C++ WeaponType hash compilation error on gcc version 5.4.0 (ubuntu 16.04)

[tsarevfs]

Old gcc has only partial C++17 support. There is known issue with enum hashes: https://stackoverflow.com/a/29618545/1762922

In file included from /usr/include/c++/5/bits/hashtable.h:35:0,
                 from /usr/include/c++/5/unordered_map:47,
                 from /home/ftsarev/Downloads/cpp/model/Properties.hpp:10,
                 from /home/ftsarev/Downloads/cpp/model/Game.hpp:7,
                 from /home/ftsarev/Downloads/cpp/MyStrategy.hpp:6,
                 from /home/ftsarev/Downloads/cpp/MyStrategy.cpp:1:
/usr/include/c++/5/bits/hashtable_policy.h: In instantiation of ‘struct std::__detail::__is_noexcept_hash<WeaponType, std::hash<WeaponType> >’:
/usr/include/c++/5/type_traits:137:12:   required from ‘struct std::__and_<std::__is_fast_hash<std::hash<WeaponType> >, std::__detail::__is_noexcept_hash<WeaponType, std::hash<WeaponType> > >’
/usr/include/c++/5/type_traits:148:38:   required from ‘struct std::__not_<std::__and_<std::__is_fast_hash<std::hash<WeaponType> >, std::__detail::__is_noexcept_hash<WeaponType, std::hash<WeaponType> > > >’
/usr/include/c++/5/bits/unordered_map.h:100:66:   required from ‘class std::unordered_map<WeaponType, WeaponParams>’
/home/ftsarev/Downloads/cpp/model/Properties.hpp:41:50:   required from here
/usr/include/c++/5/bits/hashtable_policy.h:85:34: error: no match for call to ‘(const std::hash<WeaponType>) (const WeaponType&)’
  noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
                                  ^
In file included from /usr/include/c++/5/bits/move.h:57:0,
                 from /usr/include/c++/5/bits/stl_pair.h:59,
                 from /usr/include/c++/5/bits/stl_algobase.h:64,
                 from /usr/include/c++/5/bits/char_traits.h:39,
                 from /usr/include/c++/5/string:40,
                 from /home/ftsarev/Downloads/cpp/Stream.hpp:4,
                 from /home/ftsarev/Downloads/cpp/Debug.hpp:4,
                 from /home/ftsarev/Downloads/cpp/MyStrategy.hpp:4,
                 from /home/ftsarev/Downloads/cpp/MyStrategy.cpp:1:
/usr/include/c++/5/type_traits: In instantiation of ‘struct std::__not_<std::__and_<std::__is_fast_hash<std::hash<WeaponType> >, std::__detail::__is_noexcept_hash<WeaponType, std::hash<WeaponType> > > >’:
/usr/include/c++/5/bits/unordered_map.h:100:66:   required from ‘class std::unordered_map<WeaponType, WeaponParams>’
/home/ftsarev/Downloads/cpp/model/Properties.hpp:41:50:   required from here
/usr/include/c++/5/type_traits:148:38: error: ‘value’ is not a member of ‘std::__and_<std::__is_fast_hash<std::hash<WeaponType> >, std::__detail::__is_noexcept_hash<WeaponType, std::hash<WeaponType> > >’
     : public integral_constant<bool, !_Pp::value>

Workaround is to define std::hash specialization for WeaponType