needless_pass_by_ref_mut: false negative with fn and closures

[klensy]

Summary

No clippy warning for needless_pass_by_ref_mut when both wrapping fn and closure have mutable args.

Discovered while working on rust-lang/rust#123188

checked with clippy from playground 0.1.79 (2024-03-27 c9f8f34)
https://play.rust-lang.org/?version=nightly&mode=release&edition=2021&gist=047b73855da451dd617b8d43557b8d0d

Lint Name

needless_pass_by_ref_mut

Reproducer

I tried this code:

#![warn(clippy::needless_pass_by_ref_mut)]

fn main() {}

fn foo(n: &mut u8)->u8 {
    let x = |c: &mut u8| *c;
    x(n)
}

fn foo2(n: &mut u8)->u8 {
    let x = |c: &u8| *c;
    x(n)
}

fn foo3(n: &u8)->u8 {
    let x = |c: &u8| *c;
    x(n)
}

I expected to see this happen:
For foo should warn about unused &mut in fn args and closure. Probably should first warn about closure arg, because if closure fixed, it will successfully warn about fn args (as in foo2)

Instead, this happened:

No warn for foo

Version

No response