关于#include<ext/hash_map>问题

In file included from /usr/include/c++/4.8/ext/hash_map:60:0,
from AlgorithmNBM.h:9,
from AlgorithmNBM.cpp:10:
/usr/include/c++/4.8/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date. Please use a non-deprecated interface with equivalent functionality instead. For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated. [-Wcpp]
#warning \
^
求大神相助，急，谢谢！！！