220 17242 <3c0b30ba-2947-46cf-82b9-7971bf0d267b@isocpp.org> article Path: news.gmane.org!not-for-mail From: Vittorio Romeo Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: noexcept(auto) Date: Sat, 4 Apr 2015 13:07:36 -0700 (PDT) Lines: 205 Approved: news@gmane.org Message-ID: <3c0b30ba-2947-46cf-82b9-7971bf0d267b@isocpp.org> References: <1657285.u9ziYB6mWs@tjmaciei-mobl4> <273de67b-0d68-42b9-ab94-c69f3f53da79@isocpp.org> <12209035.xqONZKyqh9@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1533_1373248836.1428178056317" X-Trace: ger.gmane.org 1428178065 29506 80.91.229.3 (4 Apr 2015 20:07:45 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 4 Apr 2015 20:07:45 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCO3NDEYZQHRBCMJQGUQKGQEW2XAKWY@isocpp.org Sat Apr 04 22:07:40 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yk0-f197.google.com ([209.85.160.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YeULz-00039Y-3r for gclcip-std-proposals@m.gmane.org; Sat, 04 Apr 2015 22:07:39 +0200 Original-Received: by ykft189 with SMTP id t189sf1595494ykf.0 for ; Sat, 04 Apr 2015 13:07:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=YPoU7SzPFrqHghIJ6UuaQ6Yz677/A3ikENFYXNkXrwk=; b=Z1g23ix/G/zlBbU/R0sKUi5r1io8ROXHcKjJHM7/mTYFZGSeE8N3ZgQuxz6UflfS74 gQ9BFlmlMD0oxLNECFXhAM3rUX/bNYyOFAOj7iwGlGbbLMxlNJrxzRwzAU9S3+p/0atT dg+SomkHt917oMAqrw9EEGbGRkuqvPRl9PuyaA6JP9zyPrzLFdlzf30/gL1fQgklA6m3 rC+A5ZBRs/U1LhaO4TPB8tVqetSSbfB206qtER4Gdyo40hj5wEZ8XZkkIKobKnttDyjO GptNRCUBcBeZpKtp93aMm9BMXjpI/talepgsTGE83R3sDQx1/wIS+rMESnDpIDrARyfw /syw== 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:message-id:in-reply-to:references :subject:mime-version:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=YPoU7SzPFrqHghIJ6UuaQ6Yz677/A3ikENFYXNkXrwk=; b=GZuGiICQwH2gzEN4R5tZgo17jiqro64N/raB730um+Gok4dtzEukCw2cX0HkiesnvR 7CZGpfoqjrQEytDzRk/HMbWXPBNaVS0qklgTqSpa512RbrWW/byWl+hIAcxDBIsuQniI DyKb5oG1qIZoJEpyKPUXCy0hgdOJqD85dZEjWhO2NXcpP6rBuNlgjJG/zZuds5rA/VIj daFAn12KBwHzJj6aLKQRntZBsdIOR36X56H9ry/VGX7U8rWT0NCcqwFDPyd3xggCEq+B a2K8ha8q23YlE9qFImeTSjPFZXAxEmw5Z3ALVQuWZh+qkJIhCnjrFLyvDqcERLg8+zwg ojNQ== X-Gm-Message-State: ALoCoQn1WgkCPMLMcGeTMHi00dP1DSa1rif4ThDPFRseakS5vuUSmRPJPE+fooiBWL8eccYnia3Y X-Received: by 10.52.170.129 with SMTP id am1mr9515919vdc.1.1428178057776; Sat, 04 Apr 2015 13:07:37 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.40.41 with SMTP id w38ls1686507qgw.85.gmail; Sat, 04 Apr 2015 13:07:37 -0700 (PDT) X-Received: by 10.140.101.148 with SMTP id u20mr97605qge.5.1428178057064; Sat, 04 Apr 2015 13:07:37 -0700 (PDT) In-Reply-To: <12209035.xqONZKyqh9@tjmaciei-mobl4> X-Original-Sender: vittorio.romeo.vee@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:17242 Archived-At: ------=_Part_1533_1373248836.1428178056317 Content-Type: multipart/alternative; boundary="----=_Part_1534_1186432343.1428178056318" ------=_Part_1534_1186432343.1428178056318 Content-Type: text/plain; charset=UTF-8 I didn't strive for correctness, just wanted to make a simple example :) In a real-life implementation even `~int()`, `~SomeClass()` and `~decltype(a + b)` have to be checked for noexcept compliancy. (...and probably some more stuff that I'm missing now.) On Saturday, 4 April 2015 21:55:03 UTC+2, Thiago Macieira wrote: > > On Saturday 04 April 2015 12:31:51 Vittorio Romeo wrote: > > I definitely have a lot of occurrences in my code where I repeat the > body > > of small functions in the noexcept qualifier. > > Something like this would help a lot. > > > > Would there be any issue in expanding this feature proposal to > non-one-line > > functions? > > > > Wouldn't the compiler be able to convert something like: > > > > void func() noexcept(auto) > > { > > int a; > > SomeClass b; > > auto c = b + a; > > std::cout << c; > > } > > > > to > > > > void func() noexcept > > ( > > noexcept(int{}) && > > noexcept(SomeClass{}) && > > noexcept(b + a) && > > noexcept(std::cout << c) > > ) > > { > > int a; > > SomeClass b; > > auto c = b + a; > > std::cout << c; > > } > > > > ? > > I don't see why not. And it's probably better than what you wrote, since > you > probably forgot the c assignment: > noexcept(decltype(SomeClass{} + int{}) = decltype(SomeClass{} + > int{})) > > It would also allow you to verify whether your code is really noexcept or > not > like you meant it to be: > > void func() noexcept; > void func() noexcept(auto) > { > int a; > SomeClass b; > auto c = b + a; > std::cout << c; > } > > Since all declarations of the same function need to have the same noexcept > specifier, the compiler needs to provide a diagnostic if the auto case > expands > to a different result from the other declaration. > > -- > 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 > > -- --- 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_1534_1186432343.1428178056318 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I didn't strive for correctness, just wanted to make a sim= ple example :)
In a real-life implementation even `~int()`, `~SomeClass(= )` and `~decltype(a + b)` have to be checked for noexcept compliancy.
(.= ...and probably some more stuff that I'm missing now.)

On Saturday, 4= April 2015 21:55:03 UTC+2, Thiago Macieira wrote:
On Saturday 04 April 2015 12:31:51 Vittorio Romeo wrot= e:
> I definitely have a lot of occurrences in my code where I repeat t= he body
> of small functions in the noexcept qualifier.
> Something like this would help a lot.
>=20
> Would there be any issue in expanding this feature proposal to non= -one-line
> functions?
>=20
> Wouldn't the compiler be able to convert something like:
>=20
> void func() noexcept(auto)
> {
>     int a;
>     SomeClass b;
>     auto c =3D b + a;
>     std::cout << c;
> }
>=20
> to
>=20
> void func() noexcept
> (
>     noexcept(int{}) &&
>     noexcept(SomeClass{}) &&
>     noexcept(b + a) &&
>     noexcept(std::cout << c)
> )
> {
>     int a;
>     SomeClass b;
>     auto c =3D b + a;
>     std::cout << c;
> }
>=20
> ?

I don't see why not. And it's probably better than what you wrote, sinc= e you=20
probably forgot the c assignment:
        noexcept(decltype(= SomeClass{} + int{}) =3D decltype(SomeClass{} + int{}))

It would also allow you to verify whether your code is really noexcept = or not=20
like you meant it to be:

void func() noexcept;
void func() noexcept(auto)
{
    int a;
    SomeClass b;
    auto c =3D b + a;
    std::cout << c;
}

Since all declarations of the same function need to have the same noexc= ept=20
specifier, the compiler needs to provide a diagnostic if the auto case = expands=20
to a different result from the other declaration.

--=20
Thiago Macieira - thiago (AT) macieira.info - th= iago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4= 5358

--

---
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.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
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