From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 2800D39BC04B; Thu, 10 Jun 2021 21:22:51 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2800D39BC04B
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/100770] Incorrect if constexpr statement in
 ranges::unique_copy
Date: Thu, 10 Jun 2021 21:22:50 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: rejects-valid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: cvs-commit at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: ppalka at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-100770-4-S8ZtlxUjAJ@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-100770-4@http.gcc.gnu.org/bugzilla/>
References: <bug-100770-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 10 Jun 2021 21:22:51 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100770

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:bee80d74f7ebc8e1ada913aa059dedc0976f28c0

commit r10-9908-gbee80d74f7ebc8e1ada913aa059dedc0976f28c0
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Jun 3 12:30:29 2021 -0400

    libstdc++: Avoid hard error in ranges::unique_copy [PR100770]

    Here, in the constexpr if condition within ranges::unique_copy, when
    input_iterator<_Out> isn't satisfied we must avoid substituting into
    iter_value_t<_Out> because the latter isn't necessarily well-formed
    then.  To that end, this patch factors out the condition into a concept
    and uses it throughout.

    This patch also makes the definition of our testsuite
    output_iterator_wrapper more minimal by setting its value_type, pointer
    and reference member types to void.  This means our existing tests for
    unique_copy already exercise the fix for this bug, so we don't need
    to add another test.  The only other fallout of this testsuite iterator
    change appears in std/ranges/range.cc, where the use of range_value_t
    on a test_output_range is now ill-formed.

            PR libstdc++/100770

    libstdc++-v3/ChangeLog:

            * include/bits/ranges_algo.h (__detail::__can_reread_output):
            Factor out this concept from ...
            (__unique_copy_fn::operator()): ... here.  Use the concept
            throughout.
            * testsuite/std/ranges/range.cc: Remove now ill-formed use
            of range_value_t on an output_range.
            * testsuite/util/testsuite_iterators.h (output_iterator_wrapper=
):
            Define value_type, pointer and reference member types to void.

    (cherry picked from commit 0614bbbe59c6953e088cffa39dfe63d86fc1fa96)=