Earlier quoted context omitted.
Rust is essentially C++ with auto-generated Move Constructors, and compiler errors on use-after-move, at the cost of preventing library developers from providing function overloads that eat temporaries as an optimization. So, yeah, really not a C replacement at all imo
I'm not super familiar with r-value references, but doesn't passing-by-value in Rust do essentially the same thing as that optimization does in C++?
But this is all a bit uglier at the call site, since either the library provides value-semantically-similar things with different names that either eat their arguments or copy-from-reference them, provides only the argument-eating version and relies on the caller to `clone` at their discretion, or provides only the referencing version and fails to elide copies.
In C++ you can provide a referencing version, and an argument-eating version with the same name that is called automatically when the user gives it a temporary or specifically requests it via `std::move`. Automatically eating temporaries is very nice in the case where the caller would like to compose a bunch of "create-new-from-a-set-of-references" operations in a single expression to create one new thing from an initial set of references.
The canonical example is eliding copies in stuff like
B*(A*x + b) + c