id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
7489	No hash function for classes containing conversion operation to ordinary type	Robert Luberda <robert@…>	Daniel James	"Hi

It seems boost::hash no longer supports calculating hashes for classes that are convertible to int. It used to work with previous versions of boost::hash 

Please see the following example (based on example from bug#7437), which compiles fine with boost::hash up to version 1.50, but fails to compile with boost 1.51

{{{
#include <boost/unordered_map.hpp>

class MyClass
{
public:
    MyClass(int i=0): v(i) {}
    operator int() const {return v;}
private:
    int v;
};

typedef boost::unordered_map<MyClass,std::string> MyMap;

int main(int argc, char* argv[])
{
    MyMap m;
    MyMap::value_type v(MyClass(1),""apples"");
    m.insert(v);

    return 0;
}

}}}

The error is:
{{{
/opt//boost_1_51_0/include/boost/functional/hash/extensions.hpp:257: error: no matching function for call to 'hash_value(const MyClass&)'
}}}

"	Bugs	closed	To Be Determined	hash	Boost 1.51.0	Problem	wontfix