Take a `const shared_ptr<widget>&` parameter to express that it might retain a reference count to the object

This makes the function's ??? explicit.

void share(shared_ptr<widget>);            // share -- "will" retain refcount

void reseat(shared_ptr<widget>&);          // "might" reseat ptr

void may_share(const shared_ptr<widget>&); // "might" retain refcount

(Simple) Warn if a function takes a Shared_pointer<T> parameter by lvalue reference and does not either assign to it or call reset() on it on at least one code path. Suggest taking a T* or T& instead.
(Simple) ((Foundation)) Warn if a function takes a Shared_pointer<T> by value or by reference to const and does not copy or move it to another Shared_pointer on at least one code path. Suggest taking a T* or T& instead.
(Simple) ((Foundation)) Warn if a function takes a Shared_pointer<T> by rvalue reference. Suggesting taking it by value instead.

Resource management

R.36

This makes the function's ??? explicit.

void share(shared_ptr<widget>);            // share -- "will" retain refcount

void reseat(shared_ptr<widget>&);          // "might" reseat ptr

void may_share(const shared_ptr<widget>&); // "might" retain refcount

(Simple) Warn if a function takes a Shared_pointer<T> parameter by lvalue reference and does not either assign to it or call reset() on it on at least one code path. Suggest taking a T* or T& instead.
(Simple) ((Foundation)) Warn if a function takes a Shared_pointer<T> by value or by reference to const and does not copy or move it to another Shared_pointer on at least one code path. Suggest taking a T* or T& instead.
(Simple) ((Foundation)) Warn if a function takes a Shared_pointer<T> by rvalue reference. Suggesting taking it by value instead.