[Bug c++/96830] GCC does not complain about redeclaration with inconsistent requires clause

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96830

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:ec62dc95c4f8776c9f4eff2a9a06f9aef6a2d98a

commit r13-6676-gec62dc95c4f8776c9f4eff2a9a06f9aef6a2d98a
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Mar 14 19:12:08 2023 -0400

    c++: constrained template friend class matching [PR96830]

    When instantiating a constrained template friend naming an already
    declared class template, tsubst_friend_class erroneously passes to
    redeclare_class_template the existing template's constraints instead of
    those of the friend declaration, which causes the constraint comparison
    check therein to trivially succeed and we fail to diagnose legitimate
    constraint mismatches.

            PR c++/96830

    gcc/cp/ChangeLog:

            * pt.cc (redeclare_class_template): Add missing "of" in
            constraint mismatch diagnostic.
            (tsubst_friend_class): For an already declared class template,
            substitute and pass the friend declaration's constraints to
            redeclare_class_template instead of passing the existing
            template's constraints.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-friend14.C: New test.