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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/65861] libstdc++ is silently generating wrong code when its std::search is given an input iterator
Date: Mon, 06 Dec 2021 14:06:43 +0000	[thread overview]
Message-ID: <bug-65861-4-LNZi5RTxe5@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-65861-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65861

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #9)
> There are actually good reasons *not* to reject input iterators at
> compile-time.
> 
> You could have an iterator which meets most, but not all, the forward
> iterator requirements, and so must have input_iterator_tag as its category.
> Such as iterator could work fine with std::search, if we don't reject it via
> a static assertion.
> 
> (istreambuf_iterator is not such an iterator, as it's genuinely a
> single-pass iterator, and so can't be used ... but we can't reliably detect
> that as the only property we can test is the iterator_category tag).

Since C++20 we can also check the iterator_concept tag. That means we can allow
iterators that identify as input iterators according to iterator_category, but
forward iterators (or stronger) according to iterator_concept.

  parent reply	other threads:[~2021-12-06 14:06 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-23 14:43 [Bug libstdc++/65861] New: " howarth.at.gcc at gmail dot com
2015-04-23 15:01 ` [Bug libstdc++/65861] " glisse at gcc dot gnu.org
2015-04-23 15:04 ` redi at gcc dot gnu.org
2015-04-23 15:14 ` howarth.at.gcc at gmail dot com
2015-04-23 15:16 ` howarth.at.gcc at gmail dot com
2015-04-23 15:21 ` redi at gcc dot gnu.org
2015-04-23 15:27 ` redi at gcc dot gnu.org
2015-04-25 10:48 ` howarth.at.gcc at gmail dot com
2015-04-25 13:40 ` redi at gcc dot gnu.org
2015-05-02 10:12 ` redi at gcc dot gnu.org
2021-12-06  5:19 ` [Bug c++/65861] " pinskia at gcc dot gnu.org
2021-12-06 10:42 ` redi at gcc dot gnu.org
2021-12-06 14:06 ` redi at gcc dot gnu.org [this message]
2021-12-06 22:01 ` pinskia at gcc dot gnu.org
2022-01-09  0:37 ` pinskia at gcc dot gnu.org

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