std::unique_ptr<S> *global;
     
     std::unique_ptr<S> S::make() {
         std::unique_ptr<S> origp = std::make_unique<S>();
         global = &origp;
         return origp;
     }
     
     void take_ownership(S *rawp) {
         delete rawp;
         *global = std::make_unique<S>();
     }

Why can't the compiler rule out that possibility? That looks like undefined behavior code to me, so thus the compiler could rule it out. S::make() is storing a pointer to a local variable (origp), and then that pointer is being accessed after S::make() has returned. I'm pretty sure that's undefined behavior.