[Bug c++/97566] [[no_unique_address]] causes miscompiles when mixed with EBO in constexpr context

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97566

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>:

https://gcc.gnu.org/g:2168bfb81448ae1bfa4351760a23d4ec051c2a00

commit r12-1827-g2168bfb81448ae1bfa4351760a23d4ec051c2a00
Author: Jason Merrill <ja...@redhat.com>
Date:   Thu Jun 24 17:32:02 2021 -0400

    c++: constexpr aggr init of empty class [PR101040]

    This is basically the aggregate initializer version of PR97566; as in that
    bug, we are trying to initialize empty field 'obj' in 'single' when there's
    no CONSTRUCTOR entry for the 'single' base class subobject of 'derived'. 
As
    with that bug, the fix is to stop trying to add entries for empty fields,
    this time in cxx_eval_bare_aggregate.

    The change to the other function isn't necessary for this version of
    the patch, but seems worthwhile for robustness anyway.

            PR c++/101040
            PR c++/97566

    gcc/cp/ChangeLog:

            * class.c (is_empty_field): Handle null argument.
            * constexpr.c (cxx_eval_bare_aggregate): Discard initializer
            for empty field.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/no_unique_address13.C: New test.