On Thu, Dec 17, 2009 at 10:07 AM, Giovanni Piero Deretta <gpderetta@gmail.com> wrote:
... but the dynamic type of the internal buffer of boost::optional has been changed via placement new, so (modulo compiler bugs) it should be safe: at any time the buffer has a specific type (when initialized) or no type at all (it is just a bunch of memory). Boost optional only dereferences the buffer when it has been initialized, and always with the same type used for placement new. Of course this is hard (impossible?) to prove statically and gcc warns even if it should be perfectly safe .
We had a discussion about warnings some time ago, I think this is an excellent example of a warning that warns about something important yet it is completely useless. To someone who doesn't know the semantics of reinterpret_cast, perhaps the warning has some value, but for the rest of us what it really says is "Warning! You have used reinterpret_cast!" Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode