is there any specific case where pass-by-value is preferred over pass-by-const-reference in C++?

Question

I read that they are conceptually equal. In practice, is there any occasion that

foo(T t) 

is preferred over

foo(const T&         


        

Answer 1

Boost.CallTraits is a lesser-known but helpful facility for doing parameter and result passing with what should be the most efficient method available for the type in question.