1/* Handle feature test macros at the start of a header.
  2   Copyright (C) 2016-2025 Free Software Foundation, Inc.
  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/* This header is internal to glibc and should not be included outside
 20   of glibc headers.  Headers including it must define
 21   __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION first.  This header
 22   cannot have multiple include guards because ISO C feature test
 23   macros depend on the definition of the macro when an affected
 24   header is included, not when the first system header is
 25   included.  */
 26
 27#ifndef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
 28# error "Never include <bits/libc-header-start.h> directly."
 29#endif
 30
 31#undef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
 32
 33#include <features.h>
 34
 35/* ISO/IEC TR 24731-2:2010 defines the __STDC_WANT_LIB_EXT2__
 36   macro.  */
 37#undef __GLIBC_USE_LIB_EXT2
 38#if (defined __USE_GNU							\
 39     || (defined __STDC_WANT_LIB_EXT2__ && __STDC_WANT_LIB_EXT2__ > 0))
 40# define __GLIBC_USE_LIB_EXT2 1
 41#else
 42# define __GLIBC_USE_LIB_EXT2 0
 43#endif
 44
 45/* ISO/IEC TS 18661-1:2014 defines the __STDC_WANT_IEC_60559_BFP_EXT__
 46   macro.  Most but not all symbols enabled by that macro in TS
 47   18661-1 are enabled unconditionally in C23.  In C23, the symbols in
 48   Annex F still require a new feature test macro
 49   __STDC_WANT_IEC_60559_EXT__ instead (C23 does not define
 50   __STDC_WANT_IEC_60559_BFP_EXT__), while a few features from TS
 51   18661-1 are not included in C23 (and thus should depend on
 52   __STDC_WANT_IEC_60559_BFP_EXT__ even when C23 features are
 53   enabled).
 54
 55   __GLIBC_USE (IEC_60559_BFP_EXT) controls those features from TS
 56   18661-1 not included in C23.
 57
 58   __GLIBC_USE (IEC_60559_BFP_EXT_C23) controls those features from TS
 59   18661-1 that are also included in C23 (with no feature test macro
 60   required in C23).
 61
 62   __GLIBC_USE (IEC_60559_EXT) controls those features from TS 18661-1
 63   that are included in C23 but conditional on
 64   __STDC_WANT_IEC_60559_EXT__.  (There are currently no features
 65   conditional on __STDC_WANT_IEC_60559_EXT__ that are not in TS
 66   18661-1.)  */
 67#undef __GLIBC_USE_IEC_60559_BFP_EXT
 68#if defined __USE_GNU || defined __STDC_WANT_IEC_60559_BFP_EXT__
 69# define __GLIBC_USE_IEC_60559_BFP_EXT 1
 70#else
 71# define __GLIBC_USE_IEC_60559_BFP_EXT 0
 72#endif
 73#undef __GLIBC_USE_IEC_60559_BFP_EXT_C23
 74#if __GLIBC_USE (IEC_60559_BFP_EXT) || __GLIBC_USE (ISOC23)
 75# define __GLIBC_USE_IEC_60559_BFP_EXT_C23 1
 76#else
 77# define __GLIBC_USE_IEC_60559_BFP_EXT_C23 0
 78#endif
 79#undef __GLIBC_USE_IEC_60559_EXT
 80#if __GLIBC_USE (IEC_60559_BFP_EXT) || defined __STDC_WANT_IEC_60559_EXT__
 81# define __GLIBC_USE_IEC_60559_EXT 1
 82#else
 83# define __GLIBC_USE_IEC_60559_EXT 0
 84#endif
 85
 86/* ISO/IEC TS 18661-4:2015 defines the
 87   __STDC_WANT_IEC_60559_FUNCS_EXT__ macro.  Other than the reduction
 88   functions, the symbols from this TS are enabled unconditionally in
 89   C23.  */
 90#undef __GLIBC_USE_IEC_60559_FUNCS_EXT
 91#if defined __USE_GNU || defined __STDC_WANT_IEC_60559_FUNCS_EXT__
 92# define __GLIBC_USE_IEC_60559_FUNCS_EXT 1
 93#else
 94# define __GLIBC_USE_IEC_60559_FUNCS_EXT 0
 95#endif
 96#undef __GLIBC_USE_IEC_60559_FUNCS_EXT_C23
 97#if __GLIBC_USE (IEC_60559_FUNCS_EXT) || __GLIBC_USE (ISOC23)
 98# define __GLIBC_USE_IEC_60559_FUNCS_EXT_C23 1
 99#else
100# define __GLIBC_USE_IEC_60559_FUNCS_EXT_C23 0
101#endif
102
103/* ISO/IEC TS 18661-3:2015 defines the
104   __STDC_WANT_IEC_60559_TYPES_EXT__ macro.  */
105#undef __GLIBC_USE_IEC_60559_TYPES_EXT
106#if defined __USE_GNU || defined __STDC_WANT_IEC_60559_TYPES_EXT__
107# define __GLIBC_USE_IEC_60559_TYPES_EXT 1
108#else
109# define __GLIBC_USE_IEC_60559_TYPES_EXT 0
110#endif