include/ansidecl.h

   1 /* ANSI and traditional C compatability macros
   2    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
   3    2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010
   4    Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  20
  21 /* ANSI and traditional C compatibility macros
  22
  23    ANSI C is assumed if __STDC__ is #defined.
  24
  25    Macro                ANSI C definition       Traditional C definition
  26    -----                ---- - ----------       ----------- - ----------
  27    ANSI_PROTOTYPES      1                       not defined
  28    PTR                  `void *'                `char *'
  29    PTRCONST             `void *const'           `char *'
  30    LONG_DOUBLE          `long double'           `double'
  31    const                not defined             `'
  32    volatile             not defined             `'
  33    signed               not defined             `'
  34    VA_START(ap, var)    va_start(ap, var)       va_start(ap)
  35
  36    Note that it is safe to write "void foo();" indicating a function
  37    with no return value, in all K+R compilers we have been able to test.
  38
  39    For declaring functions with prototypes, we also provide these:
  40
  41    PARAMS ((prototype))
  42    -- for functions which take a fixed number of arguments.  Use this
  43    when declaring the function.  When defining the function, write a
  44    K+R style argument list.  For example:
  45
  46         char *strcpy PARAMS ((char *dest, char *source));
  47         ...
  48         char *
  49         strcpy (dest, source)
  50              char *dest;
  51              char *source;
  52         { ... }
  53
  54
  55    VPARAMS ((prototype, ...))
  56    -- for functions which take a variable number of arguments.  Use
  57    PARAMS to declare the function, VPARAMS to define it.  For example:
  58
  59         int printf PARAMS ((const char *format, ...));
  60         ...
  61         int
  62         printf VPARAMS ((const char *format, ...))
  63         {
  64            ...
  65         }
  66
  67    For writing functions which take variable numbers of arguments, we
  68    also provide the VA_OPEN, VA_CLOSE, and VA_FIXEDARG macros.  These
  69    hide the differences between K+R <varargs.h> and C89 <stdarg.h> more
  70    thoroughly than the simple VA_START() macro mentioned above.
  71
  72    VA_OPEN and VA_CLOSE are used *instead of* va_start and va_end.
  73    Immediately after VA_OPEN, put a sequence of VA_FIXEDARG calls
  74    corresponding to the list of fixed arguments.  Then use va_arg
  75    normally to get the variable arguments, or pass your va_list object
  76    around.  You do not declare the va_list yourself; VA_OPEN does it
  77    for you.
  78
  79    Here is a complete example:
  80
  81         int
  82         printf VPARAMS ((const char *format, ...))
  83         {
  84            int result;
  85
  86            VA_OPEN (ap, format);
  87            VA_FIXEDARG (ap, const char *, format);
  88
  89            result = vfprintf (stdout, format, ap);
  90            VA_CLOSE (ap);
  91
  92            return result;
  93         }
  94
  95
  96    You can declare variables either before or after the VA_OPEN,
  97    VA_FIXEDARG sequence.  Also, VA_OPEN and VA_CLOSE are the beginning
  98    and end of a block.  They must appear at the same nesting level,
  99    and any variables declared after VA_OPEN go out of scope at
 100    VA_CLOSE.  Unfortunately, with a K+R compiler, that includes the
 101    argument list.  You can have multiple instances of VA_OPEN/VA_CLOSE
 102    pairs in a single function in case you need to traverse the
 103    argument list more than once.
 104
 105    For ease of writing code which uses GCC extensions but needs to be
 106    portable to other compilers, we provide the GCC_VERSION macro that
 107    simplifies testing __GNUC__ and __GNUC_MINOR__ together, and various
 108    wrappers around __attribute__.  Also, __extension__ will be #defined
 109    to nothing if it doesn't work.  See below.
 110
 111    This header also defines a lot of obsolete macros:
 112    CONST, VOLATILE, SIGNED, PROTO, EXFUN, DEFUN, DEFUN_VOID,
 113    AND, DOTS, NOARGS.  Don't use them.  */
 114
 115 #ifndef _ANSIDECL_H
 116 #define _ANSIDECL_H     1
 117
 118 #ifdef __cplusplus
 119 extern "C" {
 120 #endif
 121
 122 /* Every source file includes this file,
 123    so they will all get the switch for lint.  */
 124 /* LINTLIBRARY */
 125
 126 /* Using MACRO(x,y) in cpp #if conditionals does not work with some
 127    older preprocessors.  Thus we can't define something like this:
 128
 129 #define HAVE_GCC_VERSION(MAJOR, MINOR) \
 130   (__GNUC__ > (MAJOR) || (__GNUC__ == (MAJOR) && __GNUC_MINOR__ >= (MINOR)))
 131
 132 and then test "#if HAVE_GCC_VERSION(2,7)".
 133
 134 So instead we use the macro below and test it against specific values.  */
 135
 136 /* This macro simplifies testing whether we are using gcc, and if it
 137    is of a particular minimum version. (Both major & minor numbers are
 138    significant.)  This macro will evaluate to 0 if we are not using
 139    gcc at all.  */
 140 #ifndef GCC_VERSION
 141 #define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
 142 #endif /* GCC_VERSION */
 143
 144 #if defined (__STDC__) || defined(__cplusplus) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(_WIN32)
 145 /* All known AIX compilers implement these things (but don't always
 146    define __STDC__).  The RISC/OS MIPS compiler defines these things
 147    in SVR4 mode, but does not define __STDC__.  */
 148 /* eraxxon@alumni.rice.edu: The Compaq C++ compiler, unlike many other
 149    C++ compilers, does not define __STDC__, though it acts as if this
 150    was so. (Verified versions: 5.7, 6.2, 6.3, 6.5) */
 151
 152 #define ANSI_PROTOTYPES 1
 153 #define PTR             void *
 154 #define PTRCONST        void *const
 155 #define LONG_DOUBLE     long double
 156
 157 /* PARAMS is often defined elsewhere (e.g. by libintl.h), so wrap it in
 158    a #ifndef.  */
 159 #ifndef PARAMS
 160 #define PARAMS(ARGS)            ARGS
 161 #endif
 162
 163 #define VPARAMS(ARGS)           ARGS
 164 #define VA_START(VA_LIST, VAR)  va_start(VA_LIST, VAR)
 165
 166 /* variadic function helper macros */
 167 /* "struct Qdmy" swallows the semicolon after VA_OPEN/VA_FIXEDARG's
 168    use without inhibiting further decls and without declaring an
 169    actual variable.  */
 170 #define VA_OPEN(AP, VAR)        { va_list AP; va_start(AP, VAR); { struct Qdmy
 171 #define VA_CLOSE(AP)            } va_end(AP); }
 172 #define VA_FIXEDARG(AP, T, N)   struct Qdmy
 173
 174 #undef const
 175 #undef volatile
 176 #undef signed
 177
 178 /* inline requires special treatment; it's in C99, and GCC >=2.7 supports
 179    it too, but it's not in C89.  */
 180 #undef inline
 181 #if __STDC_VERSION__ >= 199901L || defined(__cplusplus) || (defined(__SUNPRO_C) && defined(__C99FEATURES__))
 182 /* it's a keyword */
 183 #else
 184 # if GCC_VERSION >= 2007
 185 #  define inline __inline__   /* __inline__ prevents -pedantic warnings */
 186 # else
 187 #  define inline  /* nothing */
 188 # endif
 189 #endif
 190
 191 /* These are obsolete.  Do not use.  */
 192 #ifndef IN_GCC
 193 #define CONST           const
 194 #define VOLATILE        volatile
 195 #define SIGNED          signed
 196
 197 #define PROTO(type, name, arglist)      type name arglist
 198 #define EXFUN(name, proto)              name proto
 199 #define DEFUN(name, arglist, args)      name(args)
 200 #define DEFUN_VOID(name)                name(void)
 201 #define AND             ,
 202 #define DOTS            , ...
 203 #define NOARGS          void
 204 #endif /* ! IN_GCC */
 205
 206 #else   /* Not ANSI C.  */
 207
 208 #undef  ANSI_PROTOTYPES
 209 #define PTR             char *
 210 #define PTRCONST        PTR
 211 #define LONG_DOUBLE     double
 212
 213 #define PARAMS(args)            ()
 214 #define VPARAMS(args)           (va_alist) va_dcl
 215 #define VA_START(va_list, var)  va_start(va_list)
 216
 217 #define VA_OPEN(AP, VAR)                { va_list AP; va_start(AP); { struct Qdmy
 218 #define VA_CLOSE(AP)                    } va_end(AP); }
 219 #define VA_FIXEDARG(AP, TYPE, NAME)     TYPE NAME = va_arg(AP, TYPE)
 220
 221 /* some systems define these in header files for non-ansi mode */
 222 #undef const
 223 #undef volatile
 224 #undef signed
 225 #undef inline
 226 #define const
 227 #define volatile
 228 #define signed
 229 #define inline
 230
 231 #ifndef IN_GCC
 232 #define CONST
 233 #define VOLATILE
 234 #define SIGNED
 235
 236 #define PROTO(type, name, arglist)      type name ()
 237 #define EXFUN(name, proto)              name()
 238 #define DEFUN(name, arglist, args)      name arglist args;
 239 #define DEFUN_VOID(name)                name()
 240 #define AND             ;
 241 #define DOTS
 242 #define NOARGS
 243 #endif /* ! IN_GCC */
 244
 245 #endif  /* ANSI C.  */
 246
 247 /* Define macros for some gcc attributes.  This permits us to use the
 248    macros freely, and know that they will come into play for the
 249    version of gcc in which they are supported.  */
 250
 251 #if (GCC_VERSION < 2007)
 252 # define __attribute__(x)
 253 #endif
 254
 255 /* Attribute __malloc__ on functions was valid as of gcc 2.96. */
 256 #ifndef ATTRIBUTE_MALLOC
 257 # if (GCC_VERSION >= 2096)
 258 #  define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 259 # else
 260 #  define ATTRIBUTE_MALLOC
 261 # endif /* GNUC >= 2.96 */
 262 #endif /* ATTRIBUTE_MALLOC */
 263
 264 /* Attributes on labels were valid as of gcc 2.93 and g++ 4.5.  For
 265    g++ an attribute on a label must be followed by a semicolon.  */
 266 #ifndef ATTRIBUTE_UNUSED_LABEL
 267 # ifndef __cplusplus
 268 #  if GCC_VERSION >= 2093
 269 #   define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED
 270 #  else
 271 #   define ATTRIBUTE_UNUSED_LABEL
 272 #  endif
 273 # else
 274 #  if GCC_VERSION >= 4005
 275 #   define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED ;
 276 #  else
 277 #   define ATTRIBUTE_UNUSED_LABEL
 278 #  endif
 279 # endif
 280 #endif
 281
 282 #ifndef ATTRIBUTE_UNUSED
 283 #define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 284 #endif /* ATTRIBUTE_UNUSED */
 285
 286 /* Before GCC 3.4, the C++ frontend couldn't parse attributes placed after the
 287    identifier name.  */
 288 #if ! defined(__cplusplus) || (GCC_VERSION >= 3004)
 289 # define ARG_UNUSED(NAME) NAME ATTRIBUTE_UNUSED
 290 #else /* !__cplusplus || GNUC >= 3.4 */
 291 # define ARG_UNUSED(NAME) NAME
 292 #endif /* !__cplusplus || GNUC >= 3.4 */
 293
 294 #ifndef ATTRIBUTE_NORETURN
 295 #define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
 296 #endif /* ATTRIBUTE_NORETURN */
 297
 298 /* Attribute `nonnull' was valid as of gcc 3.3.  */
 299 #ifndef ATTRIBUTE_NONNULL
 300 # if (GCC_VERSION >= 3003)
 301 #  define ATTRIBUTE_NONNULL(m) __attribute__ ((__nonnull__ (m)))
 302 # else
 303 #  define ATTRIBUTE_NONNULL(m)
 304 # endif /* GNUC >= 3.3 */
 305 #endif /* ATTRIBUTE_NONNULL */
 306
 307 /* Attribute `pure' was valid as of gcc 3.0.  */
 308 #ifndef ATTRIBUTE_PURE
 309 # if (GCC_VERSION >= 3000)
 310 #  define ATTRIBUTE_PURE __attribute__ ((__pure__))
 311 # else
 312 #  define ATTRIBUTE_PURE
 313 # endif /* GNUC >= 3.0 */
 314 #endif /* ATTRIBUTE_PURE */
 315
 316 /* Use ATTRIBUTE_PRINTF when the format specifier must not be NULL.
 317    This was the case for the `printf' format attribute by itself
 318    before GCC 3.3, but as of 3.3 we need to add the `nonnull'
 319    attribute to retain this behavior.  */
 320 #ifndef ATTRIBUTE_PRINTF
 321 #define ATTRIBUTE_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n))) ATTRIBUTE_NONNULL(m)
 322 #define ATTRIBUTE_PRINTF_1 ATTRIBUTE_PRINTF(1, 2)
 323 #define ATTRIBUTE_PRINTF_2 ATTRIBUTE_PRINTF(2, 3)
 324 #define ATTRIBUTE_PRINTF_3 ATTRIBUTE_PRINTF(3, 4)
 325 #define ATTRIBUTE_PRINTF_4 ATTRIBUTE_PRINTF(4, 5)
 326 #define ATTRIBUTE_PRINTF_5 ATTRIBUTE_PRINTF(5, 6)
 327 #endif /* ATTRIBUTE_PRINTF */
 328
 329 /* Use ATTRIBUTE_FPTR_PRINTF when the format attribute is to be set on
 330    a function pointer.  Format attributes were allowed on function
 331    pointers as of gcc 3.1.  */
 332 #ifndef ATTRIBUTE_FPTR_PRINTF
 333 # if (GCC_VERSION >= 3001)
 334 #  define ATTRIBUTE_FPTR_PRINTF(m, n) ATTRIBUTE_PRINTF(m, n)
 335 # else
 336 #  define ATTRIBUTE_FPTR_PRINTF(m, n)
 337 # endif /* GNUC >= 3.1 */
 338 # define ATTRIBUTE_FPTR_PRINTF_1 ATTRIBUTE_FPTR_PRINTF(1, 2)
 339 # define ATTRIBUTE_FPTR_PRINTF_2 ATTRIBUTE_FPTR_PRINTF(2, 3)
 340 # define ATTRIBUTE_FPTR_PRINTF_3 ATTRIBUTE_FPTR_PRINTF(3, 4)
 341 # define ATTRIBUTE_FPTR_PRINTF_4 ATTRIBUTE_FPTR_PRINTF(4, 5)
 342 # define ATTRIBUTE_FPTR_PRINTF_5 ATTRIBUTE_FPTR_PRINTF(5, 6)
 343 #endif /* ATTRIBUTE_FPTR_PRINTF */
 344
 345 /* Use ATTRIBUTE_NULL_PRINTF when the format specifier may be NULL.  A
 346    NULL format specifier was allowed as of gcc 3.3.  */
 347 #ifndef ATTRIBUTE_NULL_PRINTF
 348 # if (GCC_VERSION >= 3003)
 349 #  define ATTRIBUTE_NULL_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n)))
 350 # else
 351 #  define ATTRIBUTE_NULL_PRINTF(m, n)
 352 # endif /* GNUC >= 3.3 */
 353 # define ATTRIBUTE_NULL_PRINTF_1 ATTRIBUTE_NULL_PRINTF(1, 2)
 354 # define ATTRIBUTE_NULL_PRINTF_2 ATTRIBUTE_NULL_PRINTF(2, 3)
 355 # define ATTRIBUTE_NULL_PRINTF_3 ATTRIBUTE_NULL_PRINTF(3, 4)
 356 # define ATTRIBUTE_NULL_PRINTF_4 ATTRIBUTE_NULL_PRINTF(4, 5)
 357 # define ATTRIBUTE_NULL_PRINTF_5 ATTRIBUTE_NULL_PRINTF(5, 6)
 358 #endif /* ATTRIBUTE_NULL_PRINTF */
 359
 360 /* Attribute `sentinel' was valid as of gcc 3.5.  */
 361 #ifndef ATTRIBUTE_SENTINEL
 362 # if (GCC_VERSION >= 3005)
 363 #  define ATTRIBUTE_SENTINEL __attribute__ ((__sentinel__))
 364 # else
 365 #  define ATTRIBUTE_SENTINEL
 366 # endif /* GNUC >= 3.5 */
 367 #endif /* ATTRIBUTE_SENTINEL */
 368
 369
 370 #ifndef ATTRIBUTE_ALIGNED_ALIGNOF
 371 # if (GCC_VERSION >= 3000)
 372 #  define ATTRIBUTE_ALIGNED_ALIGNOF(m) __attribute__ ((__aligned__ (__alignof__ (m))))
 373 # else
 374 #  define ATTRIBUTE_ALIGNED_ALIGNOF(m)
 375 # endif /* GNUC >= 3.0 */
 376 #endif /* ATTRIBUTE_ALIGNED_ALIGNOF */
 377
 378 /* Useful for structures whose layout must much some binary specification
 379    regardless of the alignment and padding qualities of the compiler.  */
 380 #ifndef ATTRIBUTE_PACKED
 381 # define ATTRIBUTE_PACKED __attribute__ ((packed))
 382 #endif
 383
 384 /* Attribute `hot' and `cold' was valid as of gcc 4.3.  */
 385 #ifndef ATTRIBUTE_COLD
 386 # if (GCC_VERSION >= 4003)
 387 #  define ATTRIBUTE_COLD __attribute__ ((__cold__))
 388 # else
 389 #  define ATTRIBUTE_COLD
 390 # endif /* GNUC >= 4.3 */
 391 #endif /* ATTRIBUTE_COLD */
 392 #ifndef ATTRIBUTE_HOT
 393 # if (GCC_VERSION >= 4003)
 394 #  define ATTRIBUTE_HOT __attribute__ ((__hot__))
 395 # else
 396 #  define ATTRIBUTE_HOT
 397 # endif /* GNUC >= 4.3 */
 398 #endif /* ATTRIBUTE_HOT */
 399
 400 /* We use __extension__ in some places to suppress -pedantic warnings
 401    about GCC extensions.  This feature didn't work properly before
 402    gcc 2.8.  */
 403 #if GCC_VERSION < 2008
 404 #define __extension__
 405 #endif
 406
 407 /* This is used to declare a const variable which should be visible
 408    outside of the current compilation unit.  Use it as
 409      EXPORTED_CONST int i = 1;
 410    This is because the semantics of const are different in C and C++.
 411    "extern const" is permitted in C but it looks strange, and gcc
 412    warns about it when -Wc++-compat is not used.  */
 413 #ifdef __cplusplus
 414 #define EXPORTED_CONST extern const
 415 #else
 416 #define EXPORTED_CONST const
 417 #endif
 418
 419 /* Be conservative and only use enum bitfields with C++ or GCC.
 420    FIXME: provide a complete autoconf test for buggy enum bitfields.  */
 421
 422 #ifdef __cplusplus
 423 #define ENUM_BITFIELD(TYPE) enum TYPE
 424 #elif (GCC_VERSION > 2000)
 425 #define ENUM_BITFIELD(TYPE) __extension__ enum TYPE
 426 #else
 427 #define ENUM_BITFIELD(TYPE) unsigned int
 428 #endif
 429
 430 #ifdef __cplusplus
 431 }
 432 #endif
 433
 434 #endif  /* ansidecl.h   */