Hello, I had some code using boost 1.46.1 Multi-index library that used to compile and work very well with VS2008. I recently turned to VS2010 and some code is not compiling anymore. The problem is located in the boost_1_46_1\boost\multi_index\composite_key.hpp file and the compiler complains about not being able to distinguish between ambiguous overloads... I had to modify the composite_key.hpp file and have following changes : line 1001 : //return operator()(x,make_tuple(cref(y))); return operator()(x,make_tuple(boost::cref(y))); line 1036 : //return operator()(make_tuple(cref(x)),y); return operator()(make_tuple(boost::cref(x)),y); In order to explicitely add the boost namespace for cref. With those changes, it do compile and works very well. Can those changes in composite_key.hpp break something else ? Is there another workaround I would have missed ? I'm suspecting some conflict with new TR1 things i'm not very familiar with... Best regards, Mathieu Peyréga