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libiconv 1.16

    1: /* Copyright (C) 2001-2003, 2006-2019 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 */