Hello, I have a little problem regarding boost and ACE cooperation. ACE is an C++ class library, providing many functions for platform independency. I have also reported this to the debian team, and will also try to contact the ACE developers: Package: libboost-dev Version: 1.32.0-6 Package: libace-dev Version: 5.4.2.1.0-4 Consider the following program boostfirst.cpp: ------------------------------------------------------------ #include <boost/shared_ptr.hpp> #include <ace/OS.h> #include <iostream> using namespace std; int main (int argc, char **argv) { cout << "sizeof (boost::detail::sp_counted_base) == " << sizeof (boost::detail::sp_counted_base) << endl; } ------------------------------------------------------------ Compile and run with: $ g++ boostfirst.cpp -o boostfirst -lstd $ ./boostfirst sizeof (boost::detail::sp_counted_base) == 12 Now try including the ace header first (only the order of the include files is changed): ------------------------------------------------------------ #include <ace/OS.h> #include <boost/shared_ptr.hpp> #include <iostream> using namespace std; int main (int argc, char **argv) { cout << "sizeof (boost::detail::sp_counted_base) == " << sizeof (boost::detail::sp_counted_base) << endl; } ------------------------------------------------------------ The output of the second program is: sizeof (boost::detail::sp_counted_base) == 36 A great difference. The reason for this is, that the #include <ace/OS.h> somehow defines _REENTRANT, which triggers the boost library to include a mutex in sp_counted_base. I think, the order of the includes should not matter. Therefore, either '#include <ace/OS.h>' should not define _REENTRANT, or the boost headers should ignore it. I found out, that adding the -pthread option to the g++ command also avoids this bug. Im using Debian sarge 3.1, g++ 3.3.5-3, libc6 2.3.2.ds1-22sarge3 and libace-dev 5.4.2.1.0-4. Regards, Torsten