I'm routinely testing Boost.Python compilation with Intel C++ under Fedora 3 (64-bit). Today I tried Fedora 5, 6, 9, and I'm getting the error below. It can be reproduced by simply including boost/shared_ptr.hpp. I tried adding -pthread but it didn't make a difference. Is this a known problem? Is there a trick to get around it? Ralf P.S.: Intel C++ 9.1 behaves the same way. boost trunk svn revision 46049 % cat include_boost_shared.cpp #include <boost/shared_ptr.hpp> % icpc -V Intel(R) C++ Compiler for applications running on Intel(R) 64, Version 10.1 Build 20080312 Package ID: l_cc_p_10.1.015 Copyright (C) 1985-2008 Intel Corporation. All rights reserved. FOR NON-COMMERCIAL USE ONLY % icpc -I/net/rosie/scratch1/rwgk/hot/boost -c include_boost_shared.cpp /net/rosie/scratch1/rwgk/hot/boost/boost/detail/spinlock_sync.hpp(36): error: identifier "__sync_lock_test_and_set" is undefined int r = __sync_lock_test_and_set( &v_, 1 ); ^ /net/rosie/scratch1/rwgk/hot/boost/boost/detail/spinlock_sync.hpp(50): error: identifier "__sync_lock_release" is undefined __sync_lock_release( &v_ ); ^ compilation aborted for include_boost_shared.cpp (code 2)