220 41230 <0727d34e-0bad-3689-e315-2136bb359e65@honermann.net> article Path: news.gmane.org!.POSTED!not-for-mail From: Tom Honermann Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Modules and preambule, just why? Date: Wed, 5 Dec 2018 23:04:59 -0500 Lines: 68 Approved: news@gmane.org Message-ID: <0727d34e-0bad-3689-e315-2136bb359e65@honermann.net> References: <16989401-2f0d-4200-997e-0ac60b47bec3@isocpp.org> <08290107-c63b-3ef6-09d4-16c7b6c495ab@honermann.net> 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 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1544068977 7649 195.159.176.226 (6 Dec 2018 04:02:57 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 6 Dec 2018 04:02:57 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 Cc: ISO C++ Standard - Future Proposals To: Ville Voutilainen Original-X-From: std-proposals+bncBDBNXSHG6UDBB3F7ULQAKGQEOLR5B6I@isocpp.org Thu Dec 06 05:02:52 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk1-f197.google.com ([209.85.222.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gUksE-0001pG-9e for gclcip-std-proposals@m.gmane.org; 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[146.20.161.115]) by mx.google.com with ESMTPS id l90si1330228qte.331.2018.12.05.20.04.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Dec 2018 20:04:59 -0800 (PST) Received-SPF: pass (google.com: domain of tom@honermann.net designates 146.20.161.115 as permitted sender) client-ip=146.20.161.115; Original-Received: from smtp23.relay.iad3b.emailsrvr.com (localhost [127.0.0.1]) by smtp23.relay.iad3b.emailsrvr.com (SMTP Server) with ESMTP id 72336A06FA; Wed, 5 Dec 2018 23:04:59 -0500 (EST) X-Auth-ID: tom@honermann.net Original-Received: by smtp23.relay.iad3b.emailsrvr.com (Authenticated sender: tom-AT-honermann.net) with ESMTPSA id 47D94A06DD; Wed, 5 Dec 2018 23:04:59 -0500 (EST) X-Sender-Id: tom@honermann.net Original-Received: from [192.168.1.19] (pool-71-176-235-158.rcmdva.fios.verizon.net [71.176.235.158]) (using TLSv1.2 with cipher AES128-SHA) by 0.0.0.0:25 (trex/5.7.12); Wed, 05 Dec 2018 23:04:59 -0500 In-Reply-To: Content-Language: en-US X-Original-Sender: tom@honermann.net X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@honermann.net header.s=20180930-2j89z3ji header.b=lDTF0KNa; spf=pass (google.com: domain of tom@honermann.net designates 146.20.161.115 as permitted sender) smtp.mailfrom=tom@honermann.net; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=honermann.net 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:41230 Archived-At: On 12/5/18 5:04 PM, Ville Voutilainen wrote: > On Wed, 5 Dec 2018 at 23:43, Tom Honermann wrote: >> On 12/5/18 2:01 PM, Ville Voutilainen wrote: >>> On Wed, 5 Dec 2018 at 20:47, wrote: >>>> After reading your answer and thinking about it in the last days, I th= ing I understand things a bit better now. >>>> First I understand that module are far less related to the linking pro= blem than I first tough. >>>> Also, I think I better understand how they will actually work in real = world application. >>>> >>>> Still, one question remains for me: >>>> If for example you wanna ship a library. >>>> As of today, you generally with the library the headers so that people= using the library will be able to compile their code and make use of the l= ibrary you made. >>>> But how does it work if you wanna use modules? do you ship a module fi= le together with the lib? And if so, how do you intend to generate this mod= ule file? >>> Yes, you ship the module interface with your lib. You compile the >>> module for the target implementation you want to support. >> To be clear, I believe Ville means that you ship the module interface >> unit source code (not a binary module artifact as they are not portable) >> and you link any object files produced by compiling the module interface >> unit in your compiled library for your supported platforms. > > I think I mean that you have the choice of shipping 0-N module > interface artifacts and/or the source code. Hmm, Gaby has stated many times that .ifc files are not intended for=20 distribution.=C2=A0 Clang, from what I understand, is not promising=20 compatibility for module artifacts across major releases (which makes=20 compatibility across Xcode and LLVM Clang questionable). Gcc currently=20 ties the module artifact to the svn revision.=C2=A0 I am very much under th= e=20 impression that shipping module artifacts (without the corresponding=20 module interface unit source) will not be a viable choice in practice=20 (at least, not for anyone other than compiler implementors). > Good catch, though, Tom. However, I think the "you compile the module > for the target implementation you > want to support" is 60% correct. (Yeah, I pulled that 60% number out > of my sleeve, it doesn't really mean anything). > For the remaining 40% (the number is, again, completely artificial), > you might want to ship something else, for example the source code. I meant that, if you are shipping a pre-built library, then the portions=20 of the module interface unit that are not "interface" (e.g.,=20 non-template function definitions) probably need to be pre-compiled and=20 linked into the distributed library (which may have its own dependencies=20 on them) unless the expectation is that the recipient link objects=20 produced by compilation of module interface units into their respective=20 binaries (which seems to me a good recipe for ending up with duplicate=20 definition errors at link time).=C2=A0 I'm very curious to see how build=20 systems are going to end up managing this. Tom. --=20 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 e= mail 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/0727d34e-0bad-3689-e315-2136bb359e65%40honermann= ..net. .