gnulib/import/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__
  31 # error "You need a ISO 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          || (defined __apple_build_version__ \
  45              ? 6000000 <= __apple_build_version__ \
  46              : 3 < __clang_major__ + (5 <= __clang_minor__))))
  47 # define __glibc_has_attribute(attr) __has_attribute (attr)
  48 #else
  49 # define __glibc_has_attribute(attr) 0
  50 #endif
  51 #ifdef __has_builtin
  52 # define __glibc_has_builtin(name) __has_builtin (name)
  53 #else
  54 # define __glibc_has_builtin(name) 0
  55 #endif
  56 #ifdef __has_extension
  57 # define __glibc_has_extension(ext) __has_extension (ext)
  58 #else
  59 # define __glibc_has_extension(ext) 0
  60 #endif
  61
  62 #if defined __GNUC__ || defined __clang__
  63
  64 /* All functions, except those with callbacks or those that
  65    synchronize memory, are leaf functions.  */
  66 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  67 #  define __LEAF , __leaf__
  68 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  69 # else
  70 #  define __LEAF
  71 #  define __LEAF_ATTR
  72 # endif
  73
  74 /* GCC can always grok prototypes.  For C++ programs we add throw()
  75    to help it optimize the function calls.  But this only works with
  76    gcc 2.8.x and egcs.  For gcc 3.4 and up we even mark C functions
  77    as non-throwing using a function attribute since programs can use
  78    the -fexceptions options for C code as well.  */
  79 # if !defined __cplusplus \
  80      && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
  81 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  82 #  define __THROWNL     __attribute__ ((__nothrow__))
  83 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  84 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  85 # else
  86 #  if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
  87 #   if __cplusplus >= 201103L
  88 #    define __THROW     noexcept (true)
  89 #   else
  90 #    define __THROW     throw ()
  91 #   endif
  92 #   define __THROWNL    __THROW
  93 #   define __NTH(fct)   __LEAF_ATTR fct __THROW
  94 #   define __NTHNL(fct) fct __THROW
  95 #  else
  96 #   define __THROW
  97 #   define __THROWNL
  98 #   define __NTH(fct)   fct
  99 #   define __NTHNL(fct) fct
 100 #  endif
 101 # endif
 102
 103 #else   /* Not GCC or clang.  */
 104
 105 # if (defined __cplusplus                                               \
 106       || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 107 #  define __inline      inline
 108 # else
 109 #  define __inline              /* No inline functions.  */
 110 # endif
 111
 112 # define __THROW
 113 # define __THROWNL
 114 # define __NTH(fct)     fct
 115
 116 #endif  /* GCC || clang.  */
 117
 118 /* These two macros are not used in glibc anymore.  They are kept here
 119    only because some other projects expect the macros to be defined.  */
 120 #define __P(args)       args
 121 #define __PMT(args)     args
 122
 123 /* For these things, GCC behaves the ANSI way normally,
 124    and the non-ANSI way under -traditional.  */
 125
 126 #define __CONCAT(x,y)   x ## y
 127 #define __STRING(x)     #x
 128
 129 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 130 #define __ptr_t void *
 131
 132
 133 /* C++ needs to know that types and declarations are C, not C++.  */
 134 #ifdef  __cplusplus
 135 # define __BEGIN_DECLS  extern "C" {
 136 # define __END_DECLS    }
 137 #else
 138 # define __BEGIN_DECLS
 139 # define __END_DECLS
 140 #endif
 141
 142
 143 /* Fortify support.  */
 144 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 145 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 146
 147 /* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available.  */
 148 #if __USE_FORTIFY_LEVEL == 3 && (__glibc_clang_prereq (9, 0)                  \
 149                                  || __GNUC_PREREQ (12, 0))
 150 # define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
 151 # define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
 152 #else
 153 # define __glibc_objsize0(__o) __bos0 (__o)
 154 # define __glibc_objsize(__o) __bos (__o)
 155 #endif
 156
 157 /* Compile time conditions to choose between the regular, _chk and _chk_warn
 158    variants.  These conditions should get evaluated to constant and optimized
 159    away.  */
 160
 161 #define __glibc_safe_len_cond(__l, __s, __osz) ((__l) <= (__osz) / (__s))
 162 #define __glibc_unsigned_or_positive(__l) \
 163   ((__typeof (__l)) 0 < (__typeof (__l)) -1                                   \
 164    || (__builtin_constant_p (__l) && (__l) > 0))
 165
 166 /* Length is known to be safe at compile time if the __L * __S <= __OBJSZ
 167    condition can be folded to a constant and if it is true.  The -1 check is
 168    redundant because since it implies that __glibc_safe_len_cond is true.  */
 169 #define __glibc_safe_or_unknown_len(__l, __s, __osz) \
 170   (__glibc_unsigned_or_positive (__l)                                         \
 171    && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l),     \
 172                                                    __s, __osz))               \
 173    && __glibc_safe_len_cond ((__SIZE_TYPE__) (__l), __s, __osz))
 174
 175 /* Conversely, we know at compile time that the length is unsafe if the
 176    __L * __S <= __OBJSZ condition can be folded to a constant and if it is
 177    false.  */
 178 #define __glibc_unsafe_len(__l, __s, __osz) \
 179   (__glibc_unsigned_or_positive (__l)                                         \
 180    && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l),     \
 181                                                    __s, __osz))               \
 182    && !__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), __s, __osz))
 183
 184 /* Fortify function f.  __f_alias, __f_chk and __f_chk_warn must be
 185    declared.  */
 186
 187 #define __glibc_fortify(f, __l, __s, __osz, ...) \
 188   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 189    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 190    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 191       ? __ ## f ## _chk_warn (__VA_ARGS__, __osz)                             \
 192       : __ ## f ## _chk (__VA_ARGS__, __osz)))                        \
 193
 194 /* Fortify function f, where object size argument passed to f is the number of
 195    elements and not total size.  */
 196
 197 #define __glibc_fortify_n(f, __l, __s, __osz, ...) \
 198   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 199    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 200    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 201       ? __ ## f ## _chk_warn (__VA_ARGS__, (__osz) / (__s))                   \
 202       : __ ## f ## _chk (__VA_ARGS__, (__osz) / (__s))))                      \
 203
 204 #if __GNUC_PREREQ (4,3)
 205 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 206 # define __errordecl(name, msg) \
 207   extern void name (void) __attribute__((__error__ (msg)))
 208 #else
 209 # define __warnattr(msg)
 210 # define __errordecl(name, msg) extern void name (void)
 211 #endif
 212
 213 /* Support for flexible arrays.
 214    Headers that should use flexible arrays only if they're "real"
 215    (e.g. only if they won't affect sizeof()) should test
 216    #if __glibc_c99_flexarr_available.  */
 217 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
 218 # define __flexarr      []
 219 # define __glibc_c99_flexarr_available 1
 220 #elif __GNUC_PREREQ (2,97) || defined __clang__
 221 /* GCC 2.97 and clang support C99 flexible array members as an extension,
 222    even when in C89 mode or compiling C++ (any version).  */
 223 # define __flexarr      []
 224 # define __glibc_c99_flexarr_available 1
 225 #elif defined __GNUC__
 226 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 227    an equivalent extension with slightly different notation.  */
 228 # define __flexarr      [0]
 229 # define __glibc_c99_flexarr_available 1
 230 #else
 231 /* Some other non-C99 compiler.  Approximate with [1].  */
 232 # define __flexarr      [1]
 233 # define __glibc_c99_flexarr_available 0
 234 #endif
 235
 236
 237 /* __asm__ ("xyz") is used throughout the headers to rename functions
 238    at the assembly language level.  This is wrapped by the __REDIRECT
 239    macro, in order to support compilers that can do this some other
 240    way.  When compilers don't support asm-names at all, we have to do
 241    preprocessor tricks instead (which don't have exactly the right
 242    semantics, but it's the best we can do).
 243
 244    Example:
 245    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 246
 247 #if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
 248
 249 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 250 # ifdef __cplusplus
 251 #  define __REDIRECT_NTH(name, proto, alias) \
 252      name proto __THROW __asm__ (__ASMNAME (#alias))
 253 #  define __REDIRECT_NTHNL(name, proto, alias) \
 254      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 255 # else
 256 #  define __REDIRECT_NTH(name, proto, alias) \
 257      name proto __asm__ (__ASMNAME (#alias)) __THROW
 258 #  define __REDIRECT_NTHNL(name, proto, alias) \
 259      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 260 # endif
 261 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 262 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 263
 264 /*
 265 #elif __SOME_OTHER_COMPILER__
 266
 267 # define __REDIRECT(name, proto, alias) name proto; \
 268         _Pragma("let " #name " = " #alias)
 269 */
 270 #endif
 271
 272 /* GCC and clang have various useful declarations that can be made with
 273    the '__attribute__' syntax.  All of the ways we use this do fine if
 274    they are omitted for compilers that don't understand it.  */
 275 #if !(defined __GNUC__ || defined __clang__)
 276 # define __attribute__(xyz)     /* Ignore */
 277 #endif
 278
 279 /* At some point during the gcc 2.96 development the `malloc' attribute
 280    for functions was introduced.  We don't want to use it unconditionally
 281    (although this would be possible) since it generates warnings.  */
 282 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
 283 # define __attribute_malloc__ __attribute__ ((__malloc__))
 284 #else
 285 # define __attribute_malloc__ /* Ignore */
 286 #endif
 287
 288 /* Tell the compiler which arguments to an allocation function
 289    indicate the size of the allocation.  */
 290 #if __GNUC_PREREQ (4, 3)
 291 # define __attribute_alloc_size__(params) \
 292   __attribute__ ((__alloc_size__ params))
 293 #else
 294 # define __attribute_alloc_size__(params) /* Ignore.  */
 295 #endif
 296
 297 /* Tell the compiler which argument to an allocation function
 298    indicates the alignment of the allocation.  */
 299 #if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__alloc_align__)
 300 # define __attribute_alloc_align__(param) \
 301   __attribute__ ((__alloc_align__ param))
 302 #else
 303 # define __attribute_alloc_align__(param) /* Ignore.  */
 304 #endif
 305
 306 /* At some point during the gcc 2.96 development the `pure' attribute
 307    for functions was introduced.  We don't want to use it unconditionally
 308    (although this would be possible) since it generates warnings.  */
 309 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
 310 # define __attribute_pure__ __attribute__ ((__pure__))
 311 #else
 312 # define __attribute_pure__ /* Ignore */
 313 #endif
 314
 315 /* This declaration tells the compiler that the value is constant.  */
 316 #if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
 317 # define __attribute_const__ __attribute__ ((__const__))
 318 #else
 319 # define __attribute_const__ /* Ignore */
 320 #endif
 321
 322 #if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
 323 # define __attribute_maybe_unused__ __attribute__ ((__unused__))
 324 #else
 325 # define __attribute_maybe_unused__ /* Ignore */
 326 #endif
 327
 328 /* At some point during the gcc 3.1 development the `used' attribute
 329    for functions was introduced.  We don't want to use it unconditionally
 330    (although this would be possible) since it generates warnings.  */
 331 #if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
 332 # define __attribute_used__ __attribute__ ((__used__))
 333 # define __attribute_noinline__ __attribute__ ((__noinline__))
 334 #else
 335 # define __attribute_used__ __attribute__ ((__unused__))
 336 # define __attribute_noinline__ /* Ignore */
 337 #endif
 338
 339 /* Since version 3.2, gcc allows marking deprecated functions.  */
 340 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
 341 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 342 #else
 343 # define __attribute_deprecated__ /* Ignore */
 344 #endif
 345
 346 /* Since version 4.5, gcc also allows one to specify the message printed
 347    when a deprecated function is used.  clang claims to be gcc 4.2, but
 348    may also support this feature.  */
 349 #if __GNUC_PREREQ (4,5) \
 350     || __glibc_has_extension (__attribute_deprecated_with_message__)
 351 # define __attribute_deprecated_msg__(msg) \
 352          __attribute__ ((__deprecated__ (msg)))
 353 #else
 354 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 355 #endif
 356
 357 /* At some point during the gcc 2.8 development the `format_arg' attribute
 358    for functions was introduced.  We don't want to use it unconditionally
 359    (although this would be possible) since it generates warnings.
 360    If several `format_arg' attributes are given for the same function, in
 361    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 362    all designated arguments are considered.  */
 363 #if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
 364 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 365 #else
 366 # define __attribute_format_arg__(x) /* Ignore */
 367 #endif
 368
 369 /* At some point during the gcc 2.97 development the `strfmon' format
 370    attribute for functions was introduced.  We don't want to use it
 371    unconditionally (although this would be possible) since it
 372    generates warnings.  */
 373 #if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
 374 # define __attribute_format_strfmon__(a,b) \
 375   __attribute__ ((__format__ (__strfmon__, a, b)))
 376 #else
 377 # define __attribute_format_strfmon__(a,b) /* Ignore */
 378 #endif
 379
 380 /* The nonnull function attribute marks pointer parameters that
 381    must not be NULL.  This has the name __nonnull in glibc,
 382    and __attribute_nonnull__ in files shared with Gnulib to avoid
 383    collision with a different __nonnull in DragonFlyBSD 5.9.  */
 384 #ifndef __attribute_nonnull__
 385 # if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
 386 #  define __attribute_nonnull__(params) __attribute__ ((__nonnull__ params))
 387 # else
 388 #  define __attribute_nonnull__(params)
 389 # endif
 390 #endif
 391 #ifndef __nonnull
 392 # define __nonnull(params) __attribute_nonnull__ (params)
 393 #endif
 394
 395 /* The returns_nonnull function attribute marks the return type of the function
 396    as always being non-null.  */
 397 #ifndef __returns_nonnull
 398 # if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
 399 # define __returns_nonnull __attribute__ ((__returns_nonnull__))
 400 # else
 401 # define __returns_nonnull
 402 # endif
 403 #endif
 404
 405 /* If fortification mode, we warn about unused results of certain
 406    function calls which can lead to problems.  */
 407 #if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
 408 # define __attribute_warn_unused_result__ \
 409    __attribute__ ((__warn_unused_result__))
 410 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
 411 #  define __wur __attribute_warn_unused_result__
 412 # endif
 413 #else
 414 # define __attribute_warn_unused_result__ /* empty */
 415 #endif
 416 #ifndef __wur
 417 # define __wur /* Ignore */
 418 #endif
 419
 420 /* Forces a function to be always inlined.  */
 421 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
 422 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 423    it conflicts with this definition.  Therefore undefine it first to
 424    allow either header to be included first.  */
 425 # undef __always_inline
 426 # define __always_inline __inline __attribute__ ((__always_inline__))
 427 #else
 428 # undef __always_inline
 429 # define __always_inline __inline
 430 #endif
 431
 432 /* Associate error messages with the source location of the call site rather
 433    than with the source location inside the function.  */
 434 #if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
 435 # define __attribute_artificial__ __attribute__ ((__artificial__))
 436 #else
 437 # define __attribute_artificial__ /* Ignore */
 438 #endif
 439
 440 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 441    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 442    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 443    older than 4.3 may define these macros and still not guarantee GNU inlining
 444    semantics.
 445
 446    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 447    semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
 448    __GNUC_GNU_INLINE__ macro definitions.  */
 449 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 450      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 451                                || defined __GNUC_GNU_INLINE__)))
 452 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 453 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 454 #  define __extern_always_inline \
 455   extern __always_inline __attribute__ ((__gnu_inline__))
 456 # else
 457 #  define __extern_inline extern __inline
 458 #  define __extern_always_inline extern __always_inline
 459 # endif
 460 #endif
 461
 462 #ifdef __extern_always_inline
 463 # define __fortify_function __extern_always_inline __attribute_artificial__
 464 #endif
 465
 466 /* GCC 4.3 and above allow passing all anonymous arguments of an
 467    __extern_always_inline function to some other vararg function.  */
 468 #if __GNUC_PREREQ (4,3)
 469 # define __va_arg_pack() __builtin_va_arg_pack ()
 470 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 471 #endif
 472
 473 /* It is possible to compile containing GCC extensions even if GCC is
 474    run in pedantic mode if the uses are carefully marked using the
 475    `__extension__' keyword.  But this is not generally available before
 476    version 2.8.  */
 477 #if !(__GNUC_PREREQ (2,8) || defined __clang__)
 478 # define __extension__          /* Ignore */
 479 #endif
 480
 481 /* __restrict is known in EGCS 1.2 and above, and in clang.
 482    It works also in C++ mode (outside of arrays), but only when spelled
 483    as '__restrict', not 'restrict'.  */
 484 #if !(__GNUC_PREREQ (2,92) || __clang_major__ >= 3)
 485 # if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 486 #  define __restrict    restrict
 487 # else
 488 #  define __restrict    /* Ignore */
 489 # endif
 490 #endif
 491
 492 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 493      array_name[restrict]
 494    GCC 3.1 and clang support this.
 495    This syntax is not usable in C++ mode.  */
 496 #if (__GNUC_PREREQ (3,1) || __clang_major__ >= 3) && !defined __cplusplus
 497 # define __restrict_arr __restrict
 498 #else
 499 # ifdef __GNUC__
 500 #  define __restrict_arr        /* Not supported in old GCC.  */
 501 # else
 502 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 503 #   define __restrict_arr       restrict
 504 #  else
 505 /* Some other non-C99 compiler.  */
 506 #   define __restrict_arr       /* Not supported.  */
 507 #  endif
 508 # endif
 509 #endif
 510
 511 #if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
 512 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 513 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 514 #else
 515 # define __glibc_unlikely(cond) (cond)
 516 # define __glibc_likely(cond)   (cond)
 517 #endif
 518
 519 #if (!defined _Noreturn \
 520      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 521      &&  !(__GNUC_PREREQ (4,7) \
 522            || (3 < __clang_major__ + (5 <= __clang_minor__))))
 523 # if __GNUC_PREREQ (2,8)
 524 #  define _Noreturn __attribute__ ((__noreturn__))
 525 # else
 526 #  define _Noreturn
 527 # endif
 528 #endif
 529
 530 #if __GNUC_PREREQ (8, 0)
 531 /* Describes a char array whose address can safely be passed as the first
 532    argument to strncpy and strncat, as the char array is not necessarily
 533    a NUL-terminated string.  */
 534 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 535 #else
 536 # define __attribute_nonstring__
 537 #endif
 538
 539 /* Undefine (also defined in libc-symbols.h).  */
 540 #undef __attribute_copy__
 541 #if __GNUC_PREREQ (9, 0)
 542 /* Copies attributes from the declaration or type referenced by
 543    the argument.  */
 544 # define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
 545 #else
 546 # define __attribute_copy__(arg)
 547 #endif
 548
 549 #if (!defined _Static_assert && !defined __cplusplus \
 550      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 551      && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
 552          || defined __STRICT_ANSI__))
 553 # define _Static_assert(expr, diagnostic) \
 554     extern int (*__Static_assert_function (void)) \
 555       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 556 #endif
 557
 558 /* Gnulib avoids including these, as they don't work on non-glibc or
 559    older glibc platforms.  */
 560 #ifndef __GNULIB_CDEFS
 561 # include <bits/wordsize.h>
 562 # include <bits/long-double.h>
 563 #endif
 564
 565 #if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
 566 # ifdef __REDIRECT
 567
 568 /* Alias name defined automatically.  */
 569 #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
 570 #  define __LDBL_REDIR_DECL(name) \
 571   extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
 572
 573 /* Alias name defined automatically, with leading underscores.  */
 574 #  define __LDBL_REDIR2_DECL(name) \
 575   extern __typeof (__##name) __##name \
 576     __asm (__ASMNAME ("__" #name "ieee128"));
 577
 578 /* Alias name defined manually.  */
 579 #  define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
 580 #  define __LDBL_REDIR1_DECL(name, alias) \
 581   extern __typeof (name) name __asm (__ASMNAME (#alias));
 582
 583 #  define __LDBL_REDIR1_NTH(name, proto, alias) \
 584   __REDIRECT_NTH (name, proto, alias)
 585 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 586   __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
 587
 588 /* Unused.  */
 589 #  define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
 590 #  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
 591
 592 # else
 593 _Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
 594 # endif
 595 #elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 596 # define __LDBL_COMPAT 1
 597 # ifdef __REDIRECT
 598 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 599 #  define __LDBL_REDIR(name, proto) \
 600   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 601 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 602 #  define __LDBL_REDIR_NTH(name, proto) \
 603   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 604 #  define __LDBL_REDIR2_DECL(name) \
 605   extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
 606 #  define __LDBL_REDIR1_DECL(name, alias) \
 607   extern __typeof (name) name __asm (__ASMNAME (#alias));
 608 #  define __LDBL_REDIR_DECL(name) \
 609   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 610 #  define __REDIRECT_LDBL(name, proto, alias) \
 611   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 612 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 613   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 614 # endif
 615 #endif
 616 #if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
 617     || !defined __REDIRECT
 618 # define __LDBL_REDIR1(name, proto, alias) name proto
 619 # define __LDBL_REDIR(name, proto) name proto
 620 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 621 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 622 # define __LDBL_REDIR2_DECL(name)
 623 # define __LDBL_REDIR_DECL(name)
 624 # ifdef __REDIRECT
 625 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 626 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 627   __REDIRECT_NTH (name, proto, alias)
 628 # endif
 629 #endif
 630
 631 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 632    intended for use in preprocessor macros.
 633
 634    Note: MESSAGE must be a _single_ string; concatenation of string
 635    literals is not supported.  */
 636 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 637 # define __glibc_macro_warning1(message) _Pragma (#message)
 638 # define __glibc_macro_warning(message) \
 639   __glibc_macro_warning1 (GCC warning message)
 640 #else
 641 # define __glibc_macro_warning(msg)
 642 #endif
 643
 644 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 645    since version 4.9.  Previous versions do not provide generic
 646    selection, even though they might set __STDC_VERSION__ to 201112L,
 647    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 648    when testing __STDC_VERSION__ for generic selection support.
 649    On the other hand, Clang also defines __GNUC__, so a clang-specific
 650    check is required to enable the use of generic selection.  */
 651 #if !defined __cplusplus \
 652     && (__GNUC_PREREQ (4, 9) \
 653         || __glibc_has_extension (c_generic_selections) \
 654         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 655             && __STDC_VERSION__ >= 201112L))
 656 # define __HAVE_GENERIC_SELECTION 1
 657 #else
 658 # define __HAVE_GENERIC_SELECTION 0
 659 #endif
 660
 661 #if __GNUC_PREREQ (10, 0)
 662 /* Designates a 1-based positional argument ref-index of pointer type
 663    that can be used to access size-index elements of the pointed-to
 664    array according to access mode, or at least one element when
 665    size-index is not provided:
 666      access (access-mode, <ref-index> [, <size-index>])  */
 667 #  define __attr_access(x) __attribute__ ((__access__ x))
 668 /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may
 669    use the access attribute to get object sizes from function definition
 670    arguments, so we can't use them on functions we fortify.  Drop the object
 671    size hints for such functions.  */
 672 #  if __USE_FORTIFY_LEVEL == 3
 673 #    define __fortified_attr_access(a, o, s) __attribute__ ((__access__ (a, o)))
 674 #  else
 675 #    define __fortified_attr_access(a, o, s) __attr_access ((a, o, s))
 676 #  endif
 677 #  if __GNUC_PREREQ (11, 0)
 678 #    define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
 679 #  else
 680 #    define __attr_access_none(argno)
 681 #  endif
 682 #else
 683 #  define __fortified_attr_access(a, o, s)
 684 #  define __attr_access(x)
 685 #  define __attr_access_none(argno)
 686 #endif
 687
 688 #if __GNUC_PREREQ (11, 0)
 689 /* Designates dealloc as a function to call to deallocate objects
 690    allocated by the declared function.  */
 691 # define __attr_dealloc(dealloc, argno) \
 692     __attribute__ ((__malloc__ (dealloc, argno)))
 693 # define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
 694 #else
 695 # define __attr_dealloc(dealloc, argno)
 696 # define __attr_dealloc_free
 697 #endif
 698
 699 /* Specify that a function such as setjmp or vfork may return
 700    twice.  */
 701 #if __GNUC_PREREQ (4, 1)
 702 # define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
 703 #else
 704 # define __attribute_returns_twice__ /* Ignore.  */
 705 #endif
 706
 707 #endif   /* sys/cdefs.h */