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) || (defined(__alpha) && defined(__cplusplus))
 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 /* eraxxon@alumni.rice.edu: The Compaq C++ compiler, unlike many other
 144    C++ compilers, does not define __STDC__, though it acts as if this
 145    was so. (Verified versions: 5.7, 6.2, 6.3, 6.5) */
 146
 147 #define ANSI_PROTOTYPES 1
 148 #define PTR             void *
 149 #define PTRCONST        void *const
 150 #define LONG_DOUBLE     long double
 151
 152 #define PARAMS(ARGS)            ARGS
 153 #define VPARAMS(ARGS)           ARGS
 154 #define VA_START(VA_LIST, VAR)  va_start(VA_LIST, VAR)
 155
 156 /* variadic function helper macros */
 157 /* "struct Qdmy" swallows the semicolon after VA_OPEN/VA_FIXEDARG's
 158    use without inhibiting further decls and without declaring an
 159    actual variable.  */
 160 #define VA_OPEN(AP, VAR)        { va_list AP; va_start(AP, VAR); { struct Qdmy
 161 #define VA_CLOSE(AP)            } va_end(AP); }
 162 #define VA_FIXEDARG(AP, T, N)   struct Qdmy
 163
 164 #undef const
 165 #undef volatile
 166 #undef signed
 167
 168 /* inline requires special treatment; it's in C99, and GCC >=2.7 supports
 169    it too, but it's not in C89.  */
 170 #undef inline
 171 #if __STDC_VERSION__ > 199901L
 172 /* it's a keyword */
 173 #else
 174 # if GCC_VERSION >= 2007
 175 #  define inline __inline__   /* __inline__ prevents -pedantic warnings */
 176 # else
 177 #  define inline  /* nothing */
 178 # endif
 179 #endif
 180
 181 /* These are obsolete.  Do not use.  */
 182 #ifndef IN_GCC
 183 #define CONST           const
 184 #define VOLATILE        volatile
 185 #define SIGNED          signed
 186
 187 #define PROTO(type, name, arglist)      type name arglist
 188 #define EXFUN(name, proto)              name proto
 189 #define DEFUN(name, arglist, args)      name(args)
 190 #define DEFUN_VOID(name)                name(void)
 191 #define AND             ,
 192 #define DOTS            , ...
 193 #define NOARGS          void
 194 #endif /* ! IN_GCC */
 195
 196 #else   /* Not ANSI C.  */
 197
 198 #undef  ANSI_PROTOTYPES
 199 #define PTR             char *
 200 #define PTRCONST        PTR
 201 #define LONG_DOUBLE     double
 202
 203 #define PARAMS(args)            ()
 204 #define VPARAMS(args)           (va_alist) va_dcl
 205 #define VA_START(va_list, var)  va_start(va_list)
 206
 207 #define VA_OPEN(AP, VAR)                { va_list AP; va_start(AP); { struct Qdmy
 208 #define VA_CLOSE(AP)                    } va_end(AP); }
 209 #define VA_FIXEDARG(AP, TYPE, NAME)     TYPE NAME = va_arg(AP, TYPE)
 210
 211 /* some systems define these in header files for non-ansi mode */
 212 #undef const
 213 #undef volatile
 214 #undef signed
 215 #undef inline
 216 #define const
 217 #define volatile
 218 #define signed
 219 #define inline
 220
 221 #ifndef IN_GCC
 222 #define CONST
 223 #define VOLATILE
 224 #define SIGNED
 225
 226 #define PROTO(type, name, arglist)      type name ()
 227 #define EXFUN(name, proto)              name()
 228 #define DEFUN(name, arglist, args)      name arglist args;
 229 #define DEFUN_VOID(name)                name()
 230 #define AND             ;
 231 #define DOTS
 232 #define NOARGS
 233 #endif /* ! IN_GCC */
 234
 235 #endif  /* ANSI C.  */
 236
 237 /* Define macros for some gcc attributes.  This permits us to use the
 238    macros freely, and know that they will come into play for the
 239    version of gcc in which they are supported.  */
 240
 241 #if (GCC_VERSION < 2007)
 242 # define __attribute__(x)
 243 #endif
 244
 245 /* Attribute __malloc__ on functions was valid as of gcc 2.96. */
 246 #ifndef ATTRIBUTE_MALLOC
 247 # if (GCC_VERSION >= 2096)
 248 #  define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 249 # else
 250 #  define ATTRIBUTE_MALLOC
 251 # endif /* GNUC >= 2.96 */
 252 #endif /* ATTRIBUTE_MALLOC */
 253
 254 /* Attributes on labels were valid as of gcc 2.93. */
 255 #ifndef ATTRIBUTE_UNUSED_LABEL
 256 # if (GCC_VERSION >= 2093)
 257 #  define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED
 258 # else
 259 #  define ATTRIBUTE_UNUSED_LABEL
 260 # endif /* GNUC >= 2.93 */
 261 #endif /* ATTRIBUTE_UNUSED_LABEL */
 262
 263 #ifndef ATTRIBUTE_UNUSED
 264 #define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 265 #endif /* ATTRIBUTE_UNUSED */
 266
 267 #ifndef ATTRIBUTE_NORETURN
 268 #define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
 269 #endif /* ATTRIBUTE_NORETURN */
 270
 271 #ifndef ATTRIBUTE_PRINTF
 272 #define ATTRIBUTE_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n)))
 273 #define ATTRIBUTE_PRINTF_1 ATTRIBUTE_PRINTF(1, 2)
 274 #define ATTRIBUTE_PRINTF_2 ATTRIBUTE_PRINTF(2, 3)
 275 #define ATTRIBUTE_PRINTF_3 ATTRIBUTE_PRINTF(3, 4)
 276 #define ATTRIBUTE_PRINTF_4 ATTRIBUTE_PRINTF(4, 5)
 277 #define ATTRIBUTE_PRINTF_5 ATTRIBUTE_PRINTF(5, 6)
 278 #endif /* ATTRIBUTE_PRINTF */
 279
 280 /* We use __extension__ in some places to suppress -pedantic warnings
 281    about GCC extensions.  This feature didn't work properly before
 282    gcc 2.8.  */
 283 #if GCC_VERSION < 2008
 284 #define __extension__
 285 #endif
 286
 287 /* Bootstrap support:  Adjust certain macros defined by Autoconf,
 288    which are only valid for the stage1 compiler.  If we detect
 289    a modern version of GCC, we are probably in stage2 or beyond,
 290    so unconditionally reset the values.  Note that const, inline,
 291    etc. have been dealt with above.  */
 292 #if (GCC_VERSION >= 2007)
 293 # ifndef HAVE_LONG_DOUBLE
 294 #  define HAVE_LONG_DOUBLE 1
 295 # endif
 296 #endif /* GCC >= 2.7 */
 297
 298 #endif  /* ansidecl.h   */