From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: CPP indentation bikeshed (was: Emacs master build failing on RHEL 6.8) Date: Wed, 8 May 2019 21:25:22 -0700 Organization: UCLA Computer Science Department Message-ID: <5415dddf-325e-52ae-f05a-9d952933738d@cs.ucla.edu> References: <834l66jpty.fsf@gnu.org> <831s1ajo0w.fsf@gnu.org> <342C2B19-E4BB-40FE-B979-74B72FF96442@acm.org> <698f97fc-5034-5a82-247c-5d727af0135e@cs.ucla.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="235302"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 Cc: =?UTF-8?Q?Mattias_Engdeg=c3=a5rd?= , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu May 09 06:25:34 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hOacf-000z5a-Fm for ged-emacs-devel@m.gmane.org; Thu, 09 May 2019 06:25:33 +0200 Original-Received: from localhost ([127.0.0.1]:47726 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOace-0007kT-GY for ged-emacs-devel@m.gmane.org; Thu, 09 May 2019 00:25:32 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:59352) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOacY-0007kC-Aa for emacs-devel@gnu.org; Thu, 09 May 2019 00:25:27 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hOacX-0007gS-Hq for emacs-devel@gnu.org; Thu, 09 May 2019 00:25:26 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:33390) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hOacX-0007fX-Cc for emacs-devel@gnu.org; Thu, 09 May 2019 00:25:25 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 45F1016199A; Wed, 8 May 2019 21:25:23 -0700 (PDT) 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 TDc5EZFNNg96; Wed, 8 May 2019 21:25:22 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 88785161909; Wed, 8 May 2019 21:25:22 -0700 (PDT) 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 7907Lo1lVrmS; Wed, 8 May 2019 21:25:22 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 5E09F16186B; Wed, 8 May 2019 21:25:22 -0700 (PDT) In-Reply-To: Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x 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:236320 Archived-At: Stefan Monnier wrote: > CPP doesn't know anything about C's > syntactic structure (such as {...} nesting) That's going a bit too far, as cpp does knows about C's comments and about C's parentheses and commas. True, cpp pays no special attention to { and }. My own feeling is that in cases like these, utility trumps philosophical consistency. When an '#if' is required but otherwise has the function of a plain 'if', the code is clearer when indented consistently with plain 'if' as this gives the reader a simple and helpful visual cue: an indented "#" means that the preprocessor code is following the normal C syntactic structure, whereas an unindented "#" means the preprocessor code is unusual and is breaking the normal C structure. Always shoving the "#" to the left loses this useful information and forces the reader to work harder.