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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/100667] [11/12/13/14 Regression] std::tuple<A&&>
 cannot be constructed from A&&, if A not defined (only forward declared)
Date: Wed, 27 Mar 2024 14:14:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100667

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Oh interestingly __is_constructible(Incomplete&&, Incomplete) is already
allowed, but __is_nothrow_constructible and __is_convertible give errors:


__is_nothrow_constructible(Incomplete&&, Incomplete)

<stdin>: In function =E2=80=98int main()=E2=80=99:
<stdin>:117:68: error: invalid use of incomplete type =E2=80=98struct Incom=
plete=E2=80=99
[-fpermissive]
<stdin>:110:8: note: forward declaration of =E2=80=98struct Incomplete=E2=
=80=99

__is_convertible(Incomplete, Incomplete&&)

<stdin>: In function =E2=80=98int main()=E2=80=99:
<stdin>:117:58: error: invalid use of incomplete type =E2=80=98struct Incom=
plete=E2=80=99
[-fpermissive]
<stdin>:110:8: note: forward declaration of =E2=80=98struct Incomplete=E2=
=80=99=