You get reserve, not reserve_exact. You are right that it would be allowed to implement reserve_exact semantics instead, given the method comment. But that’s no

You get reserve, not reserve_exact. You are right that it would be allowed to implement reserve_exact semantics instead, given the method comment. But that’s not how it works, if you want reserve_exact semantics, you need to take extra steps. That said, the semantics are not exactly the same as reserve. The go compiler may optimize since allocations (I don’t know if it does though).