The two are incomparable in both quality and quantity. The complexity of Rust comes from the fact that it's solving complex problems. The complexity of C++ comes from a poorly thought out design and backwards-compatibility. (Not to slight the standards committee; they are smart people, and did the best with what they had.)
Anothere way of putting it is, if you didn't care about backwards-compatibility, you could greatly simplify C++ without losing anything. You can't say the same about Rust; the complexity of Rust is high-entropy, C++'s is low-entropy.
As someone that really enjoys C++, I would say that the current issues are cause by lack of preview implementations before being voted into the standard, this is just broken, but there are not enough people around to be able to turn the ship around.
Those folks eventually move to something else and adopt "C++ the good parts" instead.
For C++, just take lambda captures, you can do [&], [=], [a], [&a], [a = b] (and I probably forgot half), the many way you can do initialization in C++ became a meme, but it really permeates the whole language whose design is driven by enthusiasts and people who have an interest to make it more complex (trainers, book authors, consultants, etc.)
For Rust, I think it is a bit of a different story and it is harder to point to specific features. The language is clearly much better designed (because it was more designed and did not evolve so much) and because of its roots in functional programming. Just overall, the complexity is too high in my opinion and it a bit too idealistic and not pragmatic enough.
> it a bit too idealistic and not pragmatic enough
This is an ideal programming language for certain types of people. It also gives the programming language certain properties that make it useful when provable correctness is a concern (see Ferrocene).
Sorry, I didn't mean provable correctness as in using formal methods, I meant it in terms of far stronger compiler guarantees about especially things such as memory safety. I also personally find Rust code far more pleasant to write and to reason about compared to C/C++ because of how well-defined and consistent it is.
The language is highly productive, it’s pragmatic enough. There’s no perfect language until our brains can directly describe what we want a machine to do without intermediary translation layers like C.
The question was mainly meant to elicit examples for Rust (I asked about C++ just to get a baseline of what the original commenter thinks "overengineered" means), but nobody seems to have any for Rust :)
Anothere way of putting it is, if you didn't care about backwards-compatibility, you could greatly simplify C++ without losing anything. You can't say the same about Rust; the complexity of Rust is high-entropy, C++'s is low-entropy.