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Subject: [Bug c++/101194] [9/10 Regression] aggregate init requires default
 constructor
Date: Wed, 11 May 2022 17:25:07 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101194

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:5fcedef529c7564b6485ab2893c08865798a66ec

commit r10-10716-g5fcedef529c7564b6485ab2893c08865798a66ec
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Jun 30 20:44:52 2021 -0400

    c++: cxx_eval_array_reference and empty elem type [PR101194]

    Here the initializer for x is represented as an empty CONSTRUCTOR due to
    its empty element type.  So during constexpr evaluation of the ARRAY_REF
    x[0], we end up trying to value initialize the omitted element at index=
 0,
    which fails because the element type is not default constructible.

    This patch makes cxx_eval_array_reference specifically handle the case
    where the element type is an empty type.

            PR c++/101194

    gcc/cp/ChangeLog:

            * constexpr.c (cxx_eval_array_reference): When the element type
            is an empty type and the corresponding element is omitted, just
            return an empty CONSTRUCTOR instead of attempting value
            initialization.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/constexpr-empty16.C: New test.

    (cherry picked from commit a688c284dd3848b6c4ea553035f0f9769fb4fbc9)=