/* A substitute for ISO C11 . 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 General Public License as published by the Free Software Foundation; either version 3, 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see . */ /* Written by Paul Eggert and Bruno Haible. */ #ifndef _GL_STDALIGN_H #define _GL_STDALIGN_H /* ISO C11 for platforms that lack it. References: ISO C11 (latest free draft ) sections 6.5.3.4, 6.7.5, 7.15. C++11 (latest free draft ) 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 for offsetof. */ #include /* FreeBSD 9.1 , included by 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 . 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 struct __alignof_helper { char __a; __t __b; }; # define _Alignof(type) offsetof (__alignof_helper, __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__) \ || (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 */