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 F13D83858C53; Wed,  6 Apr 2022 22:31:21 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F13D83858C53
From: "ppalka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/104594] narrowing of -1 to unsigned char not detected with
 requires concepts
Date: Wed, 06 Apr 2022 22:31:21 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: accepts-invalid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ppalka 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-104594-4-aYaeaC1LXy@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-104594-4@http.gcc.gnu.org/bugzilla/>
References: <bug-104594-4@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: Wed, 06 Apr 2022 22:31:22 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104594

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Here's a testcase which illustrates that the fix must happen during
normalization, not during satisfaction, since after normalization we don't =
know
which concepts we looked through to yield the given atom:

template<class T, T X>
concept C =3D (X !=3D 0);

template<class T, T X>
concept D =3D C<int, X>;

template<auto X>
concept E =3D D<unsigned, X>;

static_assert(E<-1>); // should fail due to implicit conversion from '-1' to
unsigned=