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+/* A substitute for ISO C11 <stdalign.h>.
+
+ Copyright 2011-2022 Free Software Foundation, Inc.
+
+ This file 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 of the
+ License, or (at your option) any later version.
+
+ This file 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 and clang's __alignof__ operator, which can
+ yield a better-performing alignment for an object of that type. For
+ example, on x86 with GCC and on Linux/x86 with clang,
+ __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>.
+ clang versions < 8.0.0 have the same bug. */
+#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
+ || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
+ && !defined __clang__) \
+ || (defined __clang__ && __clang_major__ < 8))
+# 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 __attribute__ \
+ && ((defined __APPLE__ && defined __MACH__ \
+ ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \
+ : __GNUC__ && !defined __ibmxl__) \
+ || (4 <= __clang_major__) \
+ || (__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 */