[Boost-users] General: <unresolved overloaded function type>

Hello List, Just a general question: I am trying to use boost::asio::async_read_until with a these templated functions: template<typename D> struct entity { template<typename T> std::pair operator()( T begin, T end ) { if(begin == end) { return std::make_pair; } return static_cast(this)->impl(begin,end); }; }; /* http://www.w3.org/TR/REC-xml/#NT-S */ struct white_space : entity { template<typename T> std::pair impl( T begin, T end ) { for(; begin != end; begin++) { if(*begin == 0x09u || *begin == 0x0Au || *begin == 0x0Du || *begin == 0x20u) { continue; }else{ return std::make_pair; } } return std::make_pair; }; }; I get the following error: xml.hpp:146: error: conversion from ‘<unresolved overloaded function type>’ to non-scalar type ‘std::pair, bool>’ requested At every line that I have a return defined... Could someone please explain to me what I have done wrong here.... Thank you, Etienne