[Bug c++/99033] [9/10 Regression] ICE in tree_to_poly_int64, at tree.c:3091

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99033

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

https://gcc.gnu.org/g:ea535f59b19f65e5b313c990ee6c194a7b055bd7

commit r10-9468-gea535f59b19f65e5b313c990ee6c194a7b055bd7
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Feb 11 17:24:17 2021 +0100

    c++: Fix zero initialization of flexible array members [PR99033]

    array_type_nelts returns error_mark_node for type of flexible array members
    and build_zero_init_1 was placing an error_mark_node into the CONSTRUCTOR,
    on which e.g. varasm ICEs.  I think there is nothing erroneous on zero
    initialization of flexible array members though, such arrays should simply
    get no elements, like they do if such classes are constructed (everything
    except when some larger initializer comes from an explicit initializer).

    So, this patch handles [] arrays in zero initialization like [0] arrays
    and fixes handling of the [0] arrays - the
    tree_int_cst_equal (max_index, integer_minus_one_node) check
    didn't do what it thought it would do, max_index is typically unsigned
    integer (sizetype) and so it is never equal to a -1.

    What the patch doesn't do and maybe would be desirable is if it returns
    error_mark_node for other reasons let the recursive callers not stick that
    into CONSTRUCTOR but return error_mark_node instead.  But I don't have a
    testcase where that would be needed right now.

    2021-02-11  Jakub Jelinek  <jakub@redhat.com>

            PR c++/99033
            * init.c (build_zero_init_1): Handle zero initialiation of
            flexible array members like initialization of [0] arrays.
            Use integer_minus_onep instead of comparison to
integer_minus_one_node
            and integer_zerop instead of comparison against size_zero_node.
            Formatting fixes.

            * g++.dg/ext/flexary38.C: New test.

    (cherry picked from commit 2dcdd15d0bafb9b45a8d7ff580217bd6ac1f0975)