220 19330 <4632341.dbW0eupDvr@tjmaciei-mobl4> article Path: news.gmane.org!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Testing for supported features: Per-feature macros? Sentinel compilation? Date: Mon, 27 Jul 2015 16:09:12 -0700 Lines: 43 Approved: news@gmane.org Message-ID: <4632341.dbW0eupDvr@tjmaciei-mobl4> References: <53281455.oCxcCYIyeX@tjmaciei-mobl4> <726831ee-89c5-4bc5-96cc-6d5855843a03@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1438038565 30053 80.91.229.3 (27 Jul 2015 23:09:25 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 27 Jul 2015 23:09:25 +0000 (UTC) Cc: ISO C++ Standard - Future Proposals To: denis bider Original-X-From: std-proposals+bncBCB4TK757YBRBG7U3KWQKGQE34QGB4A@isocpp.org Tue Jul 28 01:09:18 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f70.google.com ([209.85.215.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZJrWH-0002oI-GY for gclcip-std-proposals@m.gmane.org; Tue, 28 Jul 2015 01:09:17 +0200 Original-Received: by laah7 with SMTP id h7sf32082179laa.2 for ; Mon, 27 Jul 2015 16:09:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-type: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=6SZrsK4BO0DZ7/PJfvNcSyGaD24pAVW+j7YaOXWmUVE=; b=arw6JZZYp1PfpycVdh2egZrst7ROPkRPZI2sG/TCVLWlS+NnpTVPnKl8P6apM6K6yW FdfB4LOMF403oYFaBoepc1oKcEq6riQsdKfwsLWJ7t9awW5N7t1GYKsmW6RGPRAXUm7F 6L+Z8bCNB+CDOjOtYKVx0SR0PlFXWmpnq/MiRpkhVGtsdGXbNIskd4vdq1UUGGOMlv5Z ZfJNHZ+8sEQO95v+w82G33r4yPWj7bKUJfNYsGV3bnhK3YJ29f9q+kxvhFsCWnf69wYv fVcrSbToDbO+LHr0YIv1qznwYGEjtJoMrsATCYwGbBnWyX9lrlDviM+tSAjlu4nQ+68b bZ X-Gm-Message-State: ALoCoQn7zP3L0P05uOsNj52SRAhaDH6lmuNIfZ9F7ANo0oTpLVcakFsFGJneHOQ6/67XT1Cp0JUM X-Received: by 10.112.9.100 with SMTP id y4mr12864945lba.20.1438038557028; Mon, 27 Jul 2015 16:09:17 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.83.200 with SMTP id s8ls751449wiy.48.canary; Mon, 27 Jul 2015 16:09:15 -0700 (PDT) X-Received: by 10.194.77.70 with SMTP id q6mr59084302wjw.70.1438038555257; Mon, 27 Jul 2015 16:09:15 -0700 (PDT) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [2a01:4f8:d13:f81:21c:14ff:fe01:12a3]) by mx.google.com with ESMTP id cr5si33412434wjb.214.2015.07.27.16.09.14 for ; Mon, 27 Jul 2015 16:09:15 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) client-ip=2a01:4f8:d13:f81:21c:14ff:fe01:12a3; Original-Received: from tjmaciei-mobl4.localnet (unknown [134.134.139.76]) by gondolin.macieira.info (Postfix) with ESMTPSA id 90BDD11B563; Mon, 27 Jul 2015 16:09:14 -0700 (PDT) User-Agent: KMail/4.14.9 (Linux/4.0.5-3-desktop; KDE/4.14.9; x86_64; ; ) In-Reply-To: <726831ee-89c5-4bc5-96cc-6d5855843a03@isocpp.org> X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) smtp.mail=thiago@macieira.org Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:19330 Archived-At: On Monday 27 July 2015 15:24:59 denis bider wrote: > Indeed; the compiler would then be expected to behave as if it launched a > child process of itself to compile that code, and report back on any > errors. If a compiler is well-architected - does not rely on global objects > and such to store state - it should be possible to do this without > launching a separate process. > > I guess, if you are saying this is hard, you're saying many compilers are > poorly implemented? Use global state such that they can't create another > instance of the compiler in-process? "Poorly implemented" is a subjective quality assessment, unless you make the objective measurement of whether it does what it set out to do. Since those compilers are working and are getting modified rapidly by their developer teams to add features, we cannot honestly say that any of them is poorly implemented, however we may feel about their architecture. Some architectures may be welcoming of some new changes and some others wouldn't. And if the committee approves a certain feature, the developers will have to implement the functionality. I was just warning that there might be quite a lot of resistance from the compiler writers, given the architectural issues I mentioned, plus: - there's already a solution for some of the use-cases presented, including foremost the one you presented - it does not go far enough to the very common case of linking a test program to see if a function does exist in a library or the not-as-common case of running a test program to see how it behaves. -- Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center PGP/GPG: 0x6EF45358; fingerprint: E067 918B B660 DBD1 105C 966C 33F5 F005 6EF4 5358 -- --- 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. 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