To be fair, this sample of code includes macro usage (every function call that ends in an exclamation point is actually a macro). The syntax inside the macros is different from normal, legal rust syntax.

Still, I agree that Rust's syntax approaches C++ level of complexity at times. I find that writing actual statements and expressions is simple enough, but writing structs, lambdas, and function definitions requires knowing how to specify types, type bounds (if using generics), lifetimes (if using references), and Fully Qualified Syntax (for referencing types/items in other modules). And that's before actually having to come to terms with the borrow checker.

For what it's worth, once you get over the initial learning curve the cognitive burden goes down. Rust's syntax, to me, is actually visually distinctive enough that it's easy to parse out types, expressions, declarations, etc. from just a quick glance.