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From: "ppalka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/112749] GCC accepts invalid code in concepts (requires
 clause incorrectly satisfied)
Date: Tue, 28 Nov 2023 20:44:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112749

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
                 CC|                            |ppalka at gcc dot gnu.org
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Thanks for the bug report, I think this is pretty much a dup of PR102419.

GCC is behaving correctly here: the normal form of the constraint C1<W1<T>>=
 is
just 'true (with empty parameter mapping)' which is independent of the temp=
late
parameter, so the constraint is trivially satisfied for any choice of T.  To
get the behavior you desire, define C1 in a way that depends on its template
parameter e.g.

template<class T> concept C1 =3D requires { typename T; };

*** This bug has been marked as a duplicate of bug 102419 ***=