`clippy::never_loop` suggests

Summary

In some cases, clippy::never_loop suggests a replacement that would still trigger clippy::iter_skip_next.

Minimizing clippy feedback loops seems important to avoid user frustration. Therefore, it seems valuable to modify never_loop suggestions based on a check against iter_skip_next (and maybe other lints?), to ensure the modified snippet won't get rejected again.

Reproducer

I tried this code in the Rust playground and ran Clippy:

fn main() {
    for thing in [1, 2, 3].iter().skip(1) {
        panic!("oh noes, too many things");
    }
}

I expected to see this happen:

    Checking playground v0.0.1 (/playground)
warning: unused variable: `thing`
<snip>

error: this loop never actually loops
 --> src/main.rs:2:5
  |
2 | /     for thing in [1, 2, 3].iter().skip(1) {
3 | |         panic!("oh noes, too many things");
4 | |     }
  | |_____^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
  = note: `#[deny(clippy::never_loop)]` on by default
help: if you need the first element of the iterator, try writing
  |
2 |     if let Some(thing) = [1, 2, 3].iter().nth(1) {
  |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

warning: `playground` (bin "playground") generated 1 warning
error: could not compile `playground` (bin "playground") due to 1 previous error; 1 warning emitted

Instead, this happened:

    Checking playground v0.0.1 (/playground)
warning: unused variable: `thing`
<snip>

error: this loop never actually loops
 --> src/main.rs:2:5
  |
2 | /     for thing in [1, 2, 3].iter().skip(1) {
3 | |         panic!("oh noes, too many things");
4 | |     }
  | |_____^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
  = note: `#[deny(clippy::never_loop)]` on by default
help: if you need the first element of the iterator, try writing
  |
2 |     if let Some(thing) = [1, 2, 3].iter().skip(1).next() {
  |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

warning: `playground` (bin "playground") generated 1 warning
error: could not compile `playground` (bin "playground") due to 1 previous error; 1 warning emitted

Version

rustc 1.78.0 (9b00956e5 2024-04-29)
binary: rustc
commit-hash: 9b00956e56009bab2aa15d7bff10916599e3d6d6
commit-date: 2024-04-29
host: aarch64-apple-darwin
release: 1.78.0
LLVM version: 18.1.2

Additional Labels

@rustbot label +I-suggestion-causes-error +L-suggestion

rust-lang / rust-clippy