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#ifndef RBIMPL_STDALIGN_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_STDALIGN_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Defines #RBIMPL_ALIGNAS / #RBIMPL_ALIGNOF
*/
#include "ruby/internal/config.h"
#ifdef HAVE_STDALIGN_H
# include <stdalign.h>
#endif
#include "ruby/internal/compiler_is.h"
#include "ruby/internal/compiler_since.h"
#include "ruby/internal/has/feature.h"
#include "ruby/internal/has/extension.h"
#include "ruby/internal/has/attribute.h"
#include "ruby/internal/has/declspec_attribute.h"
/**
* Wraps (or simulates) `alignas`. This is C++11's `alignas` and is _different_
* from C11 `_Alignas`. For instance,
*
* ```CXX
* typedef struct alignas(128) foo { int foo } foo;
* ```
*
* is a valid C++ while
*
* ```C
* typedef struct _Alignas(128) foo { int foo } foo;
* ```
*
* is an invalid C because:
*
* - You cannot `struct _Alignas`.
* - A `typedef` cannot have alignments.
*/
#if defined(__cplusplus) && RBIMPL_HAS_FEATURE(cxx_alignas)
# define RBIMPL_ALIGNAS alignas
#elif defined(__cplusplus) && (__cplusplus >= 201103L)
# define RBIMPL_ALIGNAS alignas
#elif defined(__INTEL_CXX11_MODE__)
# define RBIMPL_ALIGNAS alignas
#elif defined(__GXX_EXPERIMENTAL_CXX0X__)
# define RBIMPL_ALIGNAS alignas
#elif RBIMPL_HAS_DECLSPEC_ATTRIBUTE(align)
# define RBIMPL_ALIGNAS(_) __declspec(align(_))
#elif RBIMPL_HAS_ATTRIBUTE(aliged)
# define RBIMPL_ALIGNAS(_) __attribute__((__aligned__(_)))
#else
# define RBIMPL_ALIGNAS(_) /* void */
#endif
/**
* Wraps (or simulates) `alignof`. Unlike #RBIMPL_ALIGNAS, we can safely say
* both C/C++ definitions are effective.
*/
#if defined(__cplusplus) && RBIMPL_HAS_EXTENSION(cxx_alignof)
# define RBIMPL_ALIGNOF __extension__ alignof
#elif defined(__cplusplus) && (__cplusplus >= 201103L)
# define RBIMPL_ALIGNOF alignof
#elif defined(__INTEL_CXX11_MODE__)
# define RBIMPL_ALIGNOF alignof
#elif defined(__GXX_EXPERIMENTAL_CXX0X__)
# define RBIMPL_ALIGNOF alignof
#elif defined(__STDC_VERSION__) && RBIMPL_HAS_EXTENSION(c_alignof)
# define RBIMPL_ALIGNOF __extension__ _Alignof
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
# define RBIMPL_ALIGNOF _Alignof
#elif RBIMPL_COMPILER_IS(MSVC)
# define RBIMPL_ALIGNOF __alignof
#elif defined(__GNUC__)
# /* At least GCC 2.95 had this. */
# define RBIMPL_ALIGNOF __extension__ __alignof__
#elif defined(__alignof_is_defined) || defined(__DOXYGEN__)
# /* OK, we can safely take <stdalign.h> definition. */
# define RBIMPL_ALIGNOF alignof
#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 9, 0)
# /* According to their manual, Sun Studio 12 introduced __alignof__ for both
# * C/C++. */
# define RBIMPL_ALIGNOF __alignof__
#elif 0
# /* THIS IS NG, you cannot define a new type inside of offsetof. */
# /* see: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm */
# define RBIMPL_ALIGNOF(T) offsetof(struct { char _; T t; }, t)
#else
# error :FIXME: add your compiler here to obtain an alignment.
#endif
#endif /* RBIMPL_STDALIGN_H */
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