From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Why named structs and unions? C11 supports anonymous structs and unions Date: Sun, 11 Feb 2018 19:56:02 -0800 Organization: UCLA Computer Science Department Message-ID: <60430523-09f3-0873-de9f-c134967fdb50@cs.ucla.edu> References: <53a9ab33-cdd5-99b3-aeef-f52776a5bf8d@dancol.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1518407668 15498 195.159.176.226 (12 Feb 2018 03:54:28 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 12 Feb 2018 03:54:28 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 Cc: Emacs Development To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Feb 12 04:54:23 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1el5C4-0003I9-N1 for ged-emacs-devel@m.gmane.org; Mon, 12 Feb 2018 04:54:16 +0100 Original-Received: from localhost ([::1]:35146 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1el5E4-0003x0-G5 for ged-emacs-devel@m.gmane.org; Sun, 11 Feb 2018 22:56:20 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:58451) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1el5Ds-0003vE-Pi for Emacs-devel@gnu.org; Sun, 11 Feb 2018 22:56:09 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1el5Dp-000853-Op for Emacs-devel@gnu.org; Sun, 11 Feb 2018 22:56:08 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:56220) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1el5Dp-00083Y-Iv for Emacs-devel@gnu.org; Sun, 11 Feb 2018 22:56:05 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 0E459160156; Sun, 11 Feb 2018 19:56:04 -0800 (PST) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 8ytBpVaCsgNl; Sun, 11 Feb 2018 19:56:03 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 54ADA160186; Sun, 11 Feb 2018 19:56:03 -0800 (PST) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 1c9uREWZgvUB; Sun, 11 Feb 2018 19:56:03 -0800 (PST) Original-Received: from [192.168.1.9] (unknown [47.154.30.119]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 35AFF160156; Sun, 11 Feb 2018 19:56:03 -0800 (PST) In-Reply-To: <53a9ab33-cdd5-99b3-aeef-f52776a5bf8d@dancol.org> Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:222674 Archived-At: Daniel Colascione wrote: > Now we get all the alignment benefits of alignas, but without the ugly = "u.s." stuff. That assumes C11, though. Currently Emacs assumes only C99. Although Emac= s can=20 use C11 features when 'configure' determines them to work, I don't offhan= d see=20 how this could be done for this particular feature without contorting the= C code=20 even more than it's contorted now. > Instead of XCONS(c)->car, we now write XCONS(c)->u.s.car. Normally in C code we write XCAR (c) instead of writing either form. The = u.s.=20 business is intended to be used only within a small set of source-code lo= cations=20 that need to know the internal structure of Lisp objects, and most C code= =20 shouldn't care whether it's '->car' or '->u.s.car'. Admittedly there are = more=20 occurrences of '->u.s.' than we'd like.