[Boost-users] [mpl] erase_key confusion

From: Scott Meyers (usenet_at_[hidden])
Date: 2007-03-22 02:30:53

I expect the following code to compile cleanly.  It does not.

#include <boost/mpl/set.hpp>
#include <boost/mpl/equal.hpp>
#include <boost/mpl/erase_key.hpp>

namespace mpl = boost::mpl;
using mpl::_1;
using mpl::_2;

struct A {};
struct B {};

typedef mpl::set<A, B> set1;
typedef mpl::set<B, A> set2;

BOOST_MPL_ASSERT((
   mpl::equal<
     mpl::erase_key<set1, A>::type,
     mpl::erase_key<set2, A>::type
   >
));

I'm simply trying to assert that the sets {A,B} and {B,A} have the same 
elements after A has been removed from both.  What am I doing wrong?

Thanks,

Scott