Non-type template parameters not being matched; partial specialization missed

[Phil Edwards <phil at jaj dot com>]

The following snippet of code is taken directly from Loki.  Boost and a
couple of other similar homegrown libraries scattered around the 'net do
something similar.

    fenric 183% cat nontype.cc
    
    template <typename T>
      struct is_member_pointer
      { enum { v = false }; };
    
    template <typename T, typename U>
      struct is_member_pointer<U T::*>
      { enum { v = true }; };
    
    struct StaticMember
    {
      static int data;
      static int function (int) { return 42; }
    };
    
    bool testd = is_member_pointer< &StaticMember::data >::v;
    bool testf = is_member_pointer< &StaticMember::function >::v;
    
    fenric 184% build/install-2003-01-22-trunk/bin/g++ -c nontype.cc
    nontype.cc:16: error: type/value mismatch at argument 1 in template parameter
       list for `template<class T> struct is_member_pointer'
    nontype.cc:16: error:   expected a type, got `&StaticMember::data'
    nontype.cc:16: error: `v' is not a member of `<declaration error>'
    nontype.cc:17: error: type/value mismatch at argument 1 in template parameter
       list for `template<class T> struct is_member_pointer'
    nontype.cc:17: error:   expected a type, got `StaticMember::function(int)'
    nontype.cc:17: error: `v' is not a member of `<declaration error>'
    fenric 185%

I have the distinct feeling I'm forgetting something, but what?


Phil

-- 
I would therefore like to posit that computing's central challenge, viz. "How
not to make a mess of it," has /not/ been met.
                                                 - Edsger Dijkstra, 1930-2002