[Bug libstdc++/100667] [11/12/13/14 Regression] std::tuple<A&&> cannot be constructed from A&&, if A not defined (only forward declared)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100667

--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:8bb3ef3f6e335e8794590fb712a2661d11d21973

commit r14-9713-g8bb3ef3f6e335e8794590fb712a2661d11d21973
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Mar 27 16:14:01 2024 -0400

    c++: __is_constructible ref binding [PR100667]

    The requirement that a type argument be complete is excessive in the case
of
    direct reference binding to the same type, which does not rely on any
    properties of the type.  This is LWG 2939.

            PR c++/100667

    gcc/cp/ChangeLog:

            * semantics.cc (same_type_ref_bind_p): New.
            (finish_trait_expr): Use it.

    gcc/testsuite/ChangeLog:

            * g++.dg/ext/is_constructible8.C: New test.