boost/dynamic_bitset/dynamic_bitset.hpp:111:20: -Wdeprecated-copy warning

[Kojoley]

clang-linux.compile.c++ ../../../../bin.v2/libs/spirit/test/qi/qi_range_run.test/clang-linux-12/release/cxxstd-11-iso/stdlib-libc++/threading-multi/visibility-hidden/range_run.o
In file included from range_run.cpp:12:
In file included from ../../../../boost/dynamic_bitset.hpp:15:
../../../../boost/dynamic_bitset/dynamic_bitset.hpp:111:20: error: definition of implicit copy constructor for 'reference' is deprecated because it has a user-declared copy assignment operator [-Werror,-Wdeprecated-copy]
        reference& operator=(const reference& rhs) { do_assign(rhs); return *this; } // for b[i] = b[j]
                   ^
../../../../boost/dynamic_bitset/dynamic_bitset.hpp:306:16: note: in implicit copy constructor for 'boost::dynamic_bitset<unsigned int>::reference' first required here
        return reference(m_bits[block_index(pos)], bit_index(pos));
               ^
range_run.cpp:67:13: note: in instantiation of member function 'boost::dynamic_bitset<unsigned int>::operator[]' requested here
            bset[j-const_min] = set;
            ^
range_run.cpp:193:9: note: in instantiation of function template specialization 'acid_test<char>' requested here
        acid_test<char>();
        ^