Reference match in completion away the clippy

When completing, it will auto dereference, just like:

pub fn bar(_: &str) { }
fn main() {
    let it = &"";
    bar($0); // complete `*it`
}

But clippy outputs:

warning: deref which would be done by auto-deref
 --> src/bin/main.rs:4:9
  |
4 |     bar(*it);
  |         ^^^ help: try: `it`

But if add condition !completion_without_ref.is_reference(),
the following example will report an error:

pub fn foo<'a>(s: &'a [&'a str]) -> impl Iterator<Item = &'a str> {
    s.iter().map(|it| {
        std::convert::identity(it) // instead of `*it`
    })
}

Compile error:

error[E0271]: expected `{closure@main.rs:2:18}` to return `&str`, but it returns `&&str`
 --> src/bin/main.rs:3:9
  |
1 |   pub fn foo<'a>(s: &'a [&'a str]) -> impl Iterator<Item = &'a str> {
  |                                       ----------------------------- closure used here
2 |       s.iter().map(|it| {
  |       -            ---- this closure
  |  _____|
  | |
3 | |         std::convert::identity(it) // instead of `*it`
  | |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&str`, found `&&str`
4 | |     })

Is it worth improving on this? How to improve?

No project file or test is named; start by reproducing the two Rust completion examples and compare the generated completion with clippy's auto-deref warning and the iterator type error. Done means the intended reference match is handled without reintroducing the failing iterator case, with regression coverage for both examples.