What should be made clear IMO is that there is no good reason to pass a smart pointer by reference.
If you refer to Herb Sutter, he recommends that you "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".
Consider that and knowing that sharing a smart pointer by reference doesn't share or transfer the ownership, we have no reasons to pass a SP by reference.
What should be made clear IMO is that there is no good reason to pass a smart pointer by reference.
If you refer to Herb Sutter, he recommends that you "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".
Consider that and knowing that sharing a smart pointer by reference doesn't share or transfer the ownership, we have no reasons to pass a SP by reference.
Some corresponding rules:
isocpp.github.io/CppCoreGuidelines...
isocpp.github.io/CppCoreGuidelines...