Comment by aw1621107

> However, do you have any bench / source for std::unique_ptr ? You are the first one I hear giving critics on it.

Chandler Carruth talks about this at CppCon 2019 [0]. From a quick review he says part of the reason std::unique_ptr isn't zero-cost right now is:

- Objects passed by value (like std::unique_ptr) are passed on the stack instead of in registers, and changing that will be an ABI break

- No destructive move means extra temporaries will be created/retained

[0]: https://youtu.be/rHIkrotSwcc?t=1046