From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-72423-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 24209 invoked by alias); 23 Apr 2003 18:18:56 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 24114 invoked from network); 23 Apr 2003 18:18:53 -0000
Received: from unknown (HELO gash2.peakpeak.com) (207.174.178.17)
  by sources.redhat.com with SMTP; 23 Apr 2003 18:18:53 -0000
Received: from fleche.redhat.com (tf0199.peakpeak.com [204.144.239.199])
	by gash2.peakpeak.com (8.9.3/8.9.3.1) with ESMTP id MAA02668;
	Wed, 23 Apr 2003 12:18:42 -0600
Received: by fleche.redhat.com (Postfix, from userid 1000)
	id 6D3264F80D0; Wed, 23 Apr 2003 12:11:25 -0600 (MDT)
To: Jason Merrill <jason@redhat.com>
Cc: Jamie Lokier <jamie@shareable.org>, Andrew Haley <aph@redhat.com>,
        gcc@gcc.gnu.org
Subject: Re: On alignment
References: <200303251122.13693.kevin.hendricks@sympatico.ca>
	<wvl1y0vmhdv.fsf@prospero.boston.redhat.com>
	<wvlu1drl2kl.fsf@prospero.boston.redhat.com>
	<200303251344.59988.kevin.hendricks@sympatico.ca>
	<wvlhe9rkzgm.fsf@prospero.boston.redhat.com>
	<16037.6826.35777.756256@cuddles.redhat.com>
	<jen0ii4x27.fsf@sykes.suse.de>
	<20030423124944.GA24593@mail.jlokier.co.uk>
	<87wuhlgq5l.fsf@fleche.redhat.com>
	<wvlu1cpdv7s.fsf@prospero.boston.redhat.com>
From: Tom Tromey <tromey@redhat.com>
Reply-To: tromey@redhat.com
X-Attribution:  Tom
X-Zippy:  Uh-oh!!  I'm having TOO MUCH FUN!!
Date: Wed, 23 Apr 2003 18:42:00 -0000
In-Reply-To: <wvlu1cpdv7s.fsf@prospero.boston.redhat.com>
Message-ID: <87lly1f5ir.fsf@fleche.redhat.com>
User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3.50
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-SW-Source: 2003-04/txt/msg01166.txt.bz2

>>>>> "Jason" == Jason Merrill <jason@redhat.com> writes:

[ about  struct foo { double x; } ]

Tom> I'd like to find the most future-proof way to do this.  In the above,
Tom> is __alignof__(foo::x) the best way?  I'm only concerned with
Tom> alignment of fields.

Jason> It is since my recent patch to do all alignment calculation for
Jason> fields in layout_decl.

I can't do this.

    struct aligner { double field; };

    int compute () { return __alignof__ (aligner::field); }

fleche. gcc -c y.cc
y.cc: In function `int compute()':
y.cc:1: error: invalid use of non-static data member `aligner::field'
y.cc:3: error: from this location


I can use __alignof__(aligner), but my concern is that eventually this
will yield "8" instead of "4" on x86.  libgcj really needs to know the
alignment required in structures, for compatibility with the compiler.
Preferably we'd have the compiler tell us this info.

Tom