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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109678] [13/14 Regression] exponential time behavior on
 std::variant
Date: Tue, 02 May 2023 20:26:41 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109678

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:4b8d0d4d7fd245ef85c7801e7838845502a5a61d

commit r14-409-g4b8d0d4d7fd245ef85c7801e7838845502a5a61d
Author: Jason Merrill <jason@redhat.com>
Date:   Mon May 1 17:41:44 2023 -0400

    c++: std::variant slow to compile [PR109678]

    Here, when dealing with a class with a complex subobject structure, we
would
    try and fail to find the relevant FIELD_DECL for an empty base before
giving
    up.  And we would do this at each level, in a combinatorially problemat=
ic
    way.  Instead, we should check for an empty base first.

            PR c++/109678

    gcc/cp/ChangeLog:

            * constexpr.cc (cxx_fold_indirect_ref_1): Handle empty base fir=
st.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp1z/variant1.C: New test.=