1/* Copyright (C) 1992-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#ifndef _SYS_CDEFS_H
19#define _SYS_CDEFS_H 1
20
21/* We are almost always included from features.h. */
22#ifndef _FEATURES_H
23# include <features.h>
24#endif
25
26/* The GNU libc does not support any K&R compilers or the traditional mode
27 of ISO C compilers anymore. Check for some of the combinations not
28 supported anymore. */
29#if defined __GNUC__ && !defined __STDC__
30# error "You need a ISO C conforming compiler to use the glibc headers"
31#endif
32
33/* Some user header file might have defined this before. */
34#undef __P
35#undef __PMT
36
37/* Compilers that lack __has_attribute may object to
38 #if defined __has_attribute && __has_attribute (...)
39 even though they do not need to evaluate the right-hand side of the &&.
40 Similarly for __has_builtin, etc. */
41#if (defined __has_attribute \
42 && (!defined __clang_minor__ \
43 || 3 < __clang_major__ + (5 <= __clang_minor__)))
44# define __glibc_has_attribute(attr) __has_attribute (attr)
45#else
46# define __glibc_has_attribute(attr) 0
47#endif
48#ifdef __has_builtin
49# define __glibc_has_builtin(name) __has_builtin (name)
50#else
51# define __glibc_has_builtin(name) 0
52#endif
53#ifdef __has_extension
54# define __glibc_has_extension(ext) __has_extension (ext)
55#else
56# define __glibc_has_extension(ext) 0
57#endif
58
59#if defined __GNUC__ || defined __clang__
60
61/* All functions, except those with callbacks or those that
62 synchronize memory, are leaf functions. */
63# if __GNUC_PREREQ (4, 6) && !defined _LIBC
64# define __LEAF , __leaf__
65# define __LEAF_ATTR __attribute__ ((__leaf__))
66# else
67# define __LEAF
68# define __LEAF_ATTR
69# endif
70
71/* GCC can always grok prototypes. For C++ programs we add throw()
72 to help it optimize the function calls. But this only works with
73 gcc 2.8.x and egcs. For gcc 3.4 and up we even mark C functions
74 as non-throwing using a function attribute since programs can use
75 the -fexceptions options for C code as well. */
76# if !defined __cplusplus \
77 && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
78# define __THROW __attribute__ ((__nothrow__ __LEAF))
79# define __THROWNL __attribute__ ((__nothrow__))
80# define __NTH(fct) __attribute__ ((__nothrow__ __LEAF)) fct
81# define __NTHNL(fct) __attribute__ ((__nothrow__)) fct
82# else
83# if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
84# if __cplusplus >= 201103L
85# define __THROW noexcept (true)
86# else
87# define __THROW throw ()
88# endif
89# define __THROWNL __THROW
90# define __NTH(fct) __LEAF_ATTR fct __THROW
91# define __NTHNL(fct) fct __THROW
92# else
93# define __THROW
94# define __THROWNL
95# define __NTH(fct) fct
96# define __NTHNL(fct) fct
97# endif
98# endif
99
100#else /* Not GCC or clang. */
101
102# if (defined __cplusplus \
103 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
104# define __inline inline
105# else
106# define __inline /* No inline functions. */
107# endif
108
109# define __THROW
110# define __THROWNL
111# define __NTH(fct) fct
112
113#endif /* GCC || clang. */
114
115/* These two macros are not used in glibc anymore. They are kept here
116 only because some other projects expect the macros to be defined. */
117#define __P(args) args
118#define __PMT(args) args
119
120/* For these things, GCC behaves the ANSI way normally,
121 and the non-ANSI way under -traditional. */
122
123#define __CONCAT(x,y) x ## y
124#define __STRING(x) #x
125
126/* This is not a typedef so `const __ptr_t' does the right thing. */
127#define __ptr_t void *
128
129
130/* C++ needs to know that types and declarations are C, not C++. */
131#ifdef __cplusplus
132# define __BEGIN_DECLS extern "C" {
133# define __END_DECLS }
134#else
135# define __BEGIN_DECLS
136# define __END_DECLS
137#endif
138
139
140/* Fortify support. */
141#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
142#define __bos0(ptr) __builtin_object_size (ptr, 0)
143
144/* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available. */
145#if __USE_FORTIFY_LEVEL == 3 && __glibc_clang_prereq (9, 0)
146# define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
147# define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
148#else
149# define __glibc_objsize0(__o) __bos0 (__o)
150# define __glibc_objsize(__o) __bos (__o)
151#endif
152
153#if __GNUC_PREREQ (4,3)
154# define __warnattr(msg) __attribute__((__warning__ (msg)))
155# define __errordecl(name, msg) \
156 extern void name (void) __attribute__((__error__ (msg)))
157#else
158# define __warnattr(msg)
159# define __errordecl(name, msg) extern void name (void)
160#endif
161
162/* Support for flexible arrays.
163 Headers that should use flexible arrays only if they're "real"
164 (e.g. only if they won't affect sizeof()) should test
165 #if __glibc_c99_flexarr_available. */
166#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
167# define __flexarr []
168# define __glibc_c99_flexarr_available 1
169#elif __GNUC_PREREQ (2,97) || defined __clang__
170/* GCC 2.97 and clang support C99 flexible array members as an extension,
171 even when in C89 mode or compiling C++ (any version). */
172# define __flexarr []
173# define __glibc_c99_flexarr_available 1
174#elif defined __GNUC__
175/* Pre-2.97 GCC did not support C99 flexible arrays but did have
176 an equivalent extension with slightly different notation. */
177# define __flexarr [0]
178# define __glibc_c99_flexarr_available 1
179#else
180/* Some other non-C99 compiler. Approximate with [1]. */
181# define __flexarr [1]
182# define __glibc_c99_flexarr_available 0
183#endif
184
185
186/* __asm__ ("xyz") is used throughout the headers to rename functions
187 at the assembly language level. This is wrapped by the __REDIRECT
188 macro, in order to support compilers that can do this some other
189 way. When compilers don't support asm-names at all, we have to do
190 preprocessor tricks instead (which don't have exactly the right
191 semantics, but it's the best we can do).
192
193 Example:
194 int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
195
196#if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
197
198# define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
199# ifdef __cplusplus
200# define __REDIRECT_NTH(name, proto, alias) \
201 name proto __THROW __asm__ (__ASMNAME (#alias))
202# define __REDIRECT_NTHNL(name, proto, alias) \
203 name proto __THROWNL __asm__ (__ASMNAME (#alias))
204# else
205# define __REDIRECT_NTH(name, proto, alias) \
206 name proto __asm__ (__ASMNAME (#alias)) __THROW
207# define __REDIRECT_NTHNL(name, proto, alias) \
208 name proto __asm__ (__ASMNAME (#alias)) __THROWNL
209# endif
210# define __ASMNAME(cname) __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
211# define __ASMNAME2(prefix, cname) __STRING (prefix) cname
212
213/*
214#elif __SOME_OTHER_COMPILER__
215
216# define __REDIRECT(name, proto, alias) name proto; \
217 _Pragma("let " #name " = " #alias)
218*/
219#endif
220
221/* GCC and clang have various useful declarations that can be made with
222 the '__attribute__' syntax. All of the ways we use this do fine if
223 they are omitted for compilers that don't understand it. */
224#if !(defined __GNUC__ || defined __clang__)
225# define __attribute__(xyz) /* Ignore */
226#endif
227
228/* At some point during the gcc 2.96 development the `malloc' attribute
229 for functions was introduced. We don't want to use it unconditionally
230 (although this would be possible) since it generates warnings. */
231#if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
232# define __attribute_malloc__ __attribute__ ((__malloc__))
233#else
234# define __attribute_malloc__ /* Ignore */
235#endif
236
237/* Tell the compiler which arguments to an allocation function
238 indicate the size of the allocation. */
239#if __GNUC_PREREQ (4, 3)
240# define __attribute_alloc_size__(params) \
241 __attribute__ ((__alloc_size__ params))
242#else
243# define __attribute_alloc_size__(params) /* Ignore. */
244#endif
245
246/* At some point during the gcc 2.96 development the `pure' attribute
247 for functions was introduced. We don't want to use it unconditionally
248 (although this would be possible) since it generates warnings. */
249#if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
250# define __attribute_pure__ __attribute__ ((__pure__))
251#else
252# define __attribute_pure__ /* Ignore */
253#endif
254
255/* This declaration tells the compiler that the value is constant. */
256#if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
257# define __attribute_const__ __attribute__ ((__const__))
258#else
259# define __attribute_const__ /* Ignore */
260#endif
261
262#if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
263# define __attribute_maybe_unused__ __attribute__ ((__unused__))
264#else
265# define __attribute_maybe_unused__ /* Ignore */
266#endif
267
268/* At some point during the gcc 3.1 development the `used' attribute
269 for functions was introduced. We don't want to use it unconditionally
270 (although this would be possible) since it generates warnings. */
271#if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
272# define __attribute_used__ __attribute__ ((__used__))
273# define __attribute_noinline__ __attribute__ ((__noinline__))
274#else
275# define __attribute_used__ __attribute__ ((__unused__))
276# define __attribute_noinline__ /* Ignore */
277#endif
278
279/* Since version 3.2, gcc allows marking deprecated functions. */
280#if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
281# define __attribute_deprecated__ __attribute__ ((__deprecated__))
282#else
283# define __attribute_deprecated__ /* Ignore */
284#endif
285
286/* Since version 4.5, gcc also allows one to specify the message printed
287 when a deprecated function is used. clang claims to be gcc 4.2, but
288 may also support this feature. */
289#if __GNUC_PREREQ (4,5) \
290 || __glibc_has_extension (__attribute_deprecated_with_message__)
291# define __attribute_deprecated_msg__(msg) \
292 __attribute__ ((__deprecated__ (msg)))
293#else
294# define __attribute_deprecated_msg__(msg) __attribute_deprecated__
295#endif
296
297/* At some point during the gcc 2.8 development the `format_arg' attribute
298 for functions was introduced. We don't want to use it unconditionally
299 (although this would be possible) since it generates warnings.
300 If several `format_arg' attributes are given for the same function, in
301 gcc-3.0 and older, all but the last one are ignored. In newer gccs,
302 all designated arguments are considered. */
303#if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
304# define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
305#else
306# define __attribute_format_arg__(x) /* Ignore */
307#endif
308
309/* At some point during the gcc 2.97 development the `strfmon' format
310 attribute for functions was introduced. We don't want to use it
311 unconditionally (although this would be possible) since it
312 generates warnings. */
313#if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
314# define __attribute_format_strfmon__(a,b) \
315 __attribute__ ((__format__ (__strfmon__, a, b)))
316#else
317# define __attribute_format_strfmon__(a,b) /* Ignore */
318#endif
319
320/* The nonnull function attribute marks pointer parameters that
321 must not be NULL. */
322#ifndef __nonnull
323# if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
324# define __nonnull(params) __attribute__ ((__nonnull__ params))
325# else
326# define __nonnull(params)
327# endif
328#elif !defined __GLIBC__
329# undef __nonnull
330# define __nonnull(params) _GL_ATTRIBUTE_NONNULL (params)
331#endif
332
333/* The returns_nonnull function attribute marks the return type of the function
334 as always being non-null. */
335#ifndef __returns_nonnull
336# if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
337# define __returns_nonnull __attribute__ ((__returns_nonnull__))
338# else
339# define __returns_nonnull
340# endif
341#endif
342
343/* If fortification mode, we warn about unused results of certain
344 function calls which can lead to problems. */
345#if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
346# define __attribute_warn_unused_result__ \
347 __attribute__ ((__warn_unused_result__))
348# if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
349# define __wur __attribute_warn_unused_result__
350# endif
351#else
352# define __attribute_warn_unused_result__ /* empty */
353#endif
354#ifndef __wur
355# define __wur /* Ignore */
356#endif
357
358/* Forces a function to be always inlined. */
359#if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
360/* The Linux kernel defines __always_inline in stddef.h (283d7573), and
361 it conflicts with this definition. Therefore undefine it first to
362 allow either header to be included first. */
363# undef __always_inline
364# define __always_inline __inline __attribute__ ((__always_inline__))
365#else
366# undef __always_inline
367# define __always_inline __inline
368#endif
369
370/* Associate error messages with the source location of the call site rather
371 than with the source location inside the function. */
372#if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
373# define __attribute_artificial__ __attribute__ ((__artificial__))
374#else
375# define __attribute_artificial__ /* Ignore */
376#endif
377
378/* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
379 inline semantics, unless -fgnu89-inline is used. Using __GNUC_STDC_INLINE__
380 or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
381 older than 4.3 may define these macros and still not guarantee GNU inlining
382 semantics.
383
384 clang++ identifies itself as gcc-4.2, but has support for GNU inlining
385 semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
386 __GNUC_GNU_INLINE__ macro definitions. */
387#if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
388 || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
389 || defined __GNUC_GNU_INLINE__)))
390# if defined __GNUC_STDC_INLINE__ || defined __cplusplus
391# define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
392# define __extern_always_inline \
393 extern __always_inline __attribute__ ((__gnu_inline__))
394# else
395# define __extern_inline extern __inline
396# define __extern_always_inline extern __always_inline
397# endif
398#endif
399
400#ifdef __extern_always_inline
401# define __fortify_function __extern_always_inline __attribute_artificial__
402#endif
403
404/* GCC 4.3 and above allow passing all anonymous arguments of an
405 __extern_always_inline function to some other vararg function. */
406#if __GNUC_PREREQ (4,3)
407# define __va_arg_pack() __builtin_va_arg_pack ()
408# define __va_arg_pack_len() __builtin_va_arg_pack_len ()
409#endif
410
411/* It is possible to compile containing GCC extensions even if GCC is
412 run in pedantic mode if the uses are carefully marked using the
413 `__extension__' keyword. But this is not generally available before
414 version 2.8. */
415#if !(__GNUC_PREREQ (2,8) || defined __clang__)
416# define __extension__ /* Ignore */
417#endif
418
419/* __restrict is known in EGCS 1.2 and above, and in clang.
420 It works also in C++ mode (outside of arrays), but only when spelled
421 as '__restrict', not 'restrict'. */
422#if !(__GNUC_PREREQ (2,92) || __clang_major__ >= 3)
423# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
424# define __restrict restrict
425# else
426# define __restrict /* Ignore */
427# endif
428#endif
429
430/* ISO C99 also allows to declare arrays as non-overlapping. The syntax is
431 array_name[restrict]
432 GCC 3.1 and clang support this.
433 This syntax is not usable in C++ mode. */
434#if (__GNUC_PREREQ (3,1) || __clang_major__ >= 3) && !defined __cplusplus
435# define __restrict_arr __restrict
436#else
437# ifdef __GNUC__
438# define __restrict_arr /* Not supported in old GCC. */
439# else
440# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
441# define __restrict_arr restrict
442# else
443/* Some other non-C99 compiler. */
444# define __restrict_arr /* Not supported. */
445# endif
446# endif
447#endif
448
449#if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
450# define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
451# define __glibc_likely(cond) __builtin_expect ((cond), 1)
452#else
453# define __glibc_unlikely(cond) (cond)
454# define __glibc_likely(cond) (cond)
455#endif
456
457#if (!defined _Noreturn \
458 && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
459 && !(__GNUC_PREREQ (4,7) \
460 || (3 < __clang_major__ + (5 <= __clang_minor__))))
461# if __GNUC_PREREQ (2,8)
462# define _Noreturn __attribute__ ((__noreturn__))
463# else
464# define _Noreturn
465# endif
466#endif
467
468#if __GNUC_PREREQ (8, 0)
469/* Describes a char array whose address can safely be passed as the first
470 argument to strncpy and strncat, as the char array is not necessarily
471 a NUL-terminated string. */
472# define __attribute_nonstring__ __attribute__ ((__nonstring__))
473#else
474# define __attribute_nonstring__
475#endif
476
477/* Undefine (also defined in libc-symbols.h). */
478#undef __attribute_copy__
479#if __GNUC_PREREQ (9, 0)
480/* Copies attributes from the declaration or type referenced by
481 the argument. */
482# define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
483#else
484# define __attribute_copy__(arg)
485#endif
486
487#if (!defined _Static_assert && !defined __cplusplus \
488 && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
489 && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
490 || defined __STRICT_ANSI__))
491# define _Static_assert(expr, diagnostic) \
492 extern int (*__Static_assert_function (void)) \
493 [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
494#endif
495
496/* The #ifndef lets Gnulib avoid including these on non-glibc
497 platforms, where the includes typically do not exist. */
498#ifdef __GLIBC__
499# include <bits/wordsize.h>
500# include <bits/long-double.h>
501#endif
502
503#if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
504# ifdef __REDIRECT
505
506/* Alias name defined automatically. */
507# define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
508# define __LDBL_REDIR_DECL(name) \
509 extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
510
511/* Alias name defined automatically, with leading underscores. */
512# define __LDBL_REDIR2_DECL(name) \
513 extern __typeof (__##name) __##name \
514 __asm (__ASMNAME ("__" #name "ieee128"));
515
516/* Alias name defined manually. */
517# define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
518# define __LDBL_REDIR1_DECL(name, alias) \
519 extern __typeof (name) name __asm (__ASMNAME (#alias));
520
521# define __LDBL_REDIR1_NTH(name, proto, alias) \
522 __REDIRECT_NTH (name, proto, alias)
523# define __REDIRECT_NTH_LDBL(name, proto, alias) \
524 __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
525
526/* Unused. */
527# define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
528# define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
529
530# else
531_Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
532# endif
533#elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
534# define __LDBL_COMPAT 1
535# ifdef __REDIRECT
536# define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
537# define __LDBL_REDIR(name, proto) \
538 __LDBL_REDIR1 (name, proto, __nldbl_##name)
539# define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
540# define __LDBL_REDIR_NTH(name, proto) \
541 __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
542# define __LDBL_REDIR2_DECL(name) \
543 extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
544# define __LDBL_REDIR1_DECL(name, alias) \
545 extern __typeof (name) name __asm (__ASMNAME (#alias));
546# define __LDBL_REDIR_DECL(name) \
547 extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
548# define __REDIRECT_LDBL(name, proto, alias) \
549 __LDBL_REDIR1 (name, proto, __nldbl_##alias)
550# define __REDIRECT_NTH_LDBL(name, proto, alias) \
551 __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
552# endif
553#endif
554#if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
555 || !defined __REDIRECT
556# define __LDBL_REDIR1(name, proto, alias) name proto
557# define __LDBL_REDIR(name, proto) name proto
558# define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
559# define __LDBL_REDIR_NTH(name, proto) name proto __THROW
560# define __LDBL_REDIR2_DECL(name)
561# define __LDBL_REDIR_DECL(name)
562# ifdef __REDIRECT
563# define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
564# define __REDIRECT_NTH_LDBL(name, proto, alias) \
565 __REDIRECT_NTH (name, proto, alias)
566# endif
567#endif
568
569/* __glibc_macro_warning (MESSAGE) issues warning MESSAGE. This is
570 intended for use in preprocessor macros.
571
572 Note: MESSAGE must be a _single_ string; concatenation of string
573 literals is not supported. */
574#if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
575# define __glibc_macro_warning1(message) _Pragma (#message)
576# define __glibc_macro_warning(message) \
577 __glibc_macro_warning1 (GCC warning message)
578#else
579# define __glibc_macro_warning(msg)
580#endif
581
582/* Generic selection (ISO C11) is a C-only feature, available in GCC
583 since version 4.9. Previous versions do not provide generic
584 selection, even though they might set __STDC_VERSION__ to 201112L,
585 when in -std=c11 mode. Thus, we must check for !defined __GNUC__
586 when testing __STDC_VERSION__ for generic selection support.
587 On the other hand, Clang also defines __GNUC__, so a clang-specific
588 check is required to enable the use of generic selection. */
589#if !defined __cplusplus \
590 && (__GNUC_PREREQ (4, 9) \
591 || __glibc_has_extension (c_generic_selections) \
592 || (!defined __GNUC__ && defined __STDC_VERSION__ \
593 && __STDC_VERSION__ >= 201112L))
594# define __HAVE_GENERIC_SELECTION 1
595#else
596# define __HAVE_GENERIC_SELECTION 0
597#endif
598
599#if __GNUC_PREREQ (10, 0)
600/* Designates a 1-based positional argument ref-index of pointer type
601 that can be used to access size-index elements of the pointed-to
602 array according to access mode, or at least one element when
603 size-index is not provided:
604 access (access-mode, <ref-index> [, <size-index>]) */
605# define __attr_access(x) __attribute__ ((__access__ x))
606# if __GNUC_PREREQ (11, 0)
607# define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
608# else
609# define __attr_access_none(argno)
610# endif
611#else
612# define __attr_access(x)
613# define __attr_access_none(argno)
614#endif
615
616#if __GNUC_PREREQ (11, 0)
617/* Designates dealloc as a function to call to deallocate objects
618 allocated by the declared function. */
619# define __attr_dealloc(dealloc, argno) \
620 __attribute__ ((__malloc__ (dealloc, argno)))
621# define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
622#else
623# define __attr_dealloc(dealloc, argno)
624# define __attr_dealloc_free
625#endif
626
627/* Specify that a function such as setjmp or vfork may return
628 twice. */
629#if __GNUC_PREREQ (4, 1)
630# define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
631#else
632# define __attribute_returns_twice__ /* Ignore. */
633#endif
634
635#endif /* sys/cdefs.h */
636