 'bool'.
                     52: 
1.1.1.2 ! misho      53:        - C99 allows the use of (_Bool)0.0 in constant expressions, but
        !            54:          this substitute cannot always provide this property.
        !            55: 
1.1       misho      56:    Also, it is suggested that programs use 'bool' rather than '_Bool';
                     57:    this isn't required, but 'bool' is more common.  */
                     58: 
                     59: 
                     60: /* 7.16. Boolean type and values */
                     61: 
                     62: /* BeOS <sys/socket.h> already #defines false 0, true 1.  We use the same
                     63:    definitions below, but temporarily we have to #undef them.  */
                     64: #if defined __BEOS__ && !defined __HAIKU__
                     65: # include <OS.h> /* defines bool but not _Bool */
                     66: # undef false
                     67: # undef true
                     68: #endif
                     69: 
                     70: /* For the sake of symbolic names in gdb, we define true and false as
                     71:    enum constants, not only as macros.
                     72:    It is tempting to write
                     73:       typedef enum { false = 0, true = 1 } _Bool;
                     74:    so that gdb prints values of type 'bool' symbolically. But if we do
                     75:    this, values of type '_Bool' may promote to 'int' or 'unsigned int'
                     76:    (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
                     77:    (see ISO C 99 6.3.1.1.(2)).  So we add a negative value to the
                     78:    enum; this ensures that '_Bool' promotes to 'int'.  */
                     79: #if defined __cplusplus || (defined __BEOS__ && !defined __HAIKU__)
                     80:   /* A compiler known to have 'bool'.  */
                     81:   /* If the compiler already has both 'bool' and '_Bool', we can assume they
                     82:      are the same types.  */
                     83: # if !@HAVE__BOOL@
                     84: typedef bool _Bool;
                     85: # endif
                     86: #else
                     87: # if !defined __GNUC__
                     88:    /* If @HAVE__BOOL@:
                     89:         Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when
                     90:         the built-in _Bool type is used.  See
                     91:           http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
                     92:           http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
                     93:           http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
                     94:         Similar bugs are likely with other compilers as well; this file
                     95:         wouldn't be used if <stdbool.h> was working.
                     96:         So we override the _Bool type.
                     97:       If !@HAVE__BOOL@:
                     98:         Need to define _Bool ourselves. As 'signed char' or as an enum type?
                     99:         Use of a typedef, with SunPRO C, leads to a stupid
                    100:           "warning: _Bool is a keyword in ISO C99".
                    101:         Use of an enum type, with IRIX cc, leads to a stupid
                    102:           "warning(1185): enumerated type mixed with another type".
                    103:         Even the existence of an enum type, without a typedef,
                    104:           "Invalid enumerator. (badenum)" with HP-UX cc on Tru64.
                    105:         The only benefit of the enum, debuggability, is not important
                    106:         with these compilers.  So use 'signed char' and no enum.  */
                    107: #  define _Bool signed char
                    108: # else
                    109:    /* With this compiler, trust the _Bool type if the compiler has it.  */
                    110: #  if !@HAVE__BOOL@
                    111: typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
                    112: #  endif
                    113: # endif
                    114: #endif
                    115: #define bool _Bool
                    116: 
                    117: /* The other macros must be usable in preprocessor directives.  */
                    118: #define false 0
                    119: #define true 1
                    120: #define __bool_true_false_are_defined 1
                    121: 
                    122: #endif /* _GL_STDBOOL_H */