In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\backward\hash_set:60:0,
                 from foo.cpp:2:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\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 \
  ^
foo.cpp:5:1: error: 'hash_set' does not name a type
 hash_set <long long> chop;
 ^
foo.cpp: In function 'int main()':
foo.cpp:11:2: error: 'chop' was not declared in this scope
  chop.clear();
  ^