Hi Peter, Luigi

with clang++ the line "using StochasticProcess::evolve;" does not work. I'm getting the following error message
../ql/experimental/processes/gemanroncoroniprocess.hpp:63:37: error: 'evolve' is a private member of
      'QuantLib::StochasticProcess1D'
        using  StochasticProcess1D::evolve;

Peter, the method StochasticProcess1D::evolve(...)  in line 240 of stochasticprocess.hpp is private, therefore IMO we can't overwrite evolve in the derived class.

What works for me is the following #pragma directive 
#ifdef __clang__
#pragma clang diagnostic ignored "-Woverloaded-virtual"
#endif

I've checked the code in. Shall we use this approach?