220 40118 article Path: news.gmane.org!.POSTED!not-for-mail From: Arthur O'Dwyer Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: enumerator duplicated value attribute Date: Fri, 7 Sep 2018 18:11:32 -0700 (PDT) Lines: 119 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_474_319017980.1536369092148" X-Trace: blaine.gmane.org 1536368969 13186 195.159.176.226 (8 Sep 2018 01:09:29 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 8 Sep 2018 01:09:29 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDLZJYWNDQIMLQ6M3QCRUBG5QP7BI@isocpp.org Sat Sep 08 03:09:25 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yb1-f199.google.com ([209.85.219.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fyRka-0003L2-AO for gclcip-std-proposals@m.gmane.org; Sat, 08 Sep 2018 03:09:24 +0200 Original-Received: by mail-yb1-f199.google.com with SMTP id g139-v6sf6543653ybf.6 for ; Fri, 07 Sep 2018 18:11:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=BMfYGJCQZzSFdioJWkQMdLWoCrva5Y9N1AAQVGS0Q+M=; b=Stp2L7b/p8Z7hoDDkRnT5zvyUmUWAEZ+oUzR0y9IpSB74AlN5PLaz7hsiWo6ClHb07 Ju7Wpu7Y696bgWsXiIl6HrKpqlxEGSY5uuSj2Mye6HyoUfDMrIZ41u/Ug0z9k05gnl2H jrGmN6TY8Sol2M4DbLwqyeMDVQnfWgSpC+a88Gfa9UvQDkotowg3y88H5bbiZ03CPdzm 7G31lSkgCEsxWFxonfEJELEU7Ku5vRbn8yZYBAtP4YSj/gZH+sowadv8M32s5CzkeedY otIbWFM4IYT9t/13ZZNUTsXQgmqT/3nEyPr4+dNwALeXqWCCDmYfCtPaM1nJWRW0v5oj mRHA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=BMfYGJCQZzSFdioJWkQMdLWoCrva5Y9N1AAQVGS0Q+M=; b=Sc1Lb2mF6uM68FVV84E87WfZcDJC7rmOcVgg9Dqs8jwyE+k0M2GTiRzjkgHqQPDrH7 VgX9w3wN6LOIAB7dTa3asmH82Dd47yaLo/jnMEdtq7ssjA4keCwE1l2g3xuJJeaoSIaY 0XOwlQfEZAztKJFvJL/vWGInmrsDBH+Rf7AIQ+aHPW9MbBmOxB57G4//2ofTJVt4OYgq JvrR6jv3MSc4+1TQicIQbobxZ2qD0b/TPWt5ENzIrxLir4wNJS2PcHsCw/QHxY3HqfB3 jmRMRSUNIqI/2YUvh7L08AFWLKKQpXdOZS43BGMC7gH0bdWDq8euYI3B7rRrZfbqq69K WkVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version: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=BMfYGJCQZzSFdioJWkQMdLWoCrva5Y9N1AAQVGS0Q+M=; b=Osp5Ok8XQjZtT3PsRsFAzHEAR2NSVoaIl2z0STLPs2xTYJnSDIh9mOGWyRRuF2zhnF Kb1e5SH0ND9LO+v1XuQM9nweBC4d2dg4z7klI1nRRctlJHu9U6k7986WtLgyg30s3DIL QBVomLC/SzH1sgx65IBzu4i7pb8GbWVe7oN8AFqhArxTP6O95ZpOqz7mCqgNI+yhneXD kpVmFhLilnZsh24rnAEZN9n+RWNCyFUuGMKXWNoSNnyy5K7HhOuT7g8Z1ZpJ04qxJjYs 0pdBnShTj8/4F0+dSTaeja6pzI8xwpww4bMTr8iSYhJ44O7nRLfBR2a7UJ/QpzihL1Ox T0fQ== X-Gm-Message-State: APzg51BF95YpDEFUyYys9NvJZXci9FpWngVizA+CicFZRBhVWl8/CvnO +juTG86Xnrq8+OEvphSzt0N7Zg== X-Google-Smtp-Source: ANB0VdYZ06l61UPkRv3U0KvMTtu11MnKaxKTUnnYMS072r+iJCvai0XWZMsrYRmup6LO0uIYn2YU0Q== X-Received: by 2002:a0d:e253:: with SMTP id l80-v6mr2522470ywe.78.1536369094170; Fri, 07 Sep 2018 18:11:34 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a25:c50a:: with SMTP id v10-v6ls205330ybe.2.gmail; Fri, 07 Sep 2018 18:11:33 -0700 (PDT) X-Received: by 2002:a25:3857:: with SMTP id f84-v6mr92972yba.3.1536369092784; Fri, 07 Sep 2018 18:11:32 -0700 (PDT) In-Reply-To: X-Original-Sender: arthur.j.odwyer@gmail.com 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:40118 Archived-At: ------=_Part_474_319017980.1536369092148 Content-Type: multipart/alternative; boundary="----=_Part_475_1053782367.1536369092148" ------=_Part_475_1053782367.1536369092148 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Friday, September 7, 2018 at 11:55:57 AM UTC-7, Daniel Gutson wrote: > > Hi, > > sometimes is important to prevent duplication of enumerators in the=20 > enumerations. That's why some compilers such as clang has the=20 > -Wduplicate-enum. > However there are cases such as ranges within enums, where enumerators=20 > define a category and then are followed by the first element of the=20 > category, with the same value. > > enum Ranges > { > CategoryX =3D 100, > X1 =3D CategoryX, > X2, > X3 > CategoryY =3D 200 > // ... > }; > What Chris said: this code is already acceptable to Clang. However, if you do ever run into a situation where Clang is giving you a=20 warning that is "usually correct but I don't want to see it in this=20 particular case," there already exists markup to indicate that situation: enum Ranges { CategoryX =3D 100, X1 =3D CategoryX, X2, X3, #pragma clang diagnostic push #pragma clang diagnostic ignored "-Wduplicate-enum" DeprecatedNameX1 =3D X1, DeprecatedNameX2, DeprecatedNameX3, #pragma clang diagnostic pop }; Unfortunately, Clang currently has what-I-consider-a-bug in that it=20 requires you to put the pragma on the *first* occurrence of the value,=20 rather than on the *duplicate* occurrence. I've filed a bug report=20 . =E2=80=93Arthur --=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/e08984e8-9697-44d9-a603-2af646852647%40isocpp.or= g. ------=_Part_475_1053782367.1536369092148 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Friday, September 7, 2018 at 11:55:57 AM UTC-7, Daniel = Gutson wrote:
= Hi,

=C2=A0 =C2=A0sometimes is important to prevent dupli= cation of enumerators in the enumerations. That's why some compilers su= ch as clang has the -Wduplicate-enum.
However there are cases suc= h as ranges within enums, where enumerators define a category and then are = followed by the first element of the category, with the same value.

enum Ranges
{
=C2=A0 =C2=A0 CategoryX= =3D 100,
=C2=A0 =C2=A0 =C2=A0 =C2=A0X1 =3D CategoryX,
= =C2=A0 =C2=A0 =C2=A0 =C2=A0X2,
=C2=A0 =C2=A0 =C2=A0 =C2=A0X3
=C2=A0 =C2=A0 =C2=A0CategoryY =3D 200
=C2=A0 =C2=A0 =C2=A0 = =C2=A0// ...
};

What = Chris said: this code is already acceptable to Clang.
However, if= you do ever run into a situation where Clang is giving you a warning that = is "usually correct but I don't want to see it in this particular = case," there already exists markup to indicate that situation:

enum Ranges {
=C2=A0 =C2=A0 CategoryX =3D 100,<= /div>
=C2=A0 =C2=A0 X1 =3D CategoryX,
=C2=A0 =C2=A0 X2,
=
=C2=A0 =C2=A0 X3,
#pragma clang diagnostic push
#p= ragma clang diagnostic ignored "-Wduplicate-enum"
=C2= =A0 =C2=A0 DeprecatedNameX1 =3D X1,
=C2=A0 =C2=A0=C2=A0Deprecated= NameX2,
=C2=A0 =C2=A0=C2=A0DeprecatedNameX3,
#pragma cl= ang diagnostic pop
};

Unfortunately, Cla= ng currently has what-I-consider-a-bug in that it requires you to put the p= ragma on the first occurrence of the value, rather than on the du= plicate occurrence. I've filed a bug report.

=E2=80=93A= rthur

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/e08984e8-9697-44d9-a603-2af646852647= %40isocpp.org.
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