Indexing tuple warning misleading

[gnzlbg]

The following rust snippet:

fn main() {
  let x = (0u32, 1u64, 2isize);
  for i in 0..3 {
      println!("{}\n", x[i]);
      // ERROR: to access tuple elements, 
      // use tuple indexing syntax (e.g. `tuple.0`)
      // println!("{}\n", x.i); // This doesn't obviously work
  }
}

produces a warning that recommends using .0 to index the tuple, but what it should recommend is to match on the index.

[estebank]

Current output:

error[E0608]: cannot index into a value of type `(u32, u64, isize)`
 --> src/main.rs:4:24
  |
4 |       println!("{}\n", x[i]);
  |                        ^^^^
  |
  = help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)

[hkBst]

@gnzlbg You said a suggestion should recommend match, so is this the program you had in mind:

fn main() {
    let x = (0u32, 1u64, 2isize);
    for i in 0..3 {
        match i {
            0 => println!("{}", x.0),
            1 => println!("{}", x.1),
            2 => println!("{}", x.2),
            _ => panic!(),
        }
        
    }
}

That works, but is just a complicated way of writing:

fn main() {
    let x = (0u32, 1u64, 2isize);
    println!("{}", x.0);
    println!("{}", x.1);
    println!("{}", x.2);
}

I suppose we could explain that tuple indices need to be constant, because in principle each tuple element can have a different type than all other elements...