Am I doing something wrong, or is this patch really necessary? I'm using if_then_else_return() and the return types are different. I'm overloading return_type_2<other_action<ifthenelsereturn_action>, A, B> to let the compiler deduce the correct return type. Peter diff -w -c ./if.hpp /users/pfoelsch/boost_1_40_0/boost/lambda/if.hpp *** ./if.hpp Sat Jun 28 06:57:20 2008 --- /users/pfoelsch/boost_1_40_0/boost/lambda/if.hpp Tue Dec 15 15:19:50 2009 *************** *** 310,318 **** template<class RET, CALL_TEMPLATE_ARGS> RET call(CALL_FORMAL_ARGS) const { return (detail::select(boost::tuples::get<0>(args), CALL_ACTUAL_ARGS)) ? ! detail::select(boost::tuples::get<1>(args), CALL_ACTUAL_ARGS) : ! detail::select(boost::tuples::get<2>(args), CALL_ACTUAL_ARGS); } }; --- 310,318 ---- template<class RET, CALL_TEMPLATE_ARGS> RET call(CALL_FORMAL_ARGS) const { return (detail::select(boost::tuples::get<0>(args), CALL_ACTUAL_ARGS)) ? ! RET(detail::select(boost::tuples::get<1>(args), CALL_ACTUAL_ARGS)) : ! RET(detail::select(boost::tuples::get<2>(args), CALL_ACTUAL_ARGS)); } };