Boost 1.72: Powerpc compiler gives error on including unordered_map

Reproduce the failure with GCC 4.7.2 on PowerPC while including boost/unordered_map.hpp, then inspect boost/tuple/detail/tuple_basic.hpp at lines 704 and 836. Compare the behavior with Boost 1.42 and determine whether the reported attribute warnings can be resolved; done means the Boost 1.72 include compiles without these errors.

When including unordered_map.hpp file, the powerpc compiler (gcc 4.7.2) gives an error inside the tuple_basic.hpp.
I am actually upgrading boost on the project from 1.42 to 1.72. I dont see any errors from the 1.42 version.

In file included from /boost/1_72_0/include/boost/tuple/tuple.hpp:28:0,
                 from /boost/1_72_0/include/boost/unordered/detail/implementation.hpp:31,
                 from /boost/1_72_0/include/boost/unordered/detail/map.hpp:6,
                 from /boost/1_72_0/include/boost/unordered/unordered_map.hpp:21,
                 from /boost/1_72_0/include/boost/unordered_map.hpp:17,
                 from build/ppc2/system/util/WeakReference.h:17,
                 from build/ppc2/system/util/WeakReference.c++:8:
/boost/1_72_0/include/boost/tuple/detail/tuple_basic.hpp:704:60: error: ignoring attributes on template argument 'void (boost::tuples::detail::swallow_assign::*(void (boost::tuples::detail::swallow_assign::*)()))()' [-Werror]
/boost/1_72_0/include/boost/tuple/detail/tuple_basic.hpp:836:37: error: ignoring attributes on template argument 'void (boost::tuples::detail::swallow_assign::*(void (boost::tuples::detail::swallow_assign::*)()))()' [-Werror]