_impl     : if_c<           ( tag0_ > tag0_ )         , aux::cast0nd_impl< less_equal_impl< Tag0,Tag0 >,Tag0, Tag0 >         , aux::cast0st_impl< less_equal_impl< Tag0,Tag0 >,Tag0, Tag0 >         >::type { };  /// for Digital Mars C++/compilers with no CTPS/TTP support template<> struct 