220 29109 <0f446da6-6374-487e-b41e-5435f0dfa2c6@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: "T. C." Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Removing trivial undefined behaviour Date: Wed, 26 Oct 2016 08:55:31 -0700 (PDT) Lines: 155 Approved: news@gmane.org Message-ID: <0f446da6-6374-487e-b41e-5435f0dfa2c6@isocpp.org> References: <35daf87a-bf1d-46de-b16c-c2965fbadc8f@isocpp.org> <9e242562-aba1-4f8d-8e0a-b2de34f6a10b@isocpp.org> <1314a997-2f74-4b52-9755-bc9d1deb6982@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1889_685078059.1477497331824" X-Trace: blaine.gmane.org 1477497345 22490 195.159.176.226 (26 Oct 2016 15:55:45 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 26 Oct 2016 15:55:45 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCQ43G7NQIIRB5NDYPAAKGQES6TZ3SA@isocpp.org Wed Oct 26 17:55:41 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f199.google.com ([209.85.161.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bzQY8-0004Pm-Oe for gclcip-std-proposals@m.gmane.org; Wed, 26 Oct 2016 17:55:32 +0200 Original-Received: by mail-yw0-f199.google.com with SMTP id w3sf12649609ywg.1 for ; Wed, 26 Oct 2016 08:55:35 -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 :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=J0Z4zteJDAdrcWKeUnxPaykQ4tHnK9t4QKPbBw7BMJ8=; b=Q5YKipbI4wS4UeeMb0iHwY6PNBbFJSL0hwLGKsRYMP1Ve48oMhX9fmvEOoa5GTEHHZ sWIXwKlhkWuUuYxdYNF7Zrbl6zzk4LtV0dpv9oSLZALM7Tj3a1a+rhvomlcmM6y6rUbt lVOV4CKpRyMfJER9kfs7gMx66fiXSD43b6uXWgnxLJWZOKxQ+8ePnFpor64fnNxUpk5b I8Otbl6hA/pqgdTpIm9Pms+T4UORHAWey/WuV7AwzQKLa0Po+jx0ViwRDk5MEaCia2NG VZ1wnHh4wZVI5FW4UXKcAkttkOPOZ6epJrVrYTqSqE9N05Wp686gZ4mzasidmYbTzZOU /pTA== 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 :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=J0Z4zteJDAdrcWKeUnxPaykQ4tHnK9t4QKPbBw7BMJ8=; b=KwsFCvL4da7DKYVlBFKWGCAbbHFAnJNrxnILasp5eljX52kxbxxCQkG0xWt5ZXVSE9 bHeQ4mx3bpzCHh7WjNnBfEv1nKaThzu2qXQUL6obA/ZsVwqysq/1Lp457sKbi3LImJLR 9FAVt9KJIQdh30bfapoQDdlnKofDv7/DTZwr3/KnLkc8GezF+59IC0sbYvztoxsO+Qoh Mcb7Ze7Q6sLEueuwnuTUNNAM34DcS1jsf3BHb7bpjSFr2xeRfq5gc7T86sFj3wHMTJjH oL3TYPnUM7pqYw/L1hcy9bBwNcKw+vhV0qRlsAY5zAofs8Cxb6++vXpJYVTCsuLr720a rk4A== 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: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=J0Z4zteJDAdrcWKeUnxPaykQ4tHnK9t4QKPbBw7BMJ8=; b=IXUL0cPPxDY1+ajKUP8jKcpcgHAk+pae6Bixh0uY5e0O/2vUPzjkcpvs+lZBKbc7IG MczHqKd6MZLEICUq66ZECDIOtm2N2T1dii7npWqKoaGL90pxUmO0641UO94GxRaeG12F WkaTddq7+2jjgKNLd/QSSK1GdMoSvdHdIJY8+LOMwYHUDURm7DAZm2+mYurftXDkViZT Y/3tOPsRX4G2Yn+JAo/O8r+soIjYjY7mYZFenI8+VRs8XqqHRvipExok6vGQIYi/If5Y KqluiLkGR/8Fz01VgBhvGX2KXnoF8izwjzQvqEzmAyYAIXA6Nt8PPDE3k3Ie2XxOKYKi gFPw== X-Gm-Message-State: ABUngve3ecp/5meO1bTg01W+GoawOdkytKFvchY6eSx6bAfXfm6AHnmQGf8n0d6Nb1VGgw== X-Received: by 10.13.210.7 with SMTP id u7mr960019ywd.148.1477497335194; Wed, 26 Oct 2016 08:55:35 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.237.201 with SMTP id r192ls2145942ith.0.canary-gmail; Wed, 26 Oct 2016 08:55:33 -0700 (PDT) X-Received: by 10.36.103.2 with SMTP id u2mr611628itc.6.1477497333111; Wed, 26 Oct 2016 08:55:33 -0700 (PDT) In-Reply-To: X-Original-Sender: rs2740@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:29109 Archived-At: ------=_Part_1889_685078059.1477497331824 Content-Type: multipart/alternative; boundary="----=_Part_1890_1139757925.1477497331824" ------=_Part_1890_1139757925.1477497331824 Content-Type: text/plain; charset=UTF-8 On Wednesday, October 26, 2016 at 11:45:09 AM UTC-4, Matt Calabrese wrote: > > > > On Wed, Oct 26, 2016 at 11:34 AM, T. C. > > wrote: > >> >> >> On Wednesday, October 26, 2016 at 9:19:15 AM UTC-4, Tony V E wrote: >>> >>> >>> >>> On Wed, Oct 26, 2016 at 4:28 AM, T. C. wrote: >>> >>>> >>>> >>>> On Wednesday, October 26, 2016 at 3:20:55 AM UTC-4, Hans Guijt wrote: >>>>> >>>>> >>>>> On Wednesday, October 26, 2016 at 9:11:26 AM UTC+2, T. C. wrote: >>>>>> >>>>>> >>>>>> Because they are meant to be used as isdigit((unsigned char) c). >>>>>> >>>>> >>>>> Great, in that case I'm sure there is no opposition to changing the >>>>> signature to reflect this requirement? It's a much cleaner solution than >>>>> requiring a cast in every invocation, after all. >>>>> >>>>> >>>>> >>>> The reason they take int is because they also accept EOF. That's C's >>>> style, for better or worse. >>>> >>>> In any event, there's no way in hell C++ is going to change this. It's >>>> a massive C compatibility break. >>>> >>> >>> We could maybe overload the function: >>> >>> int isdigit(int c); >>> bool isdigit(char c); >>> >>> No idea if that is a good idea. >>> >>>> >>>> -- >>> Be seeing you, >>> Tony >>> >> >> That breaks anything that expects ::isdigit to be unambiguous (e.g., pass >> it to an algorithm). >> > > I thought the standard doesn't sanction such uses of standard library > facilities, unless I'm mistaken. > I don't recall anything that says you can't do it. (You can't take the address of *member* functions, but nonmembers is another matter.) In any event, it can also make existing calls ambiguous (with an argument that converts equally well to int and char), so there's a need to check how much this will break. -- 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/0f446da6-6374-487e-b41e-5435f0dfa2c6%40isocpp.org. ------=_Part_1890_1139757925.1477497331824 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Wednesday, October 26, 2016 at 11:45:09 AM UTC-= 4, Matt Calabrese wrote:


On Wed, Oct 26, 2016 at = 11:34 AM, T. C. <rs2...@gmail.com> wrote:
=


On Wednesday, Octob= er 26, 2016 at 9:19:15 AM UTC-4, Tony V E wrote:


On Wed, Oct 26, 2016 at 4:28 AM, T. C. <rs2...@gmail.com> wrote:


On Wednesday, October 26, 2016 at 3:20:= 55 AM UTC-4, Hans Guijt wrote:

On Wednesday, October 26, 2016 at 9:11:26 AM UTC+2, T. C. w= rote:

Because they are meant to be used as isdigit((unsigned char) c).
=C2=A0
Great, in that case I'm sure= there is no opposition to changing the signature to reflect this requireme= nt? It's a much cleaner solution than requiring a cast in every invocat= ion, after all.



<= div>The reason they take int is because they also accept EOF. That's C&= #39;s style, for better or worse.

In any event, th= ere's no way in hell C++ is going to change this. It's a massive C = compatibility break.

We could m= aybe overload the function:

int isdigit(int c);
=
bool isdigit(char c);

No idea if that is a good idea= ..


--
Be s= eeing you,
Tony

<= /div>
That breaks anything that expects ::isdigit=C2=A0to be una= mbiguous (e.g., pass it to an algorithm).=C2=A0

I thought the standard doesn't sanction such uses of s= tandard library facilities, unless I'm mistaken.=C2=A0

I don't recall anything that sa= ys you can't do it. (You can't take the address of *member* functio= ns, but nonmembers is another matter.)

In any even= t, it can also make existing calls ambiguous (with an argument that convert= s equally well to int and char), so there's a need to check how much th= is will break.

--
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