Because there's only a single function here, it has to either be Vec::reserve or Vec::reserve_exact If you don't offer Vec::reserve_exact then people who neede

Because there's only a single function here, it has to either be Vec::reserve or Vec::reserve_exact If you don't offer Vec::reserve_exact then people who needed that run out of RAM and will dub your stdlib garbage. If you don't offer Vec::reserve as we've seen C++ programmers will say "Skill issue" whenever a noob gets awful performance as a result. So, it's an easy choice.