/* A substitute for ISO C11 <stdalign.h>.

   Copyright 2011-2020 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU Lesser General Public License as published by

   the Free Software Foundation; either version 2.1, or (at your option)

   any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with this program; if not, see <https://www.gnu.org/licenses/>.  */

/* Written by Paul Eggert and Bruno Haible.  */

#ifndef _GL_STDALIGN_H

#define _GL_STDALIGN_H

/* ISO C11 <stdalign.h> for platforms that lack it.

   References:

   ISO C11 (latest free draft

   <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf>)

   sections 6.5.3.4, 6.7.5, 7.15.

   C++11 (latest free draft

   <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf>)

   section 18.10. */

/* alignof (TYPE), also known as _Alignof (TYPE), yields the alignment

   requirement of a structure member (i.e., slot or field) that is of

   type TYPE, as an integer constant expression.

   This differs from GCC's __alignof__ operator, which can yield a

   better-performing alignment for an object of that type.  For

   example, on x86 with GCC, __alignof__ (double) and __alignof__

   (long long) are 8, whereas alignof (double) and alignof (long long)

   are 4 unless the option '-malign-double' is used.

   The result cannot be used as a value for an 'enum' constant, if you

   want to be portable to HP-UX 10.20 cc and AIX 3.2.5 xlc.

   Include <stddef.h> for offsetof.  */

#include <stddef.h>

/* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other

   standard headers, defines conflicting implementations of _Alignas

   and _Alignof that are no better than ours; override them.  */

#undef _Alignas

#undef _Alignof

/* GCC releases before GCC 4.9 had a bug in _Alignof.  See GCC bug 52023

   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.  */

#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \

     || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9)))

# ifdef __cplusplus

#  if 201103 <= __cplusplus

#   define _Alignof(type) alignof (type)

#  else

   template <class __t> struct __alignof_helper { char __a; __t __b; };

#   define _Alignof(type) offsetof (__alignof_helper<type>, __b)

#  endif

# else

#  define _Alignof(type) offsetof (struct { char __a; type __b; }, __b)

# endif

#endif

#if ! (defined __cplusplus && 201103 <= __cplusplus)

# define alignof _Alignof

#endif

#define __alignof_is_defined 1

/* alignas (A), also known as _Alignas (A), aligns a variable or type

   to the alignment A, where A is an integer constant expression.  For

   example:

      int alignas (8) foo;

      struct s { int a; int alignas (8) bar; };

   aligns the address of FOO and the offset of BAR to be multiples of 8.

   A should be a power of two that is at least the type's alignment

   and at most the implementation's alignment limit.  This limit is

   2**28 on typical GNUish hosts, and 2**13 on MSVC.  To be portable

   to MSVC through at least version 10.0, A should be an integer

   constant, as MSVC does not support expressions such as 1 << 3.

   To be portable to Sun C 5.11, do not align auto variables to

   anything stricter than their default alignment.

   The following C11 requirements are not supported here:

     - If A is zero, alignas has no effect.

     - alignas can be used multiple times; the strictest one wins.

     - alignas (TYPE) is equivalent to alignas (alignof (TYPE)).

   */

#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112

# if defined __cplusplus && 201103 <= __cplusplus

#  define _Alignas(a) alignas (a)

# elif ((defined __APPLE__ && defined __MACH__                  \

         ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__)                 \

         : __GNUC__ && !defined __ibmxl__) \

        || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \

        || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__)

#  define _Alignas(a) __attribute__ ((__aligned__ (a)))

# elif 1300 <= _MSC_VER

#  define _Alignas(a) __declspec (align (a))

# endif

#endif

#if ((defined _Alignas && ! (defined __cplusplus && 201103 <= __cplusplus)) \

     || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__))

# define alignas _Alignas

#endif

#if defined alignas || (defined __cplusplus && 201103 <= __cplusplus)

# define __alignas_is_defined 1

#endif

#endif /* _GL_STDALIGN_H */