What is the order of function arguments evaluation and structs initialization in Rust?

Question

Is the order of function argument evaluation defined in Rust?

fn f(a: u64, b: u64, c: u64) {}
fn g() -> u64 { 0 }
fn h() -> u64 { 1 }
fn i() -> u64 { 2 }

fn main() {
    f(g(), h(), i());
}

Also, I am worried about the initialization order of structs:

fn f() {}
fn g() {}

A {
    a: f(),
    b: g(),
}

Is the order guaranteed to be a and then b?

For my particular use case, I am going to initialize a struct within a diesel transaction like that:

db_connection.transaction(||
    Ok(CompanyAndUser {
        company: companies::register_company(...)?, // performs diesel insert
        user: users::register_user(...)?, // performs diesel insert
    })
);

Obviously, I want these two diesel calls within a transaction to be ordered. I have not found any information about this, unfortunately. Also, I've found some more or less relevant info, but it was quite old.

Answer 1

The order used to be unspecified, but it's now left-to-right:

Many expressions contain sub-expressions, called the operands of the expression.

and:

The operands of these expressions are evaluated prior to applying the effects of the expression. Expressions taking multiple operands are evaluated left to right as written in the source code.