220 19376 <83b0b0ba-1aa3-40b7-9bb3-08a9e564fa0c@isocpp.org> article Path: news.gmane.org!not-for-mail From: Erich Keane Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Testing for supported features: Per-feature macros? Sentinel compilation? Date: Tue, 28 Jul 2015 14:15:39 -0700 (PDT) Lines: 159 Approved: news@gmane.org Message-ID: <83b0b0ba-1aa3-40b7-9bb3-08a9e564fa0c@isocpp.org> References: <4632341.dbW0eupDvr@tjmaciei-mobl4> <2435938.M1snUpQCpx@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4906_799861443.1438118139956" X-Trace: ger.gmane.org 1438118149 6869 80.91.229.3 (28 Jul 2015 21:15:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 28 Jul 2015 21:15:49 +0000 (UTC) Cc: thiago@macieira.org To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCWZXNPJO4IP3YO7VUCRUBD5VKF6Q@isocpp.org Tue Jul 28 23:15:44 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f200.google.com ([209.85.213.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZKCDv-00085q-HU for gclcip-std-proposals@m.gmane.org; Tue, 28 Jul 2015 23:15:43 +0200 Original-Received: by igbqa2 with SMTP id qa2sf316023igb.0 for ; Tue, 28 Jul 2015 14:15:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-type:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=GK9d2ZY/AcVnhCs+7S2Gt3omGnyErpgNXkfY0HFQgHM=; b=cJqBVVaSkKFHqpnjKy8OW4ytypa92JeUMqB3K2gqbj78aRGQZXG1Xmazw60izV0OTo /CQQWxG7pN9MmY/plOd4pjEywgMD1Wkb+IfJ7LxHxk/i4roKu18V7flGjokRCN0q+IBJ PeewW1kkjEIPA/2p+DkdE9Q2KpHQDqbsCKjWKCZWnHH5dMB6O8+BSOypjQwbV2KQCwzQ XDd+E/2/fGOLG0az4oNNXf4pddC4O3Fy0DYAbeMy7uOueTUfhXzE5GE1KcxGwR2nOcAn DvphHrDUC7c4KZYxROlOkZ3yV/N8V4j1KoTWiclGxFPZPzvWaFBU4vZB+9F9CDh9w7eR bpkg== X-Gm-Message-State: ALoCoQljebX/SXx0kIjf3ef0edbPpk/28iW8e1xHICJ67u3Drha85IxJj5aLNX5xxiGseZxcb053 X-Received: by 10.107.164.40 with SMTP id n40mr36937812ioe.30.1438118142051; Tue, 28 Jul 2015 14:15:42 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.79.196 with SMTP id l4ls1141763igx.22.canary; Tue, 28 Jul 2015 14:15:41 -0700 (PDT) X-Received: by 10.50.102.71 with SMTP id fm7mr104060igb.8.1438118141227; Tue, 28 Jul 2015 14:15:41 -0700 (PDT) In-Reply-To: <2435938.M1snUpQCpx@tjmaciei-mobl4> X-Original-Sender: erich.keane@verizon.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:19376 Archived-At: ------=_Part_4906_799861443.1438118139956 Content-Type: multipart/alternative; boundary="----=_Part_4907_1984553317.1438118139957" ------=_Part_4907_1984553317.1438118139957 Content-Type: text/plain; charset=UTF-8 On Tuesday, July 28, 2015 at 11:19:03 AM UTC-7, Thiago Macieira wrote: > > On Tuesday 28 July 2015 11:09:54 Erich Keane wrote: > > My concern is that we couldn't trust the compiler makers to properly set > > these macros EVEN IF they were making their best effort. By definition, > > they won't likely know if a feature is sufficiently bug free until it > has > > spent some time accruing bug reports. > > > > I believe the 'best' solution would be to have a community maintained > > include file to do this based on versions that everyone could pull into > > their projects. A simple github file with these definitions based on > the > > major compilers, as long as it is sufficiently maintained, would do a > lot > > better than trusting that the compiler manufacturers release bug-free > and > > tag appropriately. > > Erich has a point and I can actually attest to that. If you look at Qt's > qcompilerdetection.h file, you'll see quite a few places where the Qt > C++11 > feature macros disagree with the official tables from the compiler vendors > because the feature is either broken or incomplete. > > The most common cases are when one mixes the compiler from one vendor with > the > Standard Library from another. Even modern and recent libraries like > libc++ > have faults there because they aren't often tested with other compilers > besides the one from the same vendor. > > So, yeah, maybe we should keep a central list outside of the compiler so > that > it can be updated to indicate compiler bugs. > > We'll just have to squabble over a bug is really worth disabling a > feature. > -- > 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 > > I'd imagine that boost has a similar file. Perhaps someone needs to just implement the macros defined in 4440 in a github somewhere as a cross-product of the Qt and boost (and whichever other major projects have something like this!) as a starting piont. -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_4907_1984553317.1438118139957 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tuesday, July 28, 2015 at 11:19:03 AM UTC-7, Thiago Macieira wrote:On Tuesday 28 July 2015 11:09:54 Er= ich Keane wrote:
> My concern is that we couldn't trust the compiler makers to pr= operly set
> these macros EVEN IF they were making their best effort. =C2=A0By = definition,
> they won't likely know if a feature is sufficiently bug free u= ntil it has
> spent some time accruing bug reports.
>=20
> I believe the 'best' solution would be to have a community= maintained
> include file to do this based on versions that everyone could pull= into
> their projects. =C2=A0A simple github file with these definitions = based on the
> major compilers, as long as it is sufficiently maintained, would d= o a lot
> better than trusting that the compiler manufacturers release bug-f= ree and
> tag appropriately.

Erich has a point and I can actually attest to that. If you look at Qt&= #39;s=20
qcompilerdetection.h file, you'll see quite a few places where the = Qt C++11=20
feature macros disagree with the official tables from the compiler vend= ors=20
because the feature is either broken or incomplete.

The most common cases are when one mixes the compiler from one vendor w= ith the=20
Standard Library from another. Even modern and recent libraries like li= bc++=20
have faults there because they aren't often tested with other compi= lers=20
besides the one from the same vendor.

So, yeah, maybe we should keep a central list outside of the compiler s= o that=20
it can be updated to indicate compiler bugs.

We'll just have to squabble over a bug is really worth disabling a = feature.
--=20
Thiago Macieira - thiago (AT) maciei= ra.info - thiago (AT) kde.org
=C2=A0 =C2=A0Software Architect - Intel Open Source Technology Center
=C2=A0 =C2=A0 =C2=A0 PGP/GPG: 0x6EF45358; fingerprint:
=C2=A0 =C2=A0 =C2=A0 E067 918B B660 DBD1 105C =C2=A0966C 33F5 F005 6EF4= 5358



I'd imagine that boost has a similar file= ..=C2=A0 Perhaps someone needs to just implement the macros defined in 4440 = in a github somewhere as a cross-product of the Qt and boost (and whichever= other major projects have something like this!) as a starting piont.

--

---
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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
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