The C and C++ Include Header Files

/usr/include/x86_64-linux-gnu/c++/11/bits/os_defines.h


$ cat -n /usr/include/x86_64-linux-gnu/c++/11/bits/os_defines.h

     1	// Specific definitions for GNU/Linux  -*- C++ -*-
     2	
     3	// Copyright (C) 2000-2021 Free Software Foundation, Inc.
     4	//
     5	// This file is part of the GNU ISO C++ Library.  This library is free
     6	// software; you can redistribute it and/or modify it under the
     7	// terms of the GNU General Public License as published by the
     8	// Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	
    11	// This library is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU General Public License for more details.
    15	
    16	// Under Section 7 of GPL version 3, you are granted additional
    17	// permissions described in the GCC Runtime Library Exception, version
    18	// 3.1, as published by the Free Software Foundation.
    19	
    20	// You should have received a copy of the GNU General Public License and
    21	// a copy of the GCC Runtime Library Exception along with this program;
    22	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    23	// <http://www.gnu.org/licenses/>.
    24	
    25	/** @file bits/os_defines.h
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{iosfwd}
    28	 */
    29	
    30	#ifndef _GLIBCXX_OS_DEFINES
    31	#define _GLIBCXX_OS_DEFINES 1
    32	
    33	// System-specific #define, typedefs, corrections, etc, go here.  This
    34	// file will come before all others.
    35	
    36	// This keeps isanum, et al from being propagated as macros.
    37	#define __NO_CTYPE 1
    38	
    39	#include <features.h>
    40	
    41	// Provide a declaration for the possibly deprecated gets function, as
    42	// glibc 2.15 and later does not declare gets for ISO C11 when
    43	// __GNU_SOURCE is defined.
    44	#if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
    45	# undef _GLIBCXX_HAVE_GETS
    46	#endif
    47	
    48	// Glibc 2.23 removed the obsolete isinf and isnan declarations. Check the
    49	// version dynamically in case it has changed since libstdc++ was configured.
    50	#define _GLIBCXX_NO_OBSOLETE_ISINF_ISNAN_DYNAMIC __GLIBC_PREREQ(2,23)
    51	
    52	#ifdef __linux__
    53	# if __GLIBC_PREREQ(2, 27)
    54	// Since glibc 2.27 Linux' pthread_self() is usable without linking to libpthread.
    55	#  define _GLIBCXX_NATIVE_THREAD_ID pthread_self()
    56	# else
    57	// Before then it was in libc.so.6 but not libc.a, and always returns 0,
    58	// which breaks the invariant this_thread::get_id() != thread::id{}.
    59	// So only use it if we know the libpthread version is available.
    60	// Otherwise use (__gthread_t)1 as the ID of the main (and only) thread.
    61	#  define _GLIBCXX_NATIVE_THREAD_ID \
    62	   (__gthread_active_p() ? __gthread_self() : (__gthread_t)1)
    63	# endif
    64	
    65	# if __GLIBC_PREREQ(2, 34)
    66	// Since glibc 2.34 all Linux pthreads functions are usable without linking to
    67	// libpthread.
    68	#  define _GLIBCXX_GTHREAD_USE_WEAK 0
    69	# endif
    70	# if defined(_TIME_BITS)
    71	#  if _TIME_BITS == 64
    72	#   undef _GLIBCXX_TIME_BITS64_ABI_TAG
    73	#   define _GLIBCXX_TIME_BITS64_ABI_TAG [[__gnu__::__abi_tag__("__time64")]]
    74	#  endif
    75	# endif
    76	#endif
    77	
    78	#endif