220 19372 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 11:09:54 -0700 (PDT) Lines: 173 Approved: news@gmane.org Message-ID: References: <53281455.oCxcCYIyeX@tjmaciei-mobl4> <726831ee-89c5-4bc5-96cc-6d5855843a03@isocpp.org> <4632341.dbW0eupDvr@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_161_337512148.1438106994243" X-Trace: ger.gmane.org 1438107009 20161 80.91.229.3 (28 Jul 2015 18:10:09 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 28 Jul 2015 18:10:09 +0000 (UTC) Cc: isocppgroup@denisbider.com, thiago@macieira.org To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCWZXNPJO4IPHCW7VUCRUBE22SBTE@isocpp.org Tue Jul 28 20:09:57 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f72.google.com ([209.85.218.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZK9K9-0002cd-3W for gclcip-std-proposals@m.gmane.org; Tue, 28 Jul 2015 20:09:57 +0200 Original-Received: by oiax136 with SMTP id x136sf258955387oia.2 for ; Tue, 28 Jul 2015 11:09:56 -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=C/3VJI0O0sPdhsVB5pHWd1PJYZM+cTPsjcsiRcMedjU=; b=K0Qvk1//bGqkhw+V7Mjpwpg+ReAdsMtiZEGDG4V52IFOYRrQY7tq5P9UXXzJemZlJE t8z8Epi52RlamhVSCnY3eq8dfl3eEmpYzohLuxsxNSC7PN3n4hH6eM4FeX1GQvb636sy xjTohCuTyKwzlMWus7uFSINgYTp7oWX45tFGkzGlqSuE3FbnFlgCdkiRDk2YV2h9IoKM p07HbyMhBKWi9N/wvGCZWpdZ/dhn6QrwlEnv8jV7LbKA0lszFBT28XoJgbA54/ojvOLC kOPOAlIQl5c8udtvSljJWdffODnJqTg2dDLNtlpkKbMJPkBVFbJ7RO0SnP7JNfB9RxsQ bYOA== X-Gm-Message-State: ALoCoQl4yEnc8OAwp/5F6aTw9fHfaNbIPrPQD/8c9cA5+icoqxDBeA25nM/NdBp8hsMj0+Q1wZ4F X-Received: by 10.50.8.1 with SMTP id n1mr4990962iga.1.1438106996154; Tue, 28 Jul 2015 11:09:56 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.50.208 with SMTP id e16ls1362213igo.4.gmail; Tue, 28 Jul 2015 11:09:55 -0700 (PDT) X-Received: by 10.50.36.6 with SMTP id m6mr86150igj.15.1438106995580; Tue, 28 Jul 2015 11:09:55 -0700 (PDT) In-Reply-To: <4632341.dbW0eupDvr@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:19372 Archived-At: ------=_Part_161_337512148.1438106994243 Content-Type: multipart/alternative; boundary="----=_Part_162_1193958586.1438106994243" ------=_Part_162_1193958586.1438106994243 Content-Type: text/plain; charset=UTF-8 On Monday, July 27, 2015 at 4:09:18 PM UTC-7, Thiago Macieira wrote: > > 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 > > 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. -- --- 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_162_1193958586.1438106994243 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Monday, July 27, 2015 at 4:09:18 PM UTC-7, Thiago Macieira wrote:On Monday 27 July 2015 15:24:59 denis= bider wrote:
> Indeed; the compiler would then be expected to behave as if it lau= nched a
> child process of itself to compile that code, and report back on a= ny
> errors. If a compiler is well-architected - does not rely on globa= l objects
> and such to store state - it should be possible to do this without
> launching a separate process.
>=20
> I guess, if you are saying this is hard, you're saying many co= mpilers are
> poorly implemented? Use global state such that they can't crea= te another
> instance of the compiler in-process?

"Poorly implemented" is a subjective quality assessment, unle= ss you make the=20
objective measurement of whether it does what it set out to do. Since t= hose=20
compilers are working and are getting modified rapidly by their develop= er teams=20
to add features, we cannot honestly say that any of them is poorly=20
implemented, however we may feel about their architecture.

Some architectures may be welcoming of some new changes and some others= =20
wouldn't. And if the committee approves a certain feature, the deve= lopers will=20
have to implement the functionality.

I was just warning that there might be quite a lot of resistance from t= he=20
compiler writers, given the architectural issues I mentioned, plus:
=C2=A0- there's already a solution for some of the use-cases presen= ted, including=20
=C2=A0 foremost the one you presented
=C2=A0- it does not go far enough to the very common case of linking a = test program=20
=C2=A0 =C2=A0to see if a function does exist in a library or the not-as= -common case of
=C2=A0 =C2=A0running a test program to see how it behaves.

--=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


My concern is that we couldn't trust the comp= iler makers to properly set these macros EVEN IF they were making their bes= t effort.=C2=A0 By definition, they won't likely know if a feature is s= ufficiently bug free until it has spent some time accruing bug reports.
=
I believe the 'best' solution would be to have a community main= tained include file to do this based on versions that everyone could pull i= nto their projects.=C2=A0 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-fre= e and tag appropriately.

--

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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.
To post to this group, send email to std-proposals@isocpp.org.
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