[Bug c++/107558] [10/11/12 Regression] ICE in fld_incomplete_type_of with -fmerge-all-constants and openmp and LTO since r11-16-ga2f32550a085984f

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107558

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:2744af7ac0a6e46551556cdf5d6df2486e79ef3f

commit r12-9289-g2744af7ac0a6e46551556cdf5d6df2486e79ef3f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Mar 10 20:38:13 2023 +0100

    c++: Don't clear TREE_READONLY for -fmerge-all-constants for non-aggregates
[PR107558]

    The following testcase ICEs, because OpenMP lowering for shared clause
    on l variable with REFERENCE_TYPE creates POINTER_TYPE to REFERENCE_TYPE.
    The reason is that the automatic variable has non-trivial construction
    (reference to a lambda) and -fmerge-all-constants is on and so
TREE_READONLY
    isn't set - omp-low will handle automatic TREE_READONLY vars in shared
    specially and only copy to the construct and not back, while !TREE_READONLY
    are assumed to be changeable.
    The PR91529 change rationale was that the gimplification can change
    some non-addressable automatic variables to TREE_STATIC with
    -fmerge-all-constants and therefore TREE_READONLY on them is undesirable.
    But, the gimplifier does that only for aggregate variables:
      switch (TREE_CODE (type))
        {
        case RECORD_TYPE:
        case UNION_TYPE:
        case QUAL_UNION_TYPE:
        case ARRAY_TYPE:
    and not for anything else.  So, I think clearing TREE_READONLY for
    automatic integral or reference or pointer etc. vars for
    -fmerge-all-constants only is unnecessary.

    2023-03-10  Jakub Jelinek  <jakub@redhat.com>

            PR c++/107558
            * decl.cc (cp_finish_decl): Don't clear TREE_READONLY on
            automatic non-aggregate variables just because of
            -fmerge-all-constants.

            * g++.dg/gomp/pr107558.C: New test.

    (cherry picked from commit 60b6f5c0a334db3f8f6dffaf0b9aab42fd5c54a2)