[tialaramex]

You'd think right?

Except nope, it's an API design problem. If you write a std::vector or equivalent but where reserve has analogous behaviour to Vec::reserve you can't do Vec::reserve_exact at all and that can really hurt in other cases.

There really are two distinct features and C++ specifies a single API call.

[pjmlp]

Yes, it only matters that it fulfills the algorithm requirements described in ISO C++, how the implementation look like is another matter.

Still, this is going way down into the weeds and very far away that any mature AOT compiled language offers good enough speed, ignoring toy compilers done by students.