"value assigned is never used" should point to value, not binding

[sanxiyn]

People are confused when warning points to binding, because it is often the case that while value assigned is never used, binding is used.

Suggestion found in users.rust-lang.org thread.

[birkenfeld]

Problem is, this is also the case here:

let (mut a, b) = tup;
a = 5;

Where should we point here?

[CryZe]

It should point to = tup;. Where else should it point to?

[CryZe]

Oh I guess parts of tup could be used, I guess it should just say that the a binding is bound to tup which the code never reads from before assigning another value. It could potentially also point to the reassignment.

[Mark-Simulacrum]

This has since been fixed.

fn main() {
    let mut a = 10;
    a = 15;
}

warning: variable `a` is assigned to, but never used
 --> test.rs:2:9
  |
2 |     let mut a = 10;
  |         ^^^^^
  |
  = note: #[warn(unused_variables)] on by default

warning: value assigned to `a` is never read
 --> test.rs:3:5
  |
3 |     a = 15;
  |     ^
  |
  = note: #[warn(unused_assignments)] on by default