I think it's especially hasty to criticize Rust's string types in the context of C++, given the standardization of string_view in C++ as an analogue of Rust's &str :P
To me, Rust's &str seems a lot more like const char* (with a size tacked on for bounds checking). But you're the expert, so if I did agree they were the same, then C++ adopting it in the STL is practically proof it's a mistake in Rust.
You never addressed my other "too clever" items in Rust. Does that mean, other than strings, we agree?
