Michael Stevens <Michael.Stevens@epost.de> writes:
Hi All, (particularly Jaakko!)
While working on using BLL's operator return type mechanism in uBLAS I stumbled on the problem the recent (snapshot) GCC-3.4 has with BLL.
I noticed Jaakoo checked in the following patch a few days ago as a workaround.
#if BOOST_WORKAROUND(__GNUC__, == 3) && __GNUC_MINOR__ >=4 #include <vector> #else namespace std { template <class T, class Allocator> class vector; } #endif
From my own research the problem is not just restricted to 'std::vector'. It certainly also occurs with 'std::map'.
I assume (have not verified) that the problem is related to hidden template parameters in the gcc-3.4 implementations of the std containers.
OR is the problem simply a bug (an regression) in gcc 3.4
An implementation is allowed to add hidden template parameters. The "workaround" is actually the only portably correct code; the forward declaration isn't guaranteed to work. In fact, I think it invokes undefined behavior. -- Dave Abrahams Boost Consulting www.boost-consulting.com