Is the valuation order taken into account when analyzing ownership in an expression?

Question

In Rust 1.0, does the compiler consider the evaluation order when analyzing ownership in an expression? For instance:

struct Foo { val:usize }

fn main() {
    let mut v:Vec<Foo> = Vec::with_capacity(1);
    v.push(Foo{val:0});

    let f = Foo{val:0};
    v[f.val] = f; // error: use of moved value
}

It could not be compiled because the index is in the array f.val, but fmoves to the array. I do not understand why using f.valas an index on LHS may contradict the transfer of ownership of f to RHS.

Answer 1

This type of thing is not defined at the language level, although obviously the compiler has to do something.

Answer 2

Clone Copy , , , ( ) .

#[derive(Clone, Copy)]
struct Foo { val: usize }

Copy, , :

let index = f.val; // usize is copyable, so no moves here
v[index] = f;

.