Hey Hartmut, I've got a workaround, like so: If you forward declare the construct() overloads for the different primitive Attribute types, gcc seems to not greedily match this one (the current error): template <typename Attribute, typename Iterator> inline void construct(Attribute& attr, Iterator const& first, Iterator const& last) { attr = Attribute(first, last); } and instead to wait for this one (correct): template <typename Iterator> inline void construct(unsigned int& attr, Iterator const& first, Iterator const& last) { Iterator first_ = first; parse(first_, last, uint_, attr); } So I've got local mods of adding #include <boost/spirit/home/qi/detail/construct_fwd.hpp> to the top of assign_to.hpp, and the construct_fwd.hpp is attached. I don't entirely get it, but I do like the looks of this: troy@uranium:~/Projects/boost/trunk/libs/spirit/example/lex % gcc -o example4 example4.cpp -I . -I ../../../.. -lstdc++ troy@uranium:~/Projects/boost/trunk/libs/spirit/example/lex % ./example4 assignment statement to: a if expression: variable assignment statement to: b if expression: 2 assignment statement to: c assignment statement to: d if expression: x while expression: 10 assignment statement to: variable ------------------------- Parsing succeeded ------------------------- Bye... :-) Best, -t