Dear Boost Experts -- I'm using g++ 4.2.1, OS X 10.6.1, boost 1.40, although I have also seen this on linux. In attempting to understand how boost::serialization works, I've stumbled across the following curiosity. The following program compiles and runs fine (I've eliminated diagnostic output which verifies the serialization.) #include <iostream> #include <fstream> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> struct A { int v; template<class Ar> void serialize(Ar & ar, const unsigned int ver) { ar & v; } }; int main(int ac, char ** argv) { A a; a.v = 10; A * a1p = &a; const char * fname = "test.bin"; { std::ofstream ofs(fname); boost::archive::binary_oarchive ar(ofs); ar << a1p; } A * a2p; { std::ifstream ifs(fname); boost::archive::binary_iarchive ar(ifs); ar >> a2p; } return 0; } However, if I add a static_cast<A*> to either a1p or a2p (which are already declared to be type A*) in the serialization / deserialization lines, it fails to compile: #include <iostream> #include <fstream> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> struct A { int v; template<class Ar> void serialize(Ar & ar, const unsigned int ver) { ar & v; } }; int main(int ac, char ** argv) { A a; a.v = 10; A * a1p = &a; const char * fname = "test.bin"; { std::ofstream ofs(fname); boost::archive::binary_oarchive ar(ofs); ar << static_cast<A*>(a1p); } A * a2p; { std::ifstream ifs(fname); boost::archive::binary_iarchive ar(ifs); ar >> static_cast<A*>(a2p); } return 0; } Compilation started at Fri Oct 23 14:31:17 make -k debug make all "CXX_FLAGS = -g -fno-inline -m64 -I. -I.. -I/opt/local/include -Wall -Wextra -Wpointer- arith -Wcast-align -Wwrite-strings -Wconversion -Woverloaded-virtual -Wno-sign-compare -Wno- unused -fno-nonansi-builtins" \ "LD_FLAGS = -g -m64" g++ -g -fno-inline -m64 -I. -I.. -I/opt/local/include -Wall -Wextra -Wpointer-arith -Wcast-align - Wwrite-strings -Wconversion -Woverloaded-virtual -Wno-sign-compare -Wno-unused -fno- nonansi-builtins -c test.cc -o test.o test.cc: In function 'int main(int, char**)': test.cc:25: error: no match for 'operator<<' in 'ar << a1p' /opt/local/include/boost/archive/detail/interface_oarchive.hpp:63: note: candidates are: Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = A*, Archive = boost::archive::binary_oarchive] test.cc:33: error: no match for 'operator>>' in 'ar >> a2p' /opt/local/include/boost/archive/detail/interface_iarchive.hpp:60: note: candidates are: Archive& boost::archive::detail::interface_iarchive<Archive>::operator>>(T&) [with T = A*, Archive = boost::archive::binary_iarchive] make[1]: *** [test.o] Error 1 make[1]: Target `all' not remade because of errors. make: *** [debug] Error 2 Compilation exited abnormally with code 2 at Fri Oct 23 14:31:18 This completely boggles my mind. My limited understanding suggests the compiler should not be able to distinguish between the two programs! I can put the cast on either one of the two pointers and it fails, and using an old style cast to A* also fails. I seem to not understand what boost::serialization is doing generally, so I was hoping the answer to this question (which is obviously a theoretical curiosity and of no practical value) would lead to further insight. Best regards, Ben