include/ansidecl.h

   1 /* ANSI and traditional C compatability macros
   2    Copyright (C) 1991-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation; either version 2 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /* ANSI and traditional C compatibility macros
  20
  21    ANSI C is assumed if __STDC__ is #defined.
  22
  23    Macro                ANSI C definition       Traditional C definition
  24    -----                ---- - ----------       ----------- - ----------
  25    PTR                  `void *'                `char *'
  26    const                not defined             `'
  27    volatile             not defined             `'
  28    signed               not defined             `'
  29
  30    For ease of writing code which uses GCC extensions but needs to be
  31    portable to other compilers, we provide the GCC_VERSION macro that
  32    simplifies testing __GNUC__ and __GNUC_MINOR__ together, and various
  33    wrappers around __attribute__.  Also, __extension__ will be #defined
  34    to nothing if it doesn't work.  See below.  */
  35
  36 #ifndef _ANSIDECL_H
  37 #define _ANSIDECL_H     1
  38
  39 #ifdef __cplusplus
  40 extern "C" {
  41 #endif
  42
  43 /* Every source file includes this file,
  44    so they will all get the switch for lint.  */
  45 /* LINTLIBRARY */
  46
  47 /* Using MACRO(x,y) in cpp #if conditionals does not work with some
  48    older preprocessors.  Thus we can't define something like this:
  49
  50 #define HAVE_GCC_VERSION(MAJOR, MINOR) \
  51   (__GNUC__ > (MAJOR) || (__GNUC__ == (MAJOR) && __GNUC_MINOR__ >= (MINOR)))
  52
  53 and then test "#if HAVE_GCC_VERSION(2,7)".
  54
  55 So instead we use the macro below and test it against specific values.  */
  56
  57 /* This macro simplifies testing whether we are using gcc, and if it
  58    is of a particular minimum version. (Both major & minor numbers are
  59    significant.)  This macro will evaluate to 0 if we are not using
  60    gcc at all.  */
  61 #ifndef GCC_VERSION
  62 #define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
  63 #endif /* GCC_VERSION */
  64
  65 #if defined (__STDC__) || defined(__cplusplus) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(_WIN32)
  66 /* All known AIX compilers implement these things (but don't always
  67    define __STDC__).  The RISC/OS MIPS compiler defines these things
  68    in SVR4 mode, but does not define __STDC__.  */
  69 /* eraxxon@alumni.rice.edu: The Compaq C++ compiler, unlike many other
  70    C++ compilers, does not define __STDC__, though it acts as if this
  71    was so. (Verified versions: 5.7, 6.2, 6.3, 6.5) */
  72
  73 #define PTR             void *
  74
  75 #undef const
  76 #undef volatile
  77 #undef signed
  78
  79 /* inline requires special treatment; it's in C99, and GCC >=2.7 supports
  80    it too, but it's not in C89.  */
  81 #undef inline
  82 #if __STDC_VERSION__ >= 199901L || defined(__cplusplus) || (defined(__SUNPRO_C) && defined(__C99FEATURES__))
  83 /* it's a keyword */
  84 #else
  85 # if GCC_VERSION >= 2007
  86 #  define inline __inline__   /* __inline__ prevents -pedantic warnings */
  87 # else
  88 #  define inline  /* nothing */
  89 # endif
  90 #endif
  91
  92 #else   /* Not ANSI C.  */
  93
  94 #define PTR             char *
  95
  96 /* some systems define these in header files for non-ansi mode */
  97 #undef const
  98 #undef volatile
  99 #undef signed
 100 #undef inline
 101 #define const
 102 #define volatile
 103 #define signed
 104 #define inline
 105
 106 #endif  /* ANSI C.  */
 107
 108 /* Define macros for some gcc attributes.  This permits us to use the
 109    macros freely, and know that they will come into play for the
 110    version of gcc in which they are supported.  */
 111
 112 #if (GCC_VERSION < 2007)
 113 # define __attribute__(x)
 114 #endif
 115
 116 /* Attribute __malloc__ on functions was valid as of gcc 2.96. */
 117 #ifndef ATTRIBUTE_MALLOC
 118 # if (GCC_VERSION >= 2096)
 119 #  define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 120 # else
 121 #  define ATTRIBUTE_MALLOC
 122 # endif /* GNUC >= 2.96 */
 123 #endif /* ATTRIBUTE_MALLOC */
 124
 125 /* Attributes on labels were valid as of gcc 2.93 and g++ 4.5.  For
 126    g++ an attribute on a label must be followed by a semicolon.  */
 127 #ifndef ATTRIBUTE_UNUSED_LABEL
 128 # ifndef __cplusplus
 129 #  if GCC_VERSION >= 2093
 130 #   define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED
 131 #  else
 132 #   define ATTRIBUTE_UNUSED_LABEL
 133 #  endif
 134 # else
 135 #  if GCC_VERSION >= 4005
 136 #   define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED ;
 137 #  else
 138 #   define ATTRIBUTE_UNUSED_LABEL
 139 #  endif
 140 # endif
 141 #endif
 142
 143 /* Similarly to ARG_UNUSED below.  Prior to GCC 3.4, the C++ frontend
 144    couldn't parse attributes placed after the identifier name, and now
 145    the entire compiler is built with C++.  */
 146 #ifndef ATTRIBUTE_UNUSED
 147 #if GCC_VERSION >= 3004
 148 #  define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 149 #else
 150 #define ATTRIBUTE_UNUSED
 151 #endif
 152 #endif /* ATTRIBUTE_UNUSED */
 153
 154 /* Before GCC 3.4, the C++ frontend couldn't parse attributes placed after the
 155    identifier name.  */
 156 #if ! defined(__cplusplus) || (GCC_VERSION >= 3004)
 157 # define ARG_UNUSED(NAME) NAME ATTRIBUTE_UNUSED
 158 #else /* !__cplusplus || GNUC >= 3.4 */
 159 # define ARG_UNUSED(NAME) NAME
 160 #endif /* !__cplusplus || GNUC >= 3.4 */
 161
 162 #ifndef ATTRIBUTE_NORETURN
 163 #define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
 164 #endif /* ATTRIBUTE_NORETURN */
 165
 166 /* Attribute `nonnull' was valid as of gcc 3.3.  */
 167 #ifndef ATTRIBUTE_NONNULL
 168 # if (GCC_VERSION >= 3003)
 169 #  define ATTRIBUTE_NONNULL(m) __attribute__ ((__nonnull__ (m)))
 170 # else
 171 #  define ATTRIBUTE_NONNULL(m)
 172 # endif /* GNUC >= 3.3 */
 173 #endif /* ATTRIBUTE_NONNULL */
 174
 175 /* Attribute `returns_nonnull' was valid as of gcc 4.9.  */
 176 #ifndef ATTRIBUTE_RETURNS_NONNULL
 177 # if (GCC_VERSION >= 4009)
 178 #  define ATTRIBUTE_RETURNS_NONNULL __attribute__ ((__returns_nonnull__))
 179 # else
 180 #  define ATTRIBUTE_RETURNS_NONNULL
 181 # endif /* GNUC >= 4.9 */
 182 #endif /* ATTRIBUTE_RETURNS_NONNULL */
 183
 184 /* Attribute `pure' was valid as of gcc 3.0.  */
 185 #ifndef ATTRIBUTE_PURE
 186 # if (GCC_VERSION >= 3000)
 187 #  define ATTRIBUTE_PURE __attribute__ ((__pure__))
 188 # else
 189 #  define ATTRIBUTE_PURE
 190 # endif /* GNUC >= 3.0 */
 191 #endif /* ATTRIBUTE_PURE */
 192
 193 /* Use ATTRIBUTE_PRINTF when the format specifier must not be NULL.
 194    This was the case for the `printf' format attribute by itself
 195    before GCC 3.3, but as of 3.3 we need to add the `nonnull'
 196    attribute to retain this behavior.  */
 197 #ifndef ATTRIBUTE_PRINTF
 198 #define ATTRIBUTE_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n))) ATTRIBUTE_NONNULL(m)
 199 #define ATTRIBUTE_PRINTF_1 ATTRIBUTE_PRINTF(1, 2)
 200 #define ATTRIBUTE_PRINTF_2 ATTRIBUTE_PRINTF(2, 3)
 201 #define ATTRIBUTE_PRINTF_3 ATTRIBUTE_PRINTF(3, 4)
 202 #define ATTRIBUTE_PRINTF_4 ATTRIBUTE_PRINTF(4, 5)
 203 #define ATTRIBUTE_PRINTF_5 ATTRIBUTE_PRINTF(5, 6)
 204 #endif /* ATTRIBUTE_PRINTF */
 205
 206 /* Use ATTRIBUTE_FPTR_PRINTF when the format attribute is to be set on
 207    a function pointer.  Format attributes were allowed on function
 208    pointers as of gcc 3.1.  */
 209 #ifndef ATTRIBUTE_FPTR_PRINTF
 210 # if (GCC_VERSION >= 3001)
 211 #  define ATTRIBUTE_FPTR_PRINTF(m, n) ATTRIBUTE_PRINTF(m, n)
 212 # else
 213 #  define ATTRIBUTE_FPTR_PRINTF(m, n)
 214 # endif /* GNUC >= 3.1 */
 215 # define ATTRIBUTE_FPTR_PRINTF_1 ATTRIBUTE_FPTR_PRINTF(1, 2)
 216 # define ATTRIBUTE_FPTR_PRINTF_2 ATTRIBUTE_FPTR_PRINTF(2, 3)
 217 # define ATTRIBUTE_FPTR_PRINTF_3 ATTRIBUTE_FPTR_PRINTF(3, 4)
 218 # define ATTRIBUTE_FPTR_PRINTF_4 ATTRIBUTE_FPTR_PRINTF(4, 5)
 219 # define ATTRIBUTE_FPTR_PRINTF_5 ATTRIBUTE_FPTR_PRINTF(5, 6)
 220 #endif /* ATTRIBUTE_FPTR_PRINTF */
 221
 222 /* Use ATTRIBUTE_NULL_PRINTF when the format specifier may be NULL.  A
 223    NULL format specifier was allowed as of gcc 3.3.  */
 224 #ifndef ATTRIBUTE_NULL_PRINTF
 225 # if (GCC_VERSION >= 3003)
 226 #  define ATTRIBUTE_NULL_PRINTF(m, n) __attribute__ ((__format__ (__printf__, m, n)))
 227 # else
 228 #  define ATTRIBUTE_NULL_PRINTF(m, n)
 229 # endif /* GNUC >= 3.3 */
 230 # define ATTRIBUTE_NULL_PRINTF_1 ATTRIBUTE_NULL_PRINTF(1, 2)
 231 # define ATTRIBUTE_NULL_PRINTF_2 ATTRIBUTE_NULL_PRINTF(2, 3)
 232 # define ATTRIBUTE_NULL_PRINTF_3 ATTRIBUTE_NULL_PRINTF(3, 4)
 233 # define ATTRIBUTE_NULL_PRINTF_4 ATTRIBUTE_NULL_PRINTF(4, 5)
 234 # define ATTRIBUTE_NULL_PRINTF_5 ATTRIBUTE_NULL_PRINTF(5, 6)
 235 #endif /* ATTRIBUTE_NULL_PRINTF */
 236
 237 /* Attribute `sentinel' was valid as of gcc 3.5.  */
 238 #ifndef ATTRIBUTE_SENTINEL
 239 # if (GCC_VERSION >= 3005)
 240 #  define ATTRIBUTE_SENTINEL __attribute__ ((__sentinel__))
 241 # else
 242 #  define ATTRIBUTE_SENTINEL
 243 # endif /* GNUC >= 3.5 */
 244 #endif /* ATTRIBUTE_SENTINEL */
 245
 246
 247 #ifndef ATTRIBUTE_ALIGNED_ALIGNOF
 248 # if (GCC_VERSION >= 3000)
 249 #  define ATTRIBUTE_ALIGNED_ALIGNOF(m) __attribute__ ((__aligned__ (__alignof__ (m))))
 250 # else
 251 #  define ATTRIBUTE_ALIGNED_ALIGNOF(m)
 252 # endif /* GNUC >= 3.0 */
 253 #endif /* ATTRIBUTE_ALIGNED_ALIGNOF */
 254
 255 /* Useful for structures whose layout must much some binary specification
 256    regardless of the alignment and padding qualities of the compiler.  */
 257 #ifndef ATTRIBUTE_PACKED
 258 # define ATTRIBUTE_PACKED __attribute__ ((packed))
 259 #endif
 260
 261 /* Attribute `hot' and `cold' was valid as of gcc 4.3.  */
 262 #ifndef ATTRIBUTE_COLD
 263 # if (GCC_VERSION >= 4003)
 264 #  define ATTRIBUTE_COLD __attribute__ ((__cold__))
 265 # else
 266 #  define ATTRIBUTE_COLD
 267 # endif /* GNUC >= 4.3 */
 268 #endif /* ATTRIBUTE_COLD */
 269 #ifndef ATTRIBUTE_HOT
 270 # if (GCC_VERSION >= 4003)
 271 #  define ATTRIBUTE_HOT __attribute__ ((__hot__))
 272 # else
 273 #  define ATTRIBUTE_HOT
 274 # endif /* GNUC >= 4.3 */
 275 #endif /* ATTRIBUTE_HOT */
 276
 277 /* Attribute 'no_sanitize_undefined' was valid as of gcc 4.9.  */
 278 #ifndef ATTRIBUTE_NO_SANITIZE_UNDEFINED
 279 # if (GCC_VERSION >= 4009)
 280 #  define ATTRIBUTE_NO_SANITIZE_UNDEFINED __attribute__ ((no_sanitize_undefined))
 281 # else
 282 #  define ATTRIBUTE_NO_SANITIZE_UNDEFINED
 283 # endif /* GNUC >= 4.9 */
 284 #endif /* ATTRIBUTE_NO_SANITIZE_UNDEFINED */
 285
 286 /* We use __extension__ in some places to suppress -pedantic warnings
 287    about GCC extensions.  This feature didn't work properly before
 288    gcc 2.8.  */
 289 #if GCC_VERSION < 2008
 290 #define __extension__
 291 #endif
 292
 293 /* This is used to declare a const variable which should be visible
 294    outside of the current compilation unit.  Use it as
 295      EXPORTED_CONST int i = 1;
 296    This is because the semantics of const are different in C and C++.
 297    "extern const" is permitted in C but it looks strange, and gcc
 298    warns about it when -Wc++-compat is not used.  */
 299 #ifdef __cplusplus
 300 #define EXPORTED_CONST extern const
 301 #else
 302 #define EXPORTED_CONST const
 303 #endif
 304
 305 /* Be conservative and only use enum bitfields with C++ or GCC.
 306    FIXME: provide a complete autoconf test for buggy enum bitfields.  */
 307
 308 #ifdef __cplusplus
 309 #define ENUM_BITFIELD(TYPE) enum TYPE
 310 #elif (GCC_VERSION > 2000)
 311 #define ENUM_BITFIELD(TYPE) __extension__ enum TYPE
 312 #else
 313 #define ENUM_BITFIELD(TYPE) unsigned int
 314 #endif
 315
 316 /* C++11 adds the ability to add "override" after an implementation of a
 317    virtual function in a subclass, to:
 318      (A) document that this is an override of a virtual function
 319      (B) allow the compiler to issue a warning if it isn't (e.g. a mismatch
 320          of the type signature).
 321
 322    Similarly, it allows us to add a "final" to indicate that no subclass
 323    may subsequently override the vfunc.
 324
 325    Provide OVERRIDE and FINAL as macros, allowing us to get these benefits
 326    when compiling with C++11 support, but without requiring C++11.
 327
 328    For gcc, use "-std=c++11" to enable C++11 support; gcc 6 onwards enables
 329    this by default (actually GNU++14).  */
 330
 331 #if __cplusplus >= 201103
 332 /* C++11 claims to be available: use it.  final/override were only
 333    implemented in 4.7, though.  */
 334 # if GCC_VERSION < 4007
 335 #  define OVERRIDE
 336 #  define FINAL
 337 # else
 338 #  define OVERRIDE override
 339 #  define FINAL final
 340 # endif
 341 #elif GCC_VERSION >= 4007
 342 /* G++ 4.7 supports __final in C++98.  */
 343 # define OVERRIDE
 344 # define FINAL __final
 345 #else
 346 /* No C++11 support; leave the macros empty: */
 347 # define OVERRIDE
 348 # define FINAL
 349 #endif
 350
 351 #ifdef __cplusplus
 352 }
 353 #endif
 354
 355 #endif  /* ansidecl.h   */