include/ansidecl.h

   1 /* ANSI and traditional C compatability macros
   2    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* ANSI and traditional C compatibility macros
  21
  22    ANSI C is assumed if __STDC__ is #defined.
  23
  24    Macro                ANSI C definition       Traditional C definition
  25    -----                ---- - ----------       ----------- - ----------
  26    ANSI_PROTOTYPES      1                       not defined
  27    PTR                  `void *'                `char *'
  28    PTRCONST             `void *const'           `char *'
  29    LONG_DOUBLE          `long double'           `double'
  30    const                not defined             `'
  31    volatile             not defined             `'
  32    signed               not defined             `'
  33    VA_START(ap, var)    va_start(ap, var)       va_start(ap)
  34
  35    Note that it is safe to write "void foo();" indicating a function
  36    with no return value, in all K+R compilers we have been able to test.
  37
  38    For declaring functions with prototypes, we also provide these:
  39
  40    PARAMS ((prototype))
  41    -- for functions which take a fixed number of arguments.  Use this
  42    when declaring the function.  When defining the function, write a
  43    K+R style argument list.  For example:
  44
  45         char *strcpy PARAMS ((char *dest, char *source));
  46         ...
  47         char *
  48         strcpy (dest, source)
  49              char *dest;
  50              char *source;
  51         { ... }
  52
  53
  54    VPARAMS ((prototype, ...))
  55    -- for functions which take a variable number of arguments.  Use
  56    PARAMS to declare the function, VPARAMS to define it.  For example:
  57
  58         int printf PARAMS ((const char *format, ...));
  59         ...
  60         int
  61         printf VPARAMS ((const char *format, ...))
  62         {
  63            ...
  64         }
  65
  66    For writing functions which take variable numbers of arguments, we
  67    also provide the VA_OPEN, VA_CLOSE, and VA_FIXEDARG macros.  These
  68    hide the differences between K+R <varargs.h> and C89 <stdarg.h> more
  69    thoroughly than the simple VA_START() macro mentioned above.
  70
  71    VA_OPEN and VA_CLOSE are used *instead of* va_start and va_end.
  72    Immediately after VA_OPEN, put a sequence of VA_FIXEDARG calls
  73    corresponding to the list of fixed arguments.  Then use va_arg
  74    normally to get the variable arguments, or pass your va_list object
  75    around.  You do not declare the va_list yourself; VA_OPEN does it
  76    for you.
  77
  78    Here is a complete example:
  79
  80         int
  81         printf VPARAMS ((const char *format, ...))
  82         {
  83            int result;
  84
  85            VA_OPEN (ap, format);
  86            VA_FIXEDARG (ap, const char *, format);
  87
  88            result = vfprintf (stdout, format, ap);
  89            VA_CLOSE (ap);
  90
  91            return result;
  92         }
  93
  94
  95    You can declare variables either before or after the VA_OPEN,
  96    VA_FIXEDARG sequence.  Also, VA_OPEN and VA_CLOSE are the beginning
  97    and end of a block.  They must appear at the same nesting level,
  98    and any variables declared after VA_OPEN go out of scope at
  99    VA_CLOSE.  Unfortunately, with a K+R compiler, that includes the
 100    argument list.  You can have multiple instances of VA_OPEN/VA_CLOSE
 101    pairs in a single function in case you need to traverse the
 102    argument list more than once.
 103
 104    For ease of writing code which uses GCC extensions but needs to be
 105    portable to other compilers, we provide the GCC_VERSION macro that
 106    simplifies testing __GNUC__ and __GNUC_MINOR__ together, and various
 107    wrappers around __attribute__.  Also, __extension__ will be #defined
 108    to nothing if it doesn't work.  See below.
 109
 110    This header also defines a lot of obsolete macros:
 111    CONST, VOLATILE, SIGNED, PROTO, EXFUN, DEFUN, DEFUN_VOID,
 112    AND, DOTS, NOARGS.  Don't use them.  */
 113
 114 #ifndef _ANSIDECL_H
 115 #define _ANSIDECL_H     1
 116
 117 /* Every source file includes this file,
 118    so they will all get the switch for lint.  */
 119 /* LINTLIBRARY */
 120
 121 /* Using MACRO(x,y) in cpp #if conditionals does not work with some
 122    older preprocessors.  Thus we can't define something like this:
 123
 124 #define HAVE_GCC_VERSION(MAJOR, MINOR) \
 125   (__GNUC__ > (MAJOR) || (__GNUC__ == (MAJOR) && __GNUC_MINOR__ >= (MINOR)))
 126
 127 and then test "#if HAVE_GCC_VERSION(2,7)".
 128
 129 So instead we use the macro below and test it against specific values.  */
 130
 131 /* This macro simplifies testing whether we are using gcc, and if it
 132    is of a particular minimum version. (Both major & minor numbers are
 133    significant.)  This macro will evaluate to 0 if we are not using
 134    gcc at all.  */
 135 #ifndef GCC_VERSION
 136 #define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
 137 #endif /* GCC_VERSION */
 138
 139 #if defined (__STDC__) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(_WIN32)
 140 /* All known AIX compilers implement these things (but don't always
 141    define __STDC__).  The RISC/OS MIPS compiler defines these things
 142    in SVR4 mode, but does not define __STDC__.  */
 143
 144 #define ANSI_PROTOTYPES 1
 145 #define PTR             void *
 146 #define PTRCONST        void *const
 147 #define LONG_DOUBLE     long double
 148
 149 #define PARAMS(ARGS)            ARGS
 150 #define VPARAMS(ARGS)           ARGS
 151 #define VA_START(VA_LIST, VAR)  va_start(VA_LIST, VAR)
 152
 153 /* variadic function helper macros */
 154 /* "struct Qdmy" swallows the semicolon after VA_OPEN/VA_FIXEDARG's
 155    use without inhibiting further decls and without declaring an
 156    actual variable.  */
 157 #define VA_OPEN(AP, VAR)        { va_list AP; va_start(AP, VAR); { struct Qdmy
 158 #define VA_CLOSE(AP)            } va_end(AP); }
 159 #define VA_FIXEDARG(AP, T, N)   struct Qdmy
 160
 161 #undef const
 162 #undef volatile
 163 #undef signed
 164
 165 /* inline requires special treatment; it's in C99, and GCC >=2.7 supports
 166    it too, but it's not in C89.  */
 167 #undef inline
 168 #if __STDC_VERSION__ > 199901L
 169 /* it's a keyword */
 170 #else
 171 # if GCC_VERSION >= 2007
 172 #  define inline __inline__   /* __inline__ prevents -pedantic warnings */
 173 # else
 174 #  define inline  /* nothing */
 175 # endif
 176 #endif
 177
 178 /* These are obsolete.  Do not use.  */
 179 #ifndef IN_GCC
 180 #define CONST           const
 181 #define VOLATILE        volatile
 182 #define SIGNED          signed
 183
 184 #define PROTO(type, name, arglist)      type name arglist
 185 #define EXFUN(name, proto)              name proto
 186 #define DEFUN(name, arglist, args)      name(args)
 187 #define DEFUN_VOID(name)                name(void)
 188 #define AND             ,
 189 #define DOTS            , ...
 190 #define NOARGS          void
 191 #endif /* ! IN_GCC */
 192
 193 #else   /* Not ANSI C.  */
 194
 195 #undef  ANSI_PROTOTYPES
 196 #define PTR             char *
 197 #define PTRCONST        PTR
 198 #define LONG_DOUBLE     double
 199
 200 #define PARAMS(args)            ()
 201 #define VPARAMS(args)           (va_alist) va_dcl
 202 #define VA_START(va_list, var)  va_start(va_list)
 203
 204 #define VA_OPEN(AP, VAR)                { va_list AP; va_start(AP); { struct Qdmy
 205 #define VA_CLOSE(AP)                    } va_end(AP); }
 206 #define VA_FIXEDARG(AP, TYPE, NAME)     TYPE NAME = va_arg(AP, TYPE)
 207
 208 /* some systems define these in header files for non-ansi mode */
 209 #undef const
 210 #undef volatile
 211 #undef signed
 212 #undef inline
 213 #define const
 214 #define volatile
 215 #define signed
 216 #define inline
 217
 218 #ifndef IN_GCC
 219 #define CONST
 220 #define VOLATILE
 221 #define SIGNED
 222
 223 #define PROTO(type, name, arglist)      type name ()
 224 #define EXFUN(name, proto)              name()
 225 #define DEFUN(name, arglist, args)      name arglist args;
 226 #define DEFUN_VOID(name)                name()
 227 #define AND             ;
 228 #define DOTS
 229 #define NOARGS
 230 #endif /* ! IN_GCC */
 231
 232 #endif  /* ANSI C.  */
 233
 234 /* Define macros for some gcc attributes.  This permits us to use the
 235    macros freely, and know that they will come into play for the
 236    version of gcc in which they are supported.  */
 237
 238 #if (GCC_VERSION < 2007)
 239 # define __attribute__(x)
 240 #endif
 241
 242 /* Attribute __malloc__ on functions was valid as of gcc 2.96. */
 243 #ifndef ATTRIBUTE_MALLOC
 244 # if (GCC_VERSION >= 2096)
 245 #  define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 246 # else
 247 #  define ATTRIBUTE_MALLOC
 248 # endif /* GNUC >= 2.96 */
 249 #endif /* ATTRIBUTE_MALLOC */
 250
 251 /* Attributes on labels were valid as of gcc 2.93. */
 252 #ifndef ATTRIBUTE_UNUSED_LABEL
 253 # if (GCC_VERSION >= 2093)
 254 #  define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED
 255 # else
 256 #  define ATTRIBUTE_UNUSED_LABEL
 257 # endif /* GNUC >= 2.93 */
 258 #endif /* ATTRIBUTE_UNUSED_LABEL */
 259
 260 #ifndef ATTRIBUTE_UNUSED
 261 #define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 262 #endif /* ATTRIBUTE_UNUSED */
 263
 264 #ifndef ATTRIBUTE_NORETURN
 265 #define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
 266 #endif /* ATTRIBUTE_NORETURN */
 267
 268 #ifndef ATTRIBUTE_PRINTF
 269 #define ATTRIBUTE_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n)))
 270 #define ATTRIBUTE_PRINTF_1 ATTRIBUTE_PRINTF(1, 2)
 271 #define ATTRIBUTE_PRINTF_2 ATTRIBUTE_PRINTF(2, 3)
 272 #define ATTRIBUTE_PRINTF_3 ATTRIBUTE_PRINTF(3, 4)
 273 #define ATTRIBUTE_PRINTF_4 ATTRIBUTE_PRINTF(4, 5)
 274 #define ATTRIBUTE_PRINTF_5 ATTRIBUTE_PRINTF(5, 6)
 275 #endif /* ATTRIBUTE_PRINTF */
 276
 277 /* We use __extension__ in some places to suppress -pedantic warnings
 278    about GCC extensions.  This feature didn't work properly before
 279    gcc 2.8.  */
 280 #if GCC_VERSION < 2008
 281 #define __extension__
 282 #endif
 283
 284 /* Bootstrap support:  Adjust certain macros defined by Autoconf,
 285    which are only valid for the stage1 compiler.  If we detect
 286    a modern version of GCC, we are probably in stage2 or beyond,
 287    so unconditionally reset the values.  Note that const, inline,
 288    etc. have been dealt with above.  */
 289 #if (GCC_VERSION >= 2007)
 290 # ifndef HAVE_LONG_DOUBLE
 291 #  define HAVE_LONG_DOUBLE 1
 292 # endif
 293 #endif /* GCC >= 2.7 */
 294
 295 #endif  /* ansidecl.h   */