misc/sys/cdefs.h

   1 /* Copyright (C) 1992-2022 Free Software Foundation, Inc.
   2    Copyright The GNU Toolchain Authors.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _SYS_CDEFS_H
  20 #define _SYS_CDEFS_H    1
  21
  22 /* We are almost always included from features.h. */
  23 #ifndef _FEATURES_H
  24 # include <features.h>
  25 #endif
  26
  27 /* The GNU libc does not support any K&R compilers or the traditional mode
  28    of ISO C compilers anymore.  Check for some of the combinations not
  29    supported anymore.  */
  30 #if defined __GNUC__ && !defined __STDC__ && !defined __cplusplus
  31 # error "You need a ISO C or C++ conforming compiler to use the glibc headers"
  32 #endif
  33
  34 /* Some user header file might have defined this before.  */
  35 #undef  __P
  36 #undef  __PMT
  37
  38 /* Compilers that lack __has_attribute may object to
  39        #if defined __has_attribute && __has_attribute (...)
  40    even though they do not need to evaluate the right-hand side of the &&.
  41    Similarly for __has_builtin, etc.  */
  42 #if (defined __has_attribute \
  43      && (!defined __clang_minor__ \
  44          || 3 < __clang_major__ + (5 <= __clang_minor__)))
  45 # define __glibc_has_attribute(attr) __has_attribute (attr)
  46 #else
  47 # define __glibc_has_attribute(attr) 0
  48 #endif
  49 #ifdef __has_builtin
  50 # define __glibc_has_builtin(name) __has_builtin (name)
  51 #else
  52 # define __glibc_has_builtin(name) 0
  53 #endif
  54 #ifdef __has_extension
  55 # define __glibc_has_extension(ext) __has_extension (ext)
  56 #else
  57 # define __glibc_has_extension(ext) 0
  58 #endif
  59
  60 #if defined __GNUC__ || defined __clang__
  61
  62 /* All functions, except those with callbacks or those that
  63    synchronize memory, are leaf functions.  */
  64 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  65 #  define __LEAF , __leaf__
  66 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  67 # else
  68 #  define __LEAF
  69 #  define __LEAF_ATTR
  70 # endif
  71
  72 /* GCC can always grok prototypes.  For C++ programs we add throw()
  73    to help it optimize the function calls.  But this only works with
  74    gcc 2.8.x and egcs.  For gcc 3.4 and up we even mark C functions
  75    as non-throwing using a function attribute since programs can use
  76    the -fexceptions options for C code as well.  */
  77 # if !defined __cplusplus \
  78      && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
  79 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  80 #  define __THROWNL     __attribute__ ((__nothrow__))
  81 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  82 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  83 # else
  84 #  if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
  85 #   if __cplusplus >= 201103L
  86 #    define __THROW     noexcept (true)
  87 #   else
  88 #    define __THROW     throw ()
  89 #   endif
  90 #   define __THROWNL    __THROW
  91 #   define __NTH(fct)   __LEAF_ATTR fct __THROW
  92 #   define __NTHNL(fct) fct __THROW
  93 #  else
  94 #   define __THROW
  95 #   define __THROWNL
  96 #   define __NTH(fct)   fct
  97 #   define __NTHNL(fct) fct
  98 #  endif
  99 # endif
 100
 101 #else   /* Not GCC or clang.  */
 102
 103 # if (defined __cplusplus                                               \
 104       || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 105 #  define __inline      inline
 106 # else
 107 #  define __inline              /* No inline functions.  */
 108 # endif
 109
 110 # define __THROW
 111 # define __THROWNL
 112 # define __NTH(fct)     fct
 113
 114 #endif  /* GCC || clang.  */
 115
 116 /* These two macros are not used in glibc anymore.  They are kept here
 117    only because some other projects expect the macros to be defined.  */
 118 #define __P(args)       args
 119 #define __PMT(args)     args
 120
 121 /* For these things, GCC behaves the ANSI way normally,
 122    and the non-ANSI way under -traditional.  */
 123
 124 #define __CONCAT(x,y)   x ## y
 125 #define __STRING(x)     #x
 126
 127 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 128 #define __ptr_t void *
 129
 130
 131 /* C++ needs to know that types and declarations are C, not C++.  */
 132 #ifdef  __cplusplus
 133 # define __BEGIN_DECLS  extern "C" {
 134 # define __END_DECLS    }
 135 #else
 136 # define __BEGIN_DECLS
 137 # define __END_DECLS
 138 #endif
 139
 140
 141 /* Fortify support.  */
 142 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 143 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 144
 145 /* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available.  */
 146 #if __USE_FORTIFY_LEVEL == 3 && (__glibc_clang_prereq (9, 0)                  \
 147                                  || __GNUC_PREREQ (12, 0))
 148 # define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
 149 # define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
 150 #else
 151 # define __glibc_objsize0(__o) __bos0 (__o)
 152 # define __glibc_objsize(__o) __bos (__o)
 153 #endif
 154
 155 /* Compile time conditions to choose between the regular, _chk and _chk_warn
 156    variants.  These conditions should get evaluated to constant and optimized
 157    away.  */
 158
 159 #define __glibc_safe_len_cond(__l, __s, __osz) ((__l) <= (__osz) / (__s))
 160 #define __glibc_unsigned_or_positive(__l) \
 161   ((__typeof (__l)) 0 < (__typeof (__l)) -1                                   \
 162    || (__builtin_constant_p (__l) && (__l) > 0))
 163
 164 /* Length is known to be safe at compile time if the __L * __S <= __OBJSZ
 165    condition can be folded to a constant and if it is true, or unknown (-1) */
 166 #define __glibc_safe_or_unknown_len(__l, __s, __osz) \
 167   ((__builtin_constant_p (__osz) && (__osz) == (__SIZE_TYPE__) -1)            \
 168    || (__glibc_unsigned_or_positive (__l)                                     \
 169        && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), \
 170                                                        (__s), (__osz)))       \
 171        && __glibc_safe_len_cond ((__SIZE_TYPE__) (__l), (__s), (__osz))))
 172
 173 /* Conversely, we know at compile time that the length is unsafe if the
 174    __L * __S <= __OBJSZ condition can be folded to a constant and if it is
 175    false.  */
 176 #define __glibc_unsafe_len(__l, __s, __osz) \
 177   (__glibc_unsigned_or_positive (__l)                                         \
 178    && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l),     \
 179                                                    __s, __osz))               \
 180    && !__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), __s, __osz))
 181
 182 /* Fortify function f.  __f_alias, __f_chk and __f_chk_warn must be
 183    declared.  */
 184
 185 #define __glibc_fortify(f, __l, __s, __osz, ...) \
 186   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 187    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 188    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 189       ? __ ## f ## _chk_warn (__VA_ARGS__, __osz)                             \
 190       : __ ## f ## _chk (__VA_ARGS__, __osz)))                        \
 191
 192 /* Fortify function f, where object size argument passed to f is the number of
 193    elements and not total size.  */
 194
 195 #define __glibc_fortify_n(f, __l, __s, __osz, ...) \
 196   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 197    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 198    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 199       ? __ ## f ## _chk_warn (__VA_ARGS__, (__osz) / (__s))                   \
 200       : __ ## f ## _chk (__VA_ARGS__, (__osz) / (__s))))                      \
 201
 202 #if __GNUC_PREREQ (4,3)
 203 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 204 # define __errordecl(name, msg) \
 205   extern void name (void) __attribute__((__error__ (msg)))
 206 #else
 207 # define __warnattr(msg)
 208 # define __errordecl(name, msg) extern void name (void)
 209 #endif
 210
 211 /* Support for flexible arrays.
 212    Headers that should use flexible arrays only if they're "real"
 213    (e.g. only if they won't affect sizeof()) should test
 214    #if __glibc_c99_flexarr_available.  */
 215 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
 216 # define __flexarr      []
 217 # define __glibc_c99_flexarr_available 1
 218 #elif __GNUC_PREREQ (2,97) || defined __clang__
 219 /* GCC 2.97 and clang support C99 flexible array members as an extension,
 220    even when in C89 mode or compiling C++ (any version).  */
 221 # define __flexarr      []
 222 # define __glibc_c99_flexarr_available 1
 223 #elif defined __GNUC__
 224 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 225    an equivalent extension with slightly different notation.  */
 226 # define __flexarr      [0]
 227 # define __glibc_c99_flexarr_available 1
 228 #else
 229 /* Some other non-C99 compiler.  Approximate with [1].  */
 230 # define __flexarr      [1]
 231 # define __glibc_c99_flexarr_available 0
 232 #endif
 233
 234
 235 /* __asm__ ("xyz") is used throughout the headers to rename functions
 236    at the assembly language level.  This is wrapped by the __REDIRECT
 237    macro, in order to support compilers that can do this some other
 238    way.  When compilers don't support asm-names at all, we have to do
 239    preprocessor tricks instead (which don't have exactly the right
 240    semantics, but it's the best we can do).
 241
 242    Example:
 243    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 244
 245 #if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
 246
 247 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 248 # ifdef __cplusplus
 249 #  define __REDIRECT_NTH(name, proto, alias) \
 250      name proto __THROW __asm__ (__ASMNAME (#alias))
 251 #  define __REDIRECT_NTHNL(name, proto, alias) \
 252      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 253 # else
 254 #  define __REDIRECT_NTH(name, proto, alias) \
 255      name proto __asm__ (__ASMNAME (#alias)) __THROW
 256 #  define __REDIRECT_NTHNL(name, proto, alias) \
 257      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 258 # endif
 259 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 260 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 261
 262 /*
 263 #elif __SOME_OTHER_COMPILER__
 264
 265 # define __REDIRECT(name, proto, alias) name proto; \
 266         _Pragma("let " #name " = " #alias)
 267 */
 268 #endif
 269
 270 /* GCC and clang have various useful declarations that can be made with
 271    the '__attribute__' syntax.  All of the ways we use this do fine if
 272    they are omitted for compilers that don't understand it.  */
 273 #if !(defined __GNUC__ || defined __clang__)
 274 # define __attribute__(xyz)     /* Ignore */
 275 #endif
 276
 277 /* At some point during the gcc 2.96 development the `malloc' attribute
 278    for functions was introduced.  We don't want to use it unconditionally
 279    (although this would be possible) since it generates warnings.  */
 280 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
 281 # define __attribute_malloc__ __attribute__ ((__malloc__))
 282 #else
 283 # define __attribute_malloc__ /* Ignore */
 284 #endif
 285
 286 /* Tell the compiler which arguments to an allocation function
 287    indicate the size of the allocation.  */
 288 #if __GNUC_PREREQ (4, 3)
 289 # define __attribute_alloc_size__(params) \
 290   __attribute__ ((__alloc_size__ params))
 291 #else
 292 # define __attribute_alloc_size__(params) /* Ignore.  */
 293 #endif
 294
 295 /* Tell the compiler which argument to an allocation function
 296    indicates the alignment of the allocation.  */
 297 #if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__alloc_align__)
 298 # define __attribute_alloc_align__(param) \
 299   __attribute__ ((__alloc_align__ param))
 300 #else
 301 # define __attribute_alloc_align__(param) /* Ignore.  */
 302 #endif
 303
 304 /* At some point during the gcc 2.96 development the `pure' attribute
 305    for functions was introduced.  We don't want to use it unconditionally
 306    (although this would be possible) since it generates warnings.  */
 307 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
 308 # define __attribute_pure__ __attribute__ ((__pure__))
 309 #else
 310 # define __attribute_pure__ /* Ignore */
 311 #endif
 312
 313 /* This declaration tells the compiler that the value is constant.  */
 314 #if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
 315 # define __attribute_const__ __attribute__ ((__const__))
 316 #else
 317 # define __attribute_const__ /* Ignore */
 318 #endif
 319
 320 #if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
 321 # define __attribute_maybe_unused__ __attribute__ ((__unused__))
 322 #else
 323 # define __attribute_maybe_unused__ /* Ignore */
 324 #endif
 325
 326 /* At some point during the gcc 3.1 development the `used' attribute
 327    for functions was introduced.  We don't want to use it unconditionally
 328    (although this would be possible) since it generates warnings.  */
 329 #if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
 330 # define __attribute_used__ __attribute__ ((__used__))
 331 # define __attribute_noinline__ __attribute__ ((__noinline__))
 332 #else
 333 # define __attribute_used__ __attribute__ ((__unused__))
 334 # define __attribute_noinline__ /* Ignore */
 335 #endif
 336
 337 /* Since version 3.2, gcc allows marking deprecated functions.  */
 338 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
 339 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 340 #else
 341 # define __attribute_deprecated__ /* Ignore */
 342 #endif
 343
 344 /* Since version 4.5, gcc also allows one to specify the message printed
 345    when a deprecated function is used.  clang claims to be gcc 4.2, but
 346    may also support this feature.  */
 347 #if __GNUC_PREREQ (4,5) \
 348     || __glibc_has_extension (__attribute_deprecated_with_message__)
 349 # define __attribute_deprecated_msg__(msg) \
 350          __attribute__ ((__deprecated__ (msg)))
 351 #else
 352 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 353 #endif
 354
 355 /* At some point during the gcc 2.8 development the `format_arg' attribute
 356    for functions was introduced.  We don't want to use it unconditionally
 357    (although this would be possible) since it generates warnings.
 358    If several `format_arg' attributes are given for the same function, in
 359    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 360    all designated arguments are considered.  */
 361 #if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
 362 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 363 #else
 364 # define __attribute_format_arg__(x) /* Ignore */
 365 #endif
 366
 367 /* At some point during the gcc 2.97 development the `strfmon' format
 368    attribute for functions was introduced.  We don't want to use it
 369    unconditionally (although this would be possible) since it
 370    generates warnings.  */
 371 #if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
 372 # define __attribute_format_strfmon__(a,b) \
 373   __attribute__ ((__format__ (__strfmon__, a, b)))
 374 #else
 375 # define __attribute_format_strfmon__(a,b) /* Ignore */
 376 #endif
 377
 378 /* The nonnull function attribute marks pointer parameters that
 379    must not be NULL.  This has the name __nonnull in glibc,
 380    and __attribute_nonnull__ in files shared with Gnulib to avoid
 381    collision with a different __nonnull in DragonFlyBSD 5.9.  */
 382 #ifndef __attribute_nonnull__
 383 # if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
 384 #  define __attribute_nonnull__(params) __attribute__ ((__nonnull__ params))
 385 # else
 386 #  define __attribute_nonnull__(params)
 387 # endif
 388 #endif
 389 #ifndef __nonnull
 390 # define __nonnull(params) __attribute_nonnull__ (params)
 391 #endif
 392
 393 /* The returns_nonnull function attribute marks the return type of the function
 394    as always being non-null.  */
 395 #ifndef __returns_nonnull
 396 # if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
 397 # define __returns_nonnull __attribute__ ((__returns_nonnull__))
 398 # else
 399 # define __returns_nonnull
 400 # endif
 401 #endif
 402
 403 /* If fortification mode, we warn about unused results of certain
 404    function calls which can lead to problems.  */
 405 #if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
 406 # define __attribute_warn_unused_result__ \
 407    __attribute__ ((__warn_unused_result__))
 408 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
 409 #  define __wur __attribute_warn_unused_result__
 410 # endif
 411 #else
 412 # define __attribute_warn_unused_result__ /* empty */
 413 #endif
 414 #ifndef __wur
 415 # define __wur /* Ignore */
 416 #endif
 417
 418 /* Forces a function to be always inlined.  */
 419 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
 420 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 421    it conflicts with this definition.  Therefore undefine it first to
 422    allow either header to be included first.  */
 423 # undef __always_inline
 424 # define __always_inline __inline __attribute__ ((__always_inline__))
 425 #else
 426 # undef __always_inline
 427 # define __always_inline __inline
 428 #endif
 429
 430 /* Associate error messages with the source location of the call site rather
 431    than with the source location inside the function.  */
 432 #if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
 433 # define __attribute_artificial__ __attribute__ ((__artificial__))
 434 #else
 435 # define __attribute_artificial__ /* Ignore */
 436 #endif
 437
 438 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 439    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 440    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 441    older than 4.3 may define these macros and still not guarantee GNU inlining
 442    semantics.
 443
 444    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 445    semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
 446    __GNUC_GNU_INLINE__ macro definitions.  */
 447 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 448      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 449                                || defined __GNUC_GNU_INLINE__)))
 450 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 451 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 452 #  define __extern_always_inline \
 453   extern __always_inline __attribute__ ((__gnu_inline__))
 454 # else
 455 #  define __extern_inline extern __inline
 456 #  define __extern_always_inline extern __always_inline
 457 # endif
 458 #endif
 459
 460 #ifdef __extern_always_inline
 461 # define __fortify_function __extern_always_inline __attribute_artificial__
 462 #endif
 463
 464 /* GCC 4.3 and above allow passing all anonymous arguments of an
 465    __extern_always_inline function to some other vararg function.  */
 466 #if __GNUC_PREREQ (4,3)
 467 # define __va_arg_pack() __builtin_va_arg_pack ()
 468 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 469 #endif
 470
 471 /* It is possible to compile containing GCC extensions even if GCC is
 472    run in pedantic mode if the uses are carefully marked using the
 473    `__extension__' keyword.  But this is not generally available before
 474    version 2.8.  */
 475 #if !(__GNUC_PREREQ (2,8) || defined __clang__)
 476 # define __extension__          /* Ignore */
 477 #endif
 478
 479 /* __restrict is known in EGCS 1.2 and above, and in clang.
 480    It works also in C++ mode (outside of arrays), but only when spelled
 481    as '__restrict', not 'restrict'.  */
 482 #if !(__GNUC_PREREQ (2,92) || __clang_major__ >= 3)
 483 # if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 484 #  define __restrict    restrict
 485 # else
 486 #  define __restrict    /* Ignore */
 487 # endif
 488 #endif
 489
 490 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 491      array_name[restrict]
 492    GCC 3.1 and clang support this.
 493    This syntax is not usable in C++ mode.  */
 494 #if (__GNUC_PREREQ (3,1) || __clang_major__ >= 3) && !defined __cplusplus
 495 # define __restrict_arr __restrict
 496 #else
 497 # ifdef __GNUC__
 498 #  define __restrict_arr        /* Not supported in old GCC.  */
 499 # else
 500 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 501 #   define __restrict_arr       restrict
 502 #  else
 503 /* Some other non-C99 compiler.  */
 504 #   define __restrict_arr       /* Not supported.  */
 505 #  endif
 506 # endif
 507 #endif
 508
 509 #if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
 510 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 511 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 512 #else
 513 # define __glibc_unlikely(cond) (cond)
 514 # define __glibc_likely(cond)   (cond)
 515 #endif
 516
 517 #if (!defined _Noreturn \
 518      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 519      &&  !(__GNUC_PREREQ (4,7) \
 520            || (3 < __clang_major__ + (5 <= __clang_minor__))))
 521 # if __GNUC_PREREQ (2,8)
 522 #  define _Noreturn __attribute__ ((__noreturn__))
 523 # else
 524 #  define _Noreturn
 525 # endif
 526 #endif
 527
 528 #if __GNUC_PREREQ (8, 0)
 529 /* Describes a char array whose address can safely be passed as the first
 530    argument to strncpy and strncat, as the char array is not necessarily
 531    a NUL-terminated string.  */
 532 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 533 #else
 534 # define __attribute_nonstring__
 535 #endif
 536
 537 /* Undefine (also defined in libc-symbols.h).  */
 538 #undef __attribute_copy__
 539 #if __GNUC_PREREQ (9, 0)
 540 /* Copies attributes from the declaration or type referenced by
 541    the argument.  */
 542 # define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
 543 #else
 544 # define __attribute_copy__(arg)
 545 #endif
 546
 547 #if (!defined _Static_assert && !defined __cplusplus \
 548      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 549      && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
 550          || defined __STRICT_ANSI__))
 551 # define _Static_assert(expr, diagnostic) \
 552     extern int (*__Static_assert_function (void)) \
 553       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 554 #endif
 555
 556 /* Gnulib avoids including these, as they don't work on non-glibc or
 557    older glibc platforms.  */
 558 #ifndef __GNULIB_CDEFS
 559 # include <bits/wordsize.h>
 560 # include <bits/long-double.h>
 561 #endif
 562
 563 #if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
 564 # ifdef __REDIRECT
 565
 566 /* Alias name defined automatically.  */
 567 #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
 568 #  define __LDBL_REDIR_DECL(name) \
 569   extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
 570
 571 /* Alias name defined automatically, with leading underscores.  */
 572 #  define __LDBL_REDIR2_DECL(name) \
 573   extern __typeof (__##name) __##name \
 574     __asm (__ASMNAME ("__" #name "ieee128"));
 575
 576 /* Alias name defined manually.  */
 577 #  define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
 578 #  define __LDBL_REDIR1_DECL(name, alias) \
 579   extern __typeof (name) name __asm (__ASMNAME (#alias));
 580
 581 #  define __LDBL_REDIR1_NTH(name, proto, alias) \
 582   __REDIRECT_NTH (name, proto, alias)
 583 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 584   __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
 585
 586 /* Unused.  */
 587 #  define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
 588 #  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
 589
 590 # else
 591 _Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
 592 # endif
 593 #elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 594 # define __LDBL_COMPAT 1
 595 # ifdef __REDIRECT
 596 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 597 #  define __LDBL_REDIR(name, proto) \
 598   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 599 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 600 #  define __LDBL_REDIR_NTH(name, proto) \
 601   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 602 #  define __LDBL_REDIR2_DECL(name) \
 603   extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
 604 #  define __LDBL_REDIR1_DECL(name, alias) \
 605   extern __typeof (name) name __asm (__ASMNAME (#alias));
 606 #  define __LDBL_REDIR_DECL(name) \
 607   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 608 #  define __REDIRECT_LDBL(name, proto, alias) \
 609   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 610 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 611   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 612 # endif
 613 #endif
 614 #if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
 615     || !defined __REDIRECT
 616 # define __LDBL_REDIR1(name, proto, alias) name proto
 617 # define __LDBL_REDIR(name, proto) name proto
 618 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 619 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 620 # define __LDBL_REDIR2_DECL(name)
 621 # define __LDBL_REDIR_DECL(name)
 622 # ifdef __REDIRECT
 623 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 624 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 625   __REDIRECT_NTH (name, proto, alias)
 626 # endif
 627 #endif
 628
 629 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 630    intended for use in preprocessor macros.
 631
 632    Note: MESSAGE must be a _single_ string; concatenation of string
 633    literals is not supported.  */
 634 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 635 # define __glibc_macro_warning1(message) _Pragma (#message)
 636 # define __glibc_macro_warning(message) \
 637   __glibc_macro_warning1 (GCC warning message)
 638 #else
 639 # define __glibc_macro_warning(msg)
 640 #endif
 641
 642 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 643    since version 4.9.  Previous versions do not provide generic
 644    selection, even though they might set __STDC_VERSION__ to 201112L,
 645    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 646    when testing __STDC_VERSION__ for generic selection support.
 647    On the other hand, Clang also defines __GNUC__, so a clang-specific
 648    check is required to enable the use of generic selection.  */
 649 #if !defined __cplusplus \
 650     && (__GNUC_PREREQ (4, 9) \
 651         || __glibc_has_extension (c_generic_selections) \
 652         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 653             && __STDC_VERSION__ >= 201112L))
 654 # define __HAVE_GENERIC_SELECTION 1
 655 #else
 656 # define __HAVE_GENERIC_SELECTION 0
 657 #endif
 658
 659 #if __GNUC_PREREQ (10, 0)
 660 /* Designates a 1-based positional argument ref-index of pointer type
 661    that can be used to access size-index elements of the pointed-to
 662    array according to access mode, or at least one element when
 663    size-index is not provided:
 664      access (access-mode, <ref-index> [, <size-index>])  */
 665 #  define __attr_access(x) __attribute__ ((__access__ x))
 666 /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may
 667    use the access attribute to get object sizes from function definition
 668    arguments, so we can't use them on functions we fortify.  Drop the object
 669    size hints for such functions.  */
 670 #  if __USE_FORTIFY_LEVEL == 3
 671 #    define __fortified_attr_access(a, o, s) __attribute__ ((__access__ (a, o)))
 672 #  else
 673 #    define __fortified_attr_access(a, o, s) __attr_access ((a, o, s))
 674 #  endif
 675 #  if __GNUC_PREREQ (11, 0)
 676 #    define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
 677 #  else
 678 #    define __attr_access_none(argno)
 679 #  endif
 680 #else
 681 #  define __fortified_attr_access(a, o, s)
 682 #  define __attr_access(x)
 683 #  define __attr_access_none(argno)
 684 #endif
 685
 686 #if __GNUC_PREREQ (11, 0)
 687 /* Designates dealloc as a function to call to deallocate objects
 688    allocated by the declared function.  */
 689 # define __attr_dealloc(dealloc, argno) \
 690     __attribute__ ((__malloc__ (dealloc, argno)))
 691 # define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
 692 #else
 693 # define __attr_dealloc(dealloc, argno)
 694 # define __attr_dealloc_free
 695 #endif
 696
 697 /* Specify that a function such as setjmp or vfork may return
 698    twice.  */
 699 #if __GNUC_PREREQ (4, 1)
 700 # define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
 701 #else
 702 # define __attribute_returns_twice__ /* Ignore.  */
 703 #endif
 704
 705 #endif   /* sys/cdefs.h */