The solution to the latest GotW problem is now available:

GotW #91 Solution: Smart Pointer Parameters (updated for C++11/14)

by Herb Sutter

From the article:

 

Guideline: Don’t pass a smart pointer as a function parameter unless you want to use or manipulate the smart pointer itself, such as to share or transfer ownership.

Guideline: Prefer passing objects by value, *, or &, not by smart pointer.

If you’re saying, “hey, aren’t raw pointers evil?”, that’s excellent, because we’ll address that next...