stdalign.h File Reference

Defines RBIMPL_ALIGNAS / RBIMPL_ALIGNOF. More...

#include "ruby/internal/config.h"
#include "ruby/internal/compiler_is.h"
#include "ruby/internal/has/attribute.h"
#include "ruby/internal/has/declspec_attribute.h"
#include "ruby/internal/has/feature.h"

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Macros
#define	RBIMPL_ALIGNAS   alignas
	Wraps (or simulates) alignas.
#define	RBIMPL_ALIGNOF   alignof
	Wraps (or simulates) alignof.

Detailed Description

Defines RBIMPL_ALIGNAS / RBIMPL_ALIGNOF.

Author

Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.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.

Definition in file stdalign.h.

Macro Definition Documentation

RBIMPL_ALIGNAS

#define RBIMPL_ALIGNAS   alignas

Wraps (or simulates) alignas.

This is C++11's alignas and is different from C11 _Alignas. For instance,

typedef struct alignas(128) foo { int foo } foo;

is a valid C++ while

typedef struct _Alignas(128) foo { int foo } foo;

is an invalid C because:

• You cannot struct _Alignas.
• A typedef cannot have alignments.

Definition at line 57 of file stdalign.h.

RBIMPL_ALIGNOF

#define RBIMPL_ALIGNOF   alignof

Wraps (or simulates) alignof.

We want C11's _Alignof. However in spite of its clear language, compilers (including GCC and clang) tend to have buggy implementations. We have to avoid such things to resort to our own version.

See also

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69560

https://bugs.llvm.org/show_bug.cgi?id=26547

Definition at line 87 of file stdalign.h.