root/lib/cdefs.h

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     1 /* Copyright (C) 1992-2023 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, or unknown (-1) */
   168 #define __glibc_safe_or_unknown_len(__l, __s, __osz) \
   169   ((__osz) == (__SIZE_TYPE__) -1                                              \
   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 */