[Bug c++/96164] Constraints and explicit template instantiation

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96164

--- Comment #4 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:dc3d1e181445fafbbd146eb355a750c41c338794

commit r11-2417-gdc3d1e181445fafbbd146eb355a750c41c338794
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Jul 29 22:06:33 2020 -0400

    c++: constraints and explicit instantiation [PR96164]

    When considering to instantiate a member of a class template as part of
    an explicit instantiation of the class template, we need to first check
    the member's constraints before proceeding with the instantiation of the
    member.

    gcc/cp/ChangeLog:

            PR c++/96164
            * constraint.cc (constraints_satisfied_p): Return true if
            !flags_concepts.
            * pt.c (do_type_instantiation): Update a paragraph taken from
            [temp.explicit] to reflect the latest specification.  Don't
            instantiate a member with unsatisfied constraints.

    gcc/testsuite/ChangeLog:

            PR c++/96164
            * g++.dg/cpp2a/concepts-explicit-inst5.C: New test.