220 29239 <3a2b221b-0234-715c-b9d8-1504314c5b87@gmail.com> article Path: news.gmane.org!.POSTED!not-for-mail From: Andrey Semashev Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: pragma once Date: Sat, 29 Oct 2016 21:50:33 +0300 Lines: 45 Approved: news@gmane.org Message-ID: <3a2b221b-0234-715c-b9d8-1504314c5b87@gmail.com> References: <2c278558-0dbc-4568-9b6b-7f159c94707e@isocpp.org> <4610802.tOzma7na2T@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed X-Trace: blaine.gmane.org 1477767040 5322 195.159.176.226 (29 Oct 2016 18:50:40 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 29 Oct 2016 18:50:40 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCXY5TXHWYJRB7G62PAAKGQESULTOBQ@isocpp.org Sat Oct 29 20:50:35 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wm0-f70.google.com ([74.125.82.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1c0YiA-0000bE-Id for gclcip-std-proposals@m.gmane.org; Sat, 29 Oct 2016 20:50:34 +0200 Original-Received: by mail-wm0-f70.google.com with SMTP id 79sf47080051wmy.6 for ; Sat, 29 Oct 2016 11:50:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=zweZtmked9zXfOh5pQrIVWDn2rBX3/tAshBNGRFpTg0=; b=XHpRWXKWx+5rQG9mNsARmPob6/XdLkKn83p/Y/bRFbSrxebByaGh2Uz8haMo1SrQmm S+N1eTEAMfH7HIrqSA/SiMFj2pkSHRodxh6mJI/2+8SKbhIma8dXy55WraS8fjeHyQTA v3FKhjcpnxyTxyn/EAbiKG7dgbqXd4CcOpNfTWsc0GuXbzgzhYWxQh4Pd6a+SPaGBfim Fd42Yq9vTxxwWxEfi557QSNiEbXA2XZ/hOuwWBtTPcXxYwArbIpbf6Z/XFuA4bZodBVL 4qfWtbizziHl/zqalMgMU72TURe7rACS3CVBzLJ7Bm40dMtuRrulDU6bHS09IvWI1ddu QGQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=zweZtmked9zXfOh5pQrIVWDn2rBX3/tAshBNGRFpTg0=; b=emurJBZQmGnOqDOnrbbogHEVN+qYILYaNNqk+X79/qufKtHdYyOTHipmzAPOhTnFeE yEV2XmegYBTNs4xKTDqkpDRV+UbAYdgRGjRIjb/dtXfCUAyrtyIMWA1F/SxF93ZokNzM eb8G/mlqJA7A6i4C9wGG3BXzPPzgpYmNZPKpKTPpzGpklYbSckYa2IdoW5cPqr6wTpYG ucTqPdoE24ie/CWBeii60ka66KSd3ETszGcmWVZBxbHHTPiovSQ4C8Dm4zIT7AShPtlM QHyTxRwlV8CtP9t+PKEcKKRsJZyIYdikVCykbX1DjL95MFhJ8zXvFVu3wAcNGDljrhXo gxRg== X-Gm-Message-State: ABUngvdQ22AGJVKch8sDslafOGMDMh9lW6BrRKZFHhBGg40A8GDq67edSO68kPt0oxArcQ== X-Received: by 10.28.25.3 with SMTP id 3mr300786wmz.22.1477767037402; Sat, 29 Oct 2016 11:50:37 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.195.67 with SMTP id t64ls680992lff.17.gmail; Sat, 29 Oct 2016 11:50:35 -0700 (PDT) X-Received: by 10.25.19.220 with SMTP id 89mr9296552lft.179.1477767035751; Sat, 29 Oct 2016 11:50:35 -0700 (PDT) Original-Received: from mail-lf0-x22f.google.com (mail-lf0-x22f.google.com. [2a00:1450:4010:c07::22f]) by mx.google.com with ESMTPS id x205si11299880lfa.239.2016.10.29.11.50.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Oct 2016 11:50:35 -0700 (PDT) Received-SPF: pass (google.com: domain of andrey.semashev@gmail.com designates 2a00:1450:4010:c07::22f as permitted sender) client-ip=2a00:1450:4010:c07::22f; Original-Received: by mail-lf0-x22f.google.com with SMTP id b81so78060943lfe.1 for ; Sat, 29 Oct 2016 11:50:35 -0700 (PDT) X-Received: by 10.25.27.69 with SMTP id b66mr13008192lfb.36.1477767035009; Sat, 29 Oct 2016 11:50:35 -0700 (PDT) Original-Received: from [192.168.1.2] (broadband-90-154-68-136.nationalcablenetworks.ru. [90.154.68.136]) by smtp.googlemail.com with ESMTPSA id v62sm3031478lfa.44.2016.10.29.11.50.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Oct 2016 11:50:34 -0700 (PDT) In-Reply-To: X-Original-Sender: andrey.semashev@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of andrey.semashev@gmail.com designates 2a00:1450:4010:c07::22f as permitted sender) smtp.mailfrom=andrey.semashev@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:29239 Archived-At: On 10/29/16 21:08, Nevin Liber wrote: > On Thu, Oct 27, 2016 at 6:06 PM, Andrey Semashev > > wrote: > > On Fri, Oct 28, 2016 at 1:17 AM, Nevin Liber > wrote: > > > > There are three possibilities: > > > > 1. It is the same file according to the OS (e.g.: inode and device > match). > > 2. It must have different contents according to the OS (e.g. the > size doesn't > > match). > > I think, the above two bullets cannot be implemented reliably. Event > the size may not be available if the source is read from a pipe. > > > Honestly, I don't particularly care about insane development > environments. You should, if you plan to make a proposal. > I also don't know of any requirement that compilers must > be single pass. And even if so, caching should be able to address it. > Do you have a real world situation involving #pragma once and pipes > instead of regular files? I don't. But compilers do support reading input from a pipe, and nothing prevents #once to appear in that input. Compiler vendors have to implement #once in those circumstances as well, with behavior equivalent to the proposal. > And because of modules, I'm not even sure pursing a #once solution > (without specifying an identifier) is worth it. I won't argue with this. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/3a2b221b-0234-715c-b9d8-1504314c5b87%40gmail.com. .