Before I get to the details, let me start by saying that I suspect that these warnings are probably spurious. But, before I go and start asking the compiler folks if they are bugs, I'd like to check here first. If you take unmodified boost-1.38.0 and try to use boost::optional with gcc-4.4.0 -Wall -O3, you seem to get warnings about strict-aliasing rules being broken. If boost::optional (and boost::function) are really broken, then we're probably in trouble :) test.cc: #include <boost/optional.hpp> boost::optional<int> x; int func() { return *x; } On x86_64-unknown-linux-gnu: $ /opt/gcc-4.4.0/bin/g++ -Wall -O3 -I. -c -o test.o test.cc test.cc: In function ‘int func()’: test.cc:5: warning: dereferencing pointer ‘<anonymous>’ does break strict-aliasing rules ./boost/optional/optional.hpp:594: note: initialized from here I have seen some similar issues with boost::bind and boost::function, but I haven't isolated them down to something this simple yet. I figured I'd start by asking about this. So, is it safe to presume that boost::optional is not really breaking the strict aliasing rules? (It's not immediately obvious.) If so, then I can ask the gcc folks about this. Thanks! -- ---------------------------------------------------------- Brad Spencer - spencer@starscale.com - www.starscale.com