https://issues.dlang.org/show_bug.cgi?id=19598
--- Comment #7 from Simen Kjaeraas <simen.kjaras at gmail.com> ---
It seems this can be fixed by teaching assignToLvalue about StructLiteralExps:
        else if (auto sle = e1.isStructLiteralExp())
        {
            oldval = sle;
        }
There may be issues with this fix though.
--