`tuple_array_conversion` false positive on destructured tuple values

[MingweiSamuel]

Summary

The tuple_array_conversion seems to be way to zealous in detecting the original tuple identifiers, generating false positives even when the names are assigned through destructuring. These all trigger it even though it makes no sense to:

let (a, (_b, c)) = get_tuple_a();
let _ = [a, c];

let (a, [_b, c]) = get_tuple_b();
let _ = [a, c];

let (a, Wrap(b)) = get_tuple_c();
let _ = [a, b];

full code below

Lint Name

tuple_array_conversion

Reproducer

full code:

fn get_tuple_a() -> (usize, (usize, usize)) {
    (1, (2, 3))
}

fn get_tuple_b() -> (usize, [usize; 2]) {
    (1, [2, 3])
}

struct Wrap<T>(pub T);
fn get_tuple_c() -> (usize, Wrap<usize>) {
    (1, Wrap(2))
}

fn main() {
    let (a, (_b, c)) = get_tuple_a();
    let _ = [a, c];

    let (a, [_b, c]) = get_tuple_b();
    let _ = [a, c];
    
    let (a, Wrap(b)) = get_tuple_c();
    let _ = [a, b];
}

    Checking playground v0.0.1 (/playground)
warning: it looks like you're trying to convert a tuple to an array
  --> src/main.rs:16:13
   |
16 |     let _ = [a, c];
   |             ^^^^^^
   |
   = help: use `.into()` instead, or `<[T; N]>::from` if type annotations are needed
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#tuple_array_conversions
   = note: `#[warn(clippy::tuple_array_conversions)]` on by default

warning: it looks like you're trying to convert a tuple to an array
  --> src/main.rs:19:13
   |
19 |     let _ = [a, c];
   |             ^^^^^^
   |
   = help: use `.into()` instead, or `<[T; N]>::from` if type annotations are needed
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#tuple_array_conversions

warning: it looks like you're trying to convert a tuple to an array
  --> src/main.rs:22:13
   |
22 |     let _ = [a, b];
   |             ^^^^^^
   |
   = help: use `.into()` instead, or `<[T; N]>::from` if type annotations are needed
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#tuple_array_conversions

warning: `playground` (bin "playground") generated 3 warnings
    Finished dev [unoptimized + debuginfo] target(s) in 0.44s

playground: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=504c4f33d4880029600437ce2a068acf

Version

1.73.0-nightly
(2023-07-11 993deaa0bf8bab9dd3ea)

Additional Labels

No response

[Centri3]

This lint should probably be rewritten. Currently it checks if all items in the resulting array/tuple come from the same pattern, which is a tuple (which these do btw), rather than just the pattern's first parent.

[GoldsteinE]

A case I encountered:

use std::path::PathBuf;

fn main() {
    let v = std::env::var("TEST");
    let (a, b) = match &v {
        Ok(x) => ("a", &**x),
        Err(_) => ("b", "c"),
    };
    let _x = PathBuf::from_iter([a, b]);
    println!("{a}");
}

I don’t think replacing (a, b) with a single array makes sense in this case, since I use a afterwards.

[Centri3]

This is already mentioned in #11124