[Boost-users] Odd Warning in transform_iterator.hpp ?

I'm using the current Boost library on Microsoft Visual Studio 2005. I'm getting a warning on line 121 of transform_iterator.hpp, complaining "returning address of local variable or temporary". The line in question is the body of this function: typename super_t::reference dereference() const { return m_f(*this->base()); } My m_f supplied to the template is ordinary enough; it returns a value. The exact same situation in a unit test gives no complaint! Any idea what this is all about?