needless_pass_by_ref_mut: false positive with closures

[emilk]

Summary

needless_pass_by_ref_mut gives a false positive when the mutable reference is captured by a closure

Lint Name

needless_pass_by_ref_mut

Reproducer

I tried this code:

fn set_true(b: &mut bool) {
    *b = true;
}

fn true_setter(b: &mut bool) -> impl FnOnce() + '_ {
    move || set_true(b)
}

I saw this happen:

warning: this argument is a mutable reference, but not used mutably
   --> crates/egui_demo_lib/src/demo/toggle_switch.rs:116:19
    |
116 | fn true_setter(b: &mut bool) -> impl FnOnce() + '_ {
    |                   ^^^^^^^^^ help: consider changing to: `&bool`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut

I expected to see this happen: No warning

Version

rustc 1.73.0 (cc66ad468 2023-10-03)
binary: rustc
commit-hash: cc66ad468955717ab92600c770da8c1601a4ff33
commit-date: 2023-10-03
host: aarch64-apple-darwin
release: 1.73.0
LLVM version: 17.0.2

Additional Labels

No response

[GuillaumeGomez]

Taking a look.