Chapter 3.2: Example "Invalid Array Element Access" is incorrect

[andreastedile]

Running the example's code doesn't produce the proposed result.
Because of this fact, the example's explanation is incorrect too.

Check related thread on r/learnrust.

[Bert-King]

Aha, I found out, too。
By the time I read this, I doubt it, because rust already knows a lot of information during compilation。

[Lonami]

Cross-posting from the above issue:

Rust got smarter constant evaluation since that was written it seems. The following doesn't fail to compile but errors at runtime:

fn get_index() -> usize {
    10
}

fn main() {
    let a = [1, 2, 3, 4, 5];
    let index = get_index();

    let element = a[index];

    println!("The value of element is: {}", element);
}

It does make the example a tiny bit worse, but showcases the point.

[Lonami]

Should this be closed given my comment #2446 (comment)?

[Amjad50]

Oh man, so sorry I didn't notice. I'll create a fix now. Thanks @Lonami

[tculp]

I just noticed that while cargo build now returns an error, cargo check doesn't. Is this just due caught in the final code generation step?