For Rust vs C++, I'd say it'll be much easier to have a complete understanding of Rust. C++ is an immensely complex language, with a lot of feature interactions.

C# is actually fairly complex. I'm not sure if it's quite at the same level as Rust, but I wouldn't say it's that far behind in difficulty for complete understanding.

Rust managed to learn a lot from C++ and other languages' mistakes.

So while it has quite a bit of essential complexity (inherent in the design space it operates: zero overhead low-level language with memory safety), I believe it fares overall better.

Like no matter the design, a language wouldn't need 10 different kinds of initializer syntaxes, yet C++ has at least that many.

I'm pretty convinced that nobody has a full picture of Rust in their head. There isn't even a spec to read.

There is, in fact, a spec to read[1], as of earlier this year.

[1] https://rustfoundation.org/media/ferrous-systems-donates-fer...

Rust is very advanced, with things like higher-ranked trait bounds (https://doc.rust-lang.org/nomicon/hrtb.html) and generic associated types (https://www.ncameron.org/rfcs/1598) that are difficult because they are essential complexity not accidental complexity.

For Rust I'd expect the implementation to be the real beast, versus the language itself. But not sure how it compares to C++ implementation complexity.

Rust isn’t that complicated if you have some background in non GC languages.

Parent say _all_ of it, not a subset for everyday use.

There's a different question too, that I think is more important (for any language): how much of the language do you need to know in order to use it effectively. As another poster mentioned, the issue with C++ might not be the breath of features, but rather how they interact in non-obvious ways.