220 39423 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicolas Lesser Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Contract attributes and trailing return types Date: Thu, 26 Jul 2018 14:49:10 -0700 Lines: 227 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/alternative; boundary="000000000000d1ace00571edf7c1" X-Trace: blaine.gmane.org 1532641639 21228 195.159.176.226 (26 Jul 2018 21:47:19 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 26 Jul 2018 21:47:19 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDXKNLEUTADRBY4D5HNAKGQEESNLMYI@isocpp.org Thu Jul 26 23:47:15 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f69.google.com ([209.85.218.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fio6L-0005Oi-Q9 for gclcip-std-proposals@m.gmane.org; Thu, 26 Jul 2018 23:47:14 +0200 Original-Received: by mail-oi0-f69.google.com with SMTP id p11-v6sf2495691oih.17 for ; Thu, 26 Jul 2018 14:49:24 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1532641764; cv=pass; d=google.com; s=arc-20160816; b=OSARiIM3X4XZQzZdOMoxnjLnMsNwWcfgsWmdXodJ7GmpTh7Ui9oxDCwNllrg7LB+tA eDNlEcEISvA7vWfwLgu823CJ9YWzBgLuxMbDCzU/KRm7JdMYvE3Saj5y9LpQD2KogXPX XCjt7DgwJtmyWzmuY7hb32e+U4ZGso0JX6fkB+qfLzlPjxN7BPejuvqhqXVW2XzMl2Gi 4knCTzeQy3xiTIKaFnNEvEwNQe47DSym9gxnU2X+IBvlnOt1qB2ia+Lxsbc2cjm+0bfY Xe0UIYaTYgttr5CgcYN1UltQqeCtPHa004ARnCjP/jPp7l3CMyyuKbNETSW4EWIdEHAh JVIQ== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:reply-to:to:subject:message-id:date :from:in-reply-to:references:mime-version:arc-authentication-results :arc-message-signature:dkim-signature:arc-authentication-results; bh=YQX+sXn8ArOjP87fVXf7D4WPRYqSaJyZTEP6tfgQ02k=; b=C51vtdlFvHCmFeO9qtFcarKbyt2qA0bSzQIK2J3qkX6B6QvvMa4FveocVYGjBw/mIE emlz6a3+EiISU3tacEZyPQKZ6JMnbSnGRJeOWKR4DMrCwELsQn6AAuVR+cU+f8wjz9wQ 54yqjauos7AwMVXo0NunYcuJSHpYrp/UuAByCalV9WxHc/3kvWILo0Tg/bfdfAlsAYDH OkeXOWT2nCRaUk76CEwxMUKUBLiHJ9RPjq998rWN3UB7Gjom2Ur5eWeTl0okni59zq4O LJ7ynb57dEUd2Aj8Db5RorO1RxGq7iX0HLdaJw8+DriV7PnfQQJwO4jcAmf6SlX6zi3y E1Zw== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=FphHkghb; spf=pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=blitzrakete@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=YQX+sXn8ArOjP87fVXf7D4WPRYqSaJyZTEP6tfgQ02k=; b=fkouDazzfyGnZOJlTdSWjUePw0/7VMiBBeydEaNG3uBdfvcXKBn6p8fwz/XQs9N1ud 84hd4DnuD7J6Xvfj3YuDCo12R7PDqyxJrmYcNj+GXchEfLcHrQ7bjI5E3Z37l5D5bQt3 /qQcLjbvL/kv9IqcLiOeXU4sj3FYQrzYWUhlx2l8a3J43YvB3Q731g/SwLkVee1g7ZK6 or6Vv3xA2SEhm/QNs9hdJnX3Qc2L3ryptyK4g177oS1jQ7f3IivPxQnRYvEnyoDy8cwT GpO43IpPj0XQi1pyY+5U7+XJF6wHtPCpN2JBvY9ezCexjepNwvZSl290tTivmrGO2kpl TQUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=YQX+sXn8ArOjP87fVXf7D4WPRYqSaJyZTEP6tfgQ02k=; b=mSPsxgG7+p4j8mYPpRso85sNpg0jnMZSBI/JTvFhL9OBQr9uNeOIoAcIaCI/quw7sB 1zdkFdpBV2BE95cgq4FFQYY3KH559QgWZxJoIbTYLCJMnnADVICcB22DGRJzckM876jK 96Wd05OL3geqaUxNiF4wTKlD6vwmt3HRi3iiO9KJAHTThi0kBi4i3hwbTLzzk4V524GE tGEBEUtMyZ3ODcaoyGiV4VnQQTIg6d8L+/s9CfQGDYW5aO+VcweLVnDWR/0e9vRmLa9V yxUOIn3iQ0Q5AXEXvsAgfOyYlwYPgKtvRBXEZ38GIf9DnTTVny/frrh58Jui57kD4sKI i42g== X-Gm-Message-State: AOUpUlHLY0U6i4d3xno283Lj9eiztU2HbghoayHHQ9sq1+ME5JYXOnsP QSm6wix3C7bQs/BHxV18Ros+VQ== X-Google-Smtp-Source: AAOMgpfKcP71iS2rtWwb7TEV8L0SLtYBIGG33Pt1iXqoTB1GJssgW5EN6Q2mqNppiYH3prH+lw5qjw== X-Received: by 2002:aca:6c53:: with SMTP id h80-v6mr2405798oic.30.1532641764087; Thu, 26 Jul 2018 14:49:24 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:aca:ebd1:: with SMTP id j200-v6ls757291oih.11.gmail; Thu, 26 Jul 2018 14:49:23 -0700 (PDT) X-Received: by 2002:aca:6044:: with SMTP id u65-v6mr4108301oib.323.1532641762957; Thu, 26 Jul 2018 14:49:22 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1532641762; cv=none; d=google.com; s=arc-20160816; b=0VNAhXRnbj076OOf/gegtidi5iVyYA5HRVs5wwLW6wnRxv5iwihAqQbK/es4vgNdTi mq9gNOAU1zC7DiLp8Tsh//+zLbpwse3SlIZqlUd+Pa6fku34Nl6/rCTWxR4bOvV8twxr 1SorP6HxYKK/wU9erR7cA7SN0dgU6IuhNzxLLNThvsmU98b5TSpxwW9Offjze05Q1abt HpajlmmPeZROej+YcKzLcfvvcxv39Fims6rWA0tGbL20a1Lpj7ldcWo0m/4zs286RXzA T4ATJq2hBZkOtmsoFcn2Qdzfl9b/mbB2ZWYxklTiLISw3OdqZ7+180bIriObRdCW3Vhx nxWw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :dkim-signature:arc-authentication-results; bh=avgHiwjIZKaXybYmcQNrDX4cYq7HF0jdFMyEyXlQQSc=; b=R+o4Eukho4WVbX5nF4iTRSwlkP9MiSDQ1TN7Kgl9qoTXX6v4/T52mbudNhXZJHsjgc NAw75SKJILJTNYJwWq2aX6EsKs8eQHc8AdvERajRRUFavP+PawU5t3woJsJO7nDFjisT rmFGTZ+NUFEIc0WsdIbOdTsrxhxZhGOFG3guCWwE7kvmrbaHHDio9gEdW6gUDdofKq7v t1RQf+JAnnL7HVwOd5+DFWtsbCHiCqWhB66/9xq0r8ymQJwRXELa9kvLsmk6uTd3l+i0 6/u2D+V3zJnEuJrFNiiACcT6DLd0oJg6BxNI30OQMW3M3mpUeZA3Ydt1u+6wdOLlcfQd Qgrg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=FphHkghb; spf=pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=blitzrakete@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Original-Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id a6-v6sor1438701oih.153.2018.07.26.14.49.22 for (Google Transport Security); Thu, 26 Jul 2018 14:49:22 -0700 (PDT) Received-SPF: pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:aca:accd:: with SMTP id v196-v6mr3758206oie.125.1532641762453; Thu, 26 Jul 2018 14:49:22 -0700 (PDT) In-Reply-To: X-Original-Sender: blitzrakete@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=FphHkghb; spf=pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=blitzrakete@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=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:39423 Archived-At: --000000000000d1ace00571edf7c1 Content-Type: text/plain; charset="UTF-8" Attributes with trailing return type generally suffer from this problem: auto f(int x, int y) [[deprecated]] -> int; If you don't mind, you can put the contracts before, just like we normally do with attributes: [[expects: x>0]] [[expects: y!=0]] [[ensures result: result > x+y]] auto f(int x, int y) -> int; On Thu, Jul 26, 2018 at 1:02 PM 'Hamza Sood' via ISO C++ Standard - Future Proposals wrote: > If I'm interpreting the current draft standard correctly, it looks like > contract attributes don't work particularly well with trailing return types. > > E.g. here's an example from the proposal, re-written with a trailing > return type: > > > > > > *auto f(int x, int y) [[expects: x>0]] [[expects: y!=0]] [[ensures result: result > x+y]] -> int;* > > > The return type ends up really far away from the rest of the function > declaration, which makes it very difficult to spot. > > I think it'd be better if contract attributes applied to a trailing return > type are considered part of the function declaration, which would mean that > the above could be written as: > > > > > *auto f(int x, int y) -> int [[expects: x>0]] [[expects: y!=0]] [[ensures result: result > x+y]];* > > > -- > 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. > To view this discussion on the web visit > https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/b39be2a8-c0c4-4887-a4ad-d11a50107aa9%40isocpp.org > > . > -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CALmDwq3o0_8STpgWt6NVQ1eejD-krUefpJkk%3DrDmkOK-co-1LQ%40mail.gmail.com. --000000000000d1ace00571edf7c1 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Attributes with trailing return type generally suffer from= this problem:

auto f(int x, int y) [[deprecated]] ->= int;

If you don't mind, you can put the contr= acts before, just like we normally do with attributes:

=
[[expects: x>0]]
[[expects: y!=3D0]]
[[ens= ures result: result > x+y]]
auto f(int x, int y) -> i= nt;


On Thu, Jul 26, 2018 at 1:02 PM 'Hamza Sood' via ISO C++ Standar= d - Future Proposals <std-pr= oposals@isocpp.org> wrote:
<= div dir=3D"ltr">If I'm interpreting the current draft standard correctl= y, it looks like contract attributes don't work particularly well with = trailing return types.

E.g. here's an example from t= he proposal, re-written with a trailing return type:
auto f=
(int x, int y)
=C2=A0 [[expects: x>0]]
=C2=A0 [[exp=
ects: y!=3D0]]
=C2=
=A0 [[ensures result: result &=
gt; x+y]] -> int;

The return type ends up really far away from the rest of the function= declaration, which makes it very difficult to spot.

I think it'd be better if contract attributes applied to a trailing = return type are considered part of the function declaration, which would me= an that the above could be written as:
auto f(int x, int y) -> int
=C2=A0 [[expec= ts: x>0]]
=C2= =A0 [[expects: y!=3D0= ]]
=C2=A0 [[ensures result:= result > x+y]];

--
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-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/b39be2a8-c0c4-= 4887-a4ad-d11a50107aa9%40isocpp.org.

--
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 h= ttps://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CALmDwq3o0_8STp= gWt6NVQ1eejD-krUefpJkk%3DrDmkOK-co-1LQ%40mail.gmail.com.
--000000000000d1ace00571edf7c1-- .