Using: Boost 1.42.0 Visual Studio 2.0.50727 SP2 I have a managed C++ project which exposes a set of C++ utilities as a dll. One particular file transitively includes future.hpp. Deep in future.hpp's detail namespace, it comes across: <code> struct all_futures_lock { unsigned count; boost::scoped_array<boost::unique_lock<boost::mutex> > locks; all_futures_lock(std::vector<registered_waiter>& futures): count(futures.size()),locks(new boost::unique_lock<boost::mutex>[count]) { for(unsigned i=0;i<count;++i) { locks[i]=boost::unique_lock<boost::mutex>(futures[i].future->mutex); } } ... void unlock() { for(unsigned i=0;i<count;++i) { locks[i].unlock(); } } }; </code> the line : locks[i].unlock(); fails with the following error: <a path>\v1_42_0\include\boost/thread/future.hpp(414) : error C2666: 'boost::scoped_array<T>::operator []' : 2 overloads have similar conversions 1> with 1> [ 1> T=boost::unique_lock<boost::mutex> 1> ] 1> <a path>\boost\v1_42_0\include\boost/smart_ptr/scoped_array.hpp(77): could be 'boost::unique_lock<Mutex> &boost::scoped_array<T>::operator [](ptrdiff_t) const' 1> with 1> [ 1> Mutex=boost::mutex, 1> T=boost::unique_lock<boost::mutex> 1> ] 1> or 'built-in C++ operator[(void (__cdecl *)(boost::scoped_array<T> ***), unsigned int)' 1> with 1> [ 1> T=boost::unique_lock<boost::mutex> 1> ] 1> while trying to match the argument list '(boost::scoped_array<T>, unsigned int)' 1> with 1> [ 1> T=boost::unique_lock<boost::mutex> 1> ] Does anyone have any idea what is causing this, and how I might go about resolving it? Sorry if this has ever been brought up, but I could not find anything about this issue in google searches or this mailing list. Thanks in Advance! -RD