220 34843 article Path: news.gmane.org!.POSTED!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: diagnosing "unused" variables that are only constructed Date: Thu, 12 Oct 2017 18:11:17 -0400 Lines: 33 Approved: news@gmane.org Message-ID: References: <01889e44-d529-1852-b0a0-a69484b5783f@gmail.com> <90d0428b-f5a1-3749-b9cd-b0cbeac5f422@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1507846285 22114 195.159.176.226 (12 Oct 2017 22:11:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 12 Oct 2017 22:11:25 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 Cc: gmisocpp@gmail.com To: std-proposals@isocpp.org, janwilmans@gmail.com Original-X-From: std-proposals+bncBC37LBFWUIFBBCGR77HAKGQET2LN6UA@isocpp.org Fri Oct 13 00:11:21 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qt0-f198.google.com ([209.85.216.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e2lhC-0004Jb-5O for gclcip-std-proposals@m.gmane.org; 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[66.194.253.20]) by smtp.googlemail.com with ESMTPSA id l66sm6742652ywd.98.2017.10.12.15.11.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Oct 2017 15:11:19 -0700 (PDT) Original-Newsgroups: gmane.comp.lang.c++.isocpp.proposals In-Reply-To: Content-Language: en-US X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=cpNGN5ZT; spf=pass (google.com: domain of mwoehlke.floss@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=mwoehlke.floss@gmail.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: 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:34843 Archived-At: On 2017-10-12 17:46, janwilmans@gmail.com wrote: > What I was suggesting is that by introducing a syntax to explicitly make > something unnamed, the compiler would then be free to emit warnings for all > other cases where an object is not referenced after construction, without > needed to evaluate whether the constructor/destruction has side-effects or > not. > > This is what you wanted right? Yeeeee...maybe? I seem to recall that defining "not referenced after construction" was not so simple as it seems. > On the other hand, I don't really see the value in putting that specific > warning in the standard itself, but any compiler would be free do to do it > and it would be easier to implement. In any case, I don't think the standard would have anything stronger than a suggestion regarding warnings. (IIRC, there is anyway no such thing as a "warning" in the standard.) What would be proposed would be an attribute to annotate types that should not produce such warnings. IOW, the only actual *standardese* would be that an attribute with such-and-such name exists. -- Matthew -- 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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