Hi! The following code compiles fine with boost 1.34.1 (as it should) but fails to compile with 1.35.0 and the boost trunk (rev. 45896) #include "boost/archive/binary_iarchive.hpp" namespace detail { struct fu {}; } struct bar : detail::fu {}; Visual studio 2005 generates the following error message: 1>c:\dev\sandbox\using_scope_test\using_scope_test\test.cpp(7) : error C2872: 'detail' : ambiguous symbol 1> could be 'detail' 1> or 'boost::detail' It seems to me that the include file is some how leaking the boost namespace to it's surrounding? Explicitly qualifying the line: struct bar : ::detail::fu {}; works as expected. But I'm also allowed to write: struct bar : boost::detail::fu {}; which gives the error "'fu' : is not a member of 'boost::detail'" and not the expected "'boost' : is not a class or namespace name". Is this a known problem, and if so is there also a known patch? Best Regards, Anders Sundman