[Bug libstdc++/49219] New: [c++0x] comparing unordered containers illegally require key compare

[roman at binarylife dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49219

           Summary: [c++0x] comparing unordered containers illegally
                    require key compare
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: roman@binarylife.net


$ cat test.cpp 
#include <unordered_set>
#include <unordered_map>
struct K {
//  bool operator!=(K const&)const;
//  bool operator==(K const&)const;
};
struct H { std::size_t operator()(K const&)const; };
struct E { bool operator()(K const&,K const&)const; };
extern std::unordered_set<K,H,E> a;
extern std::unordered_map<K,int,H,E> b;
extern std::unordered_multiset<K,H,E> c;
extern std::unordered_multimap<K,int,H,E> d;
bool af=(a==a);
bool bf=(b==b);
bool cf=(c==c);
bool df=(d==d);

$ g++ -c -std=c++0x test.cpp
... failure

Each of "bool xf=(x==x);" require "bool K::operator!=(K const&)const" and/or
"bool K::operator==(K const&)const". The provided E type should be used for key
compare.