220 40378 article Path: news.gmane.org!.POSTED!not-for-mail From: Andrew Sandoval Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: =?UTF-8?Q?Re=3A_=5Bstd=2Dproposals=5D_Enforce_explicit_casting_on_assi?= =?UTF-8?Q?gnment_and_return_type_=E2=80=98bool=E2=80=99?= Date: Mon, 8 Oct 2018 10:30:52 -0700 Lines: 207 Approved: news@gmane.org Message-ID: References: <5df28d28-a2f4-47cd-9da7-49c91ed6d6f4@isocpp.org> <2016044.EC7RGCoeXV@tjmaciei-mobl1> <8f3f409b-43ff-4834-a383-2a5b0c5dc66e@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="0000000000004a72bf0577bafc95" X-Trace: blaine.gmane.org 1539019742 11303 195.159.176.226 (8 Oct 2018 17:29:02 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 8 Oct 2018 17:29:02 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDIZ5RW5Y4IBBWFI53OQKGQEYMQBSSQ@isocpp.org Mon Oct 08 19:28:58 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk1-f197.google.com ([209.85.221.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1g9ZKx-0002lu-Ac for gclcip-std-proposals@m.gmane.org; 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[209.85.220.65]) by mx.google.com with SMTPS id g75-v6sor2939884vke.55.2018.10.08.10.31.04 for (Google Transport Security); Mon, 08 Oct 2018 10:31:04 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.220.65 is neither permitted nor denied by best guess record for domain of sandoval@netwaysglobal.com) client-ip=209.85.220.65; X-Received: by 2002:a1f:2a50:: with SMTP id q77-v6mr9630719vkq.14.1539019863905; Mon, 08 Oct 2018 10:31:03 -0700 (PDT) In-Reply-To: X-Original-Sender: sandoval@netwaysglobal.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@netwaysglobal-com.20150623.gappssmtp.com header.s=20150623 header.b=nf34h2JS; spf=neutral (google.com: 209.85.220.65 is neither permitted nor denied by best guess record for domain of sandoval@netwaysglobal.com) smtp.mailfrom=sandoval@netwaysglobal.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:40378 Archived-At: --0000000000004a72bf0577bafc95 Content-Type: text/plain; charset="UTF-8" On Sun, Oct 7, 2018 at 10:05 AM Ville Voutilainen < ville.voutilainen@gmail.com> wrote: > On Sun, 7 Oct 2018 at 19:38, Andrew Sandoval > wrote: > > > > On Saturday, October 6, 2018 at 12:06:08 AM UTC-5, Thiago Macieira wrote: > >> > >> On Friday, 5 October 2018 18:48:32 PDT Johnny Shaw wrote: > >> > While there is value in implicit conversion under some circumstances. > >> > Explicit conversion clearly identifies the intent and eliminates > mistakes. > >> > Enforcing a standard that requires explicit conversion to bool, at > very > >> > least for a return value, will eliminate possible coding errors. > >> > >> And break a lot of existing code. Because of that, you need to provide > strong > >> justification why this should be adopted. > >> > >> -- > >> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org > >> Software Architect - Intel Open Source Technology Center > > > > > > Thiago, > > > > How does a compiler warning break any existing code? > > Very easily, this happens on every major compiler release. A compiler > adds a new warning, enables it under warning flags > that users already use, and -Werror does the rest. > > Ville, of course that is true -- we just saw things break in Visual Studio 2017 due to changes around the register and inline keywords. And frankly, I'm not trying to pick a battle with you or anyone else here -- I know you contribute greatly to C++, but let's be honest... A *warning* doesn't break the code. A *warning* doesn't "break" anything -- it just warns. And in so doing, it provides us opportunities to re-examine old code to see if the warning is warrants changes that might fix real bugs or vulnerabilities. Anyway, there is no point arguing the semantics of the word "break". I really wasn't intended that, just backing up what has been said on the topic, because I have seen where a warning on bool conversion would have saved time and therefore money. And I appreciate very much Thaigo's response to my questions. > > Instead it is going to highlight poorly written code and common mistakes. > > And break valid code that has nothing wrong in it. > > > Keep in mind that things like Intellisense, though very helpful, also > help to introduce additional mistakes. It is a very common thing that the > IDE supplies or completes the wrong variable, and the developer in a hurry > misses it, and then they return something that is NOT a bool for a function > that should return a bool. A compile-time warning would save time, money, > and embarrassment. > > > > Anything we do to improve the compiler's ability to catch mistakes makes > the language better. And one of the selling points of C++ is type safety, > which is frankly fairly badly broken with regards to bool conversions. It > is bad enough that I'm ready to start requiring (in reviews) code to use > enum class instead of bool, even if there are only two choices in the enum > -- because the compiler requires a static_cast to convert and enum class to > any other type, even if you specify a type (as in: enum class MyEnum : > unsigned int). > > Great, then you don't need a language change. > Sure, there are alternatives, and I can make rules around the code base I am responsible for, but that is kind of heartless to everyone else who has to suffer from common mistakes that we could have the compilers catch. Besides, I think the reason Johnny brought this up was as a "proposal" for discussion, not a mandate to you or anyone else. If you can find fault with the suggestion, or argue that mistakes could not be prevented by either recommending a warning, or requiring a cast (e.g. static_cast) on bool conversions, then please do so. You know some of the more intricate details of the language that may elude the rest of us, and your insights would be far more valuable than curt responses. If I seemed to deserve that response, then you have my apology for provoking it. Thanks, Andrew Sandoval -- 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/CAJEeERW_JOmR6JBfrU9cTgVi2Jt_T%3D7BeK07NWoOuLOADPUxhQ%40mail.gmail.com. --0000000000004a72bf0577bafc95 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Sun, Oct 7,= 2018 at 10:05 AM Ville Voutilainen <ville.voutilainen@gmail.com> wrote:
On Sun, 7 Oct 2018 at 19:38, Andrew Sandoval <sandoval@netwaysg= lobal.com> wrote:
>
> On Saturday, October 6, 2018 at 12:06:08 AM UTC-5, Thiago Macieira wro= te:
>>
>> On Friday, 5 October 2018 18:48:32 PDT Johnny Shaw wrote:
>> > While there is value in implicit conversion under some circum= stances.
>> > Explicit conversion clearly identifies the intent and elimina= tes mistakes.
>> > Enforcing a standard that requires explicit conversion to boo= l, at very
>> > least for a return value, will eliminate possible coding erro= rs.
>>
>> And break a lot of existing code. Because of that, you need to pro= vide strong
>> justification why this should be adopted.
>>
>> --
>> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
>>=C2=A0 =C2=A0 Software Architect - Intel Open Source Technology Cen= ter
>
>
> Thiago,
>
> How does a compiler warning break any existing code?

Very easily, this happens on every major compiler release. A compiler
adds a new warning, enables it under warning flags
that users already use, and -Werror does the rest.

Ville, of course that is true -- we just saw things b= reak in Visual Studio 2017 due to changes around the register and inline ke= ywords.=C2=A0 And frankly, I'm not trying to pick a battle with you or = anyone else here -- I know you contribute greatly to C++, but let's be = honest...=C2=A0 A warning=C2=A0doesn't break the code.=C2=A0 A <= i>warning=C2=A0doesn't "break" anything -- it just warns.= =C2=A0 And in so doing, it provides us opportunities to re-examine old code= to see if the warning is warrants changes that might fix real bugs or vuln= erabilities.

Anyway, there is no point arguing the= semantics of the word "break".=C2=A0 I really wasn't intende= d that, just backing up what has been said on the topic, because I have see= n where a warning on bool conversion would have saved time and therefore mo= ney.=C2=A0 And I appreciate very much Thaigo's response to my questions= ..
=C2=A0
> Instead it is going to highlight poorly written code and common mistak= es.

And break valid code that has nothing wrong in it.

> Keep in mind that things like Intellisense, though very helpful, also = help to introduce additional mistakes.=C2=A0 It is a very common thing that= the IDE supplies or completes the wrong variable, and the developer in a h= urry misses it, and then they return something that is NOT a bool for a fun= ction that should return a bool.=C2=A0 A compile-time warning would save ti= me, money, and embarrassment.
>
> Anything we do to improve the compiler's ability to catch mistakes= makes the language better.=C2=A0 And one of the selling points of C++ is t= ype safety, which is frankly fairly badly broken with regards to bool conve= rsions.=C2=A0 It is bad enough that I'm ready to start requiring (in re= views) code to use enum class instead of bool, even if there are only two c= hoices in the enum -- because the compiler requires a static_cast to conver= t and enum class to any other type, even if you specify a type (as in: enum= class MyEnum : unsigned int).

Great, then you don't need a language change.
Sure= , there are alternatives, and I can make rules around the code base I am re= sponsible for, but that is kind of heartless to everyone else who has to su= ffer from common mistakes that we could have the compilers catch.=C2=A0 Bes= ides, I think the reason Johnny brought this up was as a "proposal&quo= t; for discussion, not a mandate to you or anyone else.=C2=A0 If you can fi= nd fault with the suggestion, or argue that mistakes could not be prevented= by either recommending a warning, or requiring a cast (e.g. static_cast) o= n bool conversions, then please do so.=C2=A0 You know some of the more intr= icate details of the language that may elude the rest of us, and your insig= hts would be far more valuable than curt responses.=C2=A0 If I seemed to de= serve that response, then you have my apology for provoking it.
<= br>
Thanks,
Andrew Sandoval

--
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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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To view this discussion on the web visit h= ttps://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAJEeERW_JOmR6J= BfrU9cTgVi2Jt_T%3D7BeK07NWoOuLOADPUxhQ%40mail.gmail.com.
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