[BACK]Return to stdalign.h CVS log [TXT][DIR] Up to [cvs.NetBSD.org] / src / include

File: [cvs.NetBSD.org] / src / include / stdalign.h (download)

Revision 1.1, Sun Oct 2 17:19:00 2016 UTC (2 years, 5 months ago) by kamil
Branch: MAIN
CVS Tags: prg-localcount2-base3, prg-localcount2-base2, prg-localcount2-base1, prg-localcount2-base, prg-localcount2, phil-wifi-base, phil-wifi, pgoyette-localcount-20170426, pgoyette-localcount-20170320, pgoyette-localcount-20170107, pgoyette-localcount-20161104, pgoyette-compat-merge-20190127, pgoyette-compat-base, pgoyette-compat-20190127, pgoyette-compat-20190118, pgoyette-compat-1226, pgoyette-compat-1126, pgoyette-compat-1020, pgoyette-compat-0930, pgoyette-compat-0906, pgoyette-compat-0728, pgoyette-compat-0625, pgoyette-compat-0521, pgoyette-compat-0502, pgoyette-compat-0422, pgoyette-compat-0415, pgoyette-compat-0407, pgoyette-compat-0330, pgoyette-compat-0322, pgoyette-compat-0315, pgoyette-compat, perseant-stdc-iso10646-base, perseant-stdc-iso10646, netbsd-8-base, netbsd-8-0-RELEASE, netbsd-8-0-RC2, netbsd-8-0-RC1, netbsd-8, matt-nb8-mediatek-base, matt-nb8-mediatek, bouyer-socketcan-base1, bouyer-socketcan-base, bouyer-socketcan, HEAD
Branch point for: pgoyette-localcount

Import <stdalign.h>

This header conforms to the C11 standard
Reference: ISO/IEC 9899:201x 7.15 Alignment <stdalign.h>

According to ISO/IEC 9899:201x (draft) 7.15 Alignment <stdalign.h> defines
four macros:
 - alignas which expands to _Alignas
 - alignof which expands to _Alignof
 - __alignas_is_defined and __alignof_is_defined which both expand to 1

The _Alignas declaration appears as one of the type specifiers to modify
the alignment requirement of the object being declared.

The _Alignof operator is used to query the alignment requirement of its
operand type.

ISO/IEC N3242=11-0012 (C++1x) and ISO/IEC N3797 (C++1y) both note a header
<cstdalign> which defines only __alignas_is_defined and shall not define
the alignas macro. It misses the alignof case as it's probably based on an
older C1x draft, which defined only alignas. Assume that this is a bug in
the standard and treat alignof the same way as alignas in C++11.

Allow to define alignas and alignof in C++ prior the C++11 standard. It
might be broken but a nonstandard C++ compiler might support C11-like
_Alignas and _Alignof. Note that it's fatal for g++(1) v.5.4.

/*	$NetBSD: stdalign.h,v 1.1 2016/10/02 17:19:00 kamil Exp $	*/

/*-
 * Copyright (c) 2016 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Kamil Rytarowski.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _STDALIGN_H_
#define _STDALIGN_H_

/*-
 * ISO/IEC 9899:201x 7.15 Alignment <stdalign.h>
 * ISO/IEC N3242=11-0012 (C++1x) 18.10 Other runtime support 6.
 * ISO/IEC N3797 (C++1y) 18.10 Other runtime support 7.
 */

#ifndef __alignas_is_defined
#if ((__cplusplus - 0) < 201103L)
#define alignas	_Alignas
#endif
#define __alignas_is_defined 1
#endif /* __alignas_is_defined */

#ifndef __alignof_is_defined
#if ((__cplusplus - 0) < 201103L)
#define alignof	_Alignof
#endif
#define __alignof_is_defined 1
#endif /* __alignof_is_defined */

#endif