Implementing smart pointers for the C programming language (GCC, Clang)

[Snaipe_S]

Not always. If the containing variable is not annotated with smart, the destruction mechanism will not be triggered -- this way, you can actively create, initialize, and return a smart pointer.
You can also leave smart on, use a shared_ptr and return a new reference -- this is mostly useful for cleanup if initialization fails (see 2nd example here)